前面已經介紹過Mybatis的全局配置文件mybatis-config.xml文件，本篇文章將繼續介紹Mybatis的另外的一種更重要的Mapper映射器配置文件。
在Mybatis中，Mapper映射器主要用於編寫定製sql方法，而這一xml文件的命名空間通常會對應一個接口，接口全名與映射文件的命名空間一致，抽象方法名與xml定製方法名一致，這就使得Mybatis更加面向對象了。話不多說，我們通過實例來深入理解這樣配置的好處。
1、新建一個JavaProject，新建lib文件夾，導入mybatis的jar包mybatis-3.4.1.jar，mysql數據庫連接驅動包mysql-connector-java-5.1.29.jar，日誌包log4j-1.2.17.jar
2、創建數據庫表tbl_user
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for tbl_user
-- ----------------------------
DROP TABLE IF EXISTS `tbl_user`;
CREATE TABLE `tbl_user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(25) DEFAULT NULL,
`sex` char(2) DEFAULT NULL,
`age` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=14 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of tbl_user
-- ----------------------------
INSERT INTO `tbl_user` VALUES ('11', '張三', '男', '23');
INSERT INTO `tbl_user` VALUES ('12', '李四', '女', '34');
INSERT INTO `tbl_user` VALUES ('13', '張五', '男', '43');3、創建與數據表對應的pojo類
User.java
package com.gec.domain;
import java.io.Serializable;
public class User implements Serializable{
private Integer id;
private String name;
private String sex;
private Integer age;
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 String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", sex=" + sex + ", age=" + age + "]";
}
}
mybatis-config.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "mybatis-3-config.dtd" >
<configuration>
<settings>
<setting name="logImpl" value="LOG4J"/>
</settings>
<typeAliases>
<typeAlias type="com.gec.domain.User" alias="user"/>
</typeAliases>
<environments default="mysql">
<environment id="mysql">
<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="123"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="com/gec/mapper/UserMapper.xml"/>
</mappers>
</configuration>
UserMapper.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "mybatis-3-mapper.dtd" >
<mapper namespace="com.gec.mapper.UserMapper">
<insert id="insertUser" parameterType="user"
useGeneratedKeys="true" keyColumn="id" keyProperty="id">
insert into tbl_user(name,sex,age) values(#{name},#{sex},#{age});
</insert>
<update id="updateUser" parameterType="user">
update tbl_user set name=#{name},sex=#{sex},age=#{age}
where id=#{id};
</update>
<delete id="deleteUser" parameterType="int">
delete from tbl_user where id=#{id};
</delete>
<select id="queryUser" parameterType="user" resultType="user">
select * from tbl_user where name=#{name} or age=#{age};
</select>
<select id="queryUser2" resultType="user">
select * from tbl_user where name=#{name} or age=#{age};
</select>
<select id="queryUser3" resultType="user" >
select * from tbl_user where name=#{name} or age=#{age};
</select>
</mapper>
UserMapper.java
package com.gec.mapper;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Param;
import com.gec.domain.PageModel;
import com.gec.domain.User;
public interface UserMapper {
public int insertUser(User user);
public int updateUser(User user);
public int deleteUser(User user);
public List<User> queryUser(User user);
public List<User> queryUser2(Map<String,Object> map);
public List<User> queryUser3(
@Param("name") String userName,
@Param("age") Integer userAge);
}MainTest.java
package com.gec.test;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import com.gec.domain.User;
import com.gec.mapper.UserMapper;
public class MainTest {
public static void main(String[] args) throws IOException {
InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sf = new SqlSessionFactoryBuilder().build(inputStream);
// insertUser(sf);
// queryUser(sf);
// queryUser2(sf);
queryUser3(sf);
}
public static void insertUser(SqlSessionFactory sf) {
SqlSession session = sf.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User user = new User();
user.setName("張三");
user.setSex("男");
user.setAge(23);
userMapper.insertUser(user);
session.commit();
session.close();
}
public static void queryUser(SqlSessionFactory sf) {
SqlSession session = sf.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
User user = new User();
user.setName("張三");
user.setAge(34);
List<User> userList = userMapper.queryUser(user);
for (User resultUser : userList) {
System.out.println(resultUser);
}
session.close();
}
public static void queryUser2(SqlSessionFactory sf) {
SqlSession session = sf.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
Map<String,Object> userMap = new HashMap<>();
userMap.put("name", "張三");
userMap.put("age", 34);
List<User> userList = userMapper.queryUser2(userMap);
for (User resultUser : userList) {
System.out.println(resultUser);
}
session.close();
}
public static void queryUser3(SqlSessionFactory sf) {
SqlSession session = sf.openSession();
UserMapper userMapper = session.getMapper(UserMapper.class);
List<User> userList = userMapper.queryUser3("張三", 34);
for (User user : userList) {
System.out.println(user);
}
session.close();
}
}