android app记录运行日志 捕获奔溃异常 ，存储日志到文件

感恩原创：http://blog.csdn.net/u014763302/article/details/47422023

app在运行过程中，为了后期的维护升级，记录日志是一个非常好的方法。

为了读取到app运行时的日志，一般的作法是单独开一个线程，在app运行的启动线程，然后app退出时停掉线程。

然而我们更好的方法是开启一个service，然后在里面做日志记录，代码如下：

package com.hai.logcat;import java.io.BufferedReader;import java.io.DataInputStream;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.util.List;import android.app.ActivityManager;import android.app.ActivityManager.RunningAppProcessInfo;import android.app.Service;import android.content.Intent;import android.os.Environment;import android.os.IBinder;import android.os.Looper;import android.util.Log;import android.widget.Toast;public class MyLogcat extends Service {    Thread thread;    boolean readlog = true;    @Override    public IBinder onBind(Intent intent) {        return null;    }    @Override    public void onCreate() {        super.onCreate();        Log.d("hhp", "onCreate");        thread = new Thread(new Runnable() {            @Override            public void run() {                log2();//个人觉得这个方法更实用            }        });    }    @Override    public void onStart(Intent intent, int startId) {        thread.start();        Log.d("hhp", "onStart");        super.onStart(intent, startId);    }    /**     * 方法1     */    private void log2() {        Log.d("hhp", "log2 start");        String[] cmds = { "logcat", "-c" };        String shellCmd = "logcat -v time -s *:W "; // adb logcat -v time *:W        Process process = null;        Runtime runtime = Runtime.getRuntime();        BufferedReader reader = null;        try {            runtime.exec(cmds).waitFor();            process = runtime.exec(shellCmd);            reader = new BufferedReader(new InputStreamReader(process.getInputStream()));            String line = null;            while ((line = reader.readLine()) != null) {                if (line.contains(String.valueOf(android.os.Process.myPid()))) {                    // line = new String(line.getBytes("iso-8859-1"), "utf-8");                    writeTofile(line);                }            }        } catch (Exception e) {            e.printStackTrace();        }        Log.d("hhp", "log2 finished");    }    /**     * 方法2     */    private void log() {        Log.d("hhp", "log start");        String[] cmds = { "logcat", "-c" };        String shellCmd = "logcat -v time -s *:W ";// //adb logcat -v time *:W        Process process = null;        InputStream is = null;        DataInputStream dis = null;        String line = "";        Runtime runtime = Runtime.getRuntime();        try {            runtime.exec(cmds);            process = runtime.exec(shellCmd);            is = process.getInputStream();            dis = new DataInputStream(is);            // String filter = GetPid();            String filter = android.os.Process.myPid() + "";            while ((line = dis.readLine()) != null) { //这里如果输入流没断，会一直循环下去。                line = new String(line.getBytes("iso-8859-1"), "utf-8");                if (line.contains(filter)) {                    int pos = line.indexOf(":");                    Log.d("hhp2", line + "");                    writeTofile(line);                }            }        } catch (Exception e) {        }        Log.d("hhp", "log finished");    }    private void writeTofile(String line) {        String content = line + "\r\n";        File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath()                + "/logcat/myLog.txt");        if (!file.exists()) {            try {                file.createNewFile();            } catch (Exception e) {                e.printStackTrace();            }        }        FileOutputStream fos;        try {            fos = new FileOutputStream(file, true);            fos.write(content.getBytes());            fos.flush();            fos.close();        } catch (Exception e) {            e.printStackTrace();        }    }    @Override    public void onDestroy() {        super.onDestroy();        stopSelf();    }}

代码比较简单，所以没怎么注视了。说下大概思路：在service开启的时候，就开启线程不停地从logcat中读取输入流，

把读到的信息存入文件中，service停止的时候线程stop，就这么简单。

当然要读入系统日志还需要添加权限：

上面的代码基本可以记录本app运行中的日志，但如果中途有未捕获的异常导致app奔溃，那么这个未捕获的异常导致的奔溃上面代码就记录不到了。

因为这个异常导致app奔溃，虚拟机挂掉，那当然记录日志的线程也停了。那怎么捕获这类我们未捕获的异常（运行时异常）呢，幸好android这样

一个接口UncaughtExceptionHandler，当app奔溃前，它会先通知这个接口，这样我们就可以在app奔溃前做点自己想做的事了。

关于怎么捕获奔溃异常，我觉得这位哥们的一片博客写的不错http://blog.csdn.net/liuhe688/article/details/6584143#， 我借鉴着改了下：

package com.hai.logcat;import java.io.File;import java.io.FileOutputStream;import java.io.PrintWriter;import java.io.StringWriter;import java.io.Writer;import java.lang.Thread.UncaughtExceptionHandler;import java.lang.reflect.Field;import java.text.DateFormat;import java.text.SimpleDateFormat;import java.util.Date;import java.util.HashMap;import java.util.Map;import android.content.Context;import android.content.pm.PackageInfo;import android.content.pm.PackageManager;import android.content.pm.PackageManager.NameNotFoundException;import android.os.Build;import android.os.Environment;import android.os.Looper;import android.util.Log;import android.widget.Toast;public class CrashHandler implements UncaughtExceptionHandler {    public static final String TAG = "CrashHandler";    // 系统默认的UncaughtException处理类    private Thread.UncaughtExceptionHandler mDefaultHandler;    // CrashHandler实例    private static CrashHandler INSTANCE = new CrashHandler();    // 程序的Context对象    private Context mContext;    // 用来存储设备信息和异常信息    private Map<String, String> infos = new HashMap<String, String>();    // 用于格式化日期,作为日志文件名的一部分    private DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss  ");    /** 保证只有一个CrashHandler实例 */    private CrashHandler() {    }    /** 获取CrashHandler实例 ,单例模式 */    public static CrashHandler getInstance() {        return INSTANCE;    }    /**     * 初始化     *      * @param context     */    public void init(Context context) {        mContext = context;        // 获取系统默认的UncaughtException处理器        mDefaultHandler = Thread.getDefaultUncaughtExceptionHandler();        // 设置该CrashHandler为程序的默认处理器        Thread.setDefaultUncaughtExceptionHandler(this);    }    /**     * 当UncaughtException发生时会转入该函数来处理     */    @Override    public void uncaughtException(Thread thread, Throwable ex) {        if (!handleException(ex) && mDefaultHandler != null) {            // 如果用户没有处理则让系统默认的异常处理器来处理            mDefaultHandler.uncaughtException(thread, ex);        } else {            try {                Thread.sleep(3000);            } catch (InterruptedException e) {                Log.e(TAG, "error : ", e);            }            // 退出程序            android.os.Process.killProcess(android.os.Process.myPid());            System.exit(1);        }    }    /**     * 自定义错误处理,收集错误信息 发送错误报告等操作均在此完成.     *      * @param ex     * @return true:如果处理了该异常信息;否则返回false.     */    private boolean handleException(final Throwable ex) {        if (ex == null) {            return false;        }        // 使用Toast来显示异常信息        new Thread() {            @Override            public void run() {                Looper.prepare();                ex.printStackTrace();                Toast.makeText(mContext, "很抱歉,程序出现异常,即将退出.", Toast.LENGTH_LONG).show();                Looper.loop();            }        }.start();        // 收集设备参数信息        collectDeviceInfo(mContext);        // 保存日志文件        saveCrashInfo2File(ex);        return true;    }    /**     * 收集设备参数信息     *      * @param ctx     */    public void collectDeviceInfo(Context ctx) {        try {            PackageManager pm = ctx.getPackageManager();            PackageInfo pi = pm.getPackageInfo(ctx.getPackageName(), PackageManager.GET_ACTIVITIES);            if (pi != null) {                String versionName = pi.versionName == null ? "null" : pi.versionName;                String versionCode = pi.versionCode + "";                infos.put("versionName", versionName);                infos.put("versionCode", versionCode);            }        } catch (NameNotFoundException e) {            Log.e(TAG, "an error occured when collect package info", e);        }        Field[] fields = Build.class.getDeclaredFields();        for (Field field : fields) {            try {                field.setAccessible(true);                infos.put(field.getName(), field.get(null).toString());                Log.d(TAG, field.getName() + " : " + field.get(null));            } catch (Exception e) {                Log.e(TAG, "an error occured when collect crash info", e);            }        }    }    /**     * 保存错误信息到文件中     *      * @param ex     * @return 返回文件名称,便于将文件传送到服务器     */    private String saveCrashInfo2File(Throwable ex) {        StringBuffer sb = new StringBuffer();        for (Map.Entry<String, String> entry : infos.entrySet()) {            String key = entry.getKey();            String value = entry.getValue();            sb.append(key + "=" + value + "\n");        }        Writer writer = new StringWriter();        PrintWriter printWriter = new PrintWriter(writer);        ex.printStackTrace(printWriter);        Throwable cause = ex.getCause();        while (cause != null) {            cause.printStackTrace(printWriter);            cause = cause.getCause();        }        printWriter.close();        String result = writer.toString();        String time = formatter.format(new Date());        sb.append(time + result);        try {            long timestamp = System.currentTimeMillis();            String fileName = "crash.log";            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {                String path =Environment.getExternalStorageDirectory().getAbsolutePath()+ "/logcat/";                File dir = new File(path);                if (!dir.exists()) {                    dir.mkdirs();                }                FileOutputStream fos = new FileOutputStream(path + fileName, true);                fos.write((sb.toString()).getBytes());                fos.close();            }            return fileName;        } catch (Exception e) {            Log.e(TAG, "an error occured while writing file...", e);        }        return null;    }}

上面我们实现了这个接口，然后在奔溃前做了一些友好处理，如存储奔溃日志，主动杀死进程，不让弹出系统的强制关闭对话框。

然后我们在Application中这样引用即可

package com.hai;import android.app.Application;import com.hai.logcat.CrashHandler;public class MyApplication extends Application {    CrashHandler handler = null;    @Override    public void onCreate() {        super.onCreate();        handler = CrashHandler.getInstance();        handler.init(getApplicationContext());    }}