App crash原因以及解决办法

<pre name="code" class="java">package com.scott.crash;
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.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import android.content.Context;
import android.content.Intent;
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 CrashAplication softApp;
	public static final String TAG="CrashHandler";
	//系统默认的UncaughtException处理类
	private Thread.UncaughtExceptionHandler mDefaultHandler;
	//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**/
	public  CrashHandler(CrashAplication app){
		softApp=app;
	}
	/**
	 * 初始化
	 */
	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为程序默认处理器
		Thread.setDefaultUncaughtExceptionHandler(this);;
	}
	@Override
	public void uncaughtException(Thread thread, Throwable ex) {
		Log.e(TAG, "error : ", ex); 
		//收集设备参数信息   
		collectDeviceInfo(mContext);  
		//保存日志文件   
		saveCrashInfo2File(ex);
		long threadId = thread.getId();  	     
		if (threadId != 1) {  
			// 此处示例跳转到汇报异常界面。  
			Intent intent = new Intent(softApp, LoginActivity.class);  
			intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);   
			softApp.startActivity(intent);  
		} else {  
			// 此处示例发生异常后，重新启动应用  
			Intent intent = new Intent(softApp, LoginActivity.class);    
			intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);  
			softApp.startActivity(intent);  
			// kill App Progress  
			android.os.Process.killProcess(android.os.Process.myPid());  	
		}

	}

	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();
		sb.append(result);
		long timestamp=System.currentTimeMillis();
		String time=formatter.format(new Date());
		String fileName = "crash-" + time + "-" + timestamp + ".log";  
		if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
			String path="/sdcard/crash/";
			File dir=new File(path);
			if(!dir.exists()){
				dir.mkdirs();
			}
			try {
				FileOutputStream fos=new FileOutputStream(path + fileName);
				fos.write(sb.toString().getBytes());
			} catch (FileNotFoundException e) {
				// TODO Auto-generated catch block
				Log.e(TAG, "an error occured while writing file...", e);  
			} catch (IOException e) {
				// TODO Auto-generated catch block
				Log.e(TAG, "an error occured while writing file...", e);  
			}
		}
		return null;
	}
	private void collectDeviceInfo(Context ctx) {
		PackageManager pm=ctx.getPackageManager();
		PackageInfo pi;
		try {
			pi = pm.getPackageInfo(ctx.getPackageCodePath(),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) {
			// TODO Auto-generated catch block
			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 (IllegalAccessException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (IllegalArgumentException e) {
				// TODO Auto-generated catch block
				Log.e(TAG, "an error occured when collect crash info", e);
			}
		}
	}  


}