DbUtils(IOC实战)

本文介绍了如何在Spring框架中使用DbUtils库进行数据库CRUD操作,通过XML配置文件实现Account业务,包括创建数据库表、实体类、DAO接口与实现、Service接口和服务实现,以及详细的代码示例和Spring配置详解。

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1. DbUtils是什么?

DbUtilsApache的一款用于简化Dao代码的工具类,它底层封装了JDBC技术.

核心对象:

QueryRunner queryRunner = new QueryRunner(DataSource dataSource);

核心方法:

int update(); 执行增、删、改语句

T query(); 执行查询语句

ResultSetHandler<T> 这是一个接口,主要作用是将数据库返回的记录封装到实体对象

举个例子:

查询数据库所有账户信息到Account实体中:

2. Springxml整合DbUtils

2.1 介绍

需求

基于Springxml配置实现账户的CRUD案例

步骤分析

  1. 准备数据库环境
  2. 创建java项目,导入坐标
  3. 编写Account实体类
  4. 编写AccountDao接口和实现类
  5. 编写AccountService接口和实现类
  6. 编写spring核心配置文件
  7. 编写测试代码

2.2 实现

(1)准备数据库环境

CREATE DATABASE `spring_db`;

USE `spring_db`;

CREATE TABLE `account` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(32) DEFAULT NULL,
`money` double DEFAULT NULL, PRIMARY KEY (`id`)
) ;

insert	into `account`(`id`,`name`,`money`) values (1,'tom',1000), (2,'jerry',1000);

(2)创建java项目,导入坐标

<?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.lagou</groupId>
    <artifactId>spring_dbutils</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.9</version>
        </dependency>
        <dependency>
            <groupId>commons-dbutils</groupId>
            <artifactId>commons-dbutils</artifactId>
            <version>1.6</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.1.5.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>

        <dependency>
            <groupId>javax.annotation</groupId>
            <artifactId>javax.annotation-api</artifactId>
            <version>1.3.2</version>
        </dependency>


    </dependencies>


</project>

(3)编写Account实体类

package com.lagou.domain;

public class Account {

    private Integer id;
    private String name;
    private Double money;

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", money=" + money +
                '}';
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Double getMoney() {
        return money;
    }

    public void setMoney(Double money) {
        this.money = money;
    }
}

(4)编写AccountDao接口和实现类

package com.lagou.dao;

import com.lagou.domain.Account;

import java.util.List;

public interface AccountDao {


    public List<Account> findAll();

    public Account findById(Integer id);

    public void save(Account account);

    public void update(Account account);

    public void delete(Integer id);



}
package com.lagou.dao.impl;

import com.lagou.dao.AccountDao;
import com.lagou.domain.Account;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;

import java.sql.SQLException;
import java.util.List;

public class AccountDaoImpl implements AccountDao {


    private QueryRunner queryRunner;

    public void setQueryRunner(QueryRunner queryRunner) {
        this.queryRunner = queryRunner;
    }
    
    @Override
    public List<Account> findAll() {

        List<Account> list = null;
        //编写sql
        String sql = "select * from account";
        try {
            // 执行sql
            list = queryRunner.query(sql, new BeanListHandler<Account>(Account.class));

        } catch (SQLException e) {
            e.printStackTrace();
        }

        return list;
    }
    @Override
    public Account findById(Integer id) {

        Account query = null;
        // 编写sql
        String sql = "select * from account where id = ?";

        try {
             query = queryRunner.query(sql, new BeanHandler<Account>(Account.class),id);
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return query;
    }
    @Override
    public void save(Account account) {

        String sql = "insert into account values(null,?,?)";
        try {
            queryRunner.update(sql,account.getName(),account.getMoney());
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
    @Override
    public void update(Account account) {

        String sql = "update account set name = ?,money = ? where id = ?";
        try {
            queryRunner.update(sql,account.getName(),account.getMoney(),account.getId());
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
    @Override
    public void delete(Integer id) {

        String sql = "delete from account where id = ?";
        try {
            queryRunner.update(sql,id);
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
}

(5)编写AccountService接口和实现类

package com.lagou.servlet;

import com.lagou.domain.Account;

import java.util.List;

public interface AccountService {


    public List<Account> findAll();

    public Account findById(Integer id);

    public void save(Account account);

    public void update(Account account);

    public void delete(Integer id);



}
public class AccountServiceImpl implements AccountService {

private AccountDao accountDao;

public void setAccountDao(AccountDao accountDao) { this.accountDao = accountDao;
}

@Override
public List<Account> findAll() { return accountDao.findAll();
}

@Override
public Account findById(Integer id) { return accountDao.findById(id);
}

@Override
public void save(Account account) { accountDao.save(account);
}

@Override
public void update(Account account) { accountDao.update(account);
}

@Override
public void delete(Integer id) { accountDao.delete(id);
}
}

(6)编写spring核心配置文件

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

">


    <!--***注解扫描-->
    <context:component-scan base-package="com.lagou"></context:component-scan>

    <!--引入jdbc.properties-->
    <context:property-placeholder location="classpath:jdbc.properties"></context:property-placeholder>


    <!--dataSource-->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <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>


    <!--queryRunner-->
    <bean id="queryRunner" class="org.apache.commons.dbutils.QueryRunner">
        <constructor-arg name="ds" ref="dataSource"/>
    </bean>

    <!--AccountDao-->
    <bean id="accountDao" class="com.lagou.dao.impl.AccountDaoImpl">
        <property name="queryRunner" ref="queryRunner"/>
    </bean>

    <!--AccountDao2-->
    <bean id="accountDao2" class="com.lagou.dao.impl.AccountDaoImpl2">
    </bean>


    <!--AccountService-->
  <!--  <bean id="accountService" class="com.lagou.servlet.impl.AccountServiceImpl">
        <property name="accountDao" ref="accountDao"/>
    </bean>-->



</beans>
jdbc.properties
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql:///spring_db?characterEncoding=UTF-8
jdbc.username=root
jdbc.password=123456

(7)编写测试代码

package com.lagou.test;

import com.lagou.domain.Account;
import com.lagou.servlet.AccountService;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.List;

public class AccountServiceTest {

    ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
    AccountService accountService = (AccountService) classPathXmlApplicationContext.getBean("accountService");




    //测试添加
    @Test
    public void testSave(){

        Account account = new Account();
        account.setName("lucy");
        account.setMoney(888d);
        accountService.save(account);

    }

    //测试查询
    @Test
    public void testFindById(){
        Account account = accountService.findById(3);
        System.out.println(account);

    }


    //测试查询所有
    @Test
    public void testFindAll(){
        List<Account> all = accountService.findAll();
        for (Account account : all) {
            System.out.println(account);
        }
       classPathXmlApplicationContext.close();
    }

    //测试更新
    @Test
    public void testUpdate(){
        Account account = new Account();
        account.setId(3);
        account.setName("jack");
        account.setMoney(2000d);

        accountService.update(account);
    }

    //测试删除
    @Test
    public void testDelete(){
        accountService.delete(3);
    }





}

(8)抽取jdbc配置文件

3. 知识小结

  • DataSource的创建权交由Spring容器去完成

 

  • QueryRunner的创建权交由Spring容器去完成,使用构造方法传递DataSource

 

  • Spring容器加载properties文件

<context:property-placeholder location="xx.properties"/>

<property name="" value="${key}"/>

 

节选自拉钩教育JAVA系列课程

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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