Java SE 7 更好地管理资源：不仅仅是语法糖 try-with-resources

package com.xiaobu.test.daily.autoCloseAble;

import java.io.DataOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * @author xiaobu
 * @version JDK1.8.0_171
 * @date on  2019/7/31 17:33
 * @description
 */
public class AutoClose implements AutoCloseable {

    @Override
    public void close() throws Exception {
        System.out.println(">>> close()");
        throw new RuntimeException("Exception in close()");
    }


    public void work() throws RuntimeException {
        System.out.println(">>> work()");
        throw new RuntimeException("Exception in work()");
    }

    public static void main(String[] args) {
        try {
            writingWithARM();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try (AutoClose autoClose = new AutoClose()) {
            autoClose.work();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            System.out.println("123 = " + 123);
        }
    }



    private static void writingWithARM() throws IOException {
        try (DataOutputStream out
                     = new DataOutputStream(new FileOutputStream("data"));
        ) {
            out.writeInt(666);
            out.writeUTF("Hello");
        }
    }
}

java.lang.RuntimeException: Exception in work()
	at com.xiaobu.test.daily.autoCloseAble.AutoClose.work(AutoClose.java:20)
	at com.xiaobu.test.daily.autoCloseAble.AutoClose.main(AutoClose.java:25)
	Suppressed: java.lang.RuntimeException: Exception in close()
		at com.xiaobu.test.daily.autoCloseAble.AutoClose.close(AutoClose.java:14)
		at com.xiaobu.test.daily.autoCloseAble.AutoClose.main(AutoClose.java:26)
>>> work()
>>> close()
123 = 123

可以看出先执行try块里面的代码，然后再关闭在try里面声明的资源，多个资源用;隔开

Socket、OutputStream、InputStream和sql Connection在JDK7之后都实现了AutoCloseAble接口。

示例:

try (
       FileOutputStream out = new FileOutputStream("output");
       FileInputStream  in1 = new FileInputStream(“input1”);
       FileInputStream  in2 = new FileInputStream(“input2”)
   ) {
       // Do something useful with those 3 streams!
   }   // out, in1 and in2 will be closed in any case