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  Spring Boot Rest 模板

  • Rest 模板

    Rest模板用于创建使用RESTful Web服务的应用程序。您可以使用exchange()方法来使用所有HTTP方法的Web服务。下面给出的代码显示了如何为REST模板创建Bean，以自动连接REST模板对象。 
    
package com.jc2182.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()方法请求GET API
    假设此URL http://localhost:8080/products返回以下JSON，并且我们将通过使用Rest 模板使用以下代码来作为此API响应- 
    
[
   {
      "id": "1",
      "name": "Honey"
   },
   {
      "id": "2",
      "name": "Almond"
   }
]
    您将必须遵循给定的点来使用API​​-
    • 自动连接Rest模板对象。
    • 使用HttpHeaders设置请求标头。
    • 使用HttpEntity包装请求对象。
    • 提供Exchange()方法的URL，HttpMethod和Return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()方法请求POST API
    假设此URL http://localhost:8080/products返回如下所示的响应，我们将通过使用Rest模板使用此API响应。
    下面给出的代码是Request主体- 
    
{
   "id":"3",
   "name":"Ginger"
}
    下面给出的代码是Response主体- 
    
Product is created successfully
    您将必须遵循以下给定的要点才能使用API​​-
    • 自动连接Rest模板对象。
    • 使用HttpHeaders设置请求标头。
    • 使用HttpEntity包装请求对象。在这里，我们包装Product对象以将其发送到请求主体。
    • 提供用于exchange()方法的URL，HttpMethod和Return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() 方法请求PUT API
    假设此URL http://localhost:8080/products/3 返回以下响应，我们将通过使用Rest Template使用此API响应。
    下面给出的代码是Request body- 
    
{
   "name":"China Ginger"
}
    下面给出的代码是Response主体-- 
    
Product is updated successfully
    您将必须遵循以下给定的要点才能使用API​​-
    • 自动连接Rest模板对象。
    • 使用HttpHeaders设置请求标头。
    • 使用HttpEntity包装请求对象。在这里，我们包装Product对象以将其发送到请求主体。
    • 提供用于exchange()方法的URL，HttpMethod和Return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() 方法请求DELETE API
    假设此URL http://localhost:8080/products/3 返回以下响应，我们将通过使用Rest Template使用此API响应。
    下面给出的代码是Response主体-- 
    
Product is deleted successfully
    您将必须遵循以下给定的要点才能使用API​​-
    • 自动连接Rest模板对象。
    • 使用HttpHeaders设置请求标头。
    • 使用HttpEntity包装请求对象。
    • 提供用于exchange()方法的URL，HttpMethod和Return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();
   }
}

  • 完整示例代码

    完整的Rest Template Controller类文件在下面给出- 
    
package com.jc2182.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 org.springframework.context.annotation.Bean;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;

import com.jc2182.demo.model.Product;

@RestController
public class ConsumeWebService {
   @Autowired
   RestTemplate restTemplate;


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

   
}
    下面给出了– ProductServiceController.java的代码- 
    
package com.jc2182.demo.controller;

import java.util.HashMap;
import java.util.Map;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
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 com.jc2182.demo.model.Product;

@RestController
public class ProductServiceController {
   private static Map<String, Product> productRepo = new HashMap<>();
   static {
      Product honey = new Product();
      honey.setId("1");
      honey.setName("Honey");
      productRepo.put(honey.getId(), honey);
      
      Product almond = new Product();
      almond.setId("2");
      almond.setName("Almond");
      productRepo.put(almond.getId(), almond);
   }
   
   @RequestMapping(value = "/products/{id}", method = RequestMethod.DELETE)
   public ResponseEntity<Object> delete(@PathVariable("id") String id) { 
      productRepo.remove(id);
      return new ResponseEntity<>("Product is deleted successsfully", HttpStatus.OK);
   }
   
   @RequestMapping(value = "/products/{id}", method = RequestMethod.PUT)
   public ResponseEntity<Object> updateProduct(@PathVariable("id") String id, @RequestBody Product product) { 
      productRepo.remove(id);
      product.setId(id);
      productRepo.put(id, product);
      return new ResponseEntity<>("Product is updated successsfully", HttpStatus.OK);
   }
   
   @RequestMapping(value = "/products", method = RequestMethod.POST)
   public ResponseEntity<Object> createProduct(@RequestBody Product product) {
      productRepo.put(product.getId(), product);
      return new ResponseEntity<>("Product is created successfully", HttpStatus.CREATED);
   }
   
   @RequestMapping(value = "/products")
   public ResponseEntity<Object> getProduct() {
      return new ResponseEntity<>(productRepo.values(), HttpStatus.OK);
   }
}
    下面给出了 – Product.java的代码- 
    
package com.jc2182.demo.model;

public class Product {
   private String id;
   private String name;

   public String getId() {
      return id;
   }
   public void setId(String id) {
      this.id = id;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
}
    下面给出了Spring Boot应用程序类– DemoApplication.java的代码- 
    
package com.jc2182.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构建的代码– pom.xml如下所示- 
    
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
        <parent>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>2.3.0.BUILD-SNAPSHOT</version>
                <relativePath/> <!-- lookup parent from repository -->
        </parent>
        <groupId>com.jc2182</groupId>
        <artifactId>demo</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <!-- <packaging>war</packaging> -->
        <name>demo</name>
        <description>Demo project for Spring Boot</description>

        <properties>
                <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <start-class>com.jc2182.demo.DemoApplication</start-class>
        </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>
                        <exclusions>
                                <exclusion>
                                        <groupId>org.junit.vintage</groupId>
                                        <artifactId>junit-vintage-engine</artifactId>
                                </exclusion>
                        </exclusions>
                </dependency>

                <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>3.0.0.M1</version>
        </dependency>

        </dependencies>

        <build>
                <plugins>
                        <plugin>
                                <groupId>org.springframework.boot</groupId>
                                <artifactId>spring-boot-maven-plugin</artifactId>
                        </plugin>
                </plugins>
        </build>

        <repositories>
                <repository>
                        <id>spring-milestones</id>
                        <name>Spring Milestones</name>
                        <url>https://repo.spring.io/milestone</url>
                </repository>
                <repository>
                        <id>spring-snapshots</id>
                        <name>Spring Snapshots</name>
                        <url>https://repo.spring.io/snapshot</url>
                        <snapshots>
                                <enabled>true</enabled>
                        </snapshots>
                </repository>
        </repositories>
        <pluginRepositories>
                <pluginRepository>
                        <id>spring-milestones</id>
                        <name>Spring Milestones</name>
                        <url>https://repo.spring.io/milestone</url>
                </pluginRepository>
                <pluginRepository>
                        <id>spring-snapshots</id>
                        <name>Spring Snapshots</name>
                        <url>https://repo.spring.io/snapshot</url>
                        <snapshots>
                                <enabled>true</enabled>
                        </snapshots>
                </pluginRepository>
        </pluginRepositories>

</project>
    下面给出了Gradle Build – build.gradle的代码- 
    
plugins {
    id 'org.springframework.boot' version '2.3.0.BUILD-SNAPSHOT'
    id 'io.spring.dependency-management' version '1.0.9.RELEASE'
    id 'java'
}

group = 'com.jc2182'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'

repositories {
    mavenCentral()
    maven { url 'https://repo.spring.io/milestone' }
    maven { url 'https://repo.spring.io/snapshot' }
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.cloud:spring-cloud-starter-openfeign'
    testImplementation('org.springframework.boot:spring-boot-starter-test') {
        exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
    }
}

test {
    useJUnitPlatform()
}
    您可以创建一个可执行的JAR文件，并使用Maven或Gradle命令运行Spring Boot应用程序-
    对于Maven，您可以使用以下命令- 
    
mvn clean install
    在“BUILD SUCCESS”之后，您可以在target目录下找到JAR文件。
    对于Gradle，您可以使用以下命令- 
    
gradle clean build
    在“BUILD SUCCESSFUL”之后，您可以在build/libs目录下找到JAR文件。
    您可以使用以下命令运行JAR文件- 
    
java –jar <JARFILE>
    在Tomcat端口8080上启动应用程序
    现在，在POSTMAN应用程序中单击以下URL，您可以看到输出。
    GET - 通过Rest模板获取产品- http://localhost:8080/template/products
    springboot resttemp
    POST - http://localhost:8080/template/products
    springboot resttemp
    PUT - http://localhost:8080/template/products/3
    springboot resttemp
    DELETE - http://localhost:8080/template/products/3
    springboot resttemp
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