mybatis一些简单的基本用法

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一、jar包导入：

二、数据库：

数据库很简单，只有一张表tbl_user,三个字段，user_id为主键。

三、包的结构：

四、具体class及配置文件：

MybatisUtil.java

package cn.ibm.com.util;import java.io.Reader;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class MybatisUtil {    private static final ThreadLocal<SqlSession> tl = new ThreadLocal<SqlSession>();        public static SqlSession getSqlSession() throws Exception {        String resource = "cn/ibm/com/config/sqlMapConfig.xml";        Reader reader = Resources.getResourceAsReader(resource);        return new SqlSessionFactoryBuilder().build(reader).openSession();    }        public static SqlSession getSameSession() throws Exception{        SqlSession session = tl.get();        if(session==null){            session= getSqlSession();            tl.set(session);        }        return session;    }}

UserDao.java

package cn.ibm.com.dao;import java.util.List;import cn.ibm.com.domain.User;public interface UserDao {    int saveUser(User user);    int saveUser02(User user);    int deleteUserByUserId(String userId);    int updateUser(User user);    User findUserByUserId(String userId);    List<User> findAllUser();    List<User> findUserByConditions(User user);    List<User> findUserByIds(List<String> ids);}

UserDaoImpl.java

package cn.ibm.com.dao.impl;import java.util.List;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;import org.apache.ibatis.session.SqlSession;import cn.ibm.com.dao.UserDao;import cn.ibm.com.domain.User;import cn.ibm.com.util.MybatisUtil;public class UserDaoImpl implements UserDao{private static Log log = LogFactory.getLog(UserDaoImpl.class);private static SqlSession session;static{    try {        session = MybatisUtil.getSameSession();    } catch (Exception e) {        log.debug("获取session出错。。",e);    }}    @Override//如果保存成功则返回1，保存失败，且没有进行以下if的判断处理，则会抛出异常。使用parameterType    public int saveUser(User user) {        if(session.selectOne("cn.ibm.com.domain.User.selectUserByUserId", user.getUserId())!=null){            log.info(user.getUserId()+" : Id已经存在。请重新输入。");            return 0;        }        int ret = session.insert("cn.ibm.com.domain.User.insertUser", user);        log.info("save user return : " +ret);        session.commit();        return ret;    }    @Override//删除成功返回1，删除失败返回0，不会抛出异常    public int deleteUserByUserId(String userId) {        int ret = session.delete("cn.ibm.com.domain.User.deleteUserByUserId", userId);        log.info("delete user return : "+ret);        session.commit();        return ret;    }    @Override//更新失败返回0，更新成功返回1    public int updateUser(User user) {        int ret = session.update("cn.ibm.com.domain.User.updateUser", user);        log.info("update user return : "+ret);        session.commit();        return ret;    }    @Override//    public User findUserByUserId(String userId) {        User user = session.selectOne("cn.ibm.com.domain.User.selectUserByUserId", userId);        log.info("find user return : "+user);        return user;    }    @Override//查找所有用户    public List<User> findAllUser() {        List<User> users = session.selectList("cn.ibm.com.domain.User.selectAllUser");        log.info("find all user return : "+users);        log.info("users size : "+users.size());        return users;    }    @Override//使用parameterMap    public int saveUser02(User user) {        if(session.selectOne("cn.ibm.com.domain.User.selectUserByUserId", user.getUserId())!=null){            log.info(user.getUserId()+" : Id已经存在。请重新输入。");            return 0;        }        int ret = session.insert("cn.ibm.com.domain.User.insertUser02", user);        log.info("save user return : " +ret);        session.commit();        return ret;    }    @Override//多条件模糊查询    public List<User> findUserByConditions(User user) {        List<User> users = session.selectList("cn.ibm.com.domain.User.selectUserByConditions", user);        log.info("find by conditions return : "+users);        log.info("users size : "+users.size());        return users;    }    @Override//根据多个id值进行查找    public List<User> findUserByIds(List<String> ids) {        List<User> users = session.selectList("cn.ibm.com.domain.User.selectUsersByIds",ids);        log.info("users size : "+users.size());        log.info("users : "+users);        return users;    }}

User.java

package cn.ibm.com.domain;public class User {    private String userId;    private String userName;    private String userPwd;        public String getUserId() {        return userId;    }    public void setUserId(String userId) {        this.userId = userId;    }    public String getUserName() {        return userName;    }    public void setUserName(String userName) {        this.userName = userName;    }    public String getUserPwd() {        return userPwd;    }    public void setUserPwd(String userPwd) {        this.userPwd = userPwd;    }    @Override    public String toString() {        return "User [userId=" + userId + ", userName=" + userName                + ", userPwd=" + userPwd + "]";    }    }

mybatis核心配置文件sqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration>    <!-- 定义别名 -->    <typeAliases>        <typeAlias type="cn.ibm.com.domain.User" alias="User"/>    </typeAliases>        <environments default="development">        <environment id="development">            <!-- 事务管理器类型 -->            <transactionManager type="JDBC" />            <!-- 数据源信息 -->            <dataSource type="POOLED">                <property name="driver" value="com.mysql.jdbc.Driver" />                <property name="url" value="jdbc:mysql://localhost:3306/mybatisdb" />                <property name="username" value="root" />                <property name="password" value="root" />            </dataSource>        </environment>    </environments>    <!-- 注册SQL映射文件 -->    <mappers>        <mapper resource="cn/ibm/com/domain/UserMapper.xml" />    </mappers></configuration>

实体映射文件UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><!-- namespace为命名空间 ,要保证唯一--><mapper namespace="cn.ibm.com.domain.User">    <!-- 提取公共字段 -->    <sql id="someCols">        user_name,user_pwd    </sql>    <sql id="allCols">        user_id,user_name,user_pwd    </sql>        <parameterMap type="User" id="userMap">        <parameter property="userId" resultMap="user_id"/>        <parameter property="userName" resultMap="user_name"/>        <parameter property="userPwd" resultMap="user_pwd"/>    </parameterMap>        <resultMap type="User" id="UserResult">        <result property="userId" column="user_id" javaType="String" jdbcType="VARCHAR"/>        <result property="userName" column="user_name"/>        <result property="userPwd" column="user_pwd"/>    </resultMap>        <!-- select标签中是查询语句 -->    <!--        id:当前对应SQL的唯一标识        parameterType：当前SQL接收参数的类型        resultType:执行SQL后包装成什么类型返回     -->    <select id="selectUserByUserId" parameterType="int" resultMap="UserResult">        select             <include refid="allCols"/>         from tbl_user where user_id = #{id}    </select>    <!-- 以下两种插入数据方式都可以正常运行 -->    <insert id="insertUser" parameterType="User" >        insert into tbl_user (<include refid="allCols"/>) values(#{userId},#{userName},#{userPwd})    </insert>        <insert id="insertUser02" parameterMap="userMap" >        insert into tbl_user (<include refid="allCols"/>) values(#{userId},#{userName},#{userPwd})    </insert>        <delete id="deleteUserByUserId" parameterType="int" >        delete from tbl_user where user_id = #{id}    </delete>        <update id="updateUser" parameterType="User" >        update tbl_user         <set>                user_name=#{userName},                user_pwd = #{userPwd}         </set>         <where>                 user_id = #{userId}         </where>         <!-- 以上方式和下面的这种原始方式都可以实现update操作 -->        <!-- update tbl_user set user_name=#{userName},user_pwd=#{userPwd} where user_id=#{userId} -->    </update>        <select id="selectAllUser" resultMap="UserResult" >        select <include refid="allCols"/> from tbl_user    </select>    <!-- 多条件模糊查询,通过parameterType方式 -->    <select id="selectUserByConditions" parameterType="User" resultMap="UserResult">        select <include refid="allCols"/> from tbl_user        <where>           <where>            <if test="userName!=null">                user_name like concat('%',#{userName},'%')            </if>            <if test="userPwd!=null">                and user_pwd like concat('%',#{userPwd},'%')            </if>        </where>        </where>    </select>    <!-- 根据多个id进行查询 -->    <!-- 在这种情况下， parameterType="" 可以省略不写，其值也可以为list,List,java.util.List或者String,string,java.lang.String都是正确的，都可以输出结果    但是resultMap不能使用User，在本例中不可以使用，本例中User属性字段和数据库表字段是不一样的，不知道一样的话行不行，有待验证    foreach中item的属性值要和foreach内部大括号内的值相同，否则会发生异常    -->    <select id="selectUsersByIds" parameterType="java.util.List" resultMap="UserResult">    select <include refid="allCols"/> from tbl_user        <where>            user_id in            <foreach item="userId" collection="list" separator="," open="(" close=")" >            #{userId}            </foreach>        </where>    </select></mapper>

日志文件log4j.properties

log4j.rootLogger=debug,my### direct log messages to my ###log4j.appender.my=org.apache.log4j.ConsoleAppenderlog4j.appender.my.Target=System.outlog4j.appender.my.layout=org.apache.log4j.PatternLayoutlog4j.appender.my.layout.ConversionPattern=%d %5p %c{1}:%L - %m%n

测试类UserDaoTest.java

package test;import java.util.ArrayList;import java.util.List;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;import org.apache.ibatis.session.SqlSession;import org.junit.Test;import cn.ibm.com.dao.UserDao;import cn.ibm.com.dao.impl.UserDaoImpl;import cn.ibm.com.domain.User;import cn.ibm.com.util.MybatisUtil;public class UserDaoTest {        private static Log logger = LogFactory.getLog(UserDaoTest.class);    private UserDao userDao = new UserDaoImpl();        @Test//test if get the same session    public void testSameSession() throws Exception{        SqlSession s0 = MybatisUtil.getSameSession();        SqlSession s1 = MybatisUtil.getSameSession();        System.out.println(s0==s1);         //true        SqlSession s2 = MybatisUtil.getSqlSession();        SqlSession s3 = MybatisUtil.getSqlSession();        System.out.println(s2==s3);  //false    }    @Test    public void testSaveUser(){        User user = new User();        int random = (int) ((Math.random()+1)*1000);        user.setUserId(random+"");        user.setUserName("name "+random);        user.setUserPwd("name "+random);        userDao.saveUser(user);    }    @Test    public void testSaveUser01(){        User user = new User();        user.setUserId(200000+"");        user.setUserName("name ");        user.setUserPwd("name ");        userDao.saveUser(user);    }    @Test    public void testDeleteUser(){        userDao.deleteUserByUserId("200000");    }    @Test    public void testFindUserById(){        userDao.findUserByUserId("200000");    }    @Test    public void testSaveUser_parameterMap(){        User user = new User();        user.setUserId(200001+"");        user.setUserName("name1 ");        user.setUserPwd("name1 ");        userDao.saveUser02(user);    }    @Test    public void testFindAllUser(){        userDao.findAllUser();    }    @Test    public void testUpdateUser(){        User user = new User();        user.setUserId("200001");        user.setUserName("updateName");        user.setUserPwd("updatePwd");        userDao.updateUser(user);    }    @Test    public void testConditionsQuery(){        User user = new User();        user.setUserName("n");        user.setUserPwd("n");        userDao.findUserByConditions(user);    }    @Test    public void testFindUserByIds(){        List<String> ids = new ArrayList<String>();        ids.add("58");        ids.add("1862");        userDao.findUserByIds(ids);    }}

注意：有的时候可能会因为一些很小的细节出现问题，比如insert into tbl_user (<include refid="allCols"/>) values(#{userId},#{userName},#{userPwd})，这个sql语句，如果不小心将前面的括号写丢了，肯定时会发生异常的，如果参数类型是String或者其他的基本数据类型，当通过#进行取值的时候{}里面的值可以随便填写，但是如果是实体类对象，则

{}中的值必须是实体类的属性，如果不是则会发生异常。

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