Thread中的异常处理

（1）CheckedException

                1.非线程解决方案

                    对于CheckedException，通常可以通过try、catch或者声明抛出异常throws Exception2种方式来处理异常

                2.线程解决方案

                    定义线程会重写run方法，而run方法的定义如下：

public interface Runnable {    public abstract void run();}

                   可以看出并没有声明抛出异常，所以我们不能通过声明抛出异常的方式来处理异常。

                   如果我们非要声明抛出

public class Task implements Runnable {@Overridepublic void run() throws Exception {int number0 = Integer.parseInt("1");throw new Exception("Just for test");}}

                  会发现连编译都无法通过

Task.java:3: error: run() in Task cannot implement run() in Runnable    public void run() throws Exception {                ^  overridden method does not throw Exception1 error

                 那么就只能通过try、catch方式解决

import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;public class ThreadTest {      public static void main(String[] args) {      MyTask task = new MyTask();          Thread thread = new Thread(task);                    thread.start();      }  } class MyTask implements Runnable {public void run() {try {FileInputStream fInputStream = new FileInputStream(new File("xx.pdf"));} catch (FileNotFoundException e) {e.printStackTrace();}}}

           结果为（xx.pdf文件不存在）：

java.io.FileNotFoundException: xx.pdf (系统找不到指定的文件。)at java.io.FileInputStream.open(Native Method)at java.io.FileInputStream.<init>(FileInputStream.java:106)at my.MyTask.run(ThreadTest.java:20)at java.lang.Thread.run(Thread.java:619)

         总结：对于CheckedException，通过try、catch方式解决即可

（2）UnCheckedException

          也就是RuntimeException、Error等没法捕获的异常、错误

                1.问题引入

public class ThreadTest {      public static void main(String[] args) {      MyTask task = new MyTask();          Thread thread = new Thread(task);                    thread.start();      }  } class MyTask implements Runnable {public void run() {int result = 3/0;}}

               结果为：

Exception in thread "Thread-0" java.lang.ArithmeticException: / by zeroat my.MyTask.run(ThreadTest.java:14)at java.lang.Thread.run(Thread.java:619)

             实际上也抛出了异常，但是无法对异常进行处理

                2.解决方案

                    1）需要单独处理的异常

                         自定义类实现UncaughtExceptionHandler接口，然后为线程设置

import java.lang.Thread.UncaughtExceptionHandler;public class ThreadTest {      public static void main(String[] args) {      MyTask task = new MyTask();          Thread thread = new Thread(task);          thread.setUncaughtExceptionHandler(new MyUncaughtExceptionHandler());//为线程设置        thread.start();      }  } class MyTask implements Runnable {public void run() {int result = 3/0;}}class MyUncaughtExceptionHandler implements UncaughtExceptionHandler{public void uncaughtException(Thread t, Throwable e) {System.out.println("an uncaught exception occured!");System.out.println("thread state is :"+t.getState());System.out.println("thread name is :"+t.getName());System.out.println("error message is :"+e.getMessage());System.out.println("exception stack trace begin:");e.printStackTrace();System.out.println("exception stack trace end");}}

                 结果为：

an uncaught exception occured!thread state is :RUNNABLEthread name is :Thread-0error message is :/ by zeroexception stack trace begin:java.lang.ArithmeticException: / by zeroat my.MyTask.run(ThreadTest.java:16)at java.lang.Thread.run(Thread.java:619)exception stack trace end

             可见可以在其中做异常处理

                    2）处理方法基本相同的异常

                          定义ThreadFactory，使用统一的异常处理

import java.lang.Thread.UncaughtExceptionHandler;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.ThreadFactory;public class ThreadTest {      public static void main(String[] args) {      ExecutorService executorService = Executors.newCachedThreadPool(new MyThreadFacotry());    executorService.execute(new MyTask());    }  } class MyTask implements Runnable {public void run() {int result = 3/0;}}class MyUncaughtExceptionHandler implements UncaughtExceptionHandler{public void uncaughtException(Thread t, Throwable e) {System.out.println("an uncaught exception occured!");System.out.println("thread state is :"+t.getState());System.out.println("thread name is :"+t.getName());System.out.println("error message is :"+e.getMessage());System.out.println("exception stack trace begin:");e.printStackTrace();System.out.println("exception stack trace end");}}class MyThreadFacotry implements ThreadFactory{public Thread newThread(Runnable r) {System.out.println("创建一个新的线程");                Thread t = new Thread(r);                t.setUncaughtExceptionHandler(new MyUncaughtExceptionHandler());                return t;}}

             结果为：

创建一个新的线程an uncaught exception occured!thread state is :RUNNABLEthread name is :Thread-0error message is :/ by zeroexception stack trace begin:java.lang.ArithmeticException: / by zeroat my.MyTask.run(ThreadTest.java:21)at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)at java.lang.Thread.run(Thread.java:619)exception stack trace end