java如何中断这个线程？

Question

我有以下代码：

public class Net {
    public static void main(String[] args) {        
        Runnable task = new Runnable() {            
            @Override
            public void run() {
                String host = "http://example.example";
                try {
                    URL url = new URL(host);
                    StringBuilder builder = new StringBuilder();                    
                    HttpURLConnection con = (HttpURLConnection) url.openConnection();
                    try(BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()))) {  
                        String line;
                        while (null != (line = in.readLine())) builder.append(line);
                    }           
                    out.println("data: " + builder.length());
                    con.disconnect();
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        };
        Thread thread = new Thread(task);
        thread.start();
        thread.interrupt();
    }
}

当主机出错时，这个“con.getInputStream（）”会阻塞线程。如何从另一个线程中断此代码

Answer 1

用^{}设置超时值。如果超时过期，捕获SocketTimeoutException，并按照您想要的方式恢复或终止程序

Answer 2

This "con.getInputStream()" blocks thread, when host is wrong. How to interrupt this code from another thread?

这是一个常见问题。中断线程不会导致readLine(...)方法中断。引用我的回答：

I want my thread to handle interruption, but I can't catch InterruptedException because it is a checked exception

It is important to realize that t.interrupt() only sets the interrupted bit in a thread -- it doesn't actually interrupt the thread's processing per se. A thread can be interrupted at any time safely.

因此，如果线程在readLine(...)中被阻塞，则无法中断线程。但是，您可以将循环更改为：

while (!Thread.currentThread().isInterrupted()) {
   String line = in.readLine();
   if (line == null) {
       break;
   }
   builder.append(line);
}

正如其他人所提到的，您可以关闭底层InputStream，这将导致readLine()抛出Exception

Answer 3

一般规则是从“外部”中断不间断线程，即

• 线程等待连接/流-关闭连接
• 线程等待挂起进程完成-通过终止进程
• （不特别是在这种情况下）运行的长循环-通过引入一个布尔变量，该变量从外部设置，并不时在循环内部检查

Answer 4

不幸的是，你不能中断被一些I/O操作阻塞的线程（除非你使用NIO）
您可能需要（通过另一个线程）关闭读取线程阻塞的流
类似这样：

public class Foo implements Runnable{
private InputStream stream;
private int timeOut;
....
   public void run(){
    Thread.sleep(timeOut);
    if(<<ensure the victim thread still is stuck>>){
        stream.close();//this will throws an exception to the stuck thread.
    }
   }
....
}