1. DbUtils是什么?
DbUtils是Apache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. Spring的xml整合DbUtils
2.1 介绍
需求
基于Spring的xml配置实现账户的CRUD案例
步骤分析
- 准备数据库环境
- 创建java项目,导入坐标
- 编写Account实体类
- 编写AccountDao接口和实现类
- 编写AccountService接口和实现类
- 编写spring核心配置文件
- 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}"/>
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