详解Java中restTemplate的使用

本文介绍restTemplate基础用法。

Java中get和post的用法请参考：一文带你搞懂Java中Get和Post的使用

1 提供get/post接口

1.1 Controller

@RestController
@RequestMapping("/homepage")
public class MyController {

@Autowired
   MyService myService;

// 提供get接口
   @GetMapping("/provideGet")
   public Map<String, String> provideGet(){
       return myService.provideGet();
   }

// 提供post接口
   @PostMapping("/providePost")
   public Map<String, Object> providePost(@RequestParam("number") int number, @RequestParam("name") String name) {
       return myService.providePost(number, name);
   }

// 提供map参数的post接口
   @PostMapping("/providePostByMap")
   public Map<String, Object> providePostByMap(@RequestParam Map<String, Object> map) {
       return myService.providePostByMap(map);
   }

// 调用get接口
   @GetMapping("/useGet")
   public Map<String, Object> useGet() {
       return myService.useGet();
   }
}

1.2 Service

@Service
@EnableScheduling
public class MyService {

public Map<String, String> provideGet() {
       Map<String, String> res = new HashMap<>();
       res.put("number", "3");
       res.put("name", "张三get");
       System.out.println("provideGet res:" + res + "\n");
       return res;
   }

public Map<String, Object> providePost(int number, String name) {
       Map<String, Object> res = new HashMap<>();
       res.put("number", number);
       res.put("name", name);

return res;
   }

public Map<String, Object> providePostByMap(Map<String, Object> map) {
       int number = map.get("number") == null ? 0 : Integer.parseInt((String) map.get("number"));
       String name = map.get("name") == null ? "" : (String) map.get("name");
       Map<String, Object> res = new HashMap<>();
       res.put("number", number);
       res.put("name", name);

System.out.println("providePostByMap res:" + res + "\n");
       return res;
   }
}

2 调用get/post接口

使用restTemplate调用get/post接口。

• getForObject():返回值是HTTP协议的响应体

• getForEntity():返回的是ResponseEntity，ResponseEntity是对HTTP响应的封装，除了包含响应体，还包含HTTP状态码、contentType、contentLength、Header等信息

2.1 Controller

@RestController
@RequestMapping("/homepage")
public class MyController {    
   @Autowired
   MyService myService;

// 调用get接口
   @GetMapping("/useGet")
   public Map<String, Object> useGet() {
       return myService.useGet();
   }

// 调用get接口验证账号密码
   @GetMapping("/useGetByPsw")
   public Map<String, Object> useGetByPsw() {
       return myService.useGetByPsw();
   }

// 调用post接口
   @PostMapping("/usePost")
   public Map<String, Object> usePost() {
       return myService.usePost();
   }
}

2.2 Service

@Service
@EnableScheduling
public class MyService {
   @Resource
   private RestTemplate restTemplate;

String getURL = "http://localhost:8081/homepage/provideGet";
   String postURL = "http://localhost:8081/homepage/providePostByMap";

public Map<String, Object> useGet() {
       // getForObject返回值是HTTP协议的响应体
       String strObject = restTemplate.getForObject(getURL, String.class);
       JSONObject jsonObject = JSONObject.parseObject(strObject);

// getForEntity返回的是ResponseEntity，是对HTTP响应的封装
       ResponseEntity<ResponseResult> responseData = restTemplate.getForEntity(getURL, ResponseResult.class);
       Map<String, Object> returnData = new HashMap<>();
       returnData.put("StatusCode:", responseData.getStatusCode());
       returnData.put("Body:", responseData.getBody());

System.out.println("useGet jsonObject:" + jsonObject + "\n");
       System.out.println("useGet responseData:" + responseData + "\n");
       System.out.println("useGet returnData:" + returnData + "\n");
       return returnData;
   }

public Map<String, Object> useGetByPsw() {

RestTemplateBuilder builder = new RestTemplateBuilder();
       RestTemplate restTemplate = builder.basicAuthentication("username", "password").build();

// getForEntity返回的是ResponseEntity，是对HTTP响应的封装
       ResponseEntity<ResponseResult> responseData = restTemplate.getForEntity(getURL, ResponseResult.class);
       Map<String, Object> returnData = new HashMap<>();
       returnData.put("StatusCode:", responseData.getStatusCode());
       returnData.put("Body:", responseData.getBody());

System.out.println("useGetByPsw returnData:" + responseData + "\n");
       System.out.println("useGetByPsw returnData:" + returnData + "\n");
       return returnData;
   }

public Map<String, Object> usePost() {
       //RestTemplate在postForObject时，用MultiValueMap，不可使用HashMap。
       MultiValueMap<String, String> sendData = new LinkedMultiValueMap<>();
       sendData.add("number", "3");
       sendData.add("name", "张三post");

// getForObject返回值是HTTP协议的响应体
       String strObject = restTemplate.postForObject(postURL, sendData, String.class);
       JSONObject jsonObject = JSONObject.parseObject(strObject);

// getForEntity返回的是ResponseEntity，是对HTTP响应的封装
       ResponseEntity<ResponseResult> responseData = restTemplate.postForEntity(postURL, sendData, ResponseResult.class);
       Map<String, Object> returnData = new HashMap<>();
       returnData.put("StatusCode:", responseData.getStatusCode());
       returnData.put("Body:", responseData.getBody());

System.out.println("usePost jsonObject:" + jsonObject + "\n");
       System.out.println("usePost responseData:" + responseData + "\n");
       System.out.println("usePost returnData:" + returnData + "\n");
       return returnData;
   }
}

来源：https://mp.weixin.qq.com/s/0dEAl8yySdgSlbzeozQc8A