JdbcTemplate访问数据

1. pom.xml文件

<?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>
    <groupId>com.example</groupId>
    <artifactId>springbootjdbctemplate</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springbootjdbctemplate</name>
    <description>springbootjdbctemplate</description>
    <properties>
        <java.version>19</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>2.6.13</spring-boot.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>
        <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-jdbc</artifactId>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>19</source>
                    <target>19</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring-boot.version}</version>
                <configuration>
                    <mainClass>com.example.springbootjdbctemplate.SpringbootjdbctemplateApplication</mainClass>
                    <skip>true</skip>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

2.application.properties文件

# 应用服务 WEB 访问端口
server.port=8080
########
#数据源信息配置
########
#数据库地址
spring.datasource.url=jdbc:mysql://localhost:3306/jdbctemplate?characterEncoding=utf8&useSSL=false
#用户名
spring.datasource.username=root
#密码
spring.datasource.password=root
#数据库驱动
spring.datasource.driverClassName = com.mysql.cj.jdbc.Driver

3.bean层

User.java

package com.example.springbootjdbctemplate.bean;
import java.io.Serializable;
public class User implements Serializable{
    private int id;
    private String loginName;
    private String username;
    private String password;


    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getLoginName() {
        return loginName;
    }

    public void setLoginName(String loginName) {
        this.loginName = loginName;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

4.repository层

UserRepository.java

package com.example.springbootjdbctemplate.repository;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.List;
import javax.annotation.Resource;
import com.example.springbootjdbctemplate.bean.User;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.PreparedStatementCreator;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.support.GeneratedKeyHolder;
import org.springframework.jdbc.support.KeyHolder;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
/*
@Repository注解：标注这是一个持久化操作对象
 */
@Repository
public class UserRepository {
    //注入JdbcTemplate模板对象
    @Resource
    private JdbcTemplate jdbcTemplate;
    /*
    插入数据
    @return插入影响的行数
     */
    public int insertUser(){
        String sql = "insert into tb_user(login_name ,username ,passWord) "
                +"values (?,?,?),(?,?,?),(?,?,?)";
        Object[] args = new Object[]{"swk","孙悟空","123456","zbj","猪八戒","123456","ts","唐僧","123456"};
        //参数一：插入数据的SQL语句 参数二：对应SQL语句中占位符？的参数
        return jdbcTemplate.update(sql, args);
    }
    /*
    根据userName查询数据
    @param userName
    @return User对象
     */
    public User selectByUsername(String username){
        //定义SQL语句
        String sql = "select * from tb_user where username = ?";
        //定义一个RowMapper
        RowMapper<User> rowMapper = new BeanPropertyRowMapper<>(User.class);
        //执行查询方法
        User user=jdbcTemplate.queryForObject(sql,new Object[]{username},rowMapper);
        return user;
    }
    /*
    根据id查询数据
    @return User对象
     */
    public User findUserById(int id){
        //定义SQL语句
        String sql = "select * from tb_user where id = ?";
        RowMapper<User> rowMapper = new BeanPropertyRowMapper<>(User.class);
        //执行查询方法
        return jdbcTemplate.queryForObject(sql, new Object[]{id}, rowMapper);
    }
    /*
    查询所有数据
    @return包含User对象的List集合
     */
    public List<User> findAll(){
        //定义SQL语句
        String sql ="select * from tb_user";
        //声明结果级的映射rowMapper，将结果级的数据映射成User对象数据
        RowMapper<User> rowMapper=new BeanPropertyRowMapper<>(User.class);
        return jdbcTemplate.query(sql,rowMapper);
    }
    /*
    根据id删除数据
     */
    public void  delete(final Integer id){
        //定义SQL语句
        String sql = "delete from tb_user where id=?";
        //执行
        jdbcTemplate.update(sql, new Object[]{id});
    }
    /*
    修改数据
     */
    public void update(final User user){
        //定义SQL语句
        String sql="update tb_user set username=?, login_name=? where id=?";
        //执行
        jdbcTemplate.update(sql,new Object[]{user.getUsername(),user.getLoginName(),user.getId()});
    }
    /*
    插入数据，获取被插入数据的主键
     */
    public User insertGetKey(User user){
        //1.声明插入的SQL语句
        String sql="insert into tb_user(username,login_name,password) values(?,?,?)";
        //2.定义插入数据后获取主键的对象
        KeyHolder holder = new GeneratedKeyHolder();
        jdbcTemplate.update(new PreparedStatementCreator() {
            @Override
            public PreparedStatement createPreparedStatement(Connection connection) throws SQLException{
                //3.插入数据后，将被插入数据的主键返回
                PreparedStatement ps = connection.prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);
                ps.setString(1, user.getUsername());
                ps.setString(2,user.getLoginName());
                ps.setString(3, user.getPassword());
                return ps;
            }
        },holder);
        //4.获取被插入数据库的主键，注入到user对象
        int newUserId = holder.getKey().intValue();
        user.setId(newUserId);
        return user;
    }
}

5.service层（业务层）

UserService.java

package com.example.springbootjdbctemplate.service;
import java.util.List;
import javax.annotation.Resource;
import com.example.springbootjdbctemplate.bean.User;
import com.example.springbootjdbctemplate.repository.UserRepository;
import org.springframework.stereotype.Service;

@Service
public class UserService {
    //注入UserRepository
    @Resource
    private UserRepository userRepository;
    public int insertUser(){
        return userRepository.insertUser();
    }
    public User selectByUsername(String username){
        return userRepository.selectByUsername(username);
    }
    public List<User> findAll(){
        return userRepository.findAll();
    }
    public User insertGetKey(User user){
        return userRepository.insertGetKey(user);
    }
    public void update(User user){
        userRepository.update(user);
    }
    public void delete(Integer id){
        userRepository.delete(id);
    }
}

6.控制器类controller

UserController.java

package com.example.springbootjdbctemplate.controller;
import java.util.List;
import javax.annotation.Resource;
import com.example.springbootjdbctemplate.bean.User;
import com.example.springbootjdbctemplate.service.UserService;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/user")
public class UserController {
    @Resource
    private UserService userService;

    @RequestMapping("/insertUser")
    public String insertUser(){
        return "插入数据["+userService.insertUser()+"]条";
    }
    @RequestMapping("/insertGetKey")
    public User insertGetKey(User user){
        return userService.insertGetKey(user);
    }

    @RequestMapping("/selectByUsername")
    public User selectByUsername(String username){
        return userService.selectByUsername(username);
    }
    @RequestMapping("/findAll")
    public List<User> findAll(){
        return userService.findAll();
    }
    @RequestMapping("/update")
    public void update(User user){
        userService.update(user);
    }
    @RequestMapping("/delete")
    public void delete(Integer id){
        userService.delete(id);
    }
}

7.测试

启动MySQL数据库创建一个新的名为jdbctemplate的数据库，创建tb_user表。

在数据库运行脚本

脚本如下

CREATE DATABASE jdbctemplate;
USE jdbctemplate;
CREATE TABLE tb_user(
   id INT PRIMARY KEY AUTO_INCREMENT,
   login_name VARCHAR(23),
   PASSWORD VARCHAR(23),
   username VARCHAR(23)
);