通过java.net.URLConnection发送HTTP请求的方法

最近项目中有用到与外围系统对接, 总结下通过java.net.URLConnection发送HTTP请求的方法。

参考博客：http://www.cnblogs.com/nick-huang/p/3859353.html

由于项目较小，并且只查询一个外部接口数据，采用了简单的get请求；

完整代码如下：

package com.ruoyi.api;

import javax.servlet.http.HttpServletRequest;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.ruoyi.api.bus.vo.LinksV2;
import com.ruoyi.api.bus.vo.TopicItemListV2;
import org.apache.commons.collections.CollectionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

import java.util.ArrayList;
import java.util.List;

@Controller
@RequestMapping("api")
public class testcontroller {

    @Value("${config.getItemInfoUrl}")
    private String url;
    private static final Logger LOGGER = LoggerFactory.getLogger(testcontroller.class);

    @ResponseBody
    @RequestMapping("/data/getlist")
    public List<Links>  testlist(HttpServletRequest request) {
        String jsonInfo = loadJSON(url);
        List<TopicItemListV2> topicItemListV2s = JSONObject.parseArray(jsonInfo, TopicItemListV2.class);
        List<Links> linkLists = new ArrayList<>();
        if (CollectionUtils.isNotEmpty(topicItemListV2s)){
            for (TopicItemListV2 topicItemList : topicItemListV2s){
                Links links = new Links();
                links.setPid("0");
                links.setCode(String.valueOf(topicItemList.getCode()));
                links.setName(topicItemList.getName());
                linkLists.add(links);
                List<LinksV2> linkV2sss = topicItemList.getLinks();
                if (CollectionUtils.isNotEmpty(linkV2sss)){
                    for (LinksV2 li :linkV2sss){
                        Links linkvvv = new Links();
                        linkvvv.setCode(li.getTaskCode());
                        linkvvv.setName(li.getTaskName());
                        linkvvv.setPid(String.valueOf(topicItemList.getCode()));
                        linkLists.add(linkvvv);
                    }
                }
            }
        }
        LOGGER.info(JSON.toJSONString(linkLists));
        return linkLists;
    }

    public  String loadJSON(String url) {
        StringBuilder json = new StringBuilder();
        BufferedReader in = null;
        try {
            // 创建url对象
            URL reqUrl = new URL(url);
            // 打开url链接
            URLConnection yc = reqUrl.openConnection();
            // 建立实际对象
            yc.connect();
            // 定义BufferedReader 数据流来读取URL的相应,并设置编码方式
            in = new BufferedReader(new InputStreamReader(
                    yc.getInputStream(),"utf-8"));
            String inputLine = null;
            //读取内容
            while ((inputLine = in.readLine()) != null) {
                json.append(inputLine);
            }
        } catch (MalformedURLException e) {
            LOGGER.error(" error info" + e);
        } catch (IOException e) {
            LOGGER.error(" error info" + e);
        } finally {
            if (null != in){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return json.toString();
    }
}