一.问题抛出

• android运行的时候难免会有一些空指针(NullPointerException)或者下标越界(IndexOutOfBoundsException),用户使用的过程操作某一个按钮的时候,就发生了崩溃.这时候可能还没有到他感兴趣的部分,程序就Crash掉了,因此导致了用户流失.如何让程序在轻微异常情况下依然保持高可用

• 在集成一些第三方库的时候,我们不能修改里面的实现(例如 Gson,FastJson,OkHttp,OkSocket,Glide)等,那么如果他们里面抛出异常如何解决,Glide加载图片之后填充图片时,如果Activity销毁就会造成崩溃,那么我们如何解决?

二.解决效果

预防崩溃演示效果图.gif

三.解决思路

• MainLooper一定要保证在崩溃的时候持续Loop
• 子线程发生崩溃,保证主线程Looper继续Loop
• 当绘制,测量,布局出现问题导致编舞者Crash时,应该及时处理(关闭当前异常的界面)
• 生命周期方法发生了异常,在ActivityThread里面hook其中的Instrumentation.进行代理.
• 对ActivityThread中的mH 变量添加Callback,对于不能再Instrumentation中处理的异常进行再次Catch.最大限度保证不崩溃.

四.成品Library

Github项目地址: https://github.com/xuuhaoo/Android-DefenseCrash (欢迎Star)
集成方法:

• Please add the code into your project gradle file

文档 Android Defense Crash

为了方便中国同学,提供了翻译文档如下:中文文档

What's this

This’s a Crash Defense library in Android to help you catch the Java exceptions which you don’t expected.

Integration

• Step 1 Find the build.gradle file in your project and add the code into it as follow.

allprojects {
  repositories {
    //other mavens
    maven(){
      url "https://dl.bintray.com/xuuhaoo/maven"
    }
  }
}

• Step 2 Find the build.gradle file in the module that you want to integration

dependencies {
    implementation 'com.tonystark.android:defense-crash:last.version’
}

Attentions: last.versionis a substitute word, the real version will be found in [图片上传失败...(image-d56e40-1612263642898)]

Use

• Initialize should be more earlier in application create, we suggest you put the init code in Application attachBaseContext(base:Context)

  • Sample

  override fun attachBaseContext(base: Context) {
  super.attachBaseContext(base)
  DefenseCrash.initialize(this)
  ...
  }
  

• Install Defense library after initialize.

  • Sample

  override fun attachBaseContext(base: Context) {
  super.attachBaseContext(base)
  DefenseCrash.initialize(this)
  DefenseCrash.install { thread, throwable, isSafeMode, isCrashInChoreographer ->
    //thread: The crash happened’s thread.
    //throwable: The Exception exactly is.
    //isSafeMode: If application is allready crashed and we saved it that is mean you are in safe mode,
    //that happens most of the time is your Main Looper is compromised by some errors and not going to normal,and we keep it runing that’s called safe mode.
    //isCrashInChoreographer: If crash happend in OnMeasure/OnLayout/OnDraw it will case screen blank or some view not draw successfully
    //If you got this true, we suggest you restart or finish the current Activity for good
  
    //You can throw some throwables here and if you do that, will case VM got this throwable and shutdown your process.
    //And you should do somting here such as:
    Log.i("Exceptionhandler",
      "thread:${thread.name} " +
      "exception:${throwable.message} " +
      "isCrashInChoreographer:$isCrashInChoreographer " +
      "isSafeMode:$isSafeMode")
    throwable.printStackTrace()
    FirebaseCrashlytics.getInstance().recordException(throwable);
  }
  }
  

• Uninstall Defense library if you don’t need this.

  • Sample

  DefenseCrash.unInstall()