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