Java笔记-构造RESTful的WebService

悠悠 2022-12-01 05:17 150阅读 0赞

Spring Boot提供了企业级构建RESTful的webService应用

Maven添加依赖

<dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-web</artifactId>    
    </dependency>

整个porn.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>

Rest Mapping

@RequestMapping注解定义了请求的URL去访问REST端。定义消费者好生产者对象。这个注解默认的方法为GET

@RequestMapping(value = "/products")
    public ResponseEntity<Object> getProducts() { }

Request Body

@RequestBody注解用于定义请求体的类型

public ResponseEntity<Object> createProduct(@RequestBody Product product) {
    }

Path Variable

@PathVariable注解提定义了定制化的或动态的URL请求。

public ResponseEntity<Object> updateProduct(@PathVariable("id") String id) {
    }

Request Parameter

@Request Parameter注解回去读取request url中的参数。其中value是必须的。

public ResponseEntity<Object> getProduct(
       @RequestParam(value = "name", required = false, defaultValue = "honey") String name) {
    }

Get API

HTTP默认的请求就是GET，这个方法不需要HTTP的body。可以通过改变参数和路径发送不同的URL。

下面是一个简单的HTTP GET请求方法。使用HashMap存储生产者。这里使用POJO类进行存储。

下面的URL中包含/products并且将返回商品列表。下面的controller类包含了REST端的GET方法。

POST API

HTTP的POST方法用于创建资源。这个方法包含了请求的body。可以发送不同的url或者变量。

PUT API

更新一个存在的资源。此方法包含了Body。

URL请求/products\{id\}，将ID更新到HashMap的Repository中。代码如下：

DELETE API

删除存在的资源。可以添加请求Body。

下面是Spring Boot启动类

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);
       }
    }

下面是POJO类

package com.tutorialspoint.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;
       }
    }

下面是ProductServiceController.java

package com.tutorialspoint.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.tutorialspoint.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);
       }
    }