Android性能优化 Java Crash监控

1.什么是Crash

• Crash也就是APP代码异常奔溃，从而导致App闪退，也许我们在开发的时候测试一切正常，但是在线上，用户量多起来之后，什么五花八门的机子都有，多多少少会发生Crash。
• 当App奔溃后，我们应及时记录下问题，保存到文件，待下次启动app时，再上传服务器，然后分析错误日志，修改问题。
• Android 有Java层的Crash，还有Native层Carsh，这次先了解怎么拿到Java层的Crash。

2.Java层Crash

• Java的Crash比较简单，Java中的Thread定义了一个接口：UncaughtExceptionHandler，用于处理未捕获的异常导致线程的终止，但是try/catch 的错误捕获不了。
• 当我们的应用crash的时候，就会走 UncaughtExceptionHandler.uncaughtException ，在该方法中可以获取到异常的信息，通过 Thread.setDefaultUncaughtExceptionHandler 该方法来设置线程的默认异常处理器。
• 重写完成 uncaughtException 逻辑后，记得再调用一次uncaughtException(t, e)，否则可能会白屏，APP也在那傻等。
• Carsh文件可以保存后上传服务器，也可以在下次打开App上传。

2.1 保存Crash信息

public class TestCrashHandler implements Thread.UncaughtExceptionHandler {
    //crash存储文件夹， /Android/data/包名/files/crash_info/目录下
    private static final String CRASH_FILES = "crash_info";
    //crash文件后缀
    private static final String CRASH_FILE_NAME = "_crash.txt";
    private static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";

    private static Context mContext;
    private static Thread.UncaughtExceptionHandler uncaughtExceptionHandler;


    private SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT);

    public static void init(Context context) {
        mContext = context.getApplicationContext();

        uncaughtExceptionHandler = Thread.getDefaultUncaughtExceptionHandler();
        Thread.setDefaultUncaughtExceptionHandler(new TestCrashHandler());
    }

    @Override
    public void uncaughtException(@NonNull @NotNull Thread t, @NonNull @NotNull Throwable e) {
        saveCrash(t, e);
    }

    /**
     * 将Crash信息保存起来
     *
     * @param t
     * @param e
     */
    private void saveCrash(@NonNull @NotNull Thread t, @NonNull @NotNull Throwable e) {
        //创建文件夹 /Android/data/包名/files/crash_info/目录下
        File dir = mContext.getExternalFilesDir(CRASH_FILES);
        if (!dir.exists()) {
            dir.mkdirs();
        }
        //Crash时间
        String time = dateFormat.format(System.currentTimeMillis());
        File file = new File(dir, time + CRASH_FILE_NAME);

        PrintWriter printWriter = null;
        FileWriter fileWriter = null;
        try {
            fileWriter = new FileWriter(file);
            printWriter = new PrintWriter(fileWriter);
            //异常时间
            printWriter.write("Crash_Time : " + time + "\n");
            //手机信息
            printWriter.write(phoneInfo());
            //线程信息
            printWriter.write("Thread : " + t.getName() + "\n");
            //异常信息
            printWriter.write("Exception : " );
            e.printStackTrace( printWriter);
        } catch (IOException | PackageManager.NameNotFoundException ioException) {
            ioException.printStackTrace();
        } finally {
            try {
                if (printWriter != null) {
                    printWriter.flush();
                    printWriter.close();
                }
                if (fileWriter != null) {
                    fileWriter.flush();
                    fileWriter.close();
                }
            } catch (IOException ioException) {
                ioException.printStackTrace();
            }
            //如果不写，APP就可能白屏，不闪退，也就是不处理
            if (uncaughtExceptionHandler != null) {
                uncaughtExceptionHandler.uncaughtException(t, e);
            }
        }
    }

    /**
     * 获取App信息、手机信息、获取其他需要的信息
     *
     * @return
     * @throws PackageManager.NameNotFoundException
     */
    private String phoneInfo() throws PackageManager.NameNotFoundException {
        StringBuilder stringBuilder = new StringBuilder();

        PackageManager pkm = mContext.getPackageManager();
        PackageInfo packageInfo = pkm.getPackageInfo(mContext.getPackageName(), PackageManager.GET_ACTIVITIES);

        //App版本
        stringBuilder.append("App_VersionName : ");
        stringBuilder.append(packageInfo.versionName);
        stringBuilder.append("\n");
        stringBuilder.append("App_VersionCode : ");
        stringBuilder.append(packageInfo.versionCode);
        stringBuilder.append("\n");

        //Android版本号
        stringBuilder.append("Android_Version : ");
        stringBuilder.append(Build.VERSION.RELEASE);
        stringBuilder.append("\n");
        stringBuilder.append("Android_VersionCode : ");
        stringBuilder.append(Build.VERSION.SDK_INT);
        stringBuilder.append("\n");

        //手机厂商
        stringBuilder.append("Vendor : ");
        stringBuilder.append(Build.MANUFACTURER);
        stringBuilder.append("\n");

        //手机型号
        stringBuilder.append("Phone_Model : ");
        stringBuilder.append(Build.MODEL);
        stringBuilder.append("\n");

        //CPU架构
        stringBuilder.append("CPU : ");
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            stringBuilder.append(Arrays.toString(Build.SUPPORTED_ABIS));
        } else {
            stringBuilder.append(Build.CPU_ABI);
        }
        stringBuilder.append("\n");

        return stringBuilder.toString();
    }
}

2.2 测试

public class CrashTestReport {
    public static void init(Context application){
        TestCrashHandler.init(application);
    }
    
    /**
     * RuntimeException
     */
    public static void test1(){
        int i = 1/0;
    }

    /**
     * StackOverflowError
     */
    public static void test2(){
        test2();
    }
}

2.3 文件里的Crash信息

• test1方法测试结果，RuntimeException。

Crash_Time : 2021-06-04 22:43:56
App_VersionName : 1.0
App_VersionCode : 1
Android_Version : 10
Android_VersionCode : 29
Vendor : HUAWEI
Phone_Model : VOG-AL00
CPU : [arm64-v8a, armeabi-v7a, armeabi]
Thread : main
Exception : java.lang.RuntimeException: Unable to start activity ComponentInfo{com.bao.myapplication/com.bao.myapplication.MainActivity}: java.lang.ArithmeticException: divide by zero
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3898)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4081)
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:91)
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:149)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:103)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2462)
    at android.os.Handler.dispatchMessage(Handler.java:110)
    at android.os.Looper.loop(Looper.java:219)
    at android.app.ActivityThread.main(ActivityThread.java:8393)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1055)
Caused by: java.lang.ArithmeticException: divide by zero
    at com.bao.myapplication.carsh.CrashTestReport.test1(CrashTestReport.java:11)
    at com.bao.myapplication.MainActivity.onCreate(MainActivity.kt:79)
    at android.app.Activity.performCreate(Activity.java:8121)
    at android.app.Activity.performCreate(Activity.java:8109)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1320)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3871)
    ... 11 more

• test2 方法测试结果，StackOverflowError。

Crash_Time : 2021-06-05 00:49:39
App_VersionName : 1.0
App_VersionCode : 1
Android_Version : 10
Android_VersionCode : 29
Vendor : HUAWEI
Phone_Model : VOG-AL00
CPU : [arm64-v8a, armeabi-v7a, armeabi]
Thread : main
Exception : java.lang.StackOverflowError: stack size 8192KB
   at com.bao.myapplication.carsh.CrashTestReport.test2(CrashTestReport.java:15)
   at com.bao.myapplication.carsh.CrashTestReport.test2(CrashTestReport.java:15)
   at com.bao.myapplication.carsh.CrashTestReport.test2(CrashTestReport.java:15)
   .
   .
   at com.bao.myapplication.carsh.CrashTestReport.test2(CrashTestReport.java:15)
   at com.bao.myapplication.carsh.CrashTestReport.test2(CrashTestReport.java:15)
   at com.bao.myapplication.MainActivity.onCreate(MainActivity.kt:79)
   at android.app.Activity.performCreate(Activity.java:8121)
   at android.app.Activity.performCreate(Activity.java:8109)
   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1320)
   at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3871)
   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:4081)
   at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:91)
   at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:149)
   at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:103)
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2462)
   at android.os.Handler.dispatchMessage(Handler.java:110)
   at android.os.Looper.loop(Looper.java:219)
   at android.app.ActivityThread.main(ActivityThread.java:8393)
   at java.lang.reflect.Method.invoke(Native Method)
   at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1055)