Spring Boot文档阅读笔记-构建Restful风格的WebService

浅浅的花香味﹌ 2022-12-28 12:42 105阅读 0赞

Maven代码如下：

<?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 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>2.1.10.RELEASE</version>
            <relativePath/> 
        </parent>
        <groupId>cn.it1995</groupId>
        <artifactId>demo</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <name>demo</name>
        <description>Demo project for Spring Boot</description>
    
        <properties>
            <java.version>1.8</java.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </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>
    
    
        </dependencies>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <excludes>
                            <exclude>
                                <groupId>org.projectlombok</groupId>
                                <artifactId>lombok</artifactId>
                            </exclude>
                        </excludes>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    
    </project>

服务端通过处理/greeting的get方法，接收name这个string参数，返回200的json状态。

body返回如下：

{
        "id": 1,
        "content": "Hello, World!"
    }

id这个域是greetting的主键，这个值是唯一的。content里面是问候语。

Greeting.java代码如下：

package cn.it1995.demo;
    
    public class Greeting {
    
        private final long id;
        private final String content;
    
        public Greeting(long id, String content) {
    
            this.id = id;
            this.content = content;
        }
    
        public long getId() {
    
            return id;
        }
    
        public String getContent() {
    
            return content;
        }
    }

程序通过适用JaksonJson库，将Greeting自动整理成json，Jackson默认被包含在web starter的jar包中，也就是这个jar包里面：

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

使用@RestController创建Rest风格的WebService，GreetingController.java监听了/greeting的GET方法，代码如下：

package cn.it1995.demo;
    
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.concurrent.atomic.AtomicLong;
    
    @RestController
    public class GreetingController {
    
        private static final String template = "Hello, %s!";
        private final AtomicLong counter = new AtomicLong();
    
        @GetMapping("/greeting")
        public Greeting greeting(@RequestParam(value = "name", defaultValue = "World") String name){
    
            return new Greeting(counter.incrementAndGet(), String.format(template, name));
        }
    }

@GetMapping：代表适用HTTP的get方法，参数为/greeting代表http里面的url为/greeting，等同于@RequestMapping(method=GET)。

@RequestParam：为需要传入的参数，defaultValue为设置默认值。

@RestController：等同于@Controller加@ResponseBody

这里Greeting对象能够转换为json多亏了Jackson2。Spring的MappingJackson2HttpMessageConverter会将Greeting转换为JSON。

程序运行截图如下：

![20201217095035981.png][]

![20201217095040617.png][]

[20201217095035981.png]: /images/20221120/d9eddaad4f404de3bd165b75faa945b2.png
[20201217095040617.png]: /images/20221120/7f37b119c33d4aaf9aa8b53da190c12a.png