0.碎碎念

因为只是为了写这个帮助类，解耦，不敢拿已经写了一堆的代码改，就单独拆了个项目出来，持久层全是mybatisplus生成的。
所以就只展示核心的部分，代码也会传到csdn的资源里。
其实可以用Feign，但是没学透不敢用，怕太费时间，这个算是比较简单又快的解耦方式了。

1.controller层

被调用的接口

	/**
     * 根据id查询
     * service层没查询到直接返回null
     * @param gatewayId
     * @return
     */
    @GetMapping("getGatewayById/{gatewayId}")
    public R getGatewayById(@PathVariable(value = "gatewayId") Long gatewayId){
        DvcGateway gateway = dvcGatewayService.getGatewayById(gatewayId);
        Map<String, Object> map = new HashMap<>();
        if(gateway == null){
            map.put("msg", "查询单个网关失败");
            return R.ok(map);
        }else {
            map.put("gateway", gateway);
            map.put("msg", "ok");
            return R.ok(map);
        }
    }

	/**
     * 查询所有的网关信息（不分页）
     * 给其他接口调用使用
     * @return
     */
    @PostMapping("/listGateway")
    public R listGateway(){
        List<DvcGateway> dvcGatewayList = dvcGatewayService.listGateway("");
        if(dvcGatewayList.isEmpty()){
            //如果没有查询到数据
            return R.error();
        }else {
            Map<String, Object> map = new HashMap<>();
            map.put("gatewayList", dvcGatewayList);
            //给调用接口查询是否成功的标识
            map.put("msg", "ok");
            return R.ok(map);
        }
    }

调用的接口

package com.csdn.selma.controller;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.csdn.selma.pojo.DvcGateway;
import com.csdn.selma.pojo.R;
import com.csdn.selma.util.HttpRequestHelper;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RestController
@RequestMapping("/test")
public class TestController {
    @Value("${myConfig.api}")
    private String api;

    @PostMapping("/callGet")
    public R callGet(){
        //测试调用@GetMapping("getGatewayById/{gatewayId}")
        Map<String, Object> paramMap = new HashMap<>();
        JSONObject result = HttpRequestHelper.sendRequestByGet(api + "/gateway/getGatewayById/" + 1);
        if("ok".equals(result.getString("msg"))) {
            Map<String, Object> map = new HashMap<>();
            DvcGateway gateway = JSON.toJavaObject(result.getJSONObject("gateway"), DvcGateway.class);
            map.put("dvcGateway", gateway);
            return R.ok(map);
        }
        return R.error();
    }

    @PostMapping("/callPost")
    public R callPost(){
        //测试调用@PostMapping("/listGateway")
        Map<String, Object> paramMap = new HashMap<>();
        JSONObject result = HttpRequestHelper.sendRequestByPost(paramMap, api + "/gateway/listGateway");
        if("ok".equals(result.get("msg"))) {
            Map<String, Object> map = new HashMap<>();
            List<DvcGateway> gatewayList = (List<DvcGateway>) result.get("gatewayList");
            map.put("gatewayList", gatewayList);
            return R.ok(map);
        }
        return R.error();
    }
}

2.util层

第一层调用

package com.csdn.selma.util;

import com.alibaba.fastjson.JSONObject;
import lombok.extern.slf4j.Slf4j;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

@Slf4j
public class HttpRequestHelper {

    /**
     * 封装同步请求POST
     * @param paramMap
     * @param url
     * @return
     */
    public static JSONObject sendRequestByPost(Map<String, Object> paramMap, String url){
        String result = "";
        try {
            //封装post参数
            StringBuilder postdata = new StringBuilder();
            for (Map.Entry<String, Object> param : paramMap.entrySet()) {
                postdata.append(param.getKey()).append("=")
                        .append(param.getValue()).append("&");
            }
            log.info(String.format("--> 发送请求：post data %1s", postdata));
            byte[] reqData = postdata.toString().getBytes("utf-8");
            //调方法发送请求
            byte[] respData = HttpUtil.doPost(url, reqData);
            result = new String(respData);
            log.info(String.format("--> 应答结果：result data %1s", result));
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return JSONObject.parseObject(result);
    }
    /**
     * 封装同步请求GET
     * @param url
     * @return
     */
    public static JSONObject sendRequestByGet(String url){
        String result = "";
        try {
            log.info(String.format("--> 发送请求：get url %1s", url));
            //调方法发送请求
            byte[] respData = HttpUtil.doGet(url);
            result = new String(respData);
            log.info(String.format("--> 应答结果：result data %1s", result));
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return JSONObject.parseObject(result);
    }
}

第二层调用

package com.csdn.selma.util;

import lombok.extern.slf4j.Slf4j;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

@Slf4j
public class HttpUtil {

    static final String POST = "POST";
    static final String GET = "GET";
    static final int CONN_TIMEOUT = 30000;// ms
    static final int READ_TIMEOUT = 30000;// ms

    /**
     * post 方式发送http请求.
     *
     * @param strUrl
     * @param reqData
     * @return
     */
    public static byte[] doPost(String strUrl, byte[] reqData) {
        return send(strUrl, POST, reqData);
    }

    /**
     * get方式发送http请求.
     *
     * @param strUrl
     * @return
     */
    public static byte[] doGet(String strUrl) {
        return send(strUrl, GET, null);
    }

    /**
     * @param strUrl
     * @param reqmethod
     * @param reqData
     * @return
     */
    public static byte[] send(String strUrl, String reqmethod, byte[] reqData) {
        try {
            URL url = new URL(strUrl);
            HttpURLConnection httpcon = (HttpURLConnection) url.openConnection();
            httpcon.setDoOutput(true);
            httpcon.setDoInput(true);
            httpcon.setUseCaches(false);
            httpcon.setInstanceFollowRedirects(true);
            httpcon.setConnectTimeout(CONN_TIMEOUT);
            httpcon.setReadTimeout(READ_TIMEOUT);
            httpcon.setRequestMethod(reqmethod);
            httpcon.connect();
            if (reqmethod.equalsIgnoreCase(POST)) {
                OutputStream os = httpcon.getOutputStream();
                os.write(reqData);
                os.flush();
                os.close();
            }
            BufferedReader in = new BufferedReader(new InputStreamReader(httpcon.getInputStream(),"utf-8"));
            String inputLine;
            StringBuilder bankXmlBuffer = new StringBuilder();
            while ((inputLine = in.readLine()) != null) {
                bankXmlBuffer.append(inputLine);
            }
            in.close();
            httpcon.disconnect();
            return bankXmlBuffer.toString().getBytes();
        } catch (Exception ex) {
            log.error(ex.toString(), ex);
            return null;
        }
    }
}