CrudRepository接口实战

清疚 2021-07-24 17:07 416阅读 0赞

**一 pom**

<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>org.fkit</groupId>
         <artifactId>crudrepositorytest</artifactId>
         <version>0.0.1-SNAPSHOT</version>
         <packaging>jar</packaging>
         <name>crudrepositorytest</name>
         <url>http://maven.apache.org</url>
         
         <parent>
               <groupId>org.springframework.boot</groupId>
               <artifactId>spring-boot-starter-parent</artifactId>
               <version>2.0.0.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-thymeleaf</artifactId>
               </dependency>
               
               <dependency>
                    <groupId>mysql</groupId>
                    <artifactId>mysql-connector-java</artifactId>
               </dependency>
               
               <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-data-jpa</artifactId>
               </dependency>
               <dependency>
                    <groupId>junit</groupId>
                    <artifactId>junit</artifactId>
                    <scope>test</scope>
               </dependency>
         </dependencies>
    </project>

**二 启动类**

package org.fkit.crudrepositorytest;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    @SpringBootApplication
    public class App
    {
        public static void main( String[] args )
        {
            // SpringApplication 用于从main方法启动Spring应用的类。
            SpringApplication.run(App.class, args);
        }
    }

**三 持久化类**

package org.fkit.crudrepositorytest.bean;
    
    
    import java.io.Serializable;
    
    
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.Table;
    
    
    @Entity
    // 用于标记持久化类,Spring Boot项目加载后会自动根据持久化类建表
    @Table(name="tb_user")
    public class User implements Serializable{
    
    
        private static final long serialVersionUID = 1L;
    
    
        /**
         * 使用@Id指定主键. 使用代码@GeneratedValue(strategy=GenerationType.AUTO)
         * 指定主键的生成策略,mysql默认的是自增长。
         *
         */
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private int id;// 主键.
    
    
        private String username;// 姓名 username
    
    
        private String loginName;
    
    
        private char sex;// 性别
    
    
        private int age; // 年龄
    
    
        public int getId() {
            return id;
        }
    
    
        public void setId(int id) {
            this.id = id;
        }
    
    
        public String getUsername() {
            return username;
        }
    
    
        public void setUsername(String username) {
            this.username = username;
        }
    
    
        public String getLoginName() {
            return loginName;
        }
    
    
        public void setLoginName(String loginName) {
            this.loginName = loginName;
        }
    
    
        public char getSex() {
            return sex;
        }
    
    
        public void setSex(char sex) {
            this.sex = sex;
        }
    
    
        public int getAge() {
            return age;
        }
    
    
        public void setAge(int age) {
            this.age = age;
        }
    }

**四 控制器**

package org.fkit.crudrepositorytest.controller;
    
    
    import javax.annotation.Resource;
    
    
    import org.fkit.crudrepositorytest.bean.User;
    import org.fkit.crudrepositorytest.service.UserService;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    
    @RestController
    @RequestMapping("/user")
    public class UserController {
        
        // 注入UserService
        @Resource
        private UserService userService;
    
    
        @RequestMapping("/save")
        public String save() {
            User user = new User();
            user.setLoginName("dlei");
            user.setUsername("徐磊");
            user.setSex('男');
            user.setAge(3);
            user = userService.save(user);
            System.out.println("保存数据成功，返回的结果：" + user);
            return "保存数据成功！";
        }
    
    
        @RequestMapping("/update")
        public String update() {
            // 修改的对象必须是持久化对象，所以先从数据库查询出id为1的对象进行修改
            User user = userService.getById(1);
            userService.update(user);
            return "修改数据成功!";
        }
    
    
        @RequestMapping("/delete")
        public String delete() {
            userService.delete(1);
            return "删除数据成功！";
        }
    
    
        @RequestMapping("/getAll")
        public Iterable<User> getAll() {
            return userService.getAll();
        }
    }

**五 Service层**

package org.fkit.crudrepositorytest.service;
    
    
    import java.util.Optional;
    
    
    import javax.annotation.Resource;
    import javax.transaction.Transactional;
    
    
    import org.fkit.crudrepositorytest.bean.User;
    import org.fkit.crudrepositorytest.repository.UserRepository;
    import org.springframework.stereotype.Service;
    
    
    @Service
    public class UserService {
    
    
        // 注入UserRepository
        @Resource
        private UserRepository userRepository;
    
    
        /**
         * save,update ,delete 方法需要绑定事务. 使用@Transactional进行事务的绑定.
         *
         * 保存对象
         * @param User
         * @return 包含自动生成的id的User对象        
         */
        @Transactional
        public User save(User User) {
            return userRepository.save(User);
        }
    
    
        /**
         * 根据id删除对象
         *
         * @param id
         */
        @Transactional
        public void delete(int id) {
            userRepository.deleteById(id);
            
        }
    
    
        /**
         * 查询所有数据
         *
         * @return 返回所有User对象
         */
        public Iterable<User> getAll() {
            return userRepository.findAll();
        }
        
        /**
         * 根据id查询数据
         *
         * @return  返回id对应的User对象
         */
        public User getById(Integer id) {
            // 根据id查询出对应的持久化对象
            Optional<User> op = userRepository.findById(id);
             return op.get();
        }
        /**
         * 修改用户对象数据，持久化对象修改会自动更新到数据库
         *
         * @param user
         */
        @Transactional
        public void update(User user) {
            // 直接调用持久化对象的set方法修改对象的数据
            user.setUsername("孙悟空");
            user.setLoginName("swk");
        }
    
    
    }

**六 repository层**

package org.fkit.crudrepositorytest.repository;
    
    
    import org.fkit.crudrepositorytest.bean.User;
    import org.springframework.data.repository.CrudRepository;
    
    
    public interface UserRepository extends CrudRepository<User, Integer>{
    
    
    }

**七 创建数据库springdatajpa**

**八 测试**

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