Android捕获程序异常退出时的错误log信息

很多时候我们程序无缘无故的就挂掉了，让我们一头雾水，如果刚好我们在调试，那我们可以通过错误log来查看是什么原因引起的程序崩溃。但是当我们把程序发别人使用时，就没那么好运了，那我们要怎么样才能捕获到那个错误异常呢？还好android给我们提供了UncaughtExceptionHandler 这个类，我们可以通过实现这个类的接口，来全局捕获那个让程序崩掉的错误log信息。可以将错误的log保存在本地，也可以发送给服务器后台。下面来看下UncaughtExceptionHandler 的实现类CrashHandler吧。

CrashHandler.java

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
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.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

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 {

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

private static final String SINGLE_RETURN = "\n";
private static final String SINGLE_LINE = "--------------------------------";

private static CrashHandler mCrashHandler;
private Context mContext;
private UncaughtExceptionHandler mDefaultHandler;
private StringBuffer mErrorLogBuffer = new StringBuffer();

/**
 * 获取CrashHandler实例，单例模式。
 * 
 * @return 返回CrashHandler实例
 */
public static CrashHandler getInstance() {
if (mCrashHandler == null) {
synchronized (CrashHandler.class) {
if (mCrashHandler == null) {
                    mCrashHandler = new CrashHandler();
                }
            }
        }

return mCrashHandler;
    }

public void init(Context context) {
        mContext = context;
// 获取系统默认的uncaughtException处理类实例
        mDefaultHandler = Thread.getDefaultUncaughtExceptionHandler();
// 设置成我们处理uncaughtException的类
        Thread.setDefaultUncaughtExceptionHandler(this);
    }

@Override
public void uncaughtException(Thread thread, Throwable ex) {
        Log.d(TAG, "uncaughtException:" + ex);
if (!handleException(ex) && mDefaultHandler != null) {
// 如果用户没有处理异常就由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) {
                e.printStackTrace();
            }
            android.os.Process.killProcess(android.os.Process.myPid());
        }
    }

//处理异常事件
private boolean handleException(Throwable ex) {
if (ex == null) {
return false;
        }

new Thread(new Runnable() {

@Override
public void run() {
                Looper.prepare();
                Toast.makeText(mContext, "很抱歉,程序出现异常,即将退出.", Toast.LENGTH_SHORT)
                        .show();
                Looper.loop();
            }
        }).start();

// 收集设备参数信息
        collectDeviceInfo(mContext);
// 收集错误日志
        collectCrashInfo(ex);
// 保存错误日志
        saveErrorLog();
//TODO: 这里可以加一个网络的请求，发送错误log给后台
// sendErrorLog();
return true;
    }

//保存日志到/mnt/sdcard/AppLog/目录下，文件名已时间yyyy-MM-dd_hh-mm-ss.log的形式保存
private void saveErrorLog() {
if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh-mm-ss", Locale.getDefault());
            String format = sdf.format(new Date());
            format += ".log";
            String path = Environment.getExternalStorageDirectory().getPath()+"/AppLog/";
            File file = new File(path);
if (!file.exists()){
                file.mkdirs();
            }

            FileOutputStream fos = null;
try {
                fos = new FileOutputStream(path+format);
                fos.write(mErrorLogBuffer.toString().getBytes());
                fos.flush();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
if (fos != null) {
try {
                        fos.close();
                        fos = null;
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

//收集错误信息
private void collectCrashInfo(Throwable ex) {
        Writer info = new StringWriter();
        PrintWriter printWriter = new PrintWriter(info);
        ex.printStackTrace(printWriter);

        Throwable cause = ex.getCause();
while (cause != null) {
            cause.printStackTrace(printWriter);
            cause = cause.getCause();
        }

        String result = info.toString();
        printWriter.close();

//将错误信息加入mErrorLogBuffer中
        append("", result);
        mErrorLogBuffer.append(SINGLE_LINE + SINGLE_RETURN);

        Log.d(TAG, "saveCrashInfo2File:" + mErrorLogBuffer.toString());
    }

//收集应用和设备信息
private void collectDeviceInfo(Context context) {
//每次使用前，清掉mErrorLogBuffer里的内容
        mErrorLogBuffer.setLength(0);
        mErrorLogBuffer.append(SINGLE_RETURN + SINGLE_LINE + SINGLE_RETURN);

//获取应用的信息
        PackageManager pm = context.getPackageManager();
try {
            PackageInfo pi = pm.getPackageInfo(context.getPackageName(),
                    PackageManager.GET_ACTIVITIES);
if (pi != null) {
                append("versionCode", pi.versionCode);
                append("versionName", pi.versionName);
                append("packageName", pi.packageName);
            }
        } catch (NameNotFoundException e) {
            e.printStackTrace();
        }

        mErrorLogBuffer.append(SINGLE_LINE + SINGLE_RETURN);

//获取设备的信息
        Field[] fields = Build.class.getDeclaredFields();
        getDeviceInfoByReflection(fields);

        fields = Build.VERSION.class.getDeclaredFields();
        getDeviceInfoByReflection(fields);

        mErrorLogBuffer.append(SINGLE_LINE + SINGLE_RETURN);
    }

//获取设备的信息通过反射方式
private void getDeviceInfoByReflection(Field[] fields) {
for (Field field : fields) {
try {
                field.setAccessible(true);
                append(field.getName(), field.get(null));
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
    }

//mErrorLogBuffer添加友好的log信息
private void append(String key, Object value) {
        mErrorLogBuffer.append("" + key + ":" + value + SINGLE_RETURN);
    }
}

在application中的使用非常简单，只要init就好了，之后我们就只要等异常出现吧。
CrashApplication.java

 import android.app.Application;

public class CrashApplication extends Application{

@Override
public void onCreate() {
super.onCreate();

        CrashHandler.getInstance().init(this);
    }
}

不要忘记在AndroidManifest.xml声明我们的CrashApplication 。
AndroidManifest.xml

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

    <application
        android:allowBackup="true"
        android:name=".CrashApplication"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.crashtestdemo.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>