## RestTemplate
RestTemplate是spring框架提供的基于REST的服务组件，底层是对HTTP请求及响应
进行的封装，提供了很多访问REST服务的方法，可以简化代码的开发。
#### 使用RestTemplate？
**创建maven工程，pom.xml**
**创建实体类**
```java
package com.shuang.entity;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student {
private long id;
private String name;
private int age;
}
```
**Handler**
```java
package com.shuang.controller;
import com.shuang.entity.Student;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.client.RestTemplate;
import java.util.Collection;
@RestController
@RequestMapping("/rest")
public class RestHandler {
@Autowired
private RestTemplate restTemplate;
@GetMapping("/findAll")
public Collection<Student> findAll(){
return restTemplate.getForEntity("http://localhost:8010/student/findAll",Collection.class).getBody();
}
@GetMapping("/findAll2")
public Collection<Student> findAll2(){
return restTemplate.getForObject("http://localhost:8010/student/findAll",Collection.class);
}
@GetMapping("/findById/{id}")
public Student findById(@PathVariable("id") long id){
return restTemplate.getForEntity("http://localhost:8010/student/findById/{id}",Student.class,id).getBody();
}
@GetMapping("/findById2/{id}")
public Student findById2(@PathVariable("id") long id){
return restTemplate.getForObject("http://localhost:8010/student/findById/{id}",Student.class,id);
}
@PostMapping("save")
public void save(@RequestBody Student student){
restTemplate.postForEntity("http://localhost:8010/student/save",student,null).getBody();
}
@PostMapping("/save2")
public void save2(@RequestBody Student student){
restTemplate.postForObject("http://localhost:8010/student/save",student,null);
}
@PutMapping("/update")
public void update(@RequestBody Student student){
restTemplate.put("http://localhost:8010/student/update",student);
}
@DeleteMapping("/deleteById/{id}")
public void deleteById(@PathVariable("id") long id){
restTemplate.delete("http://localhost:8010/student/deleteById/{id}",id);
}
}
```
**启动类**
```java
package com.shuang;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;
@SpringBootApplication
public class RestTemplateApplication {
public static void main(String [] args){
SpringApplication.run(RestTemplateApplication.class,args);
}
@Bean
public RestTemplate restTemplate(){
return new RestTemplate();
}
}
```
