使用RestTemplate发送HTTP请求

Spring 框架已为我们封装了一套后端访问http接口的模板工具：RestTemplate。
RestTemplate非常轻量级，使用简单易上手。

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

/**
 * @Description 定义访问http服务的配置类
 */
@Configuration
public class HttpClientConfig {
    /**
     * 定义restTemplate bean
     * @return
     */
    @Bean
    public RestTemplate restTemplate(){
        return new RestTemplate();
    }
}

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestTemplate;

/**
 * @Description
 */
@SpringBootTest
public class TestRestTemplate {

    @Autowired
    private RestTemplate restTemplate;

    /**
     * 测试get请求携带url参数，访问外部接口
     */
    @Test
    public void test01(){
        String url="";
        /*
          参数1：url请求地址
          参数2：请求返回的数据类型
         */
        ResponseEntity<String> result = restTemplate.getForEntity(url, String.class);
        //获取响应头
        HttpHeaders headers = result.getHeaders();
        System.out.println(headers.toString());
        //响应状态码
        int statusCode = result.getStatusCodeValue();
        System.out.println(statusCode);
        //响应数据
        String respData = result.getBody();
        System.out.println(respData);
    }
}

    /**
     * 测试响应数据自动封装到vo对象
     */
    @Test
    public void test02(){
        String url="";
        /*
          参数1：url请求地址
          参数2：请求返回的数据类型
         */
        Account account = restTemplate.getForObject(url, Account.class);
        System.out.println(account);
    }

    @Data
    public static class Account {

        private Integer id;

        private String userName;

        private String address;
        
    }

    /**
     * 请求头设置参数，访问指定接口
     */
    @Test
    public void test03(){
        String url="http://localhost:6666/account/getHeader";
        //设置请求头参数
        HttpHeaders headers = new HttpHeaders();
        headers.add("userName","zhangsan");
        //请求头填充到请求对象下
        HttpEntity<Map> entry = new HttpEntity<>(headers);
        //发送请求
        ResponseEntity<String> responseEntity = restTemplate.exchange(url, HttpMethod.GET, entry, String.class);
        String result = responseEntity.getBody();
        System.out.println(result);
    }

    /**
     * post模拟form表单提交数据
     */
    @Test
    public void test04(){
        String url="";
        //设置请求头，指定请求数据方式
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-type","application/x-www-form-urlencoded");
        //组装模拟form表单提交数据
        LinkedMultiValueMap<String, Object> map = new LinkedMultiValueMap<>();
        map.add("id","10");
        map.add("userName","itheima");
        map.add("address","shanghai");
        HttpEntity<LinkedMultiValueMap<String, Object>> httpEntity = new HttpEntity<>(map, headers);
        /*
            参数1：请求url地址
            参数2：请求方式 POST
            参数3：请求体对象，携带了请求头和请求体相关的参数
            参数4：响应数据类型
         */
        ResponseEntity<Account> exchange = restTemplate.exchange(url, HttpMethod.POST, httpEntity, Account.class);
        Account body = exchange.getBody();
        System.out.println(body);
    }

    /**
     * post发送json数据
     */
    @Test
    public void test05(){
        String url="";
        //设置请求头的请求参数类型
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-type","application/json; charset=utf-8");
        //组装json格式数据
//        HashMap<String, String> reqMap = new HashMap<>();
//        reqMap.put("id","1");
//        reqMap.put("userName","zhangsan");
//        reqMap.put("address","上海");
//        String jsonReqData = new Gson().toJson(reqMap);
        String jsonReq="{\"address\":\"上海\",\"id\":\"1\",\"userName\":\"zhangsan\"}";
        //构建请求对象
        HttpEntity<String> httpEntity = new HttpEntity<>(jsonReq, headers);
          /*
            发送数据
            参数1：请求url地址
            参数2：请求方式
            参数3：请求体对象，携带了请求头和请求体相关的参数
            参数4：响应数据类型
         */
        ResponseEntity<Account> responseEntity = restTemplate.exchange(url, HttpMethod.POST, httpEntity, Account.class);
      //或者
     // Account account=restTemplate.postForObject(url,httpEntity,Account.class);
        Account body = responseEntity.getBody();
        System.out.println(body);
    }

    /**
     * 获取请求cookie值
     */
    @Test
    public void test06(){
        String url="";
        ResponseEntity<String> result = restTemplate.getForEntity(url, String.class);
        //获取cookie
        List<String> cookies = result.getHeaders().get("Set-Cookie");
        //获取响应数据
        String resStr = result.getBody();
        System.out.println(resStr);
        System.out.println(cookies);
    }