JpaRepository 简单条件查询

客官°小女子只卖身不卖艺 2022-05-10 10:36 277阅读 0赞

JpaRepository继承自PagingAndSortingRepository接口，JpaRepository基于JPA的Repository接口，极大减少了JPA作为数据访问的代码，JpaRepository是实现Spring Data JPA技术访问数据库的关键接口。

示例：简单条件查询

创建持久化类

程序清单：/jpa/src/main/java/com/dwx/bean/User.java

package com.dwx.bean;
    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;
    import javax.persistence.Table;
    @Entity
    @Table(name="t_user")
    public class User {
    	@Id
    	@GeneratedValue(strategy = GenerationType.IDENTITY)
    	private Integer userId;
    	private String userName;
    	private String sex;
    	private Integer age;
    	public User() {}
    	public User(String userName,String sex,Integer age) {
    		this.userName=userName;
    		this.sex=sex;
    		this.age=age;
    	}
    	public Integer getUserId() {
    		return userId;
    	}
    	public void setUserId(Integer userId) {
    		this.userId = userId;
    	}
    	public String getUserName() {
    		return userName;
    	}
    	public void setUserName(String userName) {
    		this.userName = userName;
    	}
    	public String getSex() {
    		return sex;
    	}
    	public void setSex(String sex) {
    		this.sex = sex;
    	}
    	public Integer getAge() {
    		return age;
    	}
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    }

定义数据访问层接口

程序清单：/jpa/src/main/java/com/dwx/repository/UserRepository.java

package com.dwx.repository;
    import java.util.List;
    
    import org.springframework.data.jpa.repository.JpaRepository;
    import com.dwx.bean.User;
    public interface UserRepository extends JpaRepository<User, Integer> {
    	User findByUserName(String userName);
    	List<User> findByUserNameAndAge(String userName,Integer age);
    	List<User> findByUserNameLike(String userName);
    }

定义业务层类

程序清单：/jpa/src/main/java/com/dwx/service/UserService.java

package com.dwx.service;
    import java.util.List;
    import javax.annotation.Resource;
    import javax.transaction.Transactional;
    import org.springframework.stereotype.Service;
    import com.dwx.bean.User;
    import com.dwx.repository.UserRepository;
    @Service
    public class UserService {
    	@Resource
    	private UserRepository userRepository;
    	
    	@Transactional
    	public void saveAll(List<User> users) {
    		userRepository.saveAll(users);
    	}
    	
    	public User getUserByUserName(String userName) {
    		return userRepository.findByUserName(userName);
    	}
    	
    	public List<User> getUserByUserNameAndAge(String userName,Integer age){
    		return userRepository.findByUserNameAndAge(userName, age);
    	}
    	
    	public List<User> getUserByUserNameLike(String userName){
    		return userRepository.findByUserNameLike(userName);
    	}
    }

定义控制器类

程序清单：/jpa/src/main/java/com/dwx/controller/UserController.java

package com.dwx.controller;
    import java.util.ArrayList;
    import java.util.List;
    import javax.annotation.Resource;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    import com.dwx.bean.User;
    import com.dwx.service.UserService;
    @RestController
    @RequestMapping("/user")
    public class UserController {
    	@Resource
    	private UserService userService;
    	
    	@RequestMapping("/save")
    	public String save() {
    		User user1=new User("john","男",25);
    		User user2=new User("lucy","女",18);
    		User user3=new User("Tom","男",16);
    		List<User> users=new ArrayList<>();
    		users.add(user1);
    		users.add(user2);
    		users.add(user3);
    		userService.saveAll(users);
    		return "保存成功";
    	}
    	
    	@RequestMapping("/userName")
    	public User getByUserName(String userName){
    		return userService.getUserByUserName(userName);
    	}
    	
    	@RequestMapping("/userNameAndAge")
    	public List<User> getByUserNameAndAge(String userName,Integer age){
    		return userService.getUserByUserNameAndAge(userName, age);
    	}
    	
    	@RequestMapping("/userNameLike")
    	public List<User> getByUserNameLike(String userName){
    		return userService.getUserByUserNameLike(userName);
    	}
    }

测试应用

添加用户信息，在浏览器中输入以下地址：[http://localhost:8080/user/][http_localhost_8080_user]save

![70][]

根据姓名和年龄查询，在浏览器中输入以下地址：[http://localhost:8080/user/userNameAndAge][http_localhost_8080_user]?userName=john&age=25

![70 1][]

根据姓名模糊查询，在浏览器中输入以下地址：[http://localhost:8080/user/userNameLike][http_localhost_8080_user]?userName=jack

![70 2][]

[http_localhost_8080_user]: http://localhost:8080/user/
[70]: /images/20220510/6884a6b4dfab435b9d0210707383bb6a.png
[70 1]: /images/20220510/863b1e7185dd427ea7c2d91236ade7e6.png
[70 2]: /images/20220510/bc9e844d860f4ba09cde126113b41528.png