Android Crash Exception Capture Method

The biggest headache in development is when the app suddenly explodes and jumps back to the desktop.Also, we often don't know when this will happen, it's good to be in the application debugging phase, and we can check the debugging tool's log to see where the error occurs.But when you break up when you normally use it, you will be ready to cry without tears.
So today we will focus on 1. How to catch Unchecked exceptions that occur in the system.What is an Unchecked exception, in other words, a non-checked exception that cannot be displayed with try-catch.

Let's start with Exception.Exception is divided into two categories: one is CheckedException and the other is UncheckedException.The main difference between the two Exceptions is that CheckedException needs to display capture with try... catch... and UncheckedException does not need capture.Usually UncheckedException is also called RuntimeException.effective java states that checked exceptions (CheckedException) are used for recoverable conditions, and run-time exceptions (RuntimeException) are used for program errors (meaning irrecoverable, big errors bred).Our common RuntimeExcepitons are IllegalArgumentException, IllegalStateException, NullPointerException, IndexOutOfBoundsException and so on.For those CheckedExceptions, the exception that we caught during the writing of the program is try... catch... CheckedException.IOException and its subclasses in the io package, these are CheckedException.

1. Use UncaughtExceptionHandler to catch unchecked exceptions

UncaughtException handles a class that takes over a program when an Uncaught exception occurs and records sending error reports.
Go straight to the code

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.Locale;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import android.annotation.SuppressLint;
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;
/**
* UncaughtException处理类,当程序发生Uncaught异常的时候,有该类来接管程序,并记录发送错误报告.
* 
* @author user
* 
*/
@SuppressLint("SdCardPath")
public class CrashHandler implements UncaughtExceptionHandler {
public static final String TAG = "TEST";
// CrashHandler 实例
private static CrashHandler INSTANCE = new CrashHandler();
// 程序的 Context 对象
private Context mContext;
// 系统默认的 UncaughtException 处理类
private Thread.UncaughtExceptionHandler mDefaultHandler;
// 用来存储设备信息和异常信息
private Map<String, String> infos = new HashMap<String, String>();
// 用来显示Toast中的信息
private static String error = "程序错误，额，不对，我应该说，服务器正在维护中，请稍后再试";
private static final Map<String, String> regexMap = new HashMap<String, String>();
// 用于格式化日期,作为日志文件名的1部分
private DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss",
Locale.CHINA);
/** 保证只有1个 CrashHandler 实例 */
private CrashHandler() {
//
}
/** 获取 CrashHandler 实例 ,单例模式 */
public static CrashHandler getInstance() {
initMap();
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);
Log.d("TEST", "Crash:init");
}
/**
* 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);
Log.d("TEST", "defalut");
} else {
try {
Thread.sleep();
} catch (InterruptedException e) {
Log.e(TAG, "error : ", e);
}
// 退出程序
android.os.Process.killProcess(android.os.Process.myPid());
// mDefaultHandler.uncaughtException(thread, ex);
System.exit();
}
}
/**
* 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(Throwable ex) {
if (ex == null) {
return false;
}
// 收集设备参数信息
// collectDeviceInfo(mContext);
// 保存日志文件
saveCrashInfoFile(ex);
// 使用 Toast 来显示异常信息
new Thread() {
@Override
public void run() {
Looper.prepare();
Toast.makeText(mContext, error, Toast.LENGTH_LONG).show();
Looper.loop();
}
}.start();
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 saveCrashInfoFile(Throwable ex) {
StringBuffer sb = getTraceInfo(ex);
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);
try {
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 = Environment.getExternalStorageDirectory()
+ "/crash/";
File dir = new File(path);
if (!dir.exists()) {
dir.mkdirs();
}
FileOutputStream fos = new FileOutputStream(path + fileName);
fos.write(sb.toString().getBytes());
fos.close();
}
return fileName;
} catch (Exception e) {
Log.e(TAG, "an error occured while writing file...", e);
}
return null;
}
/**
* 整理异常信息
* @param e
* @return
*/
public static StringBuffer getTraceInfo(Throwable e) {
StringBuffer sb = new StringBuffer();
Throwable ex = e.getCause() == null ? e : e.getCause();
StackTraceElement[] stacks = ex.getStackTrace();
for (int i = ; i < stacks.length; i++) {
if (i == ) {
setError(ex.toString());
}
sb.append("class: ").append(stacks[i].getClassName())
.append("; method: ").append(stacks[i].getMethodName())
.append("; line: ").append(stacks[i].getLineNumber())
.append("; Exception: ").append(ex.toString() + "\n");
}
Log.d(TAG, sb.toString());
return sb;
}
/**
* 设置错误的提示语
* @param e
*/
public static void setError(String e) {
Pattern pattern;
Matcher matcher;
for (Entry<String, String> m : regexMap.entrySet()) {
Log.d(TAG, e+"key:" + m.getKey() + "; value:" + m.getValue());
pattern = Pattern.compile(m.getKey());
matcher = pattern.matcher(e);
if(matcher.matches()){
error = m.getValue();
break;
}
}
}
/**
* 初始化错误的提示语
*/
private static void initMap() {
// Java.lang.NullPointerException
// java.lang.ClassNotFoundException
// java.lang.ArithmeticException
// java.lang.ArrayIndexOutOfBoundsException
// java.lang.IllegalArgumentException
// java.lang.IllegalAccessException
// SecturityException
// NumberFormatException
// OutOfMemoryError 
// StackOverflowError 
// RuntimeException 
regexMap.put(".*NullPointerException.*", "嘿，无中生有~Boom!");
regexMap.put(".*ClassNotFoundException.*", "你确定你能找得到它？");
regexMap.put(".*ArithmeticException.*", "我猜你的数学是体育老师教的，对吧？");
regexMap.put(".*ArrayIndexOutOfBoundsException.*", "恩，无下限=无节操，请不要跟我搭话");
regexMap.put(".*IllegalArgumentException.*", "你的出生就是1场错误。");
regexMap.put(".*IllegalAccessException.*", "很遗憾，你的信用卡账号被冻结了，无权支付");
regexMap.put(".*SecturityException.*", "死神马上降临");
regexMap.put(".*NumberFormatException.*", "想要改变1下自己形象？去泰国吧，包你满意");
regexMap.put(".*OutOfMemoryError.*", "或许你该减减肥了");
regexMap.put(".*StackOverflowError.*", "啊，啊，憋不住了！");
regexMap.put(".*RuntimeException.*", "你的人生走错了方向，重来吧");
}
}

2. Establish an Application for global monitoring

import android.app.Application;
public class CrashApplication extends Application {
@Override
public void onCreate() {
super.onCreate();
CrashHandler crashHandler = CrashHandler.getInstance();
crashHandler.init(getApplicationContext());
}
} 

Finally, add registration information to the profile

<application android:name=".CrashApplication" ... /> 

And rights

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

Submit the error log to the network server This block has not been added.If you add this feature, you can have a real-time error log for users to use, can timely feedback errors occurring at different times for different models, and can bring great convenience to our developers'later maintenance.

This site introduces you so much about Android crash exception capture methods, and I hope it will help you!