{"id":127,"date":"2022-04-17T12:55:47","date_gmt":"2022-04-17T12:55:47","guid":{"rendered":"http:\/\/www.devblog.cn\/?p=127"},"modified":"2025-03-03T17:54:58","modified_gmt":"2025-03-03T09:54:58","slug":"127","status":"publish","type":"post","link":"http:\/\/www.devblog.cn\/?p=127","title":{"rendered":"Android-Handler\u6e90\u7801\u89e3\u6790-Looper\uff08\u4e8c\uff09"},"content":{"rendered":"<h1>Android-Handler\u6e90\u7801\u89e3\u6790-Looper\uff08\u4e8c\uff09<\/h1>\n<blockquote><p>\n  \u6e90\u7801\u7248\u672c\uff1a<br \/>\n  * <strong>Handler<\/strong>\uff1aSDK-35<br \/>\n  * <strong>\u66f4\u65b0\u65f6\u95f4<\/strong>\uff1a2025-3\u6708<\/p>\n<p>  <strong>\u5bfc\u822a\uff1a<\/strong><\/p>\n<ul>\n<li><a href=\"https:\/\/juejin.cn\/post\/7475656733558652943\">Android-Handler\u6e90\u7801\u89e3\u6790-\u4f7f\u7528<\/a><\/li>\n<li><a href=\"https:\/\/juejin.cn\/post\/7085976728538972190\">Android-Handler\u6e90\u7801\u89e3\u6790-Handler\uff08\u4e00\uff09<\/a><\/li>\n<li><a href=\"https:\/\/juejin.cn\/post\/7085976341056585742\">Android-Handler\u6e90\u7801\u89e3\u6790-Looper\uff08\u4e8c\uff09<\/a><\/li>\n<li><a href=\"https:\/\/juejin.cn\/post\/7085977128092565512\">Android-Handler\u6e90\u7801\u89e3\u6790-MessageQueue\uff08\u4e09\uff09<\/a><\/li>\n<li><a href=\"https:\/\/juejin.cn\/post\/7085975951414132766\">Android-Handler\u6e90\u7801\u89e3\u6790-Message\uff08\u56db\uff09<\/a><\/li>\n<li>\u66f4\u591a\u7684\u6587\u7ae0\u770b\u8fd9\u91cc\uff1a<a href=\"https:\/\/juejin.cn\/user\/4450479132652679\/posts\">\u4e3b\u9875<\/a><\/li>\n<\/ul>\n<\/blockquote>\n<h2>\u6210\u5458\u53d8\u91cf<\/h2>\n<pre><code class=\"language-java\">\/\/ Log\u7684TAG\nprivate static final String TAG = \"Looper\";\n\n\/\/ \u7ebf\u7a0b\u672c\u5730\u53d8\u91cf\uff0c\u4fdd\u8bc1\u4e86\u6bcf\u4e2a\u7ebf\u7a0b\u4ec5\u6709\u552f\u4e00\u7684Looper\u5bf9\u8c61\u3002\n@UnsupportedAppUsage\nstatic final ThreadLocal&lt;Looper&gt; sThreadLocal = new ThreadLocal&lt;Looper&gt;();\n\/\/ \u4e3b\u7ebf\u7a0b\u7684Looper\uff0c\u7531ActivityThread\u7684main\u65b9\u6cd5\u5185\u8c03\u7528Looper.prepareMainLooper()\u8fdb\u884c\u521b\u5efa\u3002\n@UnsupportedAppUsage\nprivate static Looper sMainLooper;\n\/\/ \u6d88\u606f\u5206\u53d1\u72b6\u6001\u7684\u89c2\u5bdf\u8005\uff0c\u6709\u5206\u53d1\u5f00\u59cb\u3001\u5206\u53d1\u5f02\u5e38\u3001\u5206\u53d1\u7ed3\u675f\u3002\nprivate static Observer sObserver;\n\n\/\/ \u6d88\u606f\u961f\u5217\n@UnsupportedAppUsage\nfinal MessageQueue mQueue;\n\/\/ \u521b\u5efaLooper\u7684\u7ebf\u7a0b\nfinal Thread mThread;\n\/\/ \u662f\u5426\u5728loop\u4e2d\nprivate boolean mInLoop;\n\n\/\/ \u65e5\u5fd7\u6253\u5370\u7c7b\uff0c\u53ef\u4ee5\u6253\u5370loop\u65f6Message\u4fe1\u606f\u3002\n@UnsupportedAppUsage\nprivate Printer mLogging;\n\/\/ Trace\u8ffd\u8e2a\u6807\u8bb0\nprivate long mTraceTag;\n\n\/\/ \u6162\u5206\u53d1\u9608\u503c\u65f6\u95f4\uff0c\u5982\u679c\u8bbe\u7f6e\u4e86\u8fd9\u4e2a\u53c2\u6570\uff0c\u5982\u679c\u6d88\u606f\u5206\u53d1\u7684\u65f6\u95f4\u8d85\u8fc7\u8fd9\u4e2a\u503c\uff0c\u5219\u8fd9\u4e2alooper\u5c06\u663e\u793a\u4e00\u4e2a\u8b66\u544a\u65e5\u5fd7\u3002\nprivate long mSlowDispatchThresholdMs;\n\/\/ \u6162\u4ea4\u4ed8\u9608\u503c\u65f6\u95f4\uff0c\u5982\u679c\u8bbe\u7f6e\u4e86\u8fd9\u4e2a\u53c2\u6570\uff0c\u5982\u679c\u6d88\u606f\u6267\u884c(\u5b9e\u9645\u4ea4\u4ed8\u65f6\u523bdispatchStart - post\u65f6\u523bmsg.when)\u7684\u65f6\u95f4\u8d85\u8fc7\u8fd9\u4e2a\u503c\uff0c\u5219\u8fd9\u4e2alooper\u5c06\u663e\u793a\u4e00\u4e2a\u8b66\u544a\u65e5\u5fd7\u3002\nprivate long mSlowDeliveryThresholdMs;\n\/\/ \u662f\u5426\u6162\u4ea4\u4ed8\u68c0\u6d4b\uff0c\u5982\u679c\u6d88\u606f\u4ea4\u4ed8\u65f6\u95f4\u8d85\u8fc7mSlowDeliveryThresholdMs\uff0c\u5219\u4e3atrue\u3002\nprivate boolean mSlowDeliveryDetected;\n<\/code><\/pre>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. <code>MessageQueue<\/code>\u76f8\u5173\u4ecb\u7ecd\uff0c\u8bf7\u770b<a href=\"https:\/\/juejin.cn\/post\/7085977128092565512\">Android-Handler\u6e90\u7801\u89e3\u6790-MessageQueue<\/a>\u3002<br \/>\n  1. <code>Looper<\/code>\u4e3a\u4ec0\u4e48\u9700\u8981\u6301\u6709<code>MessageQueue<\/code>\uff0c\u56e0\u4e3a<code>Looper<\/code><strong>\u8f6e\u8be2<\/strong>\u7684\u65f6\u5019\u9700\u8981\u77e5\u9053\u8f6e\u8be2\u54ea\u4e2a<code>MessageQueue<\/code>\u3002\n<\/p><\/blockquote>\n<h2>\u521b\u5efaLooper<\/h2>\n<p>\u60f3\u8981<strong>\u4f7f\u7528<\/strong><code>Looper<\/code>\uff0c\u9996\u5148\u8981<strong>\u521b\u5efa<\/strong><code>Looper<\/code>\uff0c\u6240\u4ee5\u6211\u4eec\u63a5\u4e0b\u6765\u770b\u4e0b\u5b83\u662f\u5982\u4f55\u88ab<strong>\u521b\u5efa<\/strong>\u7684\u3002<\/p>\n<h3>Looper.prepare()<\/h3>\n<pre><code class=\"language-java\">public static void prepare() {\n    prepare(true);\n}\n\nprivate static void prepare(boolean quitAllowed) {\n    if (sThreadLocal.get() != null) {\n        \/\/ \u8c03\u7528\u7ebf\u7a0b\u5df2\u7ecf\u6709Looper\u4e86\uff0c\u518d\u8fdb\u884cprepare\uff0c\u5219\u629b\u51fa\u5f02\u5e38\uff08\u6bcf\u4e2a\u7ebf\u7a0b\u53ea\u80fd\u521b\u5efa\u4e00\u4e2aLooper\uff09\u3002\n        throw new RuntimeException(\"Only one Looper may be created per thread\");\n    }\n    \/\/ \u521b\u5efaLooper\uff0c\u5e76\u5b58\u5165\u5230sThreadLocal\u4e2d\u3002\n    sThreadLocal.set(new Looper(quitAllowed));\n}\n<\/code><\/pre>\n<p><code>prepare()<\/code>\u65b9\u6cd5\uff0c\u4e3a<strong>\u9759\u6001<\/strong>\u65b9\u6cd5\uff0c\u4e3a<strong>\u8c03\u7528\u7ebf\u7a0b<\/strong>\u521b\u5efa\u4e00\u4e2a<code>Looper<\/code>\u5e76<strong>\u5b58\u5165<\/strong>\u5230<code>sThreadLocal<\/code>\u4e2d\uff0c\u4ee5\u4fbf\u540e\u7eed<strong>\u83b7\u53d6\u6b64\u7ebf\u7a0b<\/strong>\u7684<code>Looper<\/code>\u3002<code>quitAllowed<\/code>\u53c2\u6570\u4f20\u5165\u4e3a<code>ture<\/code>\uff0c\u4ee5<strong>\u5141\u8bb8\u9000\u51fa<\/strong><code>Looper<\/code>\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. <strong>\u4e00\u4e2a\u7ebf\u7a0b<\/strong>\uff0c\u53ea\u80fd<strong>\u8c03\u7528\u4e00\u6b21<\/strong><code>prepare()<\/code>\u3001<code>prepare(boolean)<\/code>\u65b9\u6cd5\uff0c\u5426\u5219<strong>\u629b\u51fa\u5f02\u5e38<\/strong>\u3002<br \/>\n  2. <strong>\u4e00\u4e2a\u7ebf\u7a0b<\/strong>\uff0c\u53ea\u80fd<strong>\u6709\u4e00\u4e2a<\/strong><code>Looper<\/code>\u3002<br \/>\n  3. <code>prepare()<\/code>\u65b9\u6cd5\u521b\u5efa\u7684<code>Looper<\/code>\uff0c<strong>\u5141\u8bb8\u9000\u51fa<\/strong>\u3002\n<\/p><\/blockquote>\n<p>\u63a5\u4e0b\u6765\u6211\u4eec\u6765\u770b\u4e00\u4e0b<code>Looper<\/code><strong>\u6784\u9020\u65b9\u6cd5<\/strong>\u3002<\/p>\n<pre><code class=\"language-java\">private Looper(boolean quitAllowed) {\n    \/\/ \u521b\u5efa\u6d88\u606f\u961f\u5217\n    mQueue = new MessageQueue(quitAllowed);\n    \/\/ \u8bb0\u5f55\u521b\u5efa\u7ebf\u7a0b\n    mThread = Thread.currentThread();\n}\n<\/code><\/pre>\n<p><code>Looper<\/code><strong>\u6784\u9020\u65b9\u6cd5<\/strong>\uff0c\u4e3a<strong>\u79c1\u6709<\/strong>\u65b9\u6cd5\uff0c<strong>\u4e0d\u80fd<\/strong>\u901a\u8fc7<code>new<\/code>\u521b\u5efa\uff0c\u53c2\u6570<code>quitAllowed<\/code>\u4e3a<strong>\u662f\u5426\u5141\u8bb8\u9000\u51fa<\/strong>\uff0c\u521b\u5efa<code>Looper<\/code>\u4f1a\u521b\u5efa\u4e00\u4e2a<code>MessageQueue<\/code>\uff0c\u5e76\u8bb0\u5f55<strong>\u521b\u5efa\u7ebf\u7a0b<\/strong>\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. <strong>\u4e00\u4e2a<\/strong><code>Looper<\/code>\uff0c<strong>\u53ea\u6709\u4e00\u4e2a<\/strong><code>MessageQueue<\/code>\uff0c<strong>\u53ea\u6709\u4e00\u4e2a\u5173\u8054<\/strong><code>Thread<\/code>\u3002<br \/>\n  2. <code>MessageQueue<\/code>\u521b\u5efa\u7684\u76f8\u5173\u4ecb\u7ecd\uff0c\u8bf7\u770b<a href=\"https:\/\/juejin.cn\/post\/7085977128092565512\/#heading-2\">Android-Handler\u6e90\u7801\u89e3\u6790-MessageQueue-\u521b\u5efaMessageQueue<\/a>\u3002\n<\/p><\/blockquote>\n<h3>Looper.prepareMainLooper()<\/h3>\n<pre><code class=\"language-java\">@Deprecated\npublic static void prepareMainLooper() {\n    \/\/ \u51c6\u5907Looper\uff0c\u5982\u6ca1\u6709\u5219\u8fdb\u884c\u521b\u5efa\uff0c\u4e0d\u5141\u8bb8\u9000\u51fa\u3002\n    prepare(false);\n    \/\/ \u540c\u6b65\uff0c\u4fdd\u8bc1\u7ebf\u7a0b\u5b89\u5168\u3002\n    synchronized (Looper.class) {\n        if (sMainLooper != null) {\n            \/\/ \u5df2\u7ecf\u521b\u5efaMainLooper\u4e86\uff0c\u518d\u51c6\u5907\uff0c\u5219\u629b\u51fa\u5f02\u5e38\u3002\n            throw new IllegalStateException(\"The main Looper has already been prepared.\");\n        }\n        \/\/ \u83b7\u53d6\u8c03\u7528\u7ebf\u7a0b\u7684Looper\uff0c\u4e3aMainLooper\u3002\n        sMainLooper = myLooper();\n    }\n}\n<\/code><\/pre>\n<p><code>prepareMainLooper()<\/code>\u65b9\u6cd5\uff0c\u4e3a<strong>\u9759\u6001<\/strong>\u65b9\u6cd5\uff0c\u4e3a<strong>\u4e3b\u7ebf\u7a0b<\/strong>\u51c6\u5907<code>Looper<\/code>\uff0c\u5e76\u4f20\u5165<code>quitAllowed<\/code>\u4e3a<code>false<\/code>\u4f7f\u5176<strong>\u4e0d\u5141\u8bb8\u9000\u51fa<\/strong>\uff0c\u5e76\u5c06\u5176<strong>\u6807\u8bb0<\/strong>\u4e3a<code>app<\/code>\u7684<strong>\u4e3b<\/strong><code>looper<\/code>\u3002<code>myLooper()<\/code>\u76f8\u5173\u4ecb\u7ecd\uff0c\u770b\u540e\u9762\u7684-<code>\u83b7\u53d6Looper<\/code>\u3002<\/p>\n<p><strong>\u5df2\u88ab\u58f0\u660e<\/strong>\u4e3a<code>@Deprecated<\/code>\uff08\u5f03\u7528\uff09\uff0c\u56e0\u4e3a<code>app<\/code>\u7684<strong>\u4e3b\u7ebf\u7a0b<\/strong><code>looper<\/code>\u662f\u7531<code>Android<\/code>\u7cfb\u7edf<strong>\u521b\u5efa<\/strong>\u7684\uff08<code>ActivityThread<\/code>\u7684<code>main<\/code>\u65b9\u6cd5\u5185\u8c03\u7528<code>Looper.prepareMainLooper()<\/code>\u521b\u5efa\uff09\uff0c\u56e0\u6b64\u6c38\u8fdc<strong>\u4e0d\u9700\u8981<\/strong>\u81ea\u5df1<strong>\u8c03\u7528<\/strong>\u8fd9\u4e2a\u51fd\u6570\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. <strong>\u591a\u4e2a\u7ebf\u7a0b<\/strong>\u53ea\u80fd<strong>\u8c03\u7528\u4e00\u6b21<\/strong><code>prepareMainLooper()<\/code>\u65b9\u6cd5\uff0c\u5426\u5219\u629b\u51fa\u5f02\u5e38\u3002<br \/>\n  2. <strong>\u4e3b\u7ebf\u7a0b<\/strong><code>Looper<\/code>\uff0c\u662f\u7531<code>Android<\/code>\u7cfb\u7edf<strong>\u521b\u5efa<\/strong>\u7684\uff08<code>ActivityThread<\/code>\u7684<code>main<\/code>\u65b9\u6cd5\uff09\uff0c\u4e0d\u9700\u8981\u6211\u4eec\u5173\u5fc3\u3002<br \/>\n  3. <strong>\u4e3b\u7ebf\u7a0b<\/strong><code>Looper<\/code>\uff0c<strong>\u4e0d\u5141\u8bb8\u9000\u51fa<\/strong>\u3002\n<\/p><\/blockquote>\n<h3>\u5c0f\u7ed3<\/h3>\n<blockquote>\n<ol>\n<li><strong>\u521b\u5efa<\/strong>&#8211;<strong>\u975e\u4e3b\u7ebf\u7a0b<\/strong><code>Looper<\/code>\uff0c<strong>\u53ea\u80fd<\/strong>\u901a\u8fc7<code>Looper.prepare()<\/code>\u65b9\u6cd5<strong>\u521b\u5efa<\/strong>\uff0c\u5b83\u662f<strong>\u5141\u8bb8\u9000\u51fa<\/strong>\u7684\u3002<\/li>\n<li><strong>\u521b\u5efa<\/strong>&#8211;<strong>\u4e3b\u7ebf\u7a0b<\/strong><code>Looper<\/code>\uff0c\u5b83\u662f\u901a\u8fc7<code>Android<\/code>\u7cfb\u7edf<strong>\u521b\u5efa<\/strong>\uff08<code>ActivityThread<\/code>\u7684<code>main<\/code>\u65b9\u6cd5\u5185\u8c03\u7528<code>Looper.prepareMainLooper()<\/code>\u521b\u5efa\uff09\uff0c\u5b83\u662f<strong>\u4e0d\u5141\u8bb8\u9000\u51fa<\/strong>\u7684\u3002<\/li>\n<li><strong>\u5bf9\u5e94\u5173\u7cfb<\/strong>\uff1a\u4e00\u4e2a<strong>\u7ebf\u7a0b<\/strong>\u5bf9\u5e94\u4e00\u4e2a<code>Looper<\/code>\uff0c\u4e00\u4e2a<code>Looper<\/code>\u5bf9\u5e94\u4e00\u4e2a<code>MessageQueue<\/code>\u3002<\/li>\n<li><strong>\u603b\u5bf9\u5e94\u5173\u7cfb<\/strong>\uff1a\n<ol>\n<li>\u4ece<code>Looper<\/code>\u6e90\u7801\u5f97\u77e5\uff0c\u4e00\u4e2a<strong>\u7ebf\u7a0b<\/strong>\u5bf9\u5e94\u4e00\u4e2a<code>Looper<\/code>\uff0c\u4e00\u4e2a<code>Looper<\/code>\u5bf9\u5e94\u4e00\u4e2a<code>MessageQueue<\/code>\u3002<\/li>\n<li>\u4ece<code>MessageQueue<\/code>\u6e90\u7801\u5f97\u77e5\uff0c\u4e00\u4e2a<code>MessageQueue<\/code>\u5bf9\u5e94\u591a\u4e2a<code>Message<\/code>\u3002<\/li>\n<li>\u4ece<code>Message<\/code>\u6e90\u7801\u5f97\u77e5\uff0c\u4e00\u4e2a<code>Message<\/code>\u5bf9\u5e94\u4e00\u4e2a<code>Handler<\/code>\u3002<\/li>\n<li>\u4ece<code>Handler<\/code>\u6e90\u7801\u5f97\u77e5\uff0c\u591a\u4e2a<code>Message<\/code>\u53ef\u4ee5\u5171\u7528\u4e00\u4e2a<code>Handler<\/code>\u3002<\/li>\n<li>\u603b\u7ed3\uff1a\u4e00\u4e2a<strong>\u7ebf\u7a0b<\/strong>\u5bf9\u5e94\u4e00\u4e2a<code>Looper<\/code>\uff0c\u4e00\u4e2a<code>Looper<\/code>\u5bf9\u5e94\u4e00\u4e2a<code>MessageQueue<\/code>\uff0c\u4e00\u4e2a<code>MessageQueue<\/code>\u5bf9\u5e94\u591a\u4e2a<code>Message<\/code>\uff0c\u4e00\u4e2a<code>Message<\/code>\u5bf9\u5e94\u4e00\u4e2a<code>Handler<\/code>\uff0c\u4f46\u591a\u4e2a<code>Message<\/code>\u53ef\u4ee5\u5171\u7528\u4e00\u4e2a<code>Handler<\/code>\u3002<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n<\/blockquote>\n<h2>\u83b7\u53d6Looper<\/h2>\n<p><strong>\u521b\u5efa\u5b8c<\/strong><code>Looper<\/code>\u540e\uff0c\u4fbf\u53ef\u4ee5<strong>\u83b7\u53d6<\/strong><code>Looper<\/code><strong>\u4f7f\u7528<\/strong>\u4e86\uff0c\u6240\u4ee5\u6211\u4eec\u63a5\u4e0b\u6765\u770b\u4e0b\u5b83\u662f\u5982\u4f55\u88ab<strong>\u521b\u5efa<\/strong>\u7684\u3002<\/p>\n<h3>Looper.myLooper()<\/h3>\n<pre><code class=\"language-java\">public static @Nullable Looper myLooper() {\n    return sThreadLocal.get();\n}\n<\/code><\/pre>\n<p><code>myLooper()<\/code>\u65b9\u6cd5\uff0c\u4e3a<strong>\u9759\u6001<\/strong>\u65b9\u6cd5\uff0c\u8fd4\u56de\u4e0e<strong>\u5f53\u524d\u7ebf\u7a0b<\/strong>\u5173\u8054\u7684<code>Looper<\/code>\u5bf9\u8c61\u3002\u5982\u679c<strong>\u8c03\u7528\u7ebf\u7a0b\u6ca1\u6709<\/strong>\u4e0e<code>Looper<\/code>\u5173\u8054\uff0c\u5219\u8fd4\u56de<code>null<\/code>\u3002<\/p>\n<h3>Looper.getMainLooper()<\/h3>\n<pre><code class=\"language-java\">public static Looper getMainLooper() {\n    synchronized (Looper.class) {\n        return sMainLooper;\n    }\n}\n<\/code><\/pre>\n<p><code>getMainLooper()<\/code>\u65b9\u6cd5\uff0c\u4e3a<strong>\u9759\u6001<\/strong>\u65b9\u6cd5\uff0c\u8fd4\u56de<strong>\u4e3b\u7ebf\u7a0b<\/strong><code>Looper<\/code>\u5bf9\u8c61\u3002<\/p>\n<h3>\u5c0f\u7ed3<\/h3>\n<blockquote>\n<ol>\n<li><strong>\u83b7\u53d6<\/strong><code>Looper<\/code>\uff0c\u6709\u4e24\u4e2a\u65b9\u6cd5\uff1a<code>Looper.myLooper()<\/code>\u3001<code>Looper.getMainLooper()<\/code>\u3002<\/li>\n<li><code>Looper.myLooper()<\/code>\u65b9\u6cd5\uff0c\u83b7\u53d6<strong>\u8c03\u7528\u7ebf\u7a0b<\/strong>\u7684<code>Looper<\/code>\uff0c\u6709\u53ef\u80fd\u4e3a<code>null<\/code>\u3002<\/li>\n<li><code>Looper.getMainLooper()<\/code>\u65b9\u6cd5\uff0c\u83b7\u53d6<strong>\u4e3b\u7ebf\u7a0b<\/strong>\u7684<code>Looper<\/code>\uff0c\u4e0d\u4f1a\u4e3a<code>null<\/code>\u3002<\/li>\n<\/ol>\n<\/blockquote>\n<h2>\u8f6e\u8be2Looper<\/h2>\n<p>\u5f53<code>Looper<\/code>\u521b\u5efa\u597d\u540e\uff0c\u9700\u8981\u8c03\u7528<code>Looper.loop()<\/code>\u65b9\u6cd5\uff0c\u4f7f\u5176\u8fdb\u5165<strong>\u6d88\u606f\u5faa\u73af<\/strong>\u4e2d\uff0c\u6240\u4ee5\u6211\u4eec\u63a5\u4e0b\u6765\u770b\u4e0b\u5b83\u7684<code>Looper.loop()<\/code>\u65b9\u6cd5\u3002<\/p>\n<h3>Looper.loop()<\/h3>\n<pre><code class=\"language-java\">public static void loop() {\n    \/\/ \u83b7\u53d6\u5f53\u524d\u7ebf\u7a0bLooper\u5bf9\u8c61\n    final Looper me = myLooper();\n    if (me == null) {\n        \/\/ Looper\u5bf9\u8c61\u4e3a\u7a7a\uff0c\u629b\u51fa\u5f02\u5e38\uff08\u6ca1\u6709Looper; \u8fd9\u4e2a\u7ebf\u7a0b\u4e0a\u6ca1\u6709\u8c03\u7528Looper.prepare()\uff09\u3002\n        throw new RuntimeException(\"No Looper; Looper.prepare() wasn't called on this thread.\");\n    }\n    if (me.mInLoop) {\n        \/\/ \u5df2\u7ecf\u5728loop\u4e2d\uff0c\u518d\u8c03\u7528loop()\uff0c\u5219\u63d0\u793a\u8b66\u544a\uff08\u518d\u6b21loop\u5c06\u4f7f\u961f\u5217\u4e2d\u7684\u6d88\u606f\u5728\u6b64\u6d88\u606f\u5b8c\u6210\u4e4b\u524d\u88ab\u6267\u884c\uff09\u3002\n        Slog.w(TAG, \"Loop again would have the queued messages be executed\"\n                + \" before this one completed.\");\n    }\n    \/\/ \u6807\u8bb0\u5728loop\u4e2d\n    me.mInLoop = true;\n\n    \/\/ \u786e\u4fdd\u8fd9\u4e2a\u7ebf\u7a0b\u7684\u6807\u8bc6\u662f\u672c\u5730\u8fdb\u7a0b\u7684\u6807\u8bc6\uff0c\u5e76\u8ddf\u8e2a\u6807\u8bc6token\u5b9e\u9645\u4e0a\u662f\u4ec0\u4e48\u3002\n    Binder.clearCallingIdentity();\n    final long ident = Binder.clearCallingIdentity();\n\n    \/\/ \u5141\u8bb8\u7528\u7cfb\u7edf\u9053\u5177\uff08adb\u547d\u4ee4\uff09\u8986\u76d6\u4e00\u4e2a\u9608\u503c\uff0c\u4f8b\u5982\uff1a\n    \/\/ adb shell 'setprop log.looper.1000.main.slow 1 &amp;&amp; stop &amp;&amp; start'\n    final int thresholdOverride = getThresholdOverride();\n\n    \/\/ \u6162\u4ea4\u4ed8\u68c0\u6d4b\uff0c\u6062\u590d\u9ed8\u8ba4\u503c\u3002\n    me.mSlowDeliveryDetected = false;\n\n    \/\/ \u6b7b\u5faa\u73af\uff0c\u904d\u5386\u6d88\u606f\u961f\u5217\u91cc\u7684\u6d88\u606f\u3002\n    for (;;) {\n        \/\/ \u8c03\u7528loopOnce\u65b9\u6cd5\uff0c\u8fdb\u884c\u5904\u7406\u3002\n        if (!loopOnce(me, ident, thresholdOverride)) {\n            \/\/ loopOnce\u65b9\u6cd5\u8fd4\u56defalse\uff0c\u9000\u51fa\u5faa\u73af\uff0c\u7ed3\u675floop\u3002\n            return;\n        }\n    }\n}\n<\/code><\/pre>\n<pre><code class=\"language-java\">private static int getThresholdOverride() {\n    return SystemProperties.getInt(\"log.looper.\"\n            + Process.myUid() + \".\"\n            + Thread.currentThread().getName()\n            + \".slow\", -1);\n}\n<\/code><\/pre>\n<p><code>loop()<\/code>\u65b9\u6cd5\uff0c\u4e3a<strong>\u9759\u6001<\/strong>\u65b9\u6cd5\uff0c\u901a\u8fc7<code>myLooper()<\/code>\u83b7\u53d6\u5f53\u524d\u7ebf\u7a0b<code>Looper<\/code>\u5bf9\u8c61\uff0c\u8fdb\u884c<strong>\u6b7b\u5faa\u73af\u8f6e\u8be2<\/strong>\uff0c\u8c03\u7528<code>loopOnce()<\/code>\u65b9\u6cd5<strong>\u8f6e\u8be2\u5355\u4e2a\u6d88\u606f<\/strong>\u3002<code>loopOnce()<\/code>\u65b9\u6cd5\u8fd4\u56de<code>true<\/code>\uff0c\u5219\u7ee7\u7eed<strong>\u8f6e\u8be2\u4e0b\u4e00\u4e2a\u6d88\u606f<\/strong>\uff1b<strong>\u8fd4\u56de<\/strong><code>false<\/code>\uff0c\u5219<strong>\u9000\u51fa\u5faa\u73af<\/strong>\uff0c<strong>\u7ed3\u675f<\/strong><code>loop<\/code>\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. <strong>\u5f53\u524d\u7ebf\u7a0b<\/strong>\u8c03\u7528<code>Looper.loop()<\/code>\u65b9\u6cd5\u524d\uff0c<strong>\u4e00\u5b9a<\/strong>\u8981\u4e3a<strong>\u5f53\u524d\u7ebf\u7a0b<\/strong>\u51c6\u5907<code>Looper<\/code>\uff08\u8c03\u7528<code>Looper.prepare()<\/code>\uff09\uff0c\u5426\u5219<strong>\u629b\u51fa\u5f02\u5e38<\/strong>\u3002\n<\/p><\/blockquote>\n<p>\u63a5\u4e0b\u6765\uff0c\u6211\u4eec\u6765\u770b\u4e00\u4e0b<code>loopOnce()<\/code>\u65b9\u6cd5\u3002<\/p>\n<pre><code class=\"language-java\">private static boolean loopOnce(final Looper me,\n        final long ident, final int thresholdOverride) {\n    \/\/ \u83b7\u53d6\u6b64Looper\u7684\u6d88\u606f\u961f\u5217\u91cc\u9762\u7684\u4e0b\u4e2a\u6d88\u606f\uff0c\u6709\u53ef\u80fd\u4f1a\u963b\u585e\u7ebf\u7a0b\u3002\n    Message msg = me.mQueue.next();\n    if (msg == null) {\n        \/\/ \u6ca1\u6709\u6d88\u606f\uff0c\u8868\u793a\u6d88\u606f\u961f\u5217\u6b63\u5728\u9000\u51fa\uff08\u8c03\u7528quit()\u65b9\u6cd5\uff09\uff0c\u76f4\u63a5\u8fd4\u56defalse\u4ee5\u9000\u51faloop\u3002\u4eceMessageQueue\u83b7\u53d6\u6d88\u606f\uff0c\u8be6\u7ec6\u8bf7\u770bMessageQueue\u6e90\u7801\u3002\n        return false;\n    }\n\n    \/\/ \u83b7\u53d6\u65e5\u5fd7\u6253\u5370\u7c7b\uff0c\u8fd9\u5fc5\u987b\u5728\u4e00\u4e2a\u5c40\u90e8\u53d8\u91cf\u4e2d\uff0c\u4ee5\u9632UI\u4e8b\u4ef6\u8bbe\u7f6elogger\u3002\n    final Printer logging = me.mLogging;\n    if (logging != null) {\n        \/\/ \u6253\u5370\u65e5\u5fd7\uff1aDispatching\uff08\u5206\u53d1\u4e2d\uff09\n        logging.println(\"&gt;&gt;&gt;&gt;&gt; Dispatching to \" + msg.target + \" \"\n                + msg.callback + \": \" + msg.what);\n    }\n\n    \/\/ \u83b7\u53d6Looper\u7684\u5168\u5c40\u89c2\u5bdf\u8005\uff0c\u4f7f\u7528\u53d8\u91cf\uff0c\u786e\u4fdd\u89c2\u5bdf\u8005\u5728\u5904\u7406\u4e8b\u52a1\u65f6\u4e0d\u4f1a\u66f4\u6539\u3002\u6b64sObserver\u89c2\u5bdf\u8005\uff0c\u53ef\u901a\u8fc7hide\u65b9\u6cd5setObserver(Observer)\u8bbe\u7f6e\u3002\n    final Observer observer = sObserver;\n\n    \/\/ \u83b7\u53d6\u8ffd\u8e2a\u6807\u8bb0\n    final long traceTag = me.mTraceTag;\n    \/\/ \u83b7\u53d6\u6d88\u606f\u5206\u53d1\u9608\u503c\n    long slowDispatchThresholdMs = me.mSlowDispatchThresholdMs;\n    \/\/ \u83b7\u53d6\u6d88\u606f\u4ea4\u4ed8\u9608\u503c\n    long slowDeliveryThresholdMs = me.mSlowDeliveryThresholdMs;\n\n    final boolean hasOverride = thresholdOverride &gt;= 0;\n    if (hasOverride) {\n        \/\/ \u6709\u8986\u76d6\u7684\uff08adb\u547d\u4ee4\u4f20\u5165\uff09\uff0c\u5219\u7528\u8986\u76d6\u7684\u503c\u3002\n        slowDispatchThresholdMs = thresholdOverride;\n        slowDeliveryThresholdMs = thresholdOverride;\n    }\n    \/\/ \u662f\u5426\u8bb0\u5f55\u6162\u4ea4\u4ed8\n    final boolean logSlowDelivery = (slowDeliveryThresholdMs &gt; 0 || hasOverride)\n        &amp;&amp; (msg.when &gt; 0);\n    \/\/ \u662f\u5426\u8bb0\u5f55\u6162\u5206\u53d1\n    final boolean logSlowDispatch = (slowDispatchThresholdMs &gt; 0 || hasOverride);\n\n    \/\/ \u662f\u5426\u9700\u8981\u83b7\u53d6\u5f00\u59cb\u65f6\u523b\n    final boolean needStartTime = logSlowDelivery || logSlowDispatch;\n    \/\/ \u662f\u5426\u9700\u8981\u83b7\u53d6\u7ed3\u675f\u65f6\u523b\n    final boolean needEndTime = logSlowDispatch;\n\n    if (traceTag != 0 &amp;&amp; Trace.isTagEnabled(traceTag)) {\n        \/\/ \u5f00\u59cb\u8ffd\u8e2a\n        Trace.traceBegin(traceTag, msg.target.getTraceName(msg));\n    }\n\n    \/\/ \u5206\u53d1\u5f00\u59cb\u65f6\u523b\n    final long dispatchStart = needStartTime ? SystemClock.uptimeMillis() : 0;\n    \/\/ \u5206\u53d1\u7ed3\u675f\u65f6\u523b\n    final long dispatchEnd;\n    \/\/ token\u6807\u8bc6\uff0c\u7528\u4e8eObserver\u56de\u8c03\u95f4\u4f20\u9012\u3002\n    Object token = null;\n    if (observer != null) {\n        \/\/ \u83b7\u53d6token\uff0c\u901a\u77e5Observer\u6d88\u606f\u5206\u53d1\u5f00\u59cb\u3002\n        token = observer.messageDispatchStarting();\n    }\n    \/\/ \u8bbe\u7f6e\u5f53\u524d\u7ebf\u7a0b\u7684Uid\n    long origWorkSource = ThreadLocalWorkSource.setUid(msg.workSourceUid);\n    try {\n        \/\/ \u901a\u77e5Message\u7684Handler\u8fdb\u884c\u5206\u53d1\u6d88\u606f\uff08\u91cd\u8981\uff01\uff01\uff01\uff09\n        msg.target.dispatchMessage(msg);\n        if (observer != null) {\n            \/\/ \u901a\u77e5Observer\u6d88\u606f\u5206\u53d1\u7ed3\u675f\n            observer.messageDispatched(token, msg);\n        }\n        \/\/ \u8bb0\u5f55\u5206\u53d1\u7ed3\u675f\u65f6\u523b\n        dispatchEnd = needEndTime ? SystemClock.uptimeMillis() : 0;\n    } catch (Exception exception) {\n        if (observer != null) {\n              \/\/ \u901a\u77e5Observer\u6d88\u606f\u5206\u53d1\u5f02\u5e38\n            observer.dispatchingThrewException(token, msg, exception);\n        }\n        throw exception;\n    } finally {\n        \/\/ \u6062\u590d\u5f53\u524d\u7ebf\u7a0b\u7684Uid\n        ThreadLocalWorkSource.restore(origWorkSource);\n        if (traceTag != 0) {\n            \/\/ \u7ed3\u675f\u8ffd\u8e2a\n            Trace.traceEnd(traceTag);\n        }\n    }\n    if (logSlowDelivery) {\n        \/\/ \u8bb0\u5f55\u6162\u4ea4\u4ed8\uff0c\u5982\u679c\uff08dispatchStart - msg.when\uff09\u65f6\u95f4\u5927\u4e8e\u9608\u503c\uff0c\u5219\u8fdb\u884cSlog\u63d0\u793a\u8b66\u544a\u3002\n        if (me.mSlowDeliveryDetected) {\n            if ((dispatchStart - msg.when) &lt;= 10) {\n                Slog.w(TAG, \"Drained\");\n                me.mSlowDeliveryDetected = false;\n            }\n        } else {\n            if (showSlowLog(slowDeliveryThresholdMs, msg.when, dispatchStart, \"delivery\",\n                    msg)) {\n                me.mSlowDeliveryDetected = true;\n            }\n        }\n    }\n    if (logSlowDispatch) {\n        \/\/ \u8bb0\u5f55\u6162\u5206\u53d1\uff0c\u5982\u679c\uff08dispatchEnd - dispatchStart\uff09\u65f6\u95f4\u5927\u4e8e\u9608\u503c\uff0c\u5219\u8fdb\u884cSlog\u63d0\u793a\u8b66\u544a\u3002\n        showSlowLog(slowDispatchThresholdMs, dispatchStart, dispatchEnd, \"dispatch\", msg);\n    }\n\n    if (logging != null) {\n          \/\/ \u6253\u5370\u65e5\u5fd7\uff1aFinished\uff08\u5df2\u5b8c\u6210\uff09\n        logging.println(\"&lt;&lt;&lt;&lt;&lt; Finished to \" + msg.target + \" \" + msg.callback);\n    }\n\n    \/\/ \u786e\u4fdd\u5728\u5206\u53d1\u8fc7\u7a0b\u4e2d\u7ebf\u7a0b\u7684\u6807\u8bc6\u6ca1\u6709\u635f\u574f\u3002\n    final long newIdent = Binder.clearCallingIdentity();\n    if (ident != newIdent) {\n        \/\/ \u5df2\u635f\u574f\uff0c\u63d0\u793a\u3002\n        Log.wtf(TAG, \"Thread identity changed from 0x\"\n                + Long.toHexString(ident) + \" to 0x\"\n                + Long.toHexString(newIdent) + \" while dispatching to \"\n                + msg.target.getClass().getName() + \" \"\n                + msg.callback + \" what=\" + msg.what);\n    }\n    \/\/ \u56de\u6536\u6d88\u606f\uff08\u4e0d\u68c0\u67e5\uff0c\u76f4\u63a5\u56de\u6536\uff09\n    msg.recycleUnchecked();\n\n    return true;\n}\n<\/code><\/pre>\n<p><code>loopOnce()<\/code>\u65b9\u6cd5\uff0c\u4e3a<strong>\u9759\u6001<\/strong>\u65b9\u6cd5\uff0c\u4e3a<strong>\u8f6e\u8be2\u5355\u4e2a\u6d88\u606f<\/strong>\u3002\u5b83\u4f1a\u5148\u83b7\u53d6<strong>\u6d88\u606f\u961f\u5217<\/strong>\u7684<strong>\u4e0b\u4e2a<\/strong><code>Message<\/code>\uff0c\u7136\u540e\u8c03\u7528<code>Message<\/code>\u7684<code>target<\/code><strong>\u76ee\u6807<\/strong><code>Handler<\/code>\u8fdb\u884c<strong>\u5206\u53d1\u6d88\u606f<\/strong>\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. \u5f53<code>Looper<\/code>\u7684<code>MessageQueue<\/code>\u91cc\u9762<strong>\u6ca1\u6709<\/strong>\u6d88\u606f\u65f6\uff0c\u5219\u7ebf\u7a0b<strong>\u8fdb\u5165\u963b\u585e<\/strong>\uff0c\u91ca\u653e<code>CPU<\/code>\uff0c\u5b83<strong>\u4e0d\u4f1a\u56e0\u4e3a\u6ca1\u6709\u6570\u636e\u800c\u505c\u6b62<\/strong><code>loop()<\/code>\uff0c\u6240\u4ee5\u5982\u679c\u6b64<code>Looper<\/code><strong>\u4e0d\u4f7f\u7528\u4e86<\/strong>\uff0c<strong>\u4e00\u5b9a\u8981<\/strong>\u8c03\u7528<code>quit()<\/code>\u6765<strong>\u7ed3\u675f\u5faa\u73af<\/strong>\uff0c\u5b83\u4f1a\u4f7f<code>MessageQueue<\/code>\u7684<code>next()<\/code>\u65b9\u6cd5\u8fd4\u56de<code>null<\/code>\uff0c\u4ece\u800c<strong>\u7ed3\u675f\u5faa\u73af<\/strong>\u3002<br \/>\n  2. \u53ef\u901a\u8fc7\u8c03\u7528<code>looper.setMessageLogging()<\/code>\u7ed9<strong>\u6307\u5b9a<\/strong><code>Looper<\/code>\u8bbe\u7f6e\u65e5\u5fd7\u6253\u5370\u8005\uff0c\u4ee5<strong>\u76d1\u542c\u6d88\u606f\u72b6\u6001<\/strong>\uff0c<code>&gt;&gt;&gt;&gt;&gt; Dispatching to<\/code>\u4e3a<strong>\u5206\u53d1\u5f00\u59cb<\/strong>\uff0c<code>&lt;&lt;&lt;&lt;&lt; Finished to<\/code>\u4e3a<strong>\u5206\u53d1\u7ed3\u675f<\/strong>\uff0c\u53ef\u5224\u65ad<strong>\u65f6\u95f4\u5dee<\/strong>\u6765\u5224\u65ad<strong>\u5206\u53d1\u662f\u5426\u8d85\u65f6<\/strong>\u3002<br \/>\n  3. \u53ef\u901a\u8fc7<code>hide<\/code>\u65b9\u6cd5<code>setObserver(Observer)<\/code>\u8bbe\u7f6e<code>Message<\/code>\u5206\u53d1\u76d1\u542c\uff0c\u5176\u4f1a\u6536\u5230\u5206\u53d1<strong>\u5f00\u59cb<\/strong>\u3001\u5206\u53d1<strong>\u7ed3\u675f<\/strong>\u3001\u5206\u53d1<strong>\u5f02\u5e38<\/strong>\u901a\u77e5\u3002<br \/>\n  4. <code>MessageQueue<\/code>\u83b7\u53d6\u6d88\u606f\u7684\u76f8\u5173\u4ecb\u7ecd\uff0c\u8bf7\u770b<a href=\"https:\/\/juejin.cn\/post\/7085977128092565512\/#heading-16\">Android-Handler\u6e90\u7801\u89e3\u6790-MessageQueue-\u83b7\u53d6Message<\/a>\u3002<br \/>\n  5. <code>Handler<\/code>\u5206\u53d1\u6d88\u606f\u7684\u76f8\u5173\u4ecb\u7ecd\uff0c\u8bf7\u770b<a href=\"https:\/\/juejin.cn\/post\/7085976728538972190#heading-26\">Android-Handler\u6e90\u7801\u89e3\u6790-Handler-\u5206\u53d1Message<\/a>\u3002\n<\/p><\/blockquote>\n<h3>\u5c0f\u7ed3<\/h3>\n<blockquote>\n<ol>\n<li><code>loop()<\/code>\u8f6e\u8be2\u65b9\u6cd5\uff0c\u4e3a<strong>\u9759\u6001<\/strong>\u65b9\u6cd5\uff0c\u83b7\u53d6\u5f53\u524d\u7ebf\u7a0b<code>Looper<\/code>\u5bf9\u8c61\uff08\u4ee5\u83b7\u53d6\u5230<code>MessageQueue<\/code>\uff09\uff0c\u8fdb\u884c<strong>\u6b7b\u5faa\u73af\u8f6e\u8be2<\/strong>\u3002\u5b83\u4f1a\u5148\u83b7\u53d6<code>MessageQueue<\/code>\u7684<strong>\u4e0b\u4e2a<\/strong><code>Message<\/code>\uff0c\u5982\u679c\u8fd4\u56de<code>Message<\/code>\u4e3a<code>null<\/code>\u5219<strong>\u9000\u51fa\u6b7b\u5faa\u73af\u8f6e\u8be2<\/strong>\uff0c\u5982\u679c\u8fd4\u56de<code>Message<\/code>\u4e0d\u4e3a<code>null<\/code>\u5219\u8c03\u7528<code>Message<\/code>\u7684<code>target<\/code>\uff08<strong>\u76ee\u6807<\/strong><code>Handler<\/code>\uff09\u8fdb\u884c<strong>\u5206\u53d1\u6d88\u606f<\/strong>\uff08<code>handler.dispatchMessage(msg)<\/code>\uff09\uff0c\u5982\u679c<code>MessageQueue<\/code>\u6ca1\u6709<code>Message<\/code>\u5219\u7ebf\u7a0b<strong>\u8fdb\u5165\u963b\u585e<\/strong>\u4ee5\u7b49\u5f85\u6709\u65b0\u7684<code>Message<\/code>\u3002<\/li>\n<li><strong>\u8f6e\u8be2<\/strong><code>Looper<\/code>\u524d\uff0c<strong>\u8c03\u7528<\/strong>\u7ebf\u7a0b<strong>\u4e00\u5b9a<\/strong>\u8981\u6709<code>Looper<\/code>\uff08\u9700\u8c03\u7528<code>Looper.prepare()<\/code>\uff09\uff0c\u5426\u5219<strong>\u629b\u51fa\u5f02\u5e38<\/strong>\u3002<\/li>\n<li>\u5f53<code>MessageQueue<\/code>\u91cc\u9762<strong>\u6ca1\u6709<\/strong><code>Message<\/code>\u65f6\uff0c\u5219\u7ebf\u7a0b<strong>\u8fdb\u5165\u963b\u585e<\/strong>\uff0c\u91ca\u653e<code>CPU<\/code>\uff0c\u5b83<strong>\u4e0d\u4f1a\u56e0\u4e3a\u6ca1\u6709\u6570\u636e\u800c\u505c\u6b62<\/strong><code>loop()<\/code>\uff0c\u6240\u4ee5\u5982\u679c\u6b64<code>Looper<\/code><strong>\u4e0d\u4f7f\u7528\u4e86<\/strong>\uff0c<strong>\u4e00\u5b9a\u8981<\/strong>\u8c03\u7528<code>quit()<\/code>\u6765<strong>\u7ed3\u675f\u5faa\u73af<\/strong>\u3002<\/li>\n<li><strong>\u4e3b\u7ebf\u7a0b<\/strong><code>Looper<\/code>\uff0c\u4e0d\u5141\u8bb8\u9000\u51fa\u3002<strong>\u975e\u4e3b\u7ebf\u7a0b<\/strong><code>Looper<\/code>\uff0c\u5982\u679c\u4e0d\u4f7f\u7528\u4e86\uff0c<strong>\u4e00\u5b9a\u8981<\/strong>\u8c03\u7528<code>quit()<\/code>\u6765<strong>\u7ed3\u675f\u5faa\u73af<\/strong>\u3002<\/li>\n<li>\u53ef\u4ee5\u901a\u8fc7\u8bbe\u7f6e<code>setMessageLogging()<\/code>\u65b9\u6cd5\u6765\u6253\u5370<code>Message<\/code>\u5206\u53d1\u8fc7\u7a0b\uff0c\u901a\u8fc7<strong>\u53cd\u5c04<\/strong>\u8c03\u7528<code>hide<\/code>\u65b9\u6cd5<code>setObserver(Observer)<\/code>\u8bbe\u7f6e<code>Message<\/code>\u5206\u53d1\u76d1\u542c\u3002<\/li>\n<\/ol>\n<\/blockquote>\n<h2>\u9000\u51faLooper<\/h2>\n<p><code>Looper<\/code><strong>\u4e0d\u4f7f\u7528\u4e86<\/strong>\uff0c\u4fbf\u9700\u8981<strong>\u9000\u51fa<\/strong>\uff0c\u6240\u4ee5\u6211\u4eec\u63a5\u4e0b\u6765\u770b\u4e0b\u5b83\u662f\u5982\u4f55<strong>\u9000\u51fa<\/strong>\u7684\u3002<\/p>\n<h3>quit()<\/h3>\n<pre><code class=\"language-java\">public void quit() {\n    mQueue.quit(false);\n}\n<\/code><\/pre>\n<p><code>quit()<\/code>\u65b9\u6cd5\uff0c\u4e3a<strong>\u4e0d\u5b89\u5168<\/strong>\u7684<strong>\u9000\u51fa<\/strong><code>Looper<\/code>\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. \u6b64\u65b9\u6cd5\uff0c\u5bfc\u81f4<code>loop()<\/code>\u65b9\u6cd5\uff0c\u5728<strong>\u4e0d\u5904\u7406<\/strong>\u6d88\u606f\u961f\u5217\u4e2d\u7684<strong>\u4efb\u4f55\u6d88\u606f<\/strong>\u7684\u60c5\u51b5\u4e0b<strong>\u7ec8\u6b62<\/strong>\uff0c\u56e0\u4e3a\u5b83\u4f1a<strong>\u5220\u9664\u6d88\u606f\u961f\u5217<\/strong>\u4e2d<strong>\u6240\u6709\u6d88\u606f<\/strong>\u3002<br \/>\n  2. \u5728<code>looper<\/code>\u88ab\u8bf7\u6c42<strong>\u9000\u51fa<\/strong>\u540e\uff0c<strong>\u4efb\u4f55<\/strong>\u5411\u961f\u5217<strong>\u53d1\u9001\u6d88\u606f<\/strong>\u7684\u5c1d\u8bd5<strong>\u90fd\u5c06\u5931\u8d25<\/strong>\u3002\u4f8b\u5982\uff0c<code>Handler.sendMessage(Message)<\/code>\u65b9\u6cd5\u5c06\u8fd4\u56de<code>false<\/code>\u3002<br \/>\n  3. \u6b64\u65b9\u6cd5\uff0c<strong>\u53ef\u80fd<\/strong>\u662f<strong>\u4e0d\u5b89\u5168<\/strong>\u7684\uff0c\u56e0\u4e3a\u5728<code>looper<\/code><strong>\u7ec8\u6b62\u4e4b\u524d<\/strong>\u53ef\u80fd<strong>\u65e0\u6cd5\u4f20\u9012<\/strong>\u4e00\u4e9b\u6d88\u606f\u3002\u8003\u8651\u4f7f\u7528<code>quitSafely<\/code>\uff0c\u4ee5<strong>\u786e\u4fdd\u6240\u6709\u7b49\u5f85\u7684\u5de5\u4f5c<\/strong>\u90fd\u4ee5\u6709\u5e8f\u7684\u65b9\u5f0f<strong>\u5b8c\u6210<\/strong>\u3002<br \/>\n  4. <code>MessageQueue<\/code>\u9000\u51fa<code>MessageQueue<\/code>\u7684\u76f8\u5173\u4ecb\u7ecd\uff0c\u8bf7\u770b<a href=\"https:\/\/juejin.cn\/post\/7085977128092565512\/#heading-39\">Android-Handler\u6e90\u7801\u89e3\u6790-MessageQueue-\u9000\u51faMessageQueue<\/a>\u3002\n<\/p><\/blockquote>\n<h3>quitSafely()<\/h3>\n<pre><code class=\"language-java\">public void quitSafely() {\n    mQueue.quit(true);\n}\n<\/code><\/pre>\n<p><code>quitSafely()<\/code>\u65b9\u6cd5\uff0c\u4e3a<strong>\u5b89\u5168<\/strong>\u7684<strong>\u9000\u51fa<\/strong><code>Looper<\/code>\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. \u6b64\u65b9\u6cd5\uff0c\u5bfc\u81f4<code>loop()<\/code>\u65b9\u6cd5\uff0c\u5728<strong>\u5904\u7406<\/strong>\u6d88\u606f\u961f\u5217\u4e2d\u7684<strong>\u5df2\u7ecf\u5230\u671f<\/strong>\u7684<strong>\u6240\u6709\u6d88\u606f<\/strong>\uff0c<strong>\u4e0d\u5904\u7406<\/strong>\u6d88\u606f\u961f\u5217\u4e2d\u7684<strong>\u672a\u6765\uff08\u5f53\u524d\u65f6\u523b\u4ee5\u540e\uff09\u5230\u671f<\/strong>\u7684<strong>\u6240\u6709\u6d88\u606f<\/strong>\u7684\u60c5\u51b5\u4e0b<strong>\u7ec8\u6b62<\/strong>\uff0c\u56e0\u4e3a\u5b83\u4f1a<strong>\u5220\u9664\u6d88\u606f\u961f\u5217<\/strong>\u4e2d<strong>\u6240\u6709\u672a\u6765\u7684\u6d88\u606f<\/strong>\u3002\n<\/p><\/blockquote>\n<h3>\u5c0f\u7ed3<\/h3>\n<blockquote>\n<ol>\n<li><strong>\u9000\u51fa<\/strong><code>Looper<\/code>\uff0c\u6709\u4e24\u4e2a\u65b9\u6cd5\uff1a<code>quit()<\/code>\u4e0d\u5b89\u5168\u9000\u51fa\u3001<code>quitSafely()<\/code>\u5b89\u5168\u9000\u51fa\u3002<\/li>\n<li><code>quit()<\/code>\uff1a\u4e0d\u5b89\u5168\u9000\u51fa\uff0c\u5b83\u4f1a<strong>\u5220\u9664\u6d88\u606f\u961f\u5217<\/strong>\u4e2d<strong>\u6240\u6709\u6d88\u606f<\/strong>\u3002\u5728<strong>\u4e0d\u5904\u7406<\/strong>\u6d88\u606f\u961f\u5217\u4e2d\u7684<strong>\u4efb\u4f55\u6d88\u606f<\/strong>\u7684\u60c5\u51b5\u4e0b<strong>\u7ec8\u6b62<\/strong>\uff08\u6b64\u65b9\u6cd5\uff0c<strong>\u53ef\u80fd<\/strong>\u662f<strong>\u4e0d\u5b89\u5168<\/strong>\u7684\uff0c\u56e0\u4e3a\u5728<code>looper<\/code><strong>\u7ec8\u6b62\u4e4b\u524d<\/strong>\u53ef\u80fd<strong>\u65e0\u6cd5\u4f20\u9012<\/strong>\u4e00\u4e9b\u6d88\u606f\uff09\u3002<\/li>\n<li><code>quitSafely()<\/code>\uff1a\u5b89\u5168\u9000\u51fa\uff0c\u5b83\u4f1a<strong>\u5220\u9664\u6d88\u606f\u961f\u5217<\/strong>\u4e2d<strong>\u6240\u6709\u672a\u6765\uff08\u5f53\u524d\u65f6\u523b\u4ee5\u540e\uff09\u7684\u6d88\u606f<\/strong>\u3002<strong>\u5904\u7406<\/strong>\u6d88\u606f\u961f\u5217\u4e2d\u7684<strong>\u5df2\u7ecf\u5230\u671f<\/strong>\u7684<strong>\u6240\u6709\u6d88\u606f<\/strong>\uff0c<strong>\u4e0d\u5904\u7406<\/strong>\u6d88\u606f\u961f\u5217\u4e2d\u7684<strong>\u672a\u6765\uff08\u5f53\u524d\u65f6\u523b\u4ee5\u540e\uff09\u5230\u671f<\/strong>\u7684<strong>\u6240\u6709\u6d88\u606f<\/strong>\u7684\u60c5\u51b5\u4e0b<strong>\u7ec8\u6b62<\/strong>\u3002<\/li>\n<li>\u5728<code>looper<\/code>\u88ab\u8bf7\u6c42<strong>\u9000\u51fa<\/strong>\u540e\uff0c<strong>\u4efb\u4f55<\/strong>\u5411\u961f\u5217<strong>\u53d1\u9001\u6d88\u606f<\/strong>\u7684\u5c1d\u8bd5<strong>\u90fd\u5c06\u5931\u8d25<\/strong>\u3002\u4f8b\u5982\uff0c<code>Handler.sendMessage(Message)<\/code>\u65b9\u6cd5\u5c06\u8fd4\u56de<code>false<\/code>\u3002<\/li>\n<\/ol>\n<\/blockquote>\n<h2>\u5c5e\u6027set\u3001get\u65b9\u6cd5<\/h2>\n<p><code>Looper<\/code>\u7684<code>mLogging<\/code>\u3001<code>mThread<\/code>\u3001<code>mQueue<\/code>\u5c5e\u6027\u5bf9\u5916\u63d0\u4f9b\u4e86<code>set<\/code>\u3001<code>get<\/code>\u65b9\u6cd5\uff0c\u6211\u4eec\u63a5\u4e0b\u6765\u770b\u4e0b\u5b83\u4eec\u7684\u5b9e\u73b0\u3002<\/p>\n<h3>setMessageLogging()<\/h3>\n<pre><code class=\"language-java\">public void setMessageLogging(@Nullable Printer printer) {\n    mLogging = printer;\n}\n<\/code><\/pre>\n<p><strong>\u8bbe\u7f6e<\/strong>\u6b64<code>Looper<\/code><strong>\u5904\u7406\u6d88\u606f<\/strong>\u65f6<strong>\u6d88\u606f<\/strong>\u7684<strong>\u65e5\u5fd7\u8bb0\u5f55<\/strong>\u3002\u5982\u679c<strong>\u542f\u7528<\/strong>\uff0c<strong>\u65e5\u5fd7\u6d88\u606f<\/strong>\u5c06\u5728<strong>\u6bcf\u6b21<\/strong>\u6d88\u606f<strong>\u5206\u53d1<\/strong>\u7684<strong>\u5f00\u59cb<\/strong>\u548c<strong>\u7ed3\u675f<\/strong>\u65f6\u5199\u5230<code>printer<\/code>\uff0c<strong>\u6807\u8bc6<\/strong>\u76ee\u6807<code>Handler<\/code>\u548c<code>Message<\/code>\u5185\u5bb9\u3002<\/p>\n<h3>getThread()<\/h3>\n<pre><code class=\"language-java\">public @NonNull Thread getThread() {\n    return mThread;\n}\n<\/code><\/pre>\n<p><strong>\u83b7\u53d6<\/strong>\u4e0e\u6b64<code>looper<\/code><strong>\u5173\u8054<\/strong>\u7684<strong>\u7ebf\u7a0b<\/strong>\u3002<\/p>\n<h3>getQueue()<\/h3>\n<pre><code class=\"language-java\">public @NonNull MessageQueue getQueue() {\n    return mQueue;\n}\n<\/code><\/pre>\n<p><strong>\u83b7\u53d6<\/strong>\u6b64<code>looper<\/code>\u7684<strong>\u6d88\u606f\u961f\u5217<\/strong>\u3002<\/p>\n<h2>\u5176\u5b83<\/h2>\n<h3>Looper.myQueue()<\/h3>\n<pre><code class=\"language-java\">public static @NonNull MessageQueue myQueue() {\n    return myLooper().mQueue;\n}\n<\/code><\/pre>\n<p><strong>\u83b7\u53d6<\/strong>\u4e0e<strong>\u5f53\u524d\u7ebf\u7a0b<\/strong>\u5173\u8054\u7684<code>MessageQueue<\/code>\u5bf9\u8c61\u3002\u6b64\u7ebf\u7a0b<strong>\u5fc5\u987b<\/strong>\u6709<code>Looper<\/code>\uff0c<strong>\u5426\u5219<\/strong>\u5c06<strong>\u629b\u51fa<\/strong><code>NullPointerException<\/code>\u3002<\/p>\n<h3>isCurrentThread()<\/h3>\n<pre><code class=\"language-java\">public boolean isCurrentThread() {\n    return Thread.currentThread() == mThread;\n}\n<\/code><\/pre>\n<p>\u5224\u65ad<strong>\u8c03\u7528\u7ebf\u7a0b<\/strong>\u662f\u5426\u662f\u8be5<code>looper<\/code>\u7684<strong>\u7ebf\u7a0b<\/strong>\uff0c\u5982\u679c\u662f\uff0c\u5219\u8fd4\u56de<code>true<\/code>\u3002<\/p>\n<h3>dump()<\/h3>\n<pre><code class=\"language-java\">public void dump(@NonNull Printer pw, @NonNull String prefix) {\n    pw.println(prefix + toString());\n    mQueue.dump(pw, prefix + \"  \", null);\n}\n<\/code><\/pre>\n<p><strong>\u8f6c\u50a8<\/strong><code>looper<\/code>\u7684<strong>\u72b6\u6001<\/strong>\uff0c\u4ee5\u8fdb\u884c<strong>\u8c03\u8bd5<\/strong>\uff0c\u8c03\u7528<code>MessageQueue<\/code>\u7684<code>dump()<\/code>\u65b9\u6cd5\u3002<\/p>\n<blockquote><p>\n  \u8bf4\u660e\uff1a<br \/>\n  1. <code>MessageQueue<\/code>\u8f6c\u50a8\u7684\u76f8\u5173\u4ecb\u7ecd\uff0c\u8bf7\u770b<a href=\"https:\/\/juejin.cn\/post\/7085977128092565512\/#heading-45\">Android-Handler\u6e90\u7801\u89e3\u6790-MessageQueue-dump()<\/a>\u3002\n<\/p><\/blockquote>\n<h1>\u603b\u7ed3<\/h1>\n<p>\u4ee5\u4e0a\u5c31\u662f<code>Handler<\/code>\u6e90\u7801\u7684<code>Looper<\/code>\u90e8\u5206\uff0c<code>Handler<\/code>\u5176\u5b83\u6e90\u7801\u90e8\u5206\u770b\u4e0b\u9762<strong>\u5bfc\u822a<\/strong>\u3002\u6b22\u8fce\u5927\u5bb6<strong>\u70b9\u8d5e\u3001\u6536\u85cf<\/strong>\uff0c\u4ee5\u65b9\u4fbf\u60a8\u540e\u7eed\u67e5\u770b\uff0c\u4e4b\u540e\u4f1a\u51fa\u5176\u5b83<code>Android<\/code>\u6e90\u7801\u7cfb\u5217\uff0c\u8bf7\u53ca\u65f6\u5173\u6ce8\u3002\u5982\u679c\u4f60\u6709\u4ec0\u4e48\u95ee\u9898\uff0c\u53ef\u4ee5\u5728\u8bc4\u8bba\u533a\u7559\u8a00\uff01<\/p>\n<blockquote><p>\n  <strong>\u5bfc\u822a\uff1a<\/strong><\/p>\n<ul>\n<li><a href=\"https:\/\/juejin.cn\/post\/7475656733558652943\">Android-Handler\u6e90\u7801\u89e3\u6790-\u4f7f\u7528<\/a><\/li>\n<li><a href=\"https:\/\/juejin.cn\/post\/7085976728538972190\">Android-Handler\u6e90\u7801\u89e3\u6790-Handler\uff08\u4e00\uff09<\/a><\/li>\n<li><a href=\"https:\/\/juejin.cn\/post\/7085976341056585742\">Android-Handler\u6e90\u7801\u89e3\u6790-Looper\uff08\u4e8c\uff09<\/a><\/li>\n<li><a href=\"https:\/\/juejin.cn\/post\/7085977128092565512\">Android-Handler\u6e90\u7801\u89e3\u6790-MessageQueue\uff08\u4e09\uff09<\/a><\/li>\n<li><a href=\"https:\/\/juejin.cn\/post\/7085975951414132766\">Android-Handler\u6e90\u7801\u89e3\u6790-Message\uff08\u56db\uff09<\/a><\/li>\n<li>\u66f4\u591a\u7684\u6587\u7ae0\u770b\u8fd9\u91cc\uff1a<a href=\"https:\/\/juejin.cn\/user\/4450479132652679\/posts\">\u4e3b\u9875<\/a><\/li>\n<\/ul>\n<\/blockquote>\n<p>\u6700\u540e\u63a8\u8350\u4e00\u4e0b\u6211\u7684\u7f51\u7ad9\uff0c\u5f00\u53d1\u8005\uff08<code>Developer<\/code>\uff09\u7684\u535a\u5ba2\uff08<code>Blog<\/code>\uff09: <a href=\"http:\/\/www.devblog.cn\/\">devblog.cn<\/a> \uff0c\u6b22\u8fce\u5927\u5bb6\u6765\u4f53\u9a8c\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Android-Handler\u6e90\u7801\u89e3\u6790-Looper\uff08\u4e8c\uff09 \u6e90\u7801\u7248\u672c\uff1a * Handler\uff1aSDK-35 *  [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_lmt_disableupdate":"","_lmt_disable":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[24,10],"tags":[31,20],"class_list":["post-127","post","type-post","status-publish","format-standard","hentry","category-source-android","category-source","tag-android","tag-20"],"modified_by":"admin","jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"http:\/\/www.devblog.cn\/index.php?rest_route=\/wp\/v2\/posts\/127","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.devblog.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.devblog.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.devblog.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.devblog.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=127"}],"version-history":[{"count":4,"href":"http:\/\/www.devblog.cn\/index.php?rest_route=\/wp\/v2\/posts\/127\/revisions"}],"predecessor-version":[{"id":220,"href":"http:\/\/www.devblog.cn\/index.php?rest_route=\/wp\/v2\/posts\/127\/revisions\/220"}],"wp:attachment":[{"href":"http:\/\/www.devblog.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=127"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.devblog.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=127"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.devblog.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=127"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}