总结：
注解和配置文件的区别：
一、环境搭建
1.创建 maven 工程quickstart,并导入坐标
pom.xml 中的依赖：
<dependencies>
<!-- junit单元测试 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<!--spring整合测试类-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<!-- spring框架 -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.0.2.RELEASE</version>
</dependency>
<!-- dbutils
-->
<dependency>
<groupId>commons-dbutils</groupId>
<artifactId>commons-dbutils</artifactId>
<version>1.4</version>
</dependency>
<!-- mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.26</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.9</version>
</dependency>
</dependencies>
2.创建数据库和编写实体类
//创建数据库
create table account
(
id int auto_increment primary key,
name varchar(32) ,
password varchar(32),
money int
);
//编写实体类
public class Account {
private long id;
private String name;
private String password;
private long money;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public long getMoney() {
return money;
}
public void setMoney(long money) {
this.money = money;
}
@Override
public String toString() {
return "Account{" +
"id=" + id +
", name=‘" + name + ‘\‘‘ +
", password=‘" + password + ‘\‘‘ +
", money=" + money +
‘}‘;
}
}
3.编写持久层代码
//定义接口
public interface AccountDao {
//1.增加账户
public int save(Account account);
//2.根据id查询账户
public Account findById(int id);
}
//编写实现类
@Component("accountDao") //把下面这个类放到spring容器中，谁需要就用@Resource(name="accountDao")去取
public class AccountDaoImpl implements AccountDao {
@Resource(name="queryRunner") //1.从spring容器中取出queryRunner对象，当你使用注解的方式注入对象，不需要写set方法，因为配置文件属性注入方式底层采用调用setter方法，
而注解方式底层采用暴力反射
//2.此处应当注意，queryRunner来自第三方，配置文件中的声明不可省略，连接数据库的声明也不可省略
//3.注意：@Resource(name="queryRunner") 必须要写在声明变量之前，即下面这句话之前，private QueryRunner queryRunner;的前面，否则报错
private QueryRunner queryRunner;
/* public void setQueryRunner(QueryRunner queryRunner) {
this.queryRunner = queryRunner;
}*/
//1.增加账户
public int save(Account account){
String sql ="insert into account values (null,?,?,?) ";
try {
return queryRunner.update(sql,account.getName(),account.getPassword(),account.getMoney());
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
//2.根据id查询账户信息
@Override
public Account findById(int id) {
String sql ="select * from account where id=?";
try {
return queryRunner.query(sql,new BeanHandler<>(Account.class),id);
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
4.编写业务层代码
//定义接口
public interface AccountService {
//1.增加账户
public int save(Account account);
//2.根据id查询账户信息
public Account findById(int id);
}
//编写实现类
@Component("accountService ") //把下面这个类放到spring容器中，谁需要就用@Resource(name="accountService ")去取
public class AccountServiceImpl implements AccountService {
@Resource(name="accountService ") //1.从spring容器中取出accountService对象，当你使用注解的方式注入对象，不需要写set方法，因为配置文件属性注入方式底层采用调用setter方法，
而注解方式底层采用暴力反射
private AccountDao accountDao;
/*public void setAccountDao(AccountDao accountDao) { this.accountDao = accountDao; } */
//1.增加账户
@Override
public int save(Account account) { return accountDao.save(account); }
//2.根据id查询账户
@Override
public Account findById(int id) { return accountDao.findById(id); } }
二、创建配置文件
1.创建配置文件并导入约束
<?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">
<!--分析：service - dao - queryRunner - dateSource,从后往前配 -->
<!--1.配置dateSource-->
<bean id="dateSource" class="com.alibaba.druid.pool.DruidDataSource">
<property name="url" value="jdbc:mysql:///heima?characterEncoding=utf-8"/>
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</bean>
<!--2.配置queryRunner-->
<bean id="queryRunner" class="org.apache.commons.dbutils.QueryRunner">
<constructor-arg name="ds" ref="dateSource"></constructor-arg>
</bean>
<!-- <!--3.配置AccountDao-->
<bean id="accountDao" class="com.itheima.dao.impl.AccountDaoImpl">
<property name="queryRunner" ref="queryRunner"/>
</bean>
<!--4.配置AccountService，并解决依赖注入-->
<bean id="accountService" class="com.itheima.service.impl.AccountServiceImpl">
<property name="accountDao" ref="accountDao"/>
</bean>-->
</beans>
三、测试代码
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations="classpath:beans.xml")
public class AccountTest {
@Autowired
private AccountService accountService;
//1.增加账户
@Test public void testSave() {
Account account = new Account();
account.setId(2); account.setName("亚瑟");
account.setPassword("yuji");
account.setMoney(3000);
int i = accountService.save(account);
if (i == 1) { System.out.println("添加账户成功"); } else { System.out.println("添加账户失败"); } }
//2.根据id查询账户信息
@Test public void testFindById(){
Account accountById = accountService.findById(2);
System.out.println(accountById);
}
}
至此，增和查的功能已经完成，删改功能同理可得。
原文：https://www.cnblogs.com/hujunwei/p/11117103.html