一 简介
mybatis让程序将主要精力放在sql上，通过mybatis提供的映射方式，自由灵活生成（半自动化，大部分需要程序员编写sql）满足需要sql语句。
mybatis可以将向preparedStatement中输入参数自动进行输入映射，将查询结果灵活映射成java对象。（输出映射）
二 原理
mabatis框架原理
三 入门程序
1 环境搭建
（1）maven jar包
junit
junit
4.11
test
asm
asm
3.3.1
cglib
cglib
2.2.2
commons-logging
commons-logging
1.1.1
org.javassist
javassist
3.17.1-GA
log4j
log4j
1.2.17
org.apache.logging.log4j
log4j-api
2.0
org.apache.logging.log4j
log4j-core
2.0
org.slf4j
slf4j-api
1.7.5
org.slf4j
slf4j-log4j12
1.7.5
test
org.mybatis
mybatis
3.2.7
mysql
mysql-connector-java
5.1.18
（2）log4j.properties
#Global logging configuration
#在开发环境下日志级别要设置成DEBUG，生产环境设置成info或error
log4j.rootLogger=DEBUG,stdout
#Console output
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = %5p [%t] - %m%n
（3）SqlMapConfig.xml
环境搭建
2 根据id查询用户
(1) User Bean
package entity;
import java.util.Date;
public class User {
private int id;
private String username;
private Date birthday;
private String sex;
private String address;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", birthday=" + birthday +
", sex='" + sex + '\'' +
", address='" + address + '\'' +
'}';
}
}
(2) userMap.xml
(3) 在核心配置文件中加载映射文件
图片.png
(4) 测试
import entity.User;
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 org.junit.jupiter.api.Test;
import java.io.IOException;
import java.io.InputStream;
public class mybatisTest {
@Test
public void findUserById() throws IOException {
//配置文件
String resource = "SqlMapConfig.xml";
//得到配置文件流
InputStream inputStream = Resources.getResourceAsStream(resource);
//创建会话工厂
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//通过工厂得到SqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
//通过SqlSession操作数据库
//第一个参数：等于 = namespace+“.”+statement的id
//第二个参数：指定映射文件中所匹配的parameterType类型的参数
User user = sqlSession.selectOne("test.findUserById",1);
System.out.println(user);
sqlSession.close();
}
}
执行结果
3 根据用户名称模糊查询信息
(1) userMap.xml
...
...
(2) 测试
@Test
public void findUserByName() throws IOException {
InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
List list = sqlSession.selectList("test.findUserByName","马");
System.out.println(list);
}
执行结果
4 添加用户
（1）userMap.xml
....
SELECT LAST_INSERT_ID()
INSERT INTO user (username,birthday,sex,address) VALUES(#{username},#{birthday},#{sex},#{address})
....
(2) 测试
@Test
public void insertUser() throws IOException {
InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
User user = new User();
user.setUsername("张三");
user.setBirthday(new Date());
user.setSex("男");
user.setAddress("美国纽约");
sqlSession.insert("test.insertUser",user);
sqlSession.commit();
System.out.println(user.getId());
System.out.println(new Date());
sqlSession.close();
}
5 删除用户
（1）userMap.xml
....
DELETE from user where id = #{id}
....
(2) 测试
@Test
public void deleteUser() throws IOException {
InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
sqlSession.delete("test.deleteUser",12);
sqlSession.commit();
sqlSession.close();
}
6 更新用户
（1）userMap.xml
.....
UPDATE user SET username = #{username},birthday = #{birthday},sex = #{sex},address = #{address} WHERE id = #{id}
.....
(2) 测试
@Test
public void updateUser() throws IOException {
InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession= sqlSessionFactory.openSession();
User user = new User();
user.setId(12);
user.setUsername("李四");
user.setBirthday(new Date());
user.setSex("男");
user.setAddress("英国伦敦");
sqlSession.update("test.updateUser",user);
sqlSession.commit();
sqlSession.close();
}