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Spring Boot快速入门之(十五):Rest 模板

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1个月前

【注】本文译自: www.tutorialspoint.com/spring_boot…

image
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();
   }
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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"
   }
]
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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
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@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();
   }
}
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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"
}
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响应体代码如下:

Product is created successfully
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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
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@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();
   }
}
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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"
}
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响应体代码如下:

Product is updated successfully
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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
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@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();
   }
}
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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
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@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();
   }
}
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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();
   }
}
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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);
   }
}
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Maven build – pom.xml 如下:

<?xml version = "1.0" encoding = "UTF-8"?>
<project xmlns = "http://maven.apache.org/POM/4.0.0" 
   xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation = "http://maven.apache.org/POM/4.0.0 
   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>
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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')
 }
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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
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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
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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>
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现在应用已经在 Tomcat 上以 8080 端口上启动了:

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

 

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