使用try-with-resources静态关闭资源 [英] Close resource quietly using try-with-resources

问题描述

可以忽略使用try-with-resources语句关闭资源时抛出的异常吗？

Is it possible to ignore the exception thrown when a resource is closed using a try-with-resources statement?

示例：

class MyResource implements AutoCloseable{
  @Override
  public void close() throws Exception {
    throw new Exception("Could not close");
  }  
  public void read() throws Exception{      
  }
}

//this method prints an exception "Could not close"
//I want to ignore it
public static void test(){
  try(MyResource r = new MyResource()){
    r.read();
  } catch (Exception e) {
    System.out.println("Exception: " + e.getMessage());
  }
}

或者我应该继续关闭一个终于

Or should I continue to close in a finally instead?

public static void test2(){
  MyResource r = null;
  try {
     r.read();
  }
  finally{
    if(r!=null){
      try {
        r.close();
      } catch (Exception ignore) {
      }
    }
  }
}

推荐答案

我在coin-dev邮件列表中找到了这个答案：
http://mail.openjdk.java.net/pipermail/coin-dev/2009-April/001503.html

I found this answered on the coin-dev mailing list: http://mail.openjdk.java.net/pipermail/coin-dev/2009-April/001503.html

5。关闭方法的一些失败可以被安全地忽略（例如，
关闭一个打开以供读取的文件）。这个结构是否提供
？

否。虽然这个功能似乎有吸引力，但不清楚的是，
值得增加复杂性。实际上，这些无害的
例外很少发生，所以如果这些例外被忽略，程序将不再是稳健的
。如果你觉得你必须忽略它们，
有一个解决方法，但它不漂亮：

No. While this functionality seems attractive, it is not clear that it's worth the added complexity. As a practical matter these "harmless exceptions" rarely if ever occur, so a program will be no more robust if these exceptions are ignored. If you feel you must ignore them, there is a workaround, but it isn't pretty:

static void copy(String src, String dest) throws IOException {
    boolean done = false;
    try (InputStream in = new FileInputStream(src)) {
        try(OutputStream out = new FileOutputStream(dest)) {
            byte[] buf = new byte[8192];
            int n;
            while ((n = in.read(buf)) >= 0)
                out.write(buf, 0, n);
        }
        done = true;
    } catch(IOException e) {
        if (!done)
            throw e;
    }
}

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