【注】本文译自: https://www.tutorialspoint.com/spring_boot/spring_boot_rest_template.htm

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Rest 模板用于创建消费 RESTful Web 服务的应用。你可以使用 exchange() 方法来消费所有 HTTP 方法的 web 服务。下面的代码展示了如何创建 Rest 模板 Bean 来自动绑定 Rest 模板对象:

package com.tutorialspoint.demo;

  

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 DemoApplication {

 public static void main(String\[\] args) {

 SpringApplication.run(DemoApplication.class, args);

 }

 @Bean

 public RestTemplate getRestTemplate() {

 return new RestTemplate();

 }

GET

使用 RestTemplate - exchange() 方法消费 GET API

假设这个 URL http://localhost:8080/products 返回下面的 JSON ,我们要通过后面的代码使用 Rest 模板来消费这个 API 响应:

[

 {

 "id": "1",

 "name": "Honey"

 },

 {

 "id": "2",

 "name": "Almond"

 }

]

你要通过以下几点来消费 API:

  • 自动绑定 Rest 模板对象
  • 使用 HttpHeaders 设置请求头
  • 使用 HttpEntity 包装请求对象
  • 为 Exchange() 方法提供 URL、HttpMethod 和返回值类型
@RestController
public class ConsumeWebService {

 @Autowired
 RestTemplate restTemplate;

 @RequestMapping(value = "/template/products")
 public String getProductList() {
 HttpHeaders headers = new HttpHeaders();

headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));

 HttpEntity <String> entity = new HttpEntity<String>(headers);

 return restTemplate.exchange("http://localhost:8080/products", HttpMethod.GET, entity, String.class).getBody();

 }

}

POST

使用 RestTemplate - exchange() 方法消费 POST API

假设 URL http://localhost:8080/products 返回如下响应,我们要使用 Rest 模板来消费这个 API 响应。

请求体代码如下:

{
 "id":"3",
 "name":"Ginger"
}

响应体代码如下:

Product is created successfully

你要通过以下几点来消费 API:

  • 自动绑定 Rest 模板对象
  • 使用 HttpHeaders 设置请求头
  • 使用 HttpEntity 包装请求对象,这里我们包装了产品对象发送给请求体
  • 为 Exchange() 方法提供 URL、HttpMethod 和返回值类型
@RestController
public class ConsumeWebService {

 @Autowired
 RestTemplate restTemplate;

 @RequestMapping(value = "/template/products", method = RequestMethod.POST)

 public String createProducts(@RequestBody Product product) {

 HttpHeaders headers = new HttpHeaders();

headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));

 HttpEntity<Product> entity = new HttpEntity<Product>(product,headers);

 return restTemplate.exchange("http://localhost:8080/products", HttpMethod.POST, entity, String.class).getBody();

 }

}

PUT

使用 RestTemplate - exchange() 方法消费 PUT API

假设 URL http://localhost:8080/products/3 返回下面的响应,我们要使用 Rest 模板来消费这个 API 响应。

请求体代码如下:

{
 "name": "Indian Ginger"
}

响应体代码如下:

Product is updated successfully

你要通过以下几点来消费 API:

  • 自动绑定 Rest 模板对象
  • 使用 HttpHeaders 设置请求头
  • 使用 HttpEntity 包装请求对象,这里我们包装了产品对象发送给请求体
  • 为 Exchange() 方法提供 URL、HttpMethod 和返回值类型
@RestController

public class ConsumeWebService {

 @Autowired
 RestTemplate restTemplate;

  

 @RequestMapping(value = "/template/products/{id}", method = RequestMethod.PUT)

 public String updateProduct(@PathVariable("id") String id, @RequestBody Product product) {

 HttpHeaders headers = new HttpHeaders();

 headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));

 HttpEntity<Product> entity = new HttpEntity<Product>(product,headers);

 return restTemplate.exchange(
 "http://localhost:8080/products/"+id, HttpMethod.PUT, entity, String.class).getBody();

 }

}

DELETE

使用 RestTemplate - exchange() 方法消费 DELETE API

假设 URL http://localhost:8080/products/3 返回下面的响应,我们要使用 Rest 模板来消费这个 API 响应。

响应体代码如下:

Product is deleted successfully

你要通过以下几点来消费 API:

  • 自动绑定 Rest 模板对象
  • 使用 HttpHeaders 设置请求头
  • 使用 HttpEntity 包装请求对象
  • 为 Exchange() 方法提供 URL、HttpMethod 和返回值类型
@RestController

public class ConsumeWebService {

 @Autowired

 RestTemplate restTemplate;

  

 @RequestMapping(value = "/template/products/{id}", method = RequestMethod.DELETE)

 public String deleteProduct(@PathVariable("id") String id) {

 HttpHeaders headers = new HttpHeaders();

 headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));

 HttpEntity<Product> entity = new HttpEntity<Product>(headers);

 return restTemplate.exchange(

 "http://localhost:8080/products/"+id, HttpMethod.DELETE, entity, String.class).getBody();

 }

}

完整的 Rest 模板控制器类代码文件如下:

package com.tutorialspoint.demo.controller;

import java.util.Arrays;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import com.tutorialspoint.demo.model.Product;

@RestController
public class ConsumeWebService {

 @Autowired
 RestTemplate restTemplate;

 @RequestMapping(value = "/template/products")
 public String getProductList() {

 HttpHeaders headers = new HttpHeaders();
 headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));

 HttpEntity<String> entity = new HttpEntity<String>(headers);

 return restTemplate.exchange(

 "http://localhost:8080/products", HttpMethod.GET, entity, String.class).getBody();

 }

 @RequestMapping(value = "/template/products", method = RequestMethod.POST)

 public String createProducts(@RequestBody Product product) {

 HttpHeaders headers = new HttpHeaders();

 headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));

 HttpEntity<Product> entity = new HttpEntity<Product>(product,headers);

 return restTemplate.exchange(

 "http://localhost:8080/products", HttpMethod.POST, entity, String.class).getBody();

 }

 @RequestMapping(value = "/template/products/{id}", method = RequestMethod.PUT)

 public String updateProduct(@PathVariable("id") String id, @RequestBody Product product) {

 HttpHeaders headers = new HttpHeaders();

 headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));

 HttpEntity<Product> entity = new HttpEntity<Product>(product,headers);

 return restTemplate.exchange(

 "http://localhost:8080/products/"+id, HttpMethod.PUT, entity, String.class).getBody();

 }

 @RequestMapping(value = "/template/products/{id}", method = RequestMethod.DELETE)

 public String deleteProduct(@PathVariable("id") String id) {

 HttpHeaders headers = new HttpHeaders();

 headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));

 HttpEntity<Product> entity = new HttpEntity<Product>(headers);

 return restTemplate.exchange(

 "http://localhost:8080/products/"+id, HttpMethod.DELETE, entity, String.class).getBody();

 }

}

Spring Boot 应用类 – DemoApplication.java 如下所示:

package com.tutorialspoint.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

public class DemoApplication {

 public static void main(String[] args) {

 SpringApplication.run(DemoApplication.class, args);

 }

}

Maven build – pom.xml 如下:

<?xml version = "1.0" encoding = "UTF-8"?>

<project xmlns = "[http://maven.apache.org/POM/4.0.0](http://maven.apache.org/POM/4.0.0)" 

 xmlns:xsi = "[http://www.w3.org/2001/XMLSchema-instance](http://www.w3.org/2001/XMLSchema-instance)"

 xsi:schemaLocation = "[http://maven.apache.org/POM/4.0.0](http://maven.apache.org/POM/4.0.0) 

 [http://maven.apache.org/xsd/maven-4.0.0.xsd](http://maven.apache.org/xsd/maven-4.0.0.xsd)">

 <modelVersion>4.0.0</modelVersion>

 <groupId>com.tutorialspoint</groupId>

 <artifactId>demo</artifactId>

 <version>0.0.1-SNAPSHOT</version>

 <packaging>jar</packaging>

 <name>demo</name>

 <description>Demo project for Spring Boot</description>

  

 <parent>

 <groupId>org.springframework.boot</groupId>

 <artifactId>spring-boot-starter-parent</artifactId>

 <version>1.5.8.RELEASE</version>

 <relativePath> 

 </parent>

  

 <properties>

 <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

 <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

 <java.version>1.8</java.version>

 </properties>

  

 <dependencies>

 <dependency>

 <groupId>org.springframework.boot</groupId>

 <artifactId>spring-boot-starter-web</artifactId>

 </dependency>

  

 <dependency>

 <groupId>org.springframework.boot</groupId>

 <artifactId>spring-boot-starter-test</artifactId>

 <scope>test</scope>

 </dependency>

 </dependencies>

  

 <build>

 <plugins>

 <plugin>

 <groupId>org.springframework.boot</groupId>

 <artifactId>spring-boot-maven-plugin</artifactId>

 </plugin>

 </plugins>

 </build>

</project>

Gradle Build – build.gradle 如下:

buildscript {

 ext {

 springBootVersion = '1.5.8.RELEASE'

 }

 repositories {

 mavenCentral()

 }

 dependencies {

 classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")

 }

 }

 apply plugin: 'java'

 apply plugin: 'eclipse'

 apply plugin: 'org.springframework.boot'

 group = 'com.tutorialspoint'

 version = '0.0.1-SNAPSHOT'

 sourceCompatibility = 1.8

 repositories {

 mavenCentral()

 }

 dependencies {

 compile('org.springframework.boot:spring-boot-starter-web')

 testCompile('org.springframework.boot:spring-boot-starter-test')

 }

你可以使用 Maven 或 Graven 命令 创建可执行 JAR 文件,并运行 Spring Boot 应用:

Maven 可以使用以下命令:

mvn clean install

在 “BUILD SUCCESS” 之后 ,你可以在 target 目录下找到 JAR 文件:

对于 Gradle,可以使用以下命令:

gradle clean build

在 “BUILD SUCCESSFUL” 之后,你可以在 build/libs 目录下找到 JAR 文件:

使用以下命令运行 JAR 文件:

java –jar <JARFILE>

现在应用已经在 Tomcat 上以 8080 端口上启动了:
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在 POSTMAN 应用中输入 URL 可以看到下面的输出:

使用 Rest 模板 GET 产品:http://localhost:8080/template/products
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创建产品 POST:http://localhost:8080/template/products
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更新产品 PUT:http://localhost:8080/template/products/3
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删除产品:http://localhost:8080/template/products/3
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