{"id":122,"date":"2016-03-27T15:14:57","date_gmt":"2016-03-27T15:14:57","guid":{"rendered":"https:\/\/boochlin.com\/?p=122"},"modified":"2026-09-16T09:54:13","modified_gmt":"2026-09-16T09:54:13","slug":"java-reflection-in-android-%ef%bc%8dfast-scroll-bar-in-list-view-dynamic-load-apk","status":"publish","type":"post","link":"https:\/\/boochlin.com\/?p=122","title":{"rendered":"Java reflection in Android \uff0dfast scroll bar in list view \/ dynamic load apk."},"content":{"rendered":"<p>\u96d6\u7136\u6700\u8fd1\u4e26\u6c92\u6709\u627e\u5de5\u4f5c\uff0c\u4f46\u662f\u770b\u4e86\u4e00\u672c\u66f8\u300eAndroid \u5de5\u7a0b\u5e2b\u9762\u8a66\u5bf6\u5178\u300f\uff0c\u4e3b\u8981\u662f\u56e0\u70ba\u9019\u662f\u4e00\u672c\u5145\u6eff\u5c0f\u6280\u5de7\u7684\u6280\u8853\u66f8\uff0c\u770b\u4e00\u770b\u5c31\u6703\u6709\u4e00\u7a2e\u300e\u539f\u4f86\u5982\u6b64\u300f\u7684\u5947\u5999\u8b9a\u5606\uff0c\u4f46\u662f\u5982\u904e\u786c\u8981\u8aaa\u4e00\u53e5\u7d50\u8ad6\u7684\u8a71\uff0c\u5c31\u662f\u9762\u8a66\u554f\u9019\u7a2e\u554f\u984c\u771f\u7684\u8d85\u7121\u804a\uff0c\u6839\u672c\u662f stackoverflow \u554f\u984c\u5927\u96c6\u5408\uff08\u800c\u4e14\u6709\u9ede\u820a\uff09\u3002\u800c\u4e0d\u5c11\u554f\u984c\u662f\u7528 java reflection \u7684\u6280\u8853\u4f86\u89e3\u7b54\u3002\u8001\u5be6\u8aaa\u9762\u8a66\u4e2d\uff0c\u6216\u662f\u51fa\u5728\u7b46\u8a66\u8003\u5377\u4e0a\uff0c\u9019\u4e0d\u4e0a\u7db2\u67e5\u6839\u672c\u7b54\u4e0d\u51fa\u4f86\u5566\u3002\u4f46\u662f\u9019\u4e5f\u5f15\u8d77\u5c0d\u65bc java relection \u6280\u8853\u6846\u67b6\u7684\u8208\u8da3\u3002<\/p>\n<p>\u9019\u4e00\u7ae0\u7bc0\u5148\u63d0\u4e00\u4e0b\u6b64\u66f8 android \u5728 java reflection \u7684\u61c9\u7528\u60c5\u6cc1\u3002<\/p>\n<p>\uff11\uff0e\u5982\u4f55\u5728 list view \u4e0a\u52a0\u4e0a fast scroll bar ?<\/p>\n<p>\uff12\uff0e\u5982\u4f55\u52d5\u614b\u8f09\u5165 apk file \u7684 class\uff1f<\/p>\n<p>\u2014\u2014\u2014\u2014-\u5206\u5272\u7dda\u2014\u2014\u2014\u2014\u2014\u2014\u2014<\/p>\n<h3>1. \u5982\u4f55 list view \u52a0\u4e0a fast scroll bar ?<\/h3>\n<p>\u9996\u5148\u8981\u5148\u7406\u89e3 fast scroll bar \u662f\u5565\u9b3c\uff1f\u53ef\u4ee5\u5403\u55ce\uff1f<\/p>\n<p>\u5176\u5be6\u5c31\u662f\u6211\u5011\u5e38\u5728\u4f7f\u7528\u7db2\u9801\u700f\u89bd\u5668\u7684\u53f3\u908a\uff0c\u6ed1\u9f20\u53ef\u4ee5\u62d6\u66f3\u7684 bar \uff0c\u53ef\u4ee5\u5feb\u901f\u79fb\u52d5\u9801\u9762\u5167\u5bb9\uff08\u4e0a\u4e0b\u5de6\u53f3\u90fd\u53ef\u4ee5\uff09\uff0c\u9084\u6709\u4e0d\u53ef\u4ee5\u5403<\/p>\n<p>\u76f4\u63a5\u4e0a\u5716<\/p>\n<pre class=\"mermaid\">classDiagram\n    class AbsListView {\n        -FastScroller mFastScroller\n        +setFastScrollEnabled(boolean)\n    }\n    class FastScroller {\n        -ImageView mThumbImage\n        -ImageView mTrackImage\n        +setThumbDrawable(Drawable)\n    }\n    AbsListView *-- FastScroller : \u900f\u904e\u53cd\u5c04\u5b58\u53d6\u79c1\u6709\u6b04\u4f4d<\/pre>\n<p><em>(AbsListView \u5167\u90e8\u79c1\u6709\u6210\u54e1 mFastScroller \u7d50\u69cb)<\/em><\/p>\n<p>\u5b8c\u4e86\uff0c\u770b\u4e86\u6700\u65b0\u7684\u8cc7\u6599\u767c\u73fe\u9019\u6709\u9ede\u7121\u804a\uff0c\u56e0\u70ba\u5f8c\u4f86 android \u76f4\u63a5\u91cb\u51fa api \u4f86\u4e86\uff0c\u800c\u4e14\u8d85\u7c21\u55ae\u3002\u90a3\u67d0\u9019\u672c\u66f8\u5230\u5e95\u5728\u554f\u984c\u500b\u5c41\u554a\uff1f\u539f\u4f86\u9019\u554f\u984c\u662f 2011 \u7684\u554f\u984c\uff0c\u90a3\u62b9\u6211\u5c0d\u61c9\u4e00\u4e0b api level\uff0c\u539f\u4f86\u662f 3<\/p>\n<p>\u7b97\u4e86\uff0c\u90fd\u63d0\u5230\u4e86\u5c31\u7e7c\u7e8c\u5427\uff0c\u5c31\u7576\u4f5c\u662f\u7c21\u55ae\u63d0\u4e00\u4e0bjava reflection api \u4ecb\u7d39\u3002<\/p>\n<pre><code class=\"hljs language-java\"><span class=\"hljs-keyword\">if<\/span> (Build.VERSION.SDK_INT &lt; Build.VERSION_CODES.HONEYCOMB) {\n    <span class=\"hljs-keyword\">try<\/span> {\n        <span class=\"hljs-comment\">\/\/ FastScroller.mThumbDrawable \u70ba fast scroll bar \u7684\u756b\u9762\uff0c\u9996\u5148\u5fc5\u9808\u8981\u900f\u904e AbsListView.mFastScroller<\/span>\n        <span class=\"hljs-comment\">\/\/ \u53d6\u5f97 FastScroller obj.<\/span>\n        <span class=\"hljs-type\">Field<\/span> <span class=\"hljs-variable\">field<\/span> <span class=\"hljs-operator\">=<\/span> AbsListView.class.getDeclaredField(<span class=\"hljs-string\">&quot;mFastScroller&quot;<\/span>);\n        <span class=\"hljs-comment\">\/\/ \u8a2d\u5b9a\u53ef\u4ee5\u5b58\u53d6<\/span>\n        field.setAccessible(<span class=\"hljs-literal\">true<\/span>);\n        <span class=\"hljs-type\">Object<\/span> <span class=\"hljs-variable\">obj<\/span> <span class=\"hljs-operator\">=<\/span> field.get(mContentListView);\n        <span class=\"hljs-comment\">\/\/ \u53d6\u5f97 FastScroller.mThumbDrawable \u8b8a\u6578\u7684 field obj.<\/span>\n        field = field.getType().getDeclaredField(<span class=\"hljs-string\">&quot;mThumbDrawable&quot;<\/span>);\n        field.setAccessible(<span class=\"hljs-literal\">true<\/span>);\n        <span class=\"hljs-comment\">\/\/ \u53d6\u5f97\u8981\u8f09\u5165\u7684 fast scroller bar \u7684 drawable<\/span>\n        <span class=\"hljs-type\">Drawable<\/span> <span class=\"hljs-variable\">drawable<\/span> <span class=\"hljs-operator\">=<\/span> (Drawable)field.get(obj);\n        drawable = getResources().getDrawable(R.drawable.widget_button);\n        <span class=\"hljs-comment\">\/\/ \u91cd\u65b0\u8a2d\u5b9afast scroller bar \u7684 drawable<\/span>\n        field.set(obj, drawable);\n    } <span class=\"hljs-keyword\">catch<\/span> (NoSuchFieldException e) {\n        e.printStackTrace();\n    } <span class=\"hljs-keyword\">catch<\/span> (IllegalAccessException e) {\n        e.printStackTrace();\n    }\n}<\/code><\/pre>\n<p>\u9996\u5148\u53ef\u4ee5\u770b\u5f97\u51fa\u4f86\uff0c\u6211\u5011\u8981\u5148\u77e5\u9053\u6211\u8981\u8655\u7406\u7684\u5c0d\u8c61\u5230\u5e95\u5728\u54ea\u88e1\u4e14\u662f\u5565\u540d\u5b50\uff0c\u7136\u5f8c\u7528 Field \u53d6\u5f97\u5be6\u9ad4\uff0c\u8a2d\u5b9a\u53ef\u4ee5 accessible (true)\uff0c\u7136\u5f8c\u76f4\u63a5\u5c0dobj\u8a2d\u5b9a\u5167\u5bb9\uff0c\u5176\u5be6\u53ef\u4ee5\u767c\u73fe\u6700\u91cd\u8981\u7684\u5de5\u4f5c\u662f\u627e\u51fa\u70ba\u5b50\uff0c\u540c\u6642\u9019\u4e5f\u6709\u53ef\u80fd\u8981\u8003\u616e framework \u7684\u5167\u5bb9\uff0c\u5404\u5bb6\u5ee0\u5546\u4e5f\u6709\u53ef\u80fd\u532f\u6539\uff0c\u6240\u4ee5\u9019\u62db\u57fa\u672c\u4e0a\u6709\u6642\u9748\u6709\u6642\u4e0d\u9748\u3002<\/p>\n<p>\u5982\u679c\u770b\u5b98\u53ea\u662f\u60f3\u770b\u5feb\u901f\u6539\u51fa list view scroll bar.<\/p>\n<pre><code class=\"hljs language-java\">listView = (ListView) getView().findViewById(R.id.listView);\nlistView.setFastScrollEnabled(<span class=\"hljs-literal\">true<\/span>);<\/code><\/pre>\n<p>\u7a81\u7136\u89ba\u5f97\u4e0a\u9762\u7684\u5167\u5bb9\u6709\u9ede\u592a\u904e\u7c21\u55ae\u6216\u662f\u592a\u820a\uff0c\u63db\u500b\u984c\u76ee\uff0c\u5230\u7b2c\u4e8c\u984c<\/p>\n<h3>\uff12\uff0e\u5982\u4f55\u52d5\u614b\u8f09\u5165 apk file \u7684 class\uff1f<\/h3>\n<p>\u9996\u5148\u5728\u9019\u4e4b\u524d\uff0c\u5148\u64f4\u5c55\u9019\u554f\u984c\uff0c\u5982\u4f55\u52d5\u614b\u8f09\u5165<strong>\u672a\u5b89\u88dd<\/strong>\u7684 apk \u6a94\u6848?<\/p>\n<p>\u7531\u65bcandroid \u662f run on dalivk machine, \u4e26\u975e \u50b3\u7d71\u7684 jvm \u4e0a\uff0c\u56e0\u6b64\u7121\u6cd5\u76f4\u63a5\u8f09\u5165\u50b3\u7d71\u7684jar\u6a94\uff0c\u4f46apk file \u5df2\u7d93\u88ab\u7de8\u8b6f\u6210 dalivk \u7684 dex file. \u56e0\u6b64\u624d\u53ef\u4ee5\u6b63\u5e38\u8f09\u5165\u3002\u4f46\u540c\u6642\u6211\u5011\u4e5f\u5fc5\u9808\u7528\u7279\u6b8a\u7684\u65b9\u6cd5\u53bb\u958b\u555f dex file.<\/p>\n<p>\u90a3\u67d0\u9019\u65b9\u6cd5\u5565\u6642\u6703\u4f7f\u7528\u5230\uff0c\u4e3b\u8981\u662f\u8981\u907f\u514d\u983b\u7169\u66f4\u65b0 native app \u5c0d\u4f7f\u7528\u8005\u9020\u6210\u7684\u7169\u8e81\u611f\uff0c\u5229\u7528\u9019\u6280\u8853\u53ef\u4ee5\u8b93\u65b0\u5167\u5bb9\u7684 apk \u53ef\u4ee5\u518d\u4e0d\u7528play store \u66f4\u65b0\u7684\u60c5\u6cc1\uff0c\u5077\u5077\u91cd\u7db2\u8def\u4e0b\u8f09\u4e0b\u4f86\uff0c\u4e26\u66f4\u65b0\u8cc7\u6599\u3002<\/p>\n<pre><code class=\"hljs language-java\"><span class=\"hljs-keyword\">try<\/span> {\n    <span class=\"hljs-comment\">\/\/ myapk.apk \u662f\u6211\u5011\u60f3\u8981\u8f09\u5165\u7684\u5c0d\u8c61\uff0cmyapk_temp.apk \u70ba\u7cfb\u7d71\u6700\u4f73\u5316\u81e8\u6642\u7522\u751f\u7684\u6a94\u6848<\/span>\n    <span class=\"hljs-type\">DexFile<\/span> <span class=\"hljs-variable\">dexFile<\/span> <span class=\"hljs-operator\">=<\/span> DexFile.loadDex(<span class=\"hljs-string\">&quot;sdcard\/myapk.apk&quot;<\/span>,<span class=\"hljs-string\">&quot;\/sdcard\/myapk_temp.apk&quot;<\/span>,<span class=\"hljs-number\">0<\/span>);\n    <span class=\"hljs-comment\">\/\/or \u4f7f\u7528dexclassloader , \u4e26\u5229\u7528\u5b98\u65b9\u6307\u4ee4\u76f4\u63a5\u62ff\u5230\u8def\u5f91\uff0c\u9054\u5230\u4e0a\u8ff0\u7684\u6548\u679c<\/span>\n    <span class=\"hljs-comment\">\/\/ DexClassLoader \u7684 optimizedDirectory \u5fc5\u9808\u6307\u5411 App \u79c1\u6709\u7684\u5167\u90e8\u5132\u5b58\u7a7a\u9593\u3002\u6307\u5411\u5916\u90e8\u5b58\u5132\uff08SD \u5361\uff09\u6703\u9020\u6210\u56b4\u91cd\u7684 Code Injection \u5b89\u5168\u6f0f\u6d1e\uff0c\u4e14 Android 5.0+ \u6703\u76f4\u63a5\u62cb\u51fa IllegalArgumentException \u62d2\u7d55\u57f7\u884c\u3002<\/span>\n    <span class=\"hljs-type\">DexClassLoader<\/span> <span class=\"hljs-variable\">cl<\/span> <span class=\"hljs-operator\">=<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">DexClassLoader<\/span>(optimizedDexOutputPath.getAbsolutePath(),\n                    context.getDir(<span class=\"hljs-string\">&quot;dex&quot;<\/span>, Context.MODE_PRIVATE).getAbsolutePath(), <span class=\"hljs-literal\">null<\/span>, getClassLoader());\n    <span class=\"hljs-comment\">\/\/\u4e0b\u8ff0\u5169\u5177\u6548\u679c\u662f\u4e00\u6a23\u7684\uff0c \u5229\u7528 java reflection \u6280\u8853\u53d6\u5f97 getHigh \u65b9\u6cd5\u7684\u7269\u4ef6\uff0c<\/span>\n    <span class=\"hljs-type\">Object<\/span> <span class=\"hljs-variable\">obj<\/span> <span class=\"hljs-operator\">=<\/span> dexFile.loadClass(<span class=\"hljs-string\">&quot;com.android.acer.home&quot;<\/span>,<span class=\"hljs-literal\">null<\/span>).newInstance();\n    cl.loadClass(<span class=\"hljs-string\">&quot;com.android.acer.home&quot;<\/span>)\n    <span class=\"hljs-type\">Method<\/span> <span class=\"hljs-variable\">method<\/span> <span class=\"hljs-operator\">=<\/span> obj.getClass().getDeclaredMethod(<span class=\"hljs-string\">&quot;getUserName&quot;<\/span>, <span class=\"hljs-literal\">null<\/span>);\n    <span class=\"hljs-comment\">\/\/ invoke \u65b9\u6cd5\uff0c\u4e26\u53d6\u5f97\u8fd4\u56de\u503c<\/span>\n    <span class=\"hljs-type\">String<\/span> <span class=\"hljs-variable\">result<\/span> <span class=\"hljs-operator\">=<\/span> String.valueOf(method.invoke(obj,<span class=\"hljs-literal\">null<\/span>));\n} <span class=\"hljs-keyword\">catch<\/span> (IOException e) {\n    e.printStackTrace();\n} <span class=\"hljs-keyword\">catch<\/span> (InstantiationException e) {\n    e.printStackTrace();\n} <span class=\"hljs-keyword\">catch<\/span> (IllegalAccessException e) {\n    e.printStackTrace();\n} <span class=\"hljs-keyword\">catch<\/span> (NoSuchMethodException e) {\n    e.printStackTrace();\n} <span class=\"hljs-keyword\">catch<\/span> (InvocationTargetException e) {\n    e.printStackTrace();\n}<\/code><\/pre>\n<p>\u597d\u5427\uff0c\u4e00\u4e9b\u597d\u50cf\u6709\u7528\u53c8\u6c92\u6709\u7528\u7684 java reflection \u4f7f\u7528\u60c5\u5883\u4ecb\u7d39\u5230\u6b64\u70ba\u6b62\u3002\u4e0b\u4e00\u7ae0\u7bc0\u6709\u53ef\u80fd\u6703\u662f\u4ecb\u7d39java reflection\u672c\u8eab\u662f\u5565\u9b3c<\/p>\n<p>reference:<\/p>\n<p><a href=\"http:\/\/blog.coliam.net\/?p=993\">http:\/\/blog.coliam.net\/?p=993<\/a><\/p>\n<p>android \u5de5\u7a0b\u5e2b\u9762\u8a66\u5bf6\u5178<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u96d6\u7136\u6700\u8fd1\u4e26\u6c92\u6709\u627e\u5de5\u4f5c\uff0c\u4f46\u662f\u770b\u4e86\u4e00\u672c\u66f8\u300eAndroid \u5de5\u7a0b\u5e2b\u9762\u8a66\u5bf6\u5178\u300f\uff0c\u4e3b\u8981\u662f\u56e0\u70ba\u9019\u662f\u4e00\u672c\u5145\u6eff\u5c0f\u6280\u5de7\u7684\u6280\u8853\u66f8\uff0c [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[167],"tags":[101,244],"_links":{"self":[{"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/posts\/122"}],"collection":[{"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=122"}],"version-history":[{"count":5,"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/posts\/122\/revisions"}],"predecessor-version":[{"id":1411,"href":"https:\/\/boochlin.com\/index.php?rest_route=\/wp\/v2\/posts\/122\/revisions\/1411"}],"wp:attachment":[{"href":"https:\/\/boochlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=122"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=122"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/boochlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=122"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}