异常拦截 - 简书

不会crash的app.png

activity的crash监听主要分为两部分：
1、Thread.setDefaultUncaughtExceptionHandle监听所有线程的异常
比如：在activity中点击某个null控件造成的crash
2、ActivityThread.mH.mCallback监听主要是监听activity消息范围内的异常
比如：在activity中的onCreate中的null造成的crash
首先这两部分监听是包含关系，1包含2，如果在2中的异常被吃掉，则1中就拦截不到了否则1可以拦截到。
只需要在这两个地方提前拦截掉就不会造成crash(crash被吃掉)
如何吃掉？很简单在它们的回调中写入：

 while (true) {// 把crash吃掉，防止异常闪退
            try {
                Looper.loop();
            } catch (Throwable e) {
            }
        }

第一部分监听简单。第二部分比较复杂，要用hook技术
需要hook部分：
类：android.app.ActivityThread
方法：currentActivityThread
属性：mH
回调：mCallback

        Class activityThreadClass = Class.forName("android.app.ActivityThread");
        Object activityThread = activityThreadClass.getDeclaredMethod("currentActivityThread").invoke(null);
        Field mhField = activityThreadClass.getDeclaredField("mH");
        mhField.setAccessible(true);
        final Handler mhHandler = (Handler) mhField.get(activityThread);
        Field callbackField = Handler.class.getDeclaredField("mCallback");
        callbackField.setAccessible(true);

然后就可以callbackField.set(mhHandler,myCall)
在myCall中可以处理activity中的消息了。
具体什么消息可以查看:
ActivityThread.H里的消息常量
我们用到的

        final int LAUNCH_ACTIVITY = 100;// launch
        final int PAUSE_ACTIVITY = 101;// pause
        final int PAUSE_ACTIVITY_FINISHING = 102;//
        final int STOP_ACTIVITY_HIDE = 104;
        final int RESUME_ACTIVITY = 107;
        final int DESTROY_ACTIVITY = 109;

callbackField.set(mhHandler, new Handler.Callback() {
            @Override
            public boolean handleMessage(Message msg) {
                Log.d(TAG,"what:"+msg.what+" msg:"+msg.toString());
                switch (msg.what) {
                    case LAUNCH_ACTIVITY:// startActivity--> activity.attach  activity.onCreate  r.activity!=null  activity.onStart  activity.onResume
                        try {
                            mhHandler.handleMessage(msg);//正常信息
                        } catch (Throwable throwable) {//异常信息：eg：启动失败
                            //在这里利用hook技术杀死当前的activity，决定是否吃掉异常等处理
                        }
                        return true;
                }
                return false;
            }
        });

Android中的黑屏问题,通过识别Throwable中的信息来判断是否当前黑屏了

if ("android.view.Choreographer".equals(element.getClassName()) &&
                    "Choreographer.java".equals(element.getFileName())
                    && "doFrame".equals(element.getMethodName())) {// 根据多年经验，这里会造成黑屏
            }

销毁当前crash的activity
通过hook技术解决不同api版本的兼容处理,抽取：

/**
 * Created By George
 * Description:
 * 规范：api兼容处理具体实现下发，在各个对应的场景中实现杀死当前异常的activity
 */
public interface IActivityKiller {
    void finishLaunchActivity(Message message);

    void finishResumeActivity(Message message);

    void finishPauseActivity(Message message);

    void finishStopActivity(Message message);
}

例如：

/**
 * Created By George
 * Description:
 * android 7.0 and 7.1.1
 * 杀死当前异常的activity
 */
public class ActivityKillerV24_V25 implements IActivityKiller{
    @Override
    public void finishLaunchActivity(Message message) {
        try {
            Object activityClientRecord = message.obj;

            Field tokenField = activityClientRecord.getClass().getDeclaredField("token");// hook出token属性
            tokenField.setAccessible(true);
            IBinder binder = (IBinder) tokenField.get(activityClientRecord);
            finish(binder);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void finishResumeActivity(Message message) {
        finishSomeArgs(message);
    }

    @Override
    public void finishPauseActivity(Message message) {
        finishSomeArgs(message);
    }

    @Override
    public void finishStopActivity(Message message) {
        finishSomeArgs(message);
    }

    private void finish(IBinder binder) throws Exception {
        /*
         ActivityManagerNative.getDefault()
                 .finishActivity(r.token, Activity.RESULT_CANCELED, null, Activity.DONT_FINISH_TASK_WITH_ACTIVITY);
         */
        Class activityManagerNativeClass = Class.forName("android.app.ActivityManagerNative");
        Method getDefaultMethod = activityManagerNativeClass.getDeclaredMethod("getDefault");
        Object activityManager = getDefaultMethod.invoke(null);
        Method finishActivityMethod = activityManager.getClass().getDeclaredMethod("finishActivity", IBinder.class, int.class, Intent.class, int.class);
        int DONT_FINISH_TASK_WITH_ACTIVITY = 0;
        finishActivityMethod.invoke(activityManager, binder, Activity.RESULT_CANCELED, null, DONT_FINISH_TASK_WITH_ACTIVITY);
    }

    private void finishSomeArgs(Message message) {
        try {
            Object someArgs = message.obj;
            Field arg1Field = someArgs.getClass().getDeclaredField("arg1");
            arg1Field.setAccessible(true);
            IBinder binder = (IBinder) arg1Field.get(someArgs);
            finish(binder);
        } catch (Throwable throwable) {
            throwable.printStackTrace();
        }
    }
}

demo