java后台调用HttpURLConnection类模拟浏览器请求(一般用于接口调用)

爱被打了一巴掌 2023-12-08 06:44 27阅读 0赞

原文来源:[https://www.cnblogs.com/liuyitian/p/4041425.html][https_www.cnblogs.com_liuyitian_p_4041425.html]

请求地址使用的【[https://www.baidu.com/baidu?wd=1&tn=monline\_4\_dg&ie=utf-8][https_www.baidu.com_baidu_wd_1_tn_monline_4_dg_ie_utf-8]】

package com.lkstart;
    
    import java.io.BufferedReader;
    import java.io.DataOutputStream;
    import java.io.InputStreamReader;
    import java.net.HttpURLConnection;
    import java.net.URL;
    
    /**
     * @program: 没毛病这个
     * @description:
     * @author: likai
     * @create: 2019-04-17 17:25
     **/
    public class DemoTest1 {
    
    
        /**
         * 接口调用 GET
         */
        public static void httpURLConectionGET(String GET_URL) {
            try {
                URL url = new URL(GET_URL);    // 把字符串转换为URL请求地址
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();// 打开连接
                connection.connect();// 连接会话
                // 获取输入流
                BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));
                String line;
                StringBuilder sb = new StringBuilder();
                while ((line = br.readLine()) != null) {// 循环读取流
                    sb.append(line);
                }
                br.close();// 关闭流
                connection.disconnect();// 断开连接
                System.out.println(sb.toString());
            } catch (Exception e) {
                e.printStackTrace();
                System.out.println("失败!");
            }
        }
    
        /**
         * 接口调用  POST
         *
         * @param parm
         * @param POST_URL
         */
        public static void httpURLConnectionPOST(String parm, String POST_URL) {
            try {
                URL url = new URL(POST_URL);
    
                // 将url 以 open方法返回的urlConnection  连接强转为HttpURLConnection连接  (标识一个url所引用的远程对象连接)
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();// 此时cnnection只是为一个连接对象,待连接中
    
                // 设置连接输出流为true,默认false (post 请求是以流的方式隐式的传递参数)
                connection.setDoOutput(true);
    
                // 设置连接输入流为true
                connection.setDoInput(true);
    
                // 设置请求方式为post
                connection.setRequestMethod("POST");
    
                // post请求缓存设为false
                connection.setUseCaches(false);
    
                // 设置该HttpURLConnection实例是否自动执行重定向
                connection.setInstanceFollowRedirects(true);
    
                // 设置请求头里面的各个属性 (以下为设置内容的类型,设置为经过urlEncoded编码过的from参数)
                // application/x-javascript text/xml->xml数据 application/x-javascript->json对象 application/x-www-form-urlencoded->表单数据
                // ;charset=utf-8 必须要，不然妙兜那边会出现乱码【★★★★★】
                connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
    
                // 建立连接 (请求未开始,直到connection.getInputStream()方法调用时才发起,以上各个参数设置需在此方法之前进行)
                connection.connect();
    
                // 创建输入输出流,用于往连接里面输出携带的参数,(输出内容为?后面的内容)
                DataOutputStream dataout = new DataOutputStream(connection.getOutputStream());
    
    
                // 将参数输出到连接
                dataout.writeBytes(parm);
    
                // 输出完成后刷新并关闭流
                dataout.flush();
                dataout.close(); // 重要且易忽略步骤 (关闭流,切记!)
    
                System.out.println(connection.getResponseCode());
    
                // 连接发起请求,处理服务器响应  (从连接获取到输入流并包装为bufferedReader)
                BufferedReader bf = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));
                String line;
                StringBuilder sb = new StringBuilder(); // 用来存储响应数据
    
                // 循环读取流,若不到结尾处
                while ((line = bf.readLine()) != null) {
                    sb.append(line).append(System.getProperty("line.separator"));
                }
                bf.close();    // 重要且易忽略步骤 (关闭流,切记!)
                connection.disconnect(); // 销毁连接
                //System.out.println(sb.toString());
                System.out.println("response内容长度:" + String.valueOf(sb).length());
    
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        public static void main(String[] args) {
            // get方式请求的地址
            final String GET_URL = "https://www.baidu.com/baidu?wd=1&tn=monline_4_dg&ie=utf-8";
            // post方式请求的地址
            final String POST_URL = "https://www.baidu.com/baidu";
            httpURLConectionGET(GET_URL);
            System.out.println("\n**********************华丽的分割线**********************\n");
    
    
            // 格式 parm = aaa=111&bbb=222&ccc=333&ddd=444
            String parm = "wd=%E9%98%BF%E9%87%8C&tn=monline_4_dg&ie=utf-8";
            httpURLConnectionPOST(parm, POST_URL);
        }
    }

[https_www.cnblogs.com_liuyitian_p_4041425.html]: https://www.cnblogs.com/liuyitian/p/4041425.html
[https_www.baidu.com_baidu_wd_1_tn_monline_4_dg_ie_utf-8]: https://www.baidu.com/baidu?wd=1&tn=monline_4_dg&ie=utf-8