使用mybatis开发步骤

1 导包

2 搭建项目的整体架构

3 编写工具类

package com.util;
import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MybatisUtils {
private static SqlSessionFactory sqlSessionFactory;
static {
try {
            Reader reader = Resources.getResourceAsReader("mybatis.cfg.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
public static SqlSession getSqlSession() {
return sqlSessionFactory.openSession();
    }
}

4 编写配置文件

<?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>
<typeAliases>
<!-- 别名方式1，一个一个的配置，type中放置的是类的全路径，alias中放置的是类别名 -->
<typeAlias type="com.entity.User" alias="User"/>

<!-- 列名方式2，自动扫描，将Java Bean的类名作为类的别名 -->
<!-- <package name="com.entity"/> -->
</typeAliases>

<!-- 配置开发环境 -->
<environments default="development">
<environment id="development">
<!-- type="JDBC"代表使用JDBC的提交和回滚来管理事务 -->
<transactionManager type="JDBC"/>
<!-- mybatis提供了3种数据源类型，分别是：POOLED、UNPOOLED、JNDI 
 POOLED：mybatis实现简单的数据库连接池，它使得数据库连接可以复用，不必在每次请求时创建一个新的连接。
 UNPOOLED：表示不支持数据源连接池。
 JNDI表示支持外部数据源连接池。
 -->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/test"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>

<!-- 配置映射文件 -->
<mappers>
<!-- 配置映射文件方式1，一个一个的配置 -->
<mapper resource="com/dao/UserDaoMapper.xml"/>
<!-- 配置映射文件方式2，自动扫描包内的Mapper接口与配置文件 -->
<!-- <package name="com/dao"/> -->
</mappers>
</configuration>

5 编写实体类和Dao接口

6 编写映射文件

<?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.dao.UserDaoMapper">

<!-- 如果实体类的属性名与表的字段名不同时 -->
<resultMap type="User" id="userMap">
<id property="id" column="id" javaType="java.lang.Integer"/>
<result property="username" column="username" javaType="java.lang.String"/>
<result property="password" column="password" javaType="java.lang.String"/>
<result property="sex" column="sex" javaType="java.lang.String"/>
<result property="age" column="age" javaType="java.lang.Integer"/>
</resultMap>

<select id="findById" parameterType="int" resultType="User">
        select * from user 
            where id=#{id}
</select>

<select id="fingByCondition" parameterType="User" resultMap="userMap">
        select * from user where 1=1
<if test="username!=null">
                and username like#{username}
</if>
<if test="sex!=null">
                and sex#={sex}
</if>
<if test="age!=null">
                and age#={age}
</if>
</select>

<select id="findAll" resultType="User">
        select * from user
</select>

<insert id="saveUser" parameterType="User">
        insert into user
            (id,
             username,
             password,
             sex,
             age)
        values
            (#{id},
             #{username},
             #{password},
             #{sex},
             #{age})
</insert>

<update id="updateUser" parameterType="User">
        update user set
            username=#{username},
            password=#{password},
            sex=#{sex},
            age#={age}
        where id=#{id}
</update>

<delete id="removeUser" parameterType="int">
        delete from user
            where id=#{id}
</delete>
</mapper>

7 编写Dao接口的实现类

package com.dao.impl;
import java.io.Serializable;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import com.dao.UserDao;
import com.entity.User;
import com.util.MybatisUtils;

public class UserDaoImpl implements UserDao {
@Override
public User findById(int id) {
        SqlSession session = MybatisUtils.getSqlSession();
        User user = session.selectOne("com.dao.UserDaoMapper.findById", id);
        session.close();
return user;
    }
@Override
public List<User> findByCondition(User user) {
        SqlSession session = MybatisUtils.getSqlSession();
        List<User> userList = session.selectList("com.dao.UserDaoMapper.findByCondition");
        session.close();
return userList;
    }
@Override
public List<User> findAll() {
        SqlSession session = MybatisUtils.getSqlSession();
        List<User> userList = session.selectList("com.dao.UserDaoMapper.findAll");
        session.close();
return userList;
    }
@Override
public Serializable saveUser(User user) {
        SqlSession session = MybatisUtils.getSqlSession();
int result = -1;
try {
            result = session.insert("com.dao.UserDaoMapper.saveUser", user);
            session.commit();
        } catch (Exception e) {
            session.rollback();
            e.printStackTrace();
        } finally {
            session.close();
        }
return result;
    }
@Override
public Serializable removeUser(int id) {
        SqlSession session = MybatisUtils.getSqlSession();
int result = -1;
try {
            result = session.delete("com.dao.UserDaoMapper.removeUser", id);
            session.commit();
        } catch (Exception e) {
            session.rollback();
            e.printStackTrace();
        } finally {
            session.close();
        }
return result;
    }
@Override
public Serializable updateUser(User user) {
        SqlSession session = MybatisUtils.getSqlSession();
int result = -1;
try {
            result = session.update("com.dao.UserDaoMapper.updateUser", user);
            session.commit();
        } catch (Exception e) {
            session.rollback();
            e.printStackTrace();
        } finally {
            session.close();
        }
return result;
    }
}