基于注解模式的环境搭建
- 在
pom.xml中加入相关配置
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.22</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.5</version>
<scope>compile</scope>
</dependency>
</dependencies>
- 写Mybatis主配置文件
SqlMapConfig.xml(名字可不同）
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!--引入外部配置文件-->
<properties resource="jdbcConfig.properties"></properties>
<!--配置别名-->
<typeAliases>
<!--配置的是实体类所在位置-->
<package name="com.xxx.domain"/>
</typeAliases>
<!--配置环境-->
<environments default="mysql">
<environment id="mysql">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<!--指定带有注解的dao接口所在位置-->
<mappers>
<package name="com.xxx.dao"/>
</mappers>
</configuration>
jdbcConfig.properties数据库的配置文件内容
jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/eesy?characterEncoding=utf-8&useSSL=false&serverTimezone=UTC
jdbc.username=root
jdbc.password=root
- 做完上述配置 即可在
IUserDAO.interface中使用注解开发
public interface IUserDAO {
/*
* 针对CRUD一共有四个注解
* @SELECT @INSERT @UPDATE @DELETE
* */
//查询所有用户
@Select(value = "select * from user")
List<User> findAll();
}
配置文件和注解不能同时使用
基于注解的简单的增删改查
IUserDAO.interface
public interface IUserDAO {
/*
* 针对CRUD一共有四个注解
* @SELECT @INSERT @UPDATE @DELETE
* */
//查询所有用户
@Select(value = "select * from user")
List<User> findAll();
//保存用户
@Insert(value = "insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday})")
void saveUser(User user);
//更新用户信息
@Update("update user set username=#{username},sex=#{sex},address=#{address},birthday=#{birthday} where id=#{id}")
void updateUserById(User user);
//删除用户
@Delete("delete from user where id=#{id}")
void deleteUser(Integer id);
//根据id查询用户
@Select("select * from user where id=#{id}")
User findById(Integer id);
//根据姓名进行模糊查询
/*方式一：传参时需要包含% 即 “%王%”
* @Select("select * from user where username like #{name}")
*/
/*方式二：
* @Select("select * from user where username like concat('%',#{name},'%')")
*/
/*方式三:
@Select("select * from user where username like '%${value}%'")
*/
@Select("select * from user where username like '%${value}%'")
List<User> findUserByName(String name);
/*
* 查询总人数
* */
@Select("select count(1) from user")
int findTotal();
}
测试类中测试增删改查
public class AnnotationCRUDTest {
private InputStream in;
private SqlSession session;
private IUserDAO userDao;
@Before
public void init() throws IOException {
//1.读取配置文件
in = Resources.getResourceAsStream("SqlMapConfig.xml");
//2创建工厂
SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
SqlSessionFactory factory = builder.build(in);
session = factory.openSession();
userDao = session.getMapper(IUserDAO.class);
}
@After
public void destory() throws IOException {
//提交事務
session.commit();
session.close();
in.close();
}
@Test
public void testSave() {
User user = new User();
user.setUsername("王五");
user.setSex("女");
user.setAddress("上海市浦东机场");
user.setBirthday(new Date());
userDao.saveUser(user);
}
@Test
public void testUpdate() {
User user = new User();
user.setId(53);
user.setUsername("王五");
user.setSex("男");
user.setAddress("上海市浦东机场");
user.setBirthday(new Date());
userDao.updateUserById(user);
}
@Test
public void testDelete() {
userDao.deleteUser(48);
}
@Test
public void testFindById() {
User user = userDao.findById(53);
System.out.println(user);
}
@Test
public void testFindUserByName() {
List<User> users = userDao.findUserByName("王");
for (User u : users) {
System.out.println(u);
}
}
@Test
public void testFindTotal() {
int count = userDao.findTotal();
System.out.println(count);
}
}
当实体类属性名与数据表字段名对应不一致时
通过@Results注解解决
@Results注解可以有id属性，让它可以通过@ResultMap(value={"@Results的id"})被重复使用。
用法示例：
public interface IUserDAO {
/*
* 当实体类属性名与数据表字段名对应不一致时
* 方法一：查询语句中使用别名，让别名同实体类字段名一一对应即可
* 方法二：使用 @Results注解
* */
//查询所有用户
@Select(value = "select * from user")
@Results(id = "userMap",value = {
@Result(id = true ,column = "id" ,property = "uid"),
@Result(column = "username" ,property = "uname"),
@Result(column = "sex",property = "usex"),
@Result(column = "address" ,property = "uaddress"),
@Result(column = "birthday" ,property = "ubirthday")
})
List<User> findAll();
//根据id查询用户
@ResultMap(value = {
"userMap"})
@Select("select * from user where id=#{id}")
User findById(Integer id);
//根据姓名进行模糊查询
@ResultMap("userMap")
@Select("select * from user where username like #{name}")
List<User> findUserByName(String name);
}