mybatis初学记录
1.mybatis架构
2.需要的jar 包
需要加入mybatis的核心包，依赖包，数据驱动包。图中未画出的是依赖包。
3.记录日志
需要创建log4j.properties，在其中输入：
# Global logging configuration
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%n4.连接数据库xml
创建SqlMapConfig.xml
其中db.properties文件内容。
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8
jdbc.username=root
jdbc.password=root
5.创建pojo
作为mybatis进行sql映射使用，po类通常与数据库表对应。
package com.zyz.pojo;
import java.io.Serializable;
import java.util.Date;
public class User implements Serializable {
private static final long serialVersionUID = 1L;
private Integer id;
private String username;
private String sex;
private Date birthday;
private String address;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "User [id=" + id + ", username=" + username + ", sex=" + sex
+ ", birthday=" + birthday + ", address=" + address + "]";
}
}
6.sql映射文件
mybatis框架需要加载mapper.xml映射文件。在sqlmapconfig.xml进行配置，如标题4中的mappers中的配置。
SELECT LAST_INSERT_ID()
INSERT INTO user (username,birthday,sex,address) values (#{username},#{birthday},#{sex},#{address})
UPDATE user set username = #{username},birthday = #{birthday},sex=#{sex},address=#{address} where id=#{id}
DELETE from user where id=#{id}
7.测试程序
package com.zyz.test;
import com.zyz.pojo.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.Before;
import org.junit.Test;
import java.io.InputStream;
import java.util.List;
import java.util.Date;
public class MybatisTest {
private SqlSessionFactory sqlSessionFactory = null;
@Before
public void init() throws Exception{
SqlSessionFactory sqlSessionFactory = null;
//1.加载SqlSessionFactoryBuilder对象
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
//2.加载SqlMapConfig.xml
InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
//3.创建sqlSessionFactory对象
this.sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
}
@Test
public void testMybatis() throws Exception{
//4.创建sqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//5.执行语句
Object user = sqlSession.selectOne("queryUserById", 1);
//6.打印结果
System.out.println(user);
//7.释放资源
sqlSession.close();
}
@Test
public void testMybatis1() throws Exception {
//4.创建sqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//5.执行语句
List user = sqlSession.selectList("queryUserByName","王");
// for (User user2:user) {
// System.out.println(user2);
// }
//6.打印结果
System.out.println(user);
//7.释放资源
sqlSession.close();
}
@Test
public void testMybatisInsert() throws Exception {
//4.创建sqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//5.执行语句
User user=new User();
user.setUsername("王");
user.setBirthday(new Date());
user.setSex("1");
user.setAddress("aaaaaa");
int i = sqlSession.insert("insertUser", user);
System.out.println(user);
System.out.println(user.getId());
sqlSession.commit();
//6.打印结果
// System.out.println(user);
//7.释放资源
sqlSession.close();
}
@Test
public void testMybatisUpdate() throws Exception {
//4.创建sqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//5.执行语句
User user=new User();
user.setId(30);
user.setUsername("张");
user.setBirthday(new Date());
user.setSex("0");
user.setAddress("33");
int i = sqlSession.update("updateUser", user);
System.out.println(user);
System.out.println(user.getId());
sqlSession.commit();
//6.打印结果
// System.out.println(user);
//7.释放资源
sqlSession.close();
}
@Test
public void testMybatisDelete() throws Exception {
//4.创建sqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//5.执行语句
int i = sqlSession.update("deleteUser", 30);
sqlSession.commit();
//6.打印结果
// System.out.println(user);
//7.释放资源
sqlSession.close();
}
}
8.mybatis与hibernate不同
1.mybatis需要自己编写sql语句。
2.mybatis无法做到数据库无关性。
3.mybatis入门简单易学。
9.Mapper动态代理方式
需要遵循4大原则：
- Mapper.xml文件中的namespace与mapper接口的类路径相同。
- Mapper接口方法名和Mapper.xml中定义的每个statement的id相同
- Mapper接口方法的输入参数类型和mapper.xml中定义的每个sql 的parameterType的类型相同
- Mapper接口方法的输出参数类型和mapper.xml中定义的每个sql的resultType的类型相同
Mapper.xml映射文件
SELECT LAST_INSERT_ID()
INSERT INTO user (username,birthday,sex,address) values (#{username},#{birthday},#{sex},#{address})
UPDATE user set username = #{username},birthday = #{birthday},sex=#{sex},address=#{address} where id=#{id}
DELETE from user where id=#{id}
10.动态代理测试代码
package com.zyz.test;
import com.zyz.mapper.UserMapper;
import com.zyz.pojo.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.Before;
import org.junit.Test;
import java.io.InputStream;
public class UserMapperTest {
private SqlSessionFactory sqlSessionFactory = null;
@Before
public void init() throws Exception{
SqlSessionFactory sqlSessionFactory = null;
//1.加载SqlSessionFactoryBuilder对象
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
//2.加载SqlMapConfig.xml
InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
//3.创建sqlSessionFactory对象
this.sqlSessionFactory = sqlSessionFactoryBuilder.build(inputStream);
}
@Test
public void testMapper() throws Exception{
//4.创建sqlSession对象
SqlSession sqlSession = sqlSessionFactory.openSession();
//5.执行语句
UserMapper userMapper= sqlSession.getMapper(UserMapper.class);
User user = userMapper.queryUserById(30);
System.out.println(user);
}
}