文章目录
一、报错信息
二、解决方案
一、报错信息
使用场景 : 需要 Hook 住 View 的 OnClickListener 点击方法 , 该监听器在 View 的内部类 ListenerInfo 中 , 需要先通过反射 , 得到 ListenerInfo 字节码对象 ;
// 反射获取 OnClickListener 成员 // ① 先根据全类名获取 ListenerInfo 字节码 Class<?> clazz = null; try { clazz = Class.forName("android.view.View.ListenerInfo"); } catch (ClassNotFoundException e) { e.printStackTrace(); }
报错信息 :
2021-06-17 10:28:27.453 31301-31301/com.example.plugin_hook W/System.err: java.lang.ClassNotFoundException: android.view.View.ListenerInfo 2021-06-17 10:28:27.453 31301-31301/com.example.plugin_hook W/System.err: at java.lang.Class.classForName(Native Method) 2021-06-17 10:28:27.453 31301-31301/com.example.plugin_hook W/System.err: at java.lang.Class.forName(Class.java:453) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at java.lang.Class.forName(Class.java:378) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at com.example.plugin_hook.MainActivity.hook(MainActivity.java:67) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at com.example.plugin_hook.MainActivity.onCreate(MainActivity.java:32) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.Activity.performCreate(Activity.java:7144) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.Activity.performCreate(Activity.java:7135) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2931) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3086) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1816) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.os.Handler.dispatchMessage(Handler.java:106) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.os.Looper.loop(Looper.java:193) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at android.app.ActivityThread.main(ActivityThread.java:6718) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at java.lang.reflect.Method.invoke(Native Method) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: Caused by: java.lang.ClassNotFoundException: Didn't find class "android.view.View.ListenerInfo" on path: DexPathList[[zip file "/data/app/com.example.plugin_hook-IURzN0enGDqjeLown9_p1w==/base.apk"],nativeLibraryDirectories=[/data/app/com.example.plugin_hook-IURzN0enGDqjeLown9_p1w==/lib/arm64, /system/lib64]] 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:134) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at java.lang.ClassLoader.loadClass(ClassLoader.java:379) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: at java.lang.ClassLoader.loadClass(ClassLoader.java:312) 2021-06-17 10:28:27.454 31301-31301/com.example.plugin_hook W/System.err: ... 20 more 2021-06-17 10:28:27.456 31301-31301/com.example.plugin_hook E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.plugin_hook, PID: 31301 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.plugin_hook/com.example.plugin_hook.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.reflect.Field java.lang.Class.getField(java.lang.String)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2951) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3086) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1816) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:193) at android.app.ActivityThread.main(ActivityThread.java:6718) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.reflect.Field java.lang.Class.getField(java.lang.String)' on a null object reference at com.example.plugin_hook.MainActivity.hook(MainActivity.java:75) at com.example.plugin_hook.MainActivity.onCreate(MainActivity.java:32) at android.app.Activity.performCreate(Activity.java:7144) at android.app.Activity.performCreate(Activity.java:7135) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2931) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3086) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1816) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:193) at android.app.ActivityThread.main(ActivityThread.java:6718) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 2021-06-17 10:28:27.463 31301-31301/com.example.plugin_hook I/Process: Sending signal. PID: 31301 SIG: 9
二、解决方案
在此记录下 , 这种低级错误以后少犯 , 内部类要使用
包名.外部类$内部类
的形式 , 进行表示 ;
android.view.View$ListenerInfo
是 ListenerInfo 的正确表示方式 , 外部类与内部类之间使用 $ 符号 ;
修改后 :
// 反射获取 OnClickListener 成员 // ① 先根据全类名获取 ListenerInfo 字节码 Class<?> clazz = null; try { clazz = Class.forName("android.view.View$ListenerInfo"); } catch (ClassNotFoundException e) { e.printStackTrace(); }
