Java HttpURLConnection

1 什么是Java HttpURLConnection

Java HttpURLConnection类是http特定的URLConnection。它仅适用于HTTP协议。

借助于HttpURLConnection类，您可以获取任何HTTP URL的信息，例如请求头信息，状态代码，响应代码等。

java.net.HttpURLConnection是URLConnection类的子类。

2 如何获取HttpURLConnection对象

public URLConnection openConnection()throws IOException{}  

您可以将其转换为HttpURLConnection类型，如下：

URL url=new URL("http://www.yiidian.com/java");    
HttpURLConnection huc=(HttpURLConnection)url.openConnection();  

3 Java HttpURLConnection的例子

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 *  Java HttpURLConnection的例子
 */
import java.io.*;
import java.net.*;

public class Demo{
    public static void main(String[] args){
        try{
            URL url=new URL("http://www.yiidian.com/java");
            HttpURLConnection huc=(HttpURLConnection)url.openConnection();
            for(int i=1;i<=8;i++){
                System.out.println(huc.getHeaderFieldKey(i)+" = "+huc.getHeaderField(i));
            }
            huc.disconnect();
        }catch(Exception e){System.out.println(e);}
    }
}

输出结果为：

Date = Mon, 27 Apr 2020 01:12:48 GMT
Server = Apache/2.4.7 (Ubuntu)
Last-Modified = Sun, 26 Apr 2020 03:43:18 GMT
ETag = "6f10-5a429663126bf"
Accept-Ranges = bytes
Content-Length = 28432
Vary = Accept-Encoding
Keep-Alive = timeout=5, max=100