Spring MVC学习 （ RESTful）

是一套规则，不同的系统之间（Vue java Python C#  PHP）具体四种不同类型的HTTP 请求分别表示四种基本操作（CRUD）

GET ：查询（R）

POST：添加（C）

PUT：修改（U）

DELETE：删除（D）

Spring MVC 默认支持RESTful 结构

RestHandler.java

package com.xcl.controller;

import com.xcl.entity.User;
import com.xcl.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.HttpServletResponse;
import java.util.Collection;

@RestController
@RequestMapping("/rest")
public class RestHandler {

    @Autowired
    private UserRepository userRepository;

    /**
     * 查询所有  GET请求
     *
     * @param response
     * @return
     */
    @GetMapping("/findAll")
    public Collection<User> findAll(HttpServletResponse response) {
        response.setContentType("text/json;charset=UTF-8");
        return userRepository.findAll();
    }

    /**
     * 根据ID查询  GET请求
     *
     * @param response
     * @param id
     * @return
     */
    @GetMapping("/findById/{id}")
    public User findAll(HttpServletResponse response, @PathVariable("id") Integer id) {
        response.setContentType("text/json;charset=UTF-8");
        return userRepository.findById(id);
    }

    /**
     * 添加  POST请求
     *
     * @param user
     */
    @PostMapping("/save")
    public void save(User user) {
        userRepository.saveOrUpdate(user);
    }

    /**
     * 修改  PUT请求
     *
     * @param user
     */
    @PutMapping("/update")
    public void update(User user) {
        userRepository.saveOrUpdate(user);
    }

    /**
     * 删除 DELETE请求
     *
     * @param id
     */
    @DeleteMapping("/delete/{id}")
    public void deleteById(@PathVariable("id") Integer id) {
        userRepository.deleteById(id);
    }
}

User.java

package com.xcl.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private  Integer id;
    private  String name;
}

UserRepository 接口

package com.xcl.repository;

import com.xcl.entity.User;

import java.util.Collection;

public interface UserRepository {
    public Collection<User> findAll();
    public User findById(Integer id);
    public void saveOrUpdate(User user);
    public void  deleteById(Integer id);
}

UserRepositoryImpl 实现类

package com.xcl.repository.Impl;

import com.xcl.entity.User;
import com.xcl.repository.UserRepository;
import org.springframework.stereotype.Repository;

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

@Repository
public class UserRepositoryImpl implements UserRepository {

    private  static Map<Integer,User> map;
    static {
        map=new HashMap<>();
        map.put(1,new User(1,"张三"));
        map.put(2,new User(2,"李四"));
        map.put(3,new User(3,"王五"));
        map.put(4,new User(4,"小张"));

    }
    @Override
    public Collection<User> findAll() {
       return  map.values();
    }

    @Override
    public User findById(Integer id) {
        return map.get(id);
    }

    @Override
    public void saveOrUpdate(User user) {
        map.put(user.getId(),user);
    }

    @Override
    public void deleteById(Integer id) {
        map.remove(id);
    }
}

Springmvc.xml 配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/mvc
       http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">
    <!-- ⾃动扫描 -->
    <context:component-scan base-package="com.xcl"></context:component-scan>

    <!-- 视图解析器 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!-- 前缀 -->
        <property name="prefix" value="/"></property>
        <!-- 后缀 -->
        <property name="suffix" value=".jsp"></property>
    </bean>
    <!-- JSON  使用-->
    <mvc:annotation-driven>
        <!-- 消息转换器 -->
        <mvc:message-converters>
            <bean class="com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter">
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>

</beans>

pom.xml 配置

<?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.xcl</groupId>
    <artifactId>springmvc</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>springmvc Maven Webapp</name>
    <!-- FIXME change it to the project's website -->
    <url>http://www.example.com</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>12</maven.compiler.source>
        <maven.compiler.target>12</maven.compiler.target>
    </properties>

    <dependencies>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.1.7.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.0.1</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.10</version>
            <scope>provided</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.62</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>springmvc</finalName>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <plugin>
                    <artifactId>maven-clean-plugin</artifactId>
                    <version>3.1.0</version>
                </plugin>
                <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
                <plugin>
                    <artifactId>maven-resources-plugin</artifactId>
                    <version>3.0.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.0</version>
                </plugin>
                <plugin>
                    <artifactId>maven-surefire-plugin</artifactId>
                    <version>2.22.1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-war-plugin</artifactId>
                    <version>3.2.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-install-plugin</artifactId>
                    <version>2.5.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-deploy-plugin</artifactId>
                    <version>2.8.2</version>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

web.xml 配置

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  <servlet>
    <servlet-name>springmvc</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:springmvc.xml</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>springmvc</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>