Spring--jdbcTemplate

概述：jdbcTemplat对java的jdbc进行了简单封装，用来操作关系型数据库。

作用：用于与数据库交互，实现对数据库crud的操作。

 

代码实现：

环境搭建--使用的时Mysql数据库，IDEA工具，创建MAVEN工程。

1.需要导入的依赖包：

<packaging>jar</packaging>

<dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>5.0.5.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.46</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>5.0.5.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
        <version>5.0.5.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
</dependencies>

 2.对应数据库user表的实体类

public class User {
    private Integer id;
    private String uname;
    private String pwd;
    //避免代码看起来繁琐，没有贴入get/set/toString方法
}

3.jdbcTemplate基本使用

public class JDBCTemplateDemo {
    public static void main(String[] args) {
        //1.准备数据源，spring内部提供给
        DriverManagerDataSource ds = new DriverManagerDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://127.0.0.1:3306/template");
        ds.setUsername("root");
        ds.setPassword("root");
        //2.创建JDBDTemplate对象
        JdbcTemplate jt = new JdbcTemplate();
        //3.给jt设置数据源
        jt.setDataSource(ds);
        //4.执行操作
        jt.execute("INSERT INTO user(uname,pwd) VALUES('赏金','abc')");

    }
}

 4.dao实现jdbcTemplate----dao接口层

import com.pojo.User;
import java.util.List;
public interface UserDao {
    //查询所有的User数据
    List<User> findAll();
    //根据ID查询User
    User getUserById(Integer id);
    //修改User
    void updateUser(User u);
}

 4.dao实现jdbcTemplate----dao接口实现类

import com.dao.UserDao;
import com.pojo.User;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import java.util.List;

public class UserDaoImpl implements UserDao {
    private JdbcTemplate jdbcTemplate;
    //BeanPropertyRowMapper<>类，用于将数据库查询结果转换为Java类对象
    private BeanPropertyRowMapper<User> bprm= new BeanPropertyRowMapper<User>(User.class);

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }
    //查询所有User
    public List<User> findAll() {
        String sql="select * from user";
        List<User> userList = jdbcTemplate.query(sql, bprm);
        return userList;
    }
    //根据Id查询User
    public User getUserById(Integer id) {
        String sql="select * from user where id=?";
        List<User> query = jdbcTemplate.query(sql, bprm, id);
        return query.get(0);
    }
    //更新User
    public void updateUser(User u) {
        String sql="update user set uname=?,pwd=? where id=?";
        jdbcTemplate.update(sql,u.getUname(),u.getPwd(),u.getId());
    }
}

5.配置properties和xml文件

#数据源的jdbc.properties配置文件
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/template
jdbc.username=root
jdbc.password=root

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--引入jdbc文件-->
    <bean id="configurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location">
            <value>classpath:/jdbc.properties</value>
        </property>
    </bean>
    <!--配置账户持久层-->
    <bean id="userDaoImpl" class="com.dao.impl.UserDaoImpl">
        <property name="jdbcTemplate" ref="jdbcTemplate"/>
    </bean>
   <!-- 给jdbcTemplate引入数据源-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!--配置数据源-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

</beans>

6.测试

import com.dao.impl.UserDaoImpl;
import com.pojo.User;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.List;

public class JDBCtemplateDemo2 {
    public static void main(String[] args) {
        ApplicationContext ac=new ClassPathXmlApplicationContext("application.xml");
        UserDaoImpl userDao =(UserDaoImpl)ac.getBean("userDaoImpl");
        //查询所有测试
        List<User> all = userDao.findAll();
        for (User user : all) {
            System.out.println(user);
        }
        //根据ID查测试
        User user = userDao.getUserById(1);
        System.out.println(user);
        //修改User测试
        User user1 = new User();
        user1.setId(3);
        user1.setUname("赵信");
        user1.setPwd("456");
        userDao.updateUser(user1);
    }
}

//得到的测试结果，均成功实现

 

优化代码

1.将JdbcTemplate和BeanPropertyRowMapper<>抽取出来做父类，

import com.pojo.User;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

public class JdbcTemplateBase {
    private JdbcTemplate jdbcTemplate;
    //BeanPropertyRowMapper<>类，用于将数据库查询结果转换为Java类对象
    private BeanPropertyRowMapper<User> bprm= new BeanPropertyRowMapper<User>(User.class);

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    public JdbcTemplate getJdbcTemplate() {
        return jdbcTemplate;
    }

    public BeanPropertyRowMapper<User> getBprm() {
        return bprm;
    }

    public void setBprm(BeanPropertyRowMapper<User> bprm) {
        this.bprm = bprm;
    }
}

2.继承父类的实现类

import com.dao.JdbcTemplateBase;
import com.dao.UserDao;
import com.pojo.User;

import java.util.List;

public class UserDaoImplEx extends JdbcTemplateBase implements UserDao {

    //查询所有User
    public List<User> findAll() {
        String sql="select * from user";
        List<User> userList = getJdbcTemplate().query(sql, getBprm());
        return userList;
    }
    //根据Id查询User
    public User getUserById(Integer id) {
        String sql="select * from user where id=?";
        List<User> query = getJdbcTemplate().query(sql, super.getBprm(), id);
        return query.get(0);
    }
    //更新User
    public void updateUser(User u) {
        String sql="update user set uname=?,pwd=? where id=?";
        getJdbcTemplate().update(sql,u.getUname(),u.getPwd(),u.getId());
    }
}

3.修改.xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--引入jdbc文件-->
    <bean id="configurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location">
            <value>classpath:/jdbc.properties</value>
        </property>
    </bean>
    <!--配置账户持久层-->
    <bean id="userDaoImpl" class="com.dao.impl.UserDaoImpl">
        <property name="jdbcTemplate" ref="jdbcTemplate"/>
    </bean>

    <bean id="userDaoImplEx" class="com.dao.impl.UserDaoImplEx"/>

    <bean id="jdbcTemplateBase" class="com.dao.JdbcTemplateBase">
        <property name="jdbcTemplate" ref="jdbcTemplate"/>
    </bean>
   <!-- 给jdbcTemplate引入数据源-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!--配置数据源-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>

</beans>