java中带参数的try(){}语法含义详解

try(Resource res = xxx)//可指定多个资源
{
     work with res
} 

InputStream is = null;
OutputStream os = null;
try {
    //...
} catch (ioException e) {
    //...
}finally{
    try {
        if(os!=null){
            os.close();
        }
        if(is!=null){
            is.close();
        }
    } catch (IOException e2) {
        //...
    }
}    

try(
    InputStream is = new FileInputStream("...");
    OutputStream os = new FileOutputStream("...");
){
    //...
}catch (IOException e) {
    //...
}

@Test
  public void test2() throws IOException {
    File file = new File("E://test");
    if (!file.exists()) {
      file.createNewFile();
    }
    FileOutputStream fileOutputStream = new FileOutputStream(file);
    try {
      System.out.println("do something...");
      fileOutputStream.write("aaa".getBytes());
      fileOutputStream.flush();
    } catch (Exception e) {
      System.out.println("do ...");
    } finally {
      fileOutputStream.close();
    }
  }

  @Test
  public void test2() throws IOException {
    File file = new File("E://test");
    if (!file.exists()) {
      file.createNewFile();
    }
   
    try( FileOutputStream fileOutputStream = new FileOutputStream(file);) {
      System.out.println("do something...");
      fileOutputStream.write("aaa".getBytes());
      fileOutputStream.flush();
    } catch (Exception e) {
      System.out.println("do ...");
    } 
  }