Android 未捕获异常crash崩溃日志的截取

Android应用不可避免地会发生crash，也成之为崩溃。无论你的程序写得多么的完美，总是无法完全避免crash的发生，可能是由于Android系统底层的bug，也可能是由于不充分的机型适配或者糟糕的网络情况，当crash发生时，系统会kill掉正在执行的程序，现象是闪退或者提示用户程序已经停止运行。这是对用户来说很不友好，也是开发者不愿意看到的。

但是也并不是没有办法捕获，其实系统给我们提供了Tread.UncaughtExceptionHandler就是默认的未捕获异常的处理，我们只要定义一个类实现它，然后重写uncaughtException方法，把异常打印出来就可以了。

STEP 1：

/**
 * function: 截获崩溃日志：当程序产生未捕获异常
 * Created by lzq on 2017/8/10.
 */

public class CrashHandler implements Thread.UncaughtExceptionHandler{

    //手机存储路径
    private final String logPath = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "Crash";

    private static final String TAG = CrashHandler.class.getSimpleName();

    /** 系统默认的异常处理器（默认情况下，系统会终止当前的异常程序） */
    private Thread.UncaughtExceptionHandler mDefaultCrashHandler;
    private Context mContext;
    private String mProcessName;

    /** CrashHandler 实例 */
    private static CrashHandler instance = new CrashHandler();

    /** 私有构造 保证只有一个CrashHandler实例*/
    private CrashHandler(){
    }

    /** 单例模式 */
    public static CrashHandler getInstance(){
       return instance;
    }


    /** 初始化 */
    public void init(Context context){
        mDefaultCrashHandler = Thread.getDefaultUncaughtExceptionHandler();

        //将当前实例设置为系统默认的异常处理器
        Thread.setDefaultUncaughtExceptionHandler(this);

        mContext = context.getApplicationContext();
        mProcessName = context.getPackageName();
    }

    /** 用于格式化日期,作为日志文件名的一部分. */
    private final DateFormat formatter = new SimpleDateFormat("MMdd-HH:mm:ss", Locale.getDefault());


    @Override
    public void uncaughtException(Thread thread, Throwable throwable) {
        Log.e(TAG, "---------------uncaughtException start---------------\r\n");
        try {
            dumpExceptionToLocalFile(thread, throwable); //把异常日志在手机本地文件输出
            uploadExceptionToServer();  //上传crash日志到服务器
        } catch (IOException e) {
            Log.e(TAG, "uncaughtException,ex:" + e.getMessage());
            e.printStackTrace();
        }

        if (mDefaultCrashHandler != null){
            mDefaultCrashHandler.uncaughtException(thread, throwable);
        }else{
            Process.killProcess(Process.myPid());
        }

        Log.e(TAG, "---------------uncaughtException end---------------\r\n");
    }

    /** dump UncaughtException into local file */
    private void dumpExceptionToLocalFile(Thread thread, Throwable throwable) throws IOException{
        //记录数量达到10个就清理数据
        File logDir = new File(logPath);
        if (logDir.exists()){
            clearExLogWhenMax(logDir);
        }else{
            logDir.mkdirs();
        }

        //错误信息文件名
        Date date = new Date();
        String logFileName = formatter.format(date) + String.format("[%s]", thread.getName())+ ".txt";
        File logExFile = new File(logDir, logFileName);
        logExFile.createNewFile();

        //写入信息到文件中
        try {
            PrintWriter pw = new PrintWriter(new BufferedWriter(new FileWriter(logExFile)));

            //时间戳
            pw.println("Time stamp:" + date);

            pw.println("Process[" + mProcessName + "," + Process.myPid() + "]");

            pw.println();

            //手机信息
            dumpPhoneInfo(pw);

            pw.println();

            //导出异常调用栈信息
            throwable.printStackTrace(pw);
            pw.close();

        }catch (IOException ex){
            Log.e(TAG, "dump info failed");
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }

    }


    /**
     * 设置最大日志数量 10
     * @param logDir 日志目录
     */
    private void clearExLogWhenMax(File logDir){

        File[] logFileList = logDir.listFiles();
        if (logFileList == null || logFileList.length == 0){
            return;
        }

        int length = logFileList.length;
        if (length > 10){
            for (File aFile : logFileList){
                try {
                    if (aFile.delete()){
                        Log.d(TAG, "clearExLogWhenMax:" + aFile.getName());
                    }
                }catch (Exception ex){
                    Log.d(TAG, "clearExLogWhenMax:" + ex);
                }
            }
        }

    }


    private void dumpPhoneInfo(PrintWriter pw) throws IOException, PackageManager.NameNotFoundException {
        PackageManager pm = mContext.getPackageManager();
        PackageInfo pi = pm.getPackageInfo(mContext.getPackageName(), PackageManager.GET_ACTIVITIES);
        pw.println("App Version:" + pi.packageName + "_" + pi.versionCode);
        //Android版本号
        pw.println("OS Version:" + Build.VERSION.RELEASE + "_" + Build.VERSION.SDK_INT);

        //手机制造商
        pw.println("Vendor:" + Build.MANUFACTURER);

        //手机型号
        pw.println("Model:" + Build.MODEL);

        //CPU架构
        pw.println("CPU ABI:" + Build.CPU_ABI);

    }


    private void uploadExceptionToServer() {
        //TODO Upload Exception Message To Your Web Server
    }

}

STEP 2：

在整个应用入口文件中进行初始化

public class MyApp extends Application{

    @Override
    public void onCreate() {
        super.onCreate();
        CrashHandler.getInstance().init(this);
    }
}

STEP 3：

点击Button按钮，抛出一个自己定义的异常，就会产生Crash，而后在手机外存中找到捕获异常的文件。

public class MainActivity extends AppCompatActivity {

    private Button btn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn = (Button) findViewById(R.id.btn);

        checkInitPermissions();

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                throw new RuntimeException("这是自己定义的异常");
            }
        });

    }

    public static final int REQUEST_PERMISSION_CODE = 100;
    private void checkInitPermissions(){

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            String[] permissions = new String[]{
                    //放入需要授予的权限，例如需要写入的权限
                    Manifest.permission.WRITE_EXTERNAL_STORAGE
            };
            if (ContextCompat.checkSelfPermission(this, permissions[0]) != PackageManager.PERMISSION_GRANTED) {
                if (ActivityCompat.shouldShowRequestPermissionRationale(this, permissions[0])){
                    ActivityCompat.requestPermissions(this, permissions, REQUEST_PERMISSION_CODE);
                }
            }
        } else {
            handleAfterPermissions();
        }
    }

    private void  handleAfterPermissions(){

    }


    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_PERMISSION_CODE){
            handleAfterPermissions();
        }
    }
}

crash日志文件存储位置可以自定义，根据这个例子CrashHandler文件中的存储位置，在手机的内部存储Crash/目录下。