MyBatis 入门01

第一步准备jar包：

log4j-1.2.16.jar

mybatis-3.1.1.jar

mysql-connector-java-5.1.7-bin.jar.

第二步：创建数据库：

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for users
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(50) DEFAULT NULL,
`age` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of users
-- ----------------------------
INSERT INTO `users` VALUES ('1', 'tom', '20');
INSERT INTO `users` VALUES ('2', 'jack', '29');

第三步添加配置文件conf.xml:

<?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>
<!-- 配置实体类的别名 -->
<typeAliases>
<!-- <typeAlias type="com.atguigu.day03_mybaits.test1.User" alias="_User"/> -->
<package name="com.atguigu.day03_mybaits.bean"/>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/mybatis" />
<property name="username" value="root" />
<property name="password" value="root" />
</dataSource>
</environment>
</environments>
</configuration>

第四步 建造实体类：

public class User {
//shift+alt+s
private int id;
private String name;
private int age;

public User(int id, String name, int age) {
super();
this.id = id;
this.name = name;
this.age = age;
}
public User() {
super();
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
}

}

2.5. 定义操作users表的sql映射文件userMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.atguigu.mybatis_test.test1.userMapper">
<select id="getUser" parameterType="int"
resultType="com.atguigu.mybatis_test.test1.User">
select * from users where id=#{id}
</select>
</mapper>

2.6. 在conf.xml文件中注册userMapper.xml文件

<mappers>
<mapper resource="com/atguigu/mybatis_test/test1/userMapper.xml"/>
</mappers>

2.7. 编写测试代码：执行定义的select语句

public class Test {

public static void main(String[] args) throws IOException {
String resource = "conf.xml";
InputStream is = Test.class.getClassLoader().getResourceAsStream(resource);

SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);

SqlSession session = factory.openSession();

String statement = "com.atguigu.day03_mybaits.test1.userMapper.getUser";

User user = session.selectOne(statement, 2);
System.out.println(user);
}
}