SpringCloud入门——RestTemplate

​ Spring提供了一种简单便捷的模板类 RestTemplate 来调用 RESTful 接口。它提供了多种便捷访问HTTP服务的方法，能够大大提高客户端的编写效率。

需要先将RestTemplate以Bean的形式注入到Spring容器中。使用的使用@Resource调用。

    @Bean
    @LoadBalanced
    RestTemplate getRestTemplate(){
        return new RestTemplate();
    }

@GetMapping("/client5")
public Object client5(){
    //自动处理url
    String url = "http://Eureka-provider/hi";
    String object = restTemplate.getForObject(url, String.class);
    System.out.println(object);
    return object;
}

getForEntity方法的返回值是一个ResponseEntity，ResponseEntity是Spring对HTTP请求响应的封装，包括了几个重要的元素，如响应码、contentType、contentLength、响应消息体等。

<200,Hi,[Content-Type:"text/plain;charset=UTF-8", Content-Length:"8", Date:"Fri, 10 Apr 2020 09:58:44 GMT", Keep-Alive:"timeout=60", Connection:"keep-alive"]>

@GetMapping("/client6")
public Object client6(){
    //自动处理url
    String url = "http://Eureka-provider/hi";
    ResponseEntity entity = restTemplate.getForEntity(url, String.class);
    System.out.println(entity);
    return entity;
}

使用占位符

  @GetMapping("/client9")
  public Object client9(){
      //自动处理url
      String url = "http://Eureka-provider/user/{id}/{name}";
      User user = restTemplate.getForObject(url, User.class,"1","123");
      return user;
  }

使用Map

  @GetMapping("/client10")
  public Object client10(){
      //自动处理url
      String url = "http://Eureka-provider/user/{id}/{name}";
      HashMap map = new HashMap<>();
      map.put("id","1");
      map.put("name","123");
      User user = restTemplate.getForObject(url, User.class,map);
      return user;
  }

postForObject、postForEntity类似get请求。

@GetMapping("/client11")
public Object client11(){
    //自动处理url
    String url = "http://Eureka-provider/user";
    User user = restTemplate.postForObject(url, new User(1,"123"),User.class);
    ResponseEntity entity = restTemplate.postForEntity(url, new User(1, "123"), User.class);
    return user;
}

用于重定向

Cunsumer

@GetMapping("/client12")
    public Object client12(HttpServletResponse response) throws IOException {
        //自动处理url
        String url = "http://Eureka-provider/user/login";
        URI uri = restTemplate.postForLocation(url, new User(1, "123"));
        response.sendRedirect(uri.toString());
        return uri;
    }

Provider

需要设置头信息，不然返回的是null

@PostMapping("/user/login")
public URI userLogin(@RequestBody User user, HttpServletResponse response) throws URISyntaxException {
    URI uri = new URI("https://www.baidu.com/s?name="+user.getName());
    response.addHeader("Location", uri.toString());
    return uri;
}

同理get、post