# RestTemplate

## **GET请求**

### **getForEntity**

getForEntity方法的返回值是一个ResponseEntity\<T>，ResponseEntity\<T>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

```java
@RequestMapping("/getForEntity")
public ResponseEntity<String> getForEntity() {
      ResponseEntity<String> response = restTemplate.getForEntity("http://app-itmayiedu-member/getMember",
                 String.class);
      System.out.println("statusCode:" + response.getStatusCode());
      System.out.println("Body:" + response.getBody());
      return response;
}
```

getForEntity的第一个参数为我要调用的服务的地址，这里我调用了服务提供者提供的/hello接口，注意这里是通过服务名调用而不是服务地址，如果写成服务地址就没法实现客户端负载均衡了。

getForEntity第二个参数String.class表示我希望返回的body类型是String

拿到返回结果之后，将返回结果遍历打印出来

#### **Get请求传递参数**

```java
@RequestMapping("/getForOrderEntity2")
public ResponseEntity<String> getForEntity2(String name) {
      Map<String, String> map = new HashMap<String, String>();
      map.put("name", name);
      ResponseEntity<String> response = restTemplate.getForEntity("http://app-itmayiedu-member/getUser?name={name}",
                 String.class, map);
      System.out.println("statusCode:" + response.getStatusCode());
      System.out.println("Body:" + response.getBody());
      return response;
}
```

可以用一个数字做占位符，最后是一个可变长度的参数，来一一替换前面的占位符

也可以前面使用name={name}这种形式，最后一个参数是一个map，map的key即为前边占位符的名字，map的value为参数值

### **getForObject**

getForObject函数实际上是对getForEntity函数的进一步封装，如果你只关注返回的消息体的内容，对其他信息都不关注，此时可以使用getForObject，举一个简单的例子，如下：

```java
@RequestMapping("/getOrder")
public String getOrder() {
      // 有两种方式，一种是采用服务别名方式调用，另一种是直接调用 使用别名去注册中心上获取对应的服务调用地址
      String url = "http://app-itmayiedu-member/getMember";
      String result = restTemplate.getForObject(url, String.class);
      System.out.println("订单服务调用会员服务result:" + result);
      return result;
}
```

## **POST请求**

### **PostForEntity**

### **postForObject**

如果你只关注，返回的消息体，可以直接使用postForObject。用法和getForObject一致

## **PUT请求**

## **DELETE请求**


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