java - 使用线程时如何安全关闭流

Question

我有这个代码的线程:

public void run() {

try {
    fileProcessor = new FileProcessor();
    fileProcessor.process();
  } catch (RuntimeException e) {
    // ...
  } finally {
    if (fileProcessor != null) {
      fileProcessor.close();
    }
  }
}

方法fileProcessor.process();也运行一些新线程:

protected void process() {
    this.writer = new Writer();
    final MyClient client = new MyClient();
    client.start();
}

此代码有时会引发异常

Caused by: java.io.IOException: Stream closed
        at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:26)
        at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:99)
        at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:116)
        at java.io.OutputStreamWriter.write(OutputStreamWriter.java:203)
        at java.io.Writer.write(Writer.java:140)
        at java.io.Writer.append(Writer.java:210) 

如何安全地关闭流？因为使用 fileProcessor.close(); 现在我可能关闭这个流，但仍然有一些线程使用它。

Answer 1

对 fileProcessor 中的所有线程使用 thread.join()。这样它将等待所有线程完成其任务。

client.start();
client.join(); // this will make sure client thread finished before proceed to next step

Link to simple tutorial on thread.join for clear understanding