传统的try catch finally 方式是这样的

    public static void main(String[] args)  {
        FileInputStream fileInputStream = null;
        try{
            // 捕获异常
            fileInputStream = new FileInputStream(new File("/Users/mac/Documents/合规业务组照片.zip"));
            byte[] bytes = new byte[1024];
            int line = 0;
            while ((line = fileInputStream.read(bytes))!= -1){
                System.out.println(new String(bytes,0,line));
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭流
            if(null != fileInputStream){
                try {
                    fileInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

传统的写法导致层级太多，易读性差，不够简洁，JDK 1.8 之后推出了 try-with-resource 写法，大大提高了代码的可读性，使代码更加简洁，使用了try-with-resource是这样的

    public static void main(String[] args) {
       //把打开流的操作都放入try()块里
        try( FileInputStream fileInputStream = new FileInputStream(new File("/Users/mac/Documents/合规业务组照片.zip"))) {
            byte[] bytes = new byte[1024];
            int line = 0;
            while ((line = fileInputStream.read(bytes))!= -1){
                System.out.println(new String(bytes,0,line));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

try-with-resource 本质上跟我们自己关闭流是一样的，只不过是在编译的时候加上了 finally的代码块，让我们看看jdk的编译器帮我们做了什么事吧！

以下是反编译后的代码

package com.network;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
 
public class NetworkUtil {
 
   public static void main(String[] args) {
      try {
         FileInputStream e = new FileInputStream(new File("/Users/mac/Documents/合规业务组照片.zip"));
         Throwable var2 = null;
 
         try {
            byte[] bytes = new byte[1024];
            boolean line = false;
 
            int line1;
            while((line1 = e.read(bytes)) != -1) {
               System.out.println(new String(bytes, 0, line1));
            }
         } catch (Throwable var13) {
            var2 = var13;
            throw var13;
         } finally {
            if(e != null) {
               if(var2 != null) {
                  try {
                     e.close();
                  } catch (Throwable var12) {
                     var2.addSuppressed(var12);
                  }
               } else {
                  e.close();
               }
            }
 
         }
      } catch (IOException var15) {
         var15.printStackTrace();
      }
 
   }
}