Java如何调用接口API并返回数据（两种方法）

Java如何调用接口API并返回数据（两种方法）
java处理请求接口后返回的json数据-直接处理json字符串
处理思路：

将返回的数据接收到一个String对象中（有时候需要自己选择性的取舍接收）
再将string转换为JSONObject对象
用get（）方法获取到对应的值
注意：基于第三点的特殊情况，如果返回的json里面出现多组数据的情况，则需要转换为数据（用JSONObject.parseArrat()转换再进行操作 ，可无限套娃）

调用接口，请求数据

1.post方法

import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import org.springframework.beans.factory.annotation.Autowired;

import java.io.IOException;
import java.net.URI;
import java.util.*;   
public static JSONObject postResponse(String url,JSONObject jsonParam){

       HttpClient client = HttpClients.createDefault();
//     要调用的接口方法
        HttpPost post = new HttpPost(url);
        JSONObject jsonObject = null;
        try {
        StringEntity s = new StringEntity(jsonParam.toString(),"UTF-8");
        s.setContentType("application/json");
        post.setEntity(s);
        post.setHeader("Content-Type","application/json");

            HttpResponse res = client.execute(post);
        if(res.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
            /*返回json格式*/
            jsonObject = JSONObject.parseObject(EntityUtils.toString(res.getEntity()));
        }
        } catch (IOException e) {
            System.out.println("接口调用出错！");
            e.printStackTrace();
            throw new RuntimeException(e);

        }
        return jsonObject;
    }

2.get方法

import com.alibaba.fastjson.JSONObject;
import edu.zhku.fire_ant_project.config.WxConstant;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class HttpCallOtherInterfaceUtils {
    public static void main(String args[]) {
        HttpClient client = HttpClients.createDefault();
        // 要调用的接口方法
        String url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid="+ WxConstant.appid +"&secret="+WxConstant.secret;
        HttpGet httpGet=new HttpGet(url);
        JSONObject jsonObject = null;
        try {
            HttpResponse res = client.execute(httpGet);
            if (res.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                // 返回json格式：
                jsonObject = JSONObject.parseObject(EntityUtils.toString(res.getEntity()));
                System.out.println(jsonObject);
            }
        } catch (Exception e) {
            System.out.println("服务间接口调用出错！");
            e.printStackTrace();
        }
    }
}

处理返回后的json数据

参考代码：

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

public class JsonStr {
    public static void main(String[] args) {
        //1.比如从前端接收的是这个样子的json字符串,但是我们是不能直接获取到经度 纬度所对应的值的，所以必须要对这个字符串进行解析，
        String str = "{\"code\":\"0\"," +
                            "\"error\":null," +
                            "\"msg\":\"success\"," +
                            "\"detail\":[\n" +
                             "    {\"phoneNum\":\"013012401091\",\n" +
                             "    \"lat\":34.431864,\n" +
                             "    \"lon\":109.25992,\n" +
                             "    \"height\":360,\n" +
                             "    \"speed\":33,\n" +
                             "    \"direction\":10,\n" +
                             "    \"gpsTime\":1615420800000,\n" +
                             "    \"gpsDateTime\":1615420800000,\n" +
                             "    \"mileage\":253830800,\n" +
                             "    \"alarms\":[24],\n" +
                             "    \"status\":[1,2,21],\n" +
                             "    \"property\":{}\n" +
                             "    }" +
                            " ]" +
                         " }";
        //先转换成JSONObject类型
        JSONObject jsonObj = JSON.parseObject(str);
        //通过JSONObject中的getString("key")方法，得到对应的值  {"code":"0","error":null,"msg":"success"}这种类型
        System.out.println("code："+jsonObj.getString("code"));
        
        //2.字符串中含有数组的，比如像detail中的数据
        JSONArray jsonInfo = JSONObject.parseArray(jsonObj.getString("detail"));//将jsonObj解析成json数组
        for (int i = 0; i < jsonInfo.size(); i++) {//遍历detail信息
            JSONObject jsonDetailInfo = jsonInfo.getJSONObject(i);//根据下标以此拿数据，每一个数据又是一个JSONObject对象，所以用JSONObject接收
            String lat = jsonDetailInfo.getString("lat");
            String lon = jsonDetailInfo.getString("lon");
            String gpsDateTime = jsonDetailInfo.getString("gpsDateTime");
            //然后进行其他处理
            System.out.println("lat："+lat+";lon:"+lon+";gpsDateTime："+gpsDateTime);
        }
    }
}

例子： 请求数据要求分页 所以采取循环
 返回值说明：
  {
  "code": "200",
  "data": {
      "endRow": 2,
      "firstPage": 1,
      "hasNextPage": true,
      "hasPreviousPage": false,
      "isFirstPage": true,
      "isLastPage": false,
      "lastPage": 8,
      "list": [
          {
              "packingUnit": "盒", //包装单位
              "factory": "河北百善药业有限公司", //生产企业
              "salePrice": 11.7, //销售价
              "fullSalePrice": 11.5, //整件销售价
              "inventoryQuantity": 172, //库存
              "pictureUrl": "/upload/product/pic/2021/11/20101013-2-424389.png", //商品图片
              "policyTitle": "10盒起积0.5分/盒，20盒起积1分/盒",//商品政策：比如10盒积1分意思是10盒每盒减1元，10s5：表示买10盒送5盒
              "policyStartDate": "2022-11-01",//商品政策开始日期
              "policyEndDate": "2022-11-30",//商品政策结束日期
              "validDateStr": "2024-09-07",//最近批号有效期
              "batchNumber": "2207012",    //最近批号
              "registerFileUrl": "https://img.zc511.com/data/uploadRegisterFileOne.shtml?productCode=20101013-2",    //    注册资料下载URL
              "authorizeNumber": "国药准字Z20063720",
              "rowId": 1,
              "barCode": "6909557000263",//商品条码
              "parseProductName": "接骨片",//商品名称
              "productCode": "20101013-2",//商品条码
              "countryCode": "ZG01AAJ0247010302685",//国家码 医保码
              "packingAmount": 200,//大包装
              "parseProductSpec": "60片",//规格
              "retailPrice": 196,//市场零售价
              "minPackingNumber": 0//最小购买包装
          }
      ],
      "navigatePages": 8,
      "navigatepageNums": [
          1,
          2,
          3,
          4,
          5,
          6,
          7,
          8
      ],
      "nextPage": 2,
      "pageNum": 1,
      "pageSize": 2,
      "pages": 5627,
      "prePage": 0,
      "size": 2,
      "startRow": 1,
      "total": 11254
  },
  "msg": "",
  "success": true
}

HttpCilentutil

请求接口数据

import com.alibaba.fastjson.JSONObject;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import org.springframework.beans.factory.annotation.Autowired;

import java.io.IOException;
import java.net.URI;
import java.util.*;
public class HttpClientUtil 
{
    public static JSONObject postResponse(String url,JSONObject jsonParam){
       HttpClient client = HttpClients.createDefault();
//     要调用的接口方法
        HttpPost post = new HttpPost(url);
        JSONObject jsonObject = null;
        try {
        StringEntity s = new StringEntity(jsonParam.toString(),"UTF-8");
        s.setContentType("application/json");
        post.setEntity(s);
        post.setHeader("Content-Type","application/json");
            HttpResponse res = client.execute(post);
        if(res.getStatusLine().getStatusCode() == HttpStatus.SC_OK){
            /*返回json格式*/
            jsonObject = JSONObject.parseObject(EntityUtils.toString(res.getEntity()));
        }
        } catch (IOException e) {
            System.out.println("接口调用出错！");
            e.printStackTrace();
            throw new RuntimeException(e);

        }
        return jsonObject;
    }
//请求一次接口 先获取分页后的总数据
    public static Map<String,Object> getOneRequest(){
        String url ="http://gateway.zc511.com/getway/v2/product_list_get.shtml";
        JSONObject params = new JSONObject();
        params.put("timestamp","1650865510301");
        params.put("appKey","ZBKJ");
        params.put("secret","123");
        params.put("sign","1186D2A92FC3AB4E5671EBF58B9896A6");
        params.put("buyerCode","3330020298-1");
        params.put("pageNum","1");
        params.put("pageSize","2000");
        JSONObject jsonObject = HttpClientUtil.postResponse(url,params);
//        System.out.println("第一次请求："+jsonObject);
        Boolean success = (Boolean) jsonObject.get("success");
        JSONObject data = (JSONObject) jsonObject.get("data");
        Boolean isLastPage =(Boolean) data.get("isLastPage");//是否为最后一页
        Integer pages =(Integer) data.get("pages");//一共多少页  按每页取多少条进行计算的(共可以获取多少次)
        Integer total = (Integer)data.get("total");// 总数据
        Integer pageNum = (Integer) data.get("pageNum");//当前页数
        Map<String, Object> response = new HashMap<>();
        response.put("pages",pages);
        response.put("isLastPage",isLastPage);
        response.put("total",total);
        response.put("data",data);
        response.put("pageNum",pageNum);
        return response;
    }
}

controller

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.sun.org.apache.xpath.internal.operations.Bool;
import com.zc.zcdj.domain.LhkjHzhnData;
import com.zc.zcdj.domain.ResponseEntity;
import com.zc.zcdj.mapper.LhkjHzhnDataMapper;
import com.zc.zcdj.service.ILhkjHzhnDataService;
import com.zc.zcdj.utils.HttpClientUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcOperations;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collector;
import java.util.stream.Collectors;

/**
 * 

 * 前端控制器
 * 
 *
 * @author guoshanshan
 * @since 2023-03-21
 */

@Component
public class LhkjHzhnDataController {

    @Autowired
    private ILhkjHzhnDataService lhkjHzhnDataService;
    @Autowired
    private LhkjHzhnDataMapper lhkjHzhnDataMapper;
    @Autowired
    private JdbcOperations jdbcTemplate;

    private static final Logger log = LoggerFactory.getLogger("获取珍诚全量数据");

    /**
     * 获取珍诚全量数据
     */
//    @Scheduled(cron = "0 14 13 ? * *")
//    public void getAll(){
//        System.out.println("111111111111111111111111111111");
//        lhkjHzhnDataService.getProductList();
//    }
    @Scheduled(cron = "0 49 19 ? * *")
    public void getProductList() {
        Map<String, String> AllTybm = lhkjHzhnDataMapper.getTybm().stream().filter(s -> s.get统一商品编码() != null).filter(s -> s.get规则() != null).collect(Collectors.toMap(s -> s.get规则(), s -> s.get统一商品编码()));

        log.info("第一次请求珍诚接口...");
//        请求第一次获取数据总条数 以及分页后循环次数
        Map<String, Object> response = HttpClientUtil.getOneRequest();
        Integer pages = (Integer) response.get("pages");//
        Integer total = (Integer) response.get("total");
        Integer pageNum = (Integer) response.get("pageNum");//当前页数
//        Boolean isLastPage = (Boolean) response.get("isLastPage");
//        JSONObject data = (JSONObject) response.get("data");
        log.info("获取珍诚商品列表全量数据共有" + total + "条,共有" + pages + "页数据");
        log.info("珍诚全量开始执行...");
        for (int i = 1; i <= pages; i++) {
            String url = "http://gateway.zc511.com/getway/v2/product_list_get.shtml";
            JSONObject params = new JSONObject();
            params.put("timestamp", "1650865510301");
            params.put("appKey", "ZBKJ");
            params.put("secret", "123");
            params.put("sign", "1186D2A92FC3AB4E5671EBF58B9896A6");
            params.put("buyerCode", "3330020298-1");
            params.put("pageNum", pageNum);
            params.put("pageSize", "2000");
            JSONObject jsonObject = HttpClientUtil.postResponse(url, params);
            log.info("开始获取第" + i + "页数据");
            JSONObject data = (JSONObject) jsonObject.get("data");
            Boolean isLastPage = (Boolean) data.get("isLastPage");//是否为最后一页
            //        获取list中的商品数据 JSONArray
            JSONArray list = data.getJSONArray("list");
            for (int j = 0; j < list.size(); j++) {
                LhkjHzhnData hzhnData = new LhkjHzhnData();
                String packingUnit = list.getJSONObject(j).getString("packingUnit");//包装单位
                Double salePrice = list.getJSONObject(j).getDouble("salePrice");//销售价
                String factory = list.getJSONObject(j).getString("factory");//生产企业
                Integer inventoryQuantity = list.getJSONObject(j).getInteger("inventoryQuantity");//库存
                Date validDateStr = list.getJSONObject(j).getDate("validDateStr");//有效期
                String authorizeNumber = list.getJSONObject(j).getString("authorizeNumber");//国药准字
                String barCode = list.getJSONObject(j).getString("barCode");//商品条码
                String parseProductName = list.getJSONObject(j).getString("parseProductName");//商品名称
                String packingAmount = list.getJSONObject(j).getString("packingAmount");//大包装
                String parseProductSpec = list.getJSONObject(j).getString("parseProductSpec");//规格
                String minPackingNumber = list.getJSONObject(j).getString("minPackingNumber");//最小购买包装
                if (authorizeNumber != null && parseProductSpec != null) {
                    String authorizeNumberNew = authorizeNumber.replaceAll("[^a-zA-Z/0-9]", "");
                    String parseProductSpecNew = parseProductSpec.replaceAll("[^0-9]", "");
                    String tj = authorizeNumberNew.toUpperCase() + parseProductSpecNew;
                    hzhnData.set统一编码("0");
                    String tybm = (String) AllTybm.get(tj);
                    if (tybm != null && tybm != "0") {
                        hzhnData.set统一编码(tybm);
                    }
                }
                hzhnData.set药品名称(parseProductName);
                hzhnData.set规格(parseProductSpec);
                hzhnData.set产地(factory);
                hzhnData.set单位(packingUnit);
                hzhnData.set大包装(packingAmount);
                hzhnData.set批准文号(authorizeNumber);
                hzhnData.set库存数量(inventoryQuantity);
                hzhnData.set价格(salePrice);
                hzhnData.setTxm(barCode);
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
                if (validDateStr != null) {
                    hzhnData.set有效期(sdf.format(validDateStr));
                } else {
                    hzhnData.set有效期(null);
                }
                hzhnData.set库区("珍诚");
                hzhnData.set供应商("珍诚");
                hzhnData.set中包装(minPackingNumber);
                Date date = new Date();
                SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                hzhnData.setStoragedate(sdf1.format(date));
//            hzhnData.set备注();
//            hzhnData.setHyid();
                System.out.println("第" + (j + 1) + "条" + hzhnData);
            lhkjHzhnDataMapper.insert(hzhnData);
            }
            pageNum += 1;

        }

     log.info("获取珍诚全量数据运行完毕...");
    }

}

若是使用频率比较多，推荐使用对象的形式处理
利用阿里的fastjson，请注意前引用

关于Java对json字符串的处理，可以直接获取；但当使用频率较多的时候，就不太方便了。既然是面向对象编程，那就向json的数据转化为对象！

处理思路：

需要根据接收到的json对象构建对象。
将所有需要的数据全部封装为对象！
再利用阿里（fastjson）/google(Gson)的json转对象的方法
直接转为对象，再直接操作对象
假设以下是我们接收到的json，我们需要的是detail中的数据；

则需要构建实体dataItems以及包含dataItems的实体

然后直接进行转换：

示例代码：实体（假设都是String类型）

dataItems

@Data
public class DataIteams {
        private  String  phoneNum;
        private  String  aramDateTime;
        private  String  aramType;
        private  String  lon;
        private  String  lat;
        private  String  devNo;
        private  String  descripton;
        private  String  since;
        private  String  amc;
        }

detail的实体

import java.util.List;
@Data
public class Detail {
    private String pageCount;
    private String totalCount;
    private String pageIndex;
    private String pageSize;
    /**
     *这个实体就是DataItems里面的数据体
     */
    private List<DataItems> dataItems;
    }

当构建了实体以后就可以利用方法转换了！

示例代码：

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;

import java.util.HashMap;

public class Main {

    public static void main(String[] args) {
       String str = "{\n" +
               "    \"code\": \"0\",\n" +
               "    \"error\": \"\",\n" +
               "    \"msg\": \"success\",\n" +
               "    \"detail\": {\n" +
               "        \"pageCount\": 1,\n" +
               "        \"totalCount\": 9,\n" +
               "        \"pageIndex\": 1,\n" +
               "        \"pageSize\": 1000,\n" +
               "        \"dataItems\": [\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1616990185000,\n" +
               "                \"aramType\": 1,\n" +
               "                \"lon\": 114.224438,\n" +
               "                \"lat\": 30.55706,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            },\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1616990186000,\n" +
               "                \"aramType\": 1,\n" +
               "                \"lon\": 114.224457,\n" +
               "                \"lat\": 30.557187,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            },\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1616990190000,\n" +
               "                \"aramType\": 1,\n" +
               "                \"lon\": 114.224484,\n" +
               "                \"lat\": 30.557565,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            },\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1616990195000,\n" +
               "                \"aramType\": 1,\n" +
               "                \"lon\": 114.224434,\n" +
               "                \"lat\": 30.557971,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            },\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1616990196000,\n" +
               "                \"aramType\": 1,\n" +
               "                \"lon\": 114.224388,\n" +
               "                \"lat\": 30.558073,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            },\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1616990200000,\n" +
               "                \"aramType\": 1,\n" +
               "                \"lon\": 114.224297,\n" +
               "                \"lat\": 30.558436,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            },\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1614736039000,\n" +
               "                \"aramType\": 27,\n" +
               "                \"lon\": 114.204813,\n" +
               "                \"lat\": 30.553443,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            },\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1615342530000,\n" +
               "                \"aramType\": 27,\n" +
               "                \"lon\": 114.216378,\n" +
               "                \"lat\": 30.561051,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            },\n" +
               "            {\n" +
               "                \"phoneNum\": \"027044039989\",\n" +
               "                \"aramDateTime\": 1616990178000,\n" +
               "                \"aramType\": 27,\n" +
               "                \"lon\": 114.222609,\n" +
               "                \"lat\": 30.554516,\n" +
               "                \"devNo\": \"\",\n" +
               "                \"descripton\": \"\",\n" +
               "                \"since\": \"\",\n" +
               "                \"amc\": \"\"\n" +
               "            }\n" +
               "        ]\n" +
               "    },\n" +
               "}";


        //先转换成JSONObject类型
        String json = JSON.parseObject(str).getString("detail");
        Detail detail = JSONObject.parseObject(json, Detail.class);
        System.out.println(detail);
    }

}

获得的对象就可以直接使用get和set方法获取数据了

方法：

//Javabean对象转换成String类型的JSON字符串
JSONObject.toJSONString(Javabean对象)

//String类型的JSON字符串转换成Javabean对象
JSONObject.toJavaObject(JSON字符串,Javabean.class)

//Json字符串转换成JSONObject对象
JSONObject.parseObject(JSON字符串)

//JSON字符串转换成Javabean对象
JSONObject.parseObject(JSON字符串,Javabean.class)