Mybatis学习笔记---day01基础知识
一、Mybatis执行流程图及优缺点
1、执行流程
2、与hibernate对比优缺点
二：Mybatis入门小案例
1.创建java项目，导入mybatis、mysql、junit 依赖的jar包
2.创建并编写mybatis核心配置文件
3、log4j.properties
### direct log messages to stdout ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n
### direct messages to file mylog.log ###
log4j.appender.file=org.apache.log4j.FileAppender
log4j.appender.file.File=c:/mylog.log
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n
### set log levels - for more verbose logging change 'info' to 'debug' ###
log4j.rootLogger=debug, stdout
4.创建POJO类
package com.mybatis.pojo;
import java.io.Serializable;
import java.util.Date;
public class User implements Serializable{
private static final long serialVersionUID = 1L;
private int id;
private String username;// 用户姓名
private String sex;// 性别
private Date birthday;// 生日
private String address;// 地址
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 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 + "]";
}
}5.创建Mapper.xml文件
update user set username = #{username} where id = #{id}
insert into user(username,address) values (#{username},#{address});
delete from user where id = #{id}
6.创建Junit单元测试类
package com.mybatis.junit;
import java.io.InputStream;
import java.util.List;
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 com.mybatis.pojo.User;
/**
* junit单元测试类
* @author Administrator
*
*/
public class MybatisJunit {
private SqlSessionFactory sqlSessionFactory = null;
@Before
public void testBefore() throws Exception{
//读取配置文件到输入流中
String resource = "sqlMapConfig.xml";
InputStream in = Resources.getResourceAsStream(resource);
//工厂构建类
//创建sqlSessionFactory工厂
sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
}
@Test
public void testMybatis() {
//打开sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
//查询一条数据
User user = sqlSession.selectOne("test.selectUserById",1);
System.out.println(user);
}
/*
* 根据用户名模糊查询
*/
@Test
public void testMybatisByName(){
//打开sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
List list = sqlSession.selectList("test.selectUsersByName", "王五");
for (User user : list) {
System.out.println(user);
}
}
/*
* 根据ID修改用户信息
*/
@Test
public void testUpdate(){
//打开sqlSessiono
SqlSession sqlSession = sqlSessionFactory.openSession();
User user = sqlSession.selectOne("test.selectUserById",1);
user.setUsername("王者1");
sqlSession.update("test.updateUserById", user);
sqlSession.commit();
}
/*
* 新增用户
*/
@Test
public void testAddUser(){
//打开sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
User user = new User();
user.setUsername("你好");
user.setAddress("河南平顶山");
sqlSession.insert("test.insertUser", user);
sqlSession.commit();
}
/*
* 根据id删除用户信息
*/
@Test
public void testDelete(){
//打开sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
sqlSession.delete("test.deleteUserById", 28);
sqlSession.commit();
}
}
三：使用原始Dao实现MyBatis小案例
1.dao接口以及实现类
a、接口
package com.mybatis.dao;
import com.mybatis.pojo.User;
public interface UserDao {
public User selectUserById(Integer id) throws Exception;
}b、实现类
package com.mybatis.dao;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import com.mybatis.pojo.User;
public class UserDaoImpl implements UserDao {
private SqlSessionFactory sqlSessionFactory = null;
public UserDaoImpl(SqlSessionFactory sqlSessionFactory){
this.sqlSessionFactory = sqlSessionFactory;
};
public User selectUserById(Integer id) throws Exception{
SqlSession sqlSession = sqlSessionFactory.openSession();
//返回一个用户
User user = sqlSession.selectOne("test.selectUserById", id);
return user;
}
}2.编写测试类
package com.mybatis.junit;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;
import com.mybatis.dao.UserDao;
import com.mybatis.dao.UserDaoImpl;
import com.mybatis.pojo.User;
/**
* junit单元测试类
* @author Administrator
*
*/
public class MybatisDaoJunit {
private SqlSessionFactory sqlSessionFactory = null;
@Before
public void testBefore() throws Exception{
//读取配置文件到输入流中
String resource = "sqlMapConfig.xml";
InputStream in = Resources.getResourceAsStream(resource);
//工厂构建类
//创建sqlSessionFactory工厂
sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
}
@Test
public void testSelectUser() throws Exception{
UserDao userDao = new UserDaoImpl(sqlSessionFactory);
User user = userDao.selectUserById(1);
System.out.println(user);
}
}
四：使用接口动态代理实现MyBatis小案例
1.规则：
a、
Mapper.xml文件中的namespace与mapper接口的类路径相同。
b、 Mapper接口方法名和Mapper.xml中定义的每个statement的id相同
c、 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
d、 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
b、 Mapper接口方法名和Mapper.xml中定义的每个statement的id相同
c、 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
d、 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
2.编写mapper接口类
package com.mybatis.mapper;
import com.mybatis.pojo.User;
public interface UserMapper {
//根据id获取用户信息
public User selectUserById(Integer id);
}3.编写mapper.xml文件
4.编写junit测试类
package com.mybatis.junit;
import java.io.InputStream;
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 com.mybatis.dao.UserDao;
import com.mybatis.dao.UserDaoImpl;
import com.mybatis.mapper.UserMapper;
import com.mybatis.pojo.User;
/**
* junit单元测试类
* @author Administrator
*
*/
public class MybatisMapperDaoJunit {
private SqlSessionFactory sqlSessionFactory = null;
@Before
public void testBefore() throws Exception{
//读取配置文件到输入流中
String resource = "sqlMapConfig.xml";
InputStream in = Resources.getResourceAsStream(resource);
//工厂构建类
//创建sqlSessionFactory工厂
sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
}
@Test
public void testSelectUser() throws Exception{
SqlSession sqlSession = sqlSessionFactory.openSession();
//获取接口代理
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.selectUserById(10);
System.out.println(user);
}
}
五：sqlMapConfig.xml配置文件说明
1.properties配置
2.setting配置
mybatis全局配置参数
3.typeAliases
配置别名，配置完成之后直接可在mapper.xml中使用
4.typeHandlers
类处理器，将java类型和jdbc类型映射，例如：将java中的string转换成jdbc中的varchar等，mybatis中自带的已经基本满足要求
5.mappers
指定mapper.xml文件的位置
a、
相对于类路径的资源，例如：
b、
使用完全限定路径，该方式几乎不用。例如：
c、
使用Mapper接口类路径，例如：
注意：
此方式要求mapper接口名称和mapper.xml映射文件的
名称相同，且位于
同一个包中，且只能使用
接口代理开发方式进行开发
缺点：
此种方式只能扫描单个接口，如果接口多，则不适用
d、
注册指定包下的所有mapper接口，例如：
注意：
此方式要求mapper接口名称和mapper.xml映射文件的
名称相同，且位于
一个包中，且只能使用接口代理开发方式进行开发
六：Mapper.xml文件配置说明
1.当入参类型为pojo时，${}中的内容应该为pojo类的属性字段名称，不能随意写
例如：
insert into user(username,address) values (#{username},#{address});
2.当入参为包装类时
a、编写包装类
package com.mybatis.pojo;
/**
* 查询的包装类
* @author Administrator
*
*/
public class QueryVo {
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}b、编写Mapper接口文件中的方法
package com.mybatis.mapper;
import java.util.List;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
public interface UserMapper {
//根据id获取用户信息
public User selectUserById(Integer id);
//使用包装类，根据用户名模糊查询
public List selectUserByQuery(QueryVo queryVo);
} c、编写mapper.xml映射文件
d、编写junit测试类
package com.mybatis.junit;
import java.io.InputStream;
import java.util.List;
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 com.mybatis.mapper.UserMapper;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
/**
* junit单元测试类
* @author Administrator
*
*/
public class MybatisMapperDaoJunit {
private SqlSessionFactory sqlSessionFactory = null;
@Before
public void testBefore() throws Exception{
//读取配置文件到输入流中
String resource = "sqlMapConfig.xml";
InputStream in = Resources.getResourceAsStream(resource);
//工厂构建类
//创建sqlSessionFactory工厂
sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
}
//使用包装类进行模糊查询
@Test
public void testSelectByQuery(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = new User();
user.setUsername("明");
QueryVo queryVo = new QueryVo();
queryVo.setUser(user);
List list = userMapper.selectUserByQuery(queryVo);
for (User user1 : list) {
System.out.println(user1);
}
}
} 3.当入参为包装类型中的数组时
a、编写包装类的pojo
package com.mybatis.pojo;
/**
* 查询的包装类
* @author Administrator
*
*/
public class QueryVo {
private User user;
private Object[] object;
public Object[] getObject() {
return object;
}
public void setObject(Object[] object) {
this.object = object;
}b、编写Mapper接口方法
package com.mybatis.mapper;
import java.util.List;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
public interface UserMapper {
//根据id获取用户信息
public User selectUserById(Integer id);
//使用包装类，根据用户名模糊查询
public List selectUserByQuery(QueryVo queryVo);
//使用包装类，数组
public List selectUserByQueryArray(QueryVo queryVo);
} c、编写Mapper.xml映射文件
d、编写junit测试类
package com.mybatis.junit;
import java.io.InputStream;
import java.util.List;
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 com.mybatis.mapper.UserMapper;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
/**
* junit单元测试类
*
* @author Administrator
*
*/
public class MybatisMapperDaoJunit {
private SqlSessionFactory sqlSessionFactory = null;
@Before
public void testBefore() throws Exception {
// 读取配置文件到输入流中
String resource = "sqlMapConfig.xml";
InputStream in = Resources.getResourceAsStream(resource);
// 工厂构建类
// 创建sqlSessionFactory工厂
sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
}
// 使用包装类进行模糊查询
@Test
public void testQueryArray() {
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
QueryVo queryVo = new QueryVo();
Object[] object = new Object[2];
object[0] = 1;
object[1] = 29;
queryVo.setObject(object);
List list = userMapper.selectUserByQueryArray(queryVo);
for (User user1 : list) {
System.out.println(user1);
}
}
} 4.当传递的参数类型为HashMap时
a、编写mapper接口文件
package com.mybatis.mapper;
import java.util.List;
import java.util.Map;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
public interface UserMapper {
//根据id获取用户信息
public User selectUserById(Integer id);
//使用包装类，根据用户名模糊查询
public List selectUserByQuery(QueryVo queryVo);
//使用包装类 数组
public List selectUserByQueryArray(QueryVo queryVo);
//使用hashMap封装参数
public List selectUsersByHashMap(Map map);
} b、编写mapper.xml映射文件
c、编写junit测试类
//测试HashMap封装参数
@Test
public void testQueryHashMap(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
Map map = new HashMap();
map.put("username", "明");
map.put("address", "河南郑州");
List users = userMapper.selectUsersByHashMap(map);
for (User user : users) {
System.out.println(user);
}
} 5.当返回值类型为Integer时
a、编写Mapper接口文件中的方法
import java.util.List;
import java.util.Map;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
public interface UserMapper {
//根据id获取用户信息
public User selectUserById(Integer id);
//使用包装类，根据用户名模糊查询
public List selectUserByQuery(QueryVo queryVo);
//使用包装类 数组
public List selectUserByQueryArray(QueryVo queryVo);
//使用hashMap封装参数
public List selectUsersByHashMap(Map map);
//返回类型为Integer
public Integer selectUsersCount(String username);
} b、编写Mapper.xml文件
c、编写junit测试类
//测试返回结果类型为Integer
@Test
public void testCount(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = new User();
user.setUsername("明");
int count = userMapper.selectUsersCount("明");
System.out.println(count);
}6.使用resultMap手动映射pojo类属性和数据库表字段之间的关系
a、编写mapper接口方法
package com.mybatis.mapper;
import java.util.List;
import java.util.Map;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
public interface UserMapper {
//根据id获取用户信息
public User selectUserById(Integer id);
//使用包装类，根据用户名模糊查询
public List selectUserByQuery(QueryVo queryVo);
//使用包装类 数组
public List selectUserByQueryArray(QueryVo queryVo);
//使用hashMap封装参数
public List selectUsersByHashMap(Map map);
//返回类型为Integer
public Integer selectUsersCount(String username);
//使用resultMap手动映射
public List selectUserByUsername(String username);
} b、编写mapper.xml映射文件
c、编写junit测试类
//测试数据库表字段与pojo类属性名称不相同时
@Test
public void testResultMap(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List users = userMapper.selectUserByUsername("明");
for (User user : users) {
System.out.println(user);
}
} 7.使用动态sql --- < if >
a、编写mapper接口
package com.mybatis.mapper;
import java.util.List;
import java.util.Map;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
public interface UserMapper {
// 动态sql查询， 使用if
public List selectUsersByIf(Map map);
} b、编写mapper.xml映射文件
c、编写junit测试类
//测试动态sql中的if的使用
@Test
public void testDynamicSQLWithIf(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
Map map = new HashMap();
map.put("username", "明");
map.put("address", "河南郑州");
List usersByIf = userMapper.selectUsersByIf(map);
for (User user : usersByIf) {
System.out.println(user);
}
} 8.动态sql --- < foreach > 当传递的参数直接为数组时
a、编写mapper接口
package com.mybatis.mapper;
import java.util.List;
import java.util.Map;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
public interface UserMapper {
//参数直接是array数组时
public List selectUsersByIdArray(Integer[] ids);
} b、编写mapper.xml映射文件
c、编写junit测试类
//测试动态sql中的foreach
@Test
public void testDynamicForEach(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
Integer[] ids = new Integer[]{1,29};
List users = userMapper.selectUsersByIdArray(ids);
for (User user : users) {
System.out.println(user);
}
} 9.动态sql，当传递的参数为list集合时
a、编写mapper接口
package com.mybatis.mapper;
import java.util.List;
import java.util.Map;
import com.mybatis.pojo.QueryVo;
import com.mybatis.pojo.User;
public interface UserMapper {
//参数为list集合
public List selectUsersByList(List ids);
} b、编写mapper.xml映射文件
c、编写junit测试类
//动态测试-- 入参类型为list
@Test
public void testDynamicForEachWithList(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
List ids = new ArrayList();
ids.add(1);
ids.add(29);
List users = userMapper.selectUsersByList(ids);
for (User user : users) {
System.out.println(user);
}
} 10.sql片段
mapper.xml配置文件中的书写方式
select * from user