java远程URLConnection调用链接接口get、post两种方式

最原始URLConnection方式如下，除此之外还有更加优化版的http请求方式，如HttpClient、okhttp3请求方式。

HttpClient案例详解：https://blog.csdn.net/justry_deng/article/details/81042379

okhttp3案例详解：https://blog.csdn.net/WoAiShuiGeGe/article/details/108325882

一、调用端

提供get、post两种方式

package com.example.consumer.controller.Http;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.StandardCharsets;
import java.util.Map;

public class RequestHttpUtil {


    /**
     * 向指定URL发送GET方法的请求
     * 有参数或者无参数
     * @param url 发送请求的URL
     * @return 所代表远程资源的响应结果
     */
    public static String sendGet(String url, Map requestHeader) {
        String result = "";
        BufferedReader in = null;
        try {
            String urlNameString = url;
            URL realUrl = new URL(urlNameString);
            // 打开和URL之间的连接
            URLConnection conn = realUrl.openConnection();
            if (requestHeader == null) {
                // 设置通用的请求属性
                conn.setRequestProperty("accept", "*/*");
                conn.setRequestProperty("connection", "Keep-Alive");
                conn.setRequestProperty("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
                //可设置header内的如token、密钥等功能，当然可以将此作为接口正式参数进行传递
                conn.addRequestProperty("appkey","123465789");
            } else {
                // 设置自定义的请求属性
                // connection.setRequestProperty("user-agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
                for (String key : requestHeader.keySet())
                    conn.setRequestProperty(key, requestHeader.get(key));
            }
            // 建立实际的连接
            conn.connect();
            // 定义 BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "utf-8"));// 防止乱码
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 使用finally块来关闭输入流
        finally {
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
        return result;
    }


    /**
     * 向指定URL发送POST方法的请求
     *
     * @param url   请求URL
     * @param param 请求体字符串
     * @return 响应结果
     */
    public static String sendPost(String url, String param, Map requestheader) {
        PrintWriter out = null;
        BufferedReader in = null;
        String result = "";
        try {
            URL realUrl = new URL(url);
            // 打开和URL之间的连接
            URLConnection conn = null;
            conn = realUrl.openConnection();
            conn.setConnectTimeout(2000);
            conn.setReadTimeout(1000);
            if (requestheader != null) {
                // 自定义请求属性
                for (String key : requestheader.keySet())
                    conn.setRequestProperty(key, requestheader.get(key));
            } else {
                // 设置通用的请求属性
                conn.setRequestProperty("Content-Type","application/json");
                conn.setRequestProperty("accept", "*/*");
                conn.setRequestProperty("connection", "Keep-Alive");
                conn.setRequestProperty("user-agent",
                        "User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36");
                //可设置header内的如token、密钥等功能，当然可以将此作为接口正式参数进行传递
                conn.addRequestProperty("appkey","123465789");
            }
            // 发送POST请求必须设置如下两行
            conn.setDoOutput(true);
            conn.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            out = new PrintWriter(conn.getOutputStream());
            // 发送请求参数
            out.print(param);
            // flush输出流的缓冲
            out.flush();
            // 定义BufferedReader输入流来读取URL的响应
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(), StandardCharsets.UTF_8));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 使用finally块来关闭输出流、输入流
        finally {
            try {
                if (out != null) {
                    out.close();
                }
                if (in != null) {
                    in.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
        return result;
    }

}

测试调用代码

    /**
     * get 无参
     */
    public static void main(String[] args) throws Exception {
        String result = RequestHttpUtil.sendGet("http://localhost:8001/getHttp", null);
        System.out.println(result);
    }

    /**
     * get 有参
     */
    public static void main(String[] args) throws Exception {
        String param = URLEncoder.encode("大家好");
        String result = RequestHttpUtil.sendGet("http://localhost:8001/getHttpParam?param="+param, null);
        System.out.println(result);
    }

    /**
     * post 无参
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        String result = RequestHttpUtil.sendPost("http://localhost:8001/postHttp", "",null);
        System.out.println(result);
    }

    /**
     * post 有参, json对象传值
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        JSONObject object = new JSONObject();
        object.put("param","一个参数");
        String result = RequestHttpUtil.sendPost("http://localhost:8001/postHttpParam", object.toJSONString(),null);
        System.out.println(result);
    }

二、被调用端

接口地址代码

@Api(tags = "接口Http")
@RestController
public class HttpController {

    @ApiOperation(value = "1.getHttp")
    @GetMapping("/getHttp")
    public String getHttp(){
        return "get无参调用成功";
    }

    @ApiOperation(value = "2.getHttpParam")
    @GetMapping("/getHttpParam")
    public String getHttpParam(String param){
        return "get有参调用成功，参数为:"+param;
    }

    @ApiOperation(value = "3.postHttp")
    @PostMapping("/postHttp")
    public String postHttp(){
        return "post无参调用成功";
    }

    @ApiOperation(value = "4.postHttpJson")
    @PostMapping("/postHttpJson")
    public String getHttpParam(@RequestBody String param, HttpServletRequest request){
        //获取header内的如密钥、token等自定义信息
        String key = request.getHeader("appkey");
        System.out.println(key);
        return "post有参调用成功，参数为:"+param;
    }

}