java - 资源已关闭但 sonarlint 仍显示资源未关闭

Question

我已经定义了输出流，如下所示 OutputStream os=new FileOutputStream(文件);

尝试关闭如下资源

if(os != null) {
    try {
       os.close();
    } catch (IOException e) {
       e.printStackTrace();
    }}    

仍然 sonarlint 显示“使用 try-with-resources 或在“finally”子句中关闭此“FileOutputStream”。”

Answer 1

如果您在同一方法中执行操作，请将关闭放在涉及流的打开部分的 try 的 finally 语句中，这一点很重要。这确保了在发生故障(异常)时，如果需要，流始终关闭

错误的声纳代码:

OutputStream os=new FileOutputStream(file);

... // your code operations with os

// If something is going really bad here and ends in exception the
// stream will never be closed

if(os != null) {
    try {
       os.close();
    } catch (IOException e) {
       e.printStackTrace();
    }
} 

更好的代码:

OutputStream os = null;
try{
    os = new FileOutputStream(file);

    ... // your code operations with os

} finally{
    // The stream is allways closed at the end of the method execution
    if(os != null) {
        try {
           os.close();
        } catch (IOException e) {
           e.printStackTrace();
        }
    } 
 } 

最佳代码(Java 1.7 或更高版本的情况)

try (OutputStream  os = new FileOutputStream(file)){

  ... // your code operations with os

  // The stream is allways closed at the end of the try block
}