MyBatis总结（一）

一、创建测试项目工程

二、导包（一个myBatis所需的包，以及一个数据库操作的包）

三、创建实体类

四、配置文件的建立（最佳命名为（SqlMapConfig.xml））

<?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>
    <properties resource="datasource.properties"></properties>
    <typeAliases>
        <typeAlias type="com.lovo.pojo.User" alias="User"/>
    </typeAliases>
    <environments default="development">
    <environment id="development">
        <transactionManager type="JDBC" />
        <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>
    </environment>
    </environments>
    <mappers>
    <mapper resource="com/lovo/mapper/UserMapper.xml"/>
    </mappers>
    
</configuration>

 用以上方式配置需要先创立配置文件（datasource.properties）

配置文件代码如下：

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/myBatis?useUnicode=true&characterEncoding=UTF-8
jdbc.username=root
jdbc.password=123

然后创建一个获得连接对象的类，我习惯命名为DbUtil放在util包中，代码如下：

public class DbUtil {
    private static SqlSessionFactory sessionFactory = null;

    private DbUtil() {
        InputStream in = null;
        try {
            in = Resources.getResourceAsStream("SqlMapConfig.xml");
            sessionFactory = new SqlSessionFactoryBuilder().build(in);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    public static SqlSession getSession() {
        if (sessionFactory == null) {
            new DbUtil();
        }
        return sessionFactory.openSession();

    }

然后再对实体pojo配置一个XML文件和一个接口：

XML最好与接口同名，以便自己好辨识

xml文件如下：

<?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" >
<!--namespace与mapper接口相对应  -->
<mapper namespace="com.lovo.mapper.UserMapper">
    <resultMap  type="User" id="UserMap">
    <id property="id" column="id" javaType="int"/>
    <result property="userName" column="username" javaType="java.lang.String"/>
    <result property="userPwd" column="pwd" javaType="java.lang.String"/>
    <result property="state" column="state" javaType="int"/>
    </resultMap>
    
    
    <insert id="addUser" parameterType="User">
    insert into user values(null,#{User.userName},#{User.userPwd},#{User.state})
    
    </insert>
    <delete id="delUserById" parameterType="int">
        delete from user where id=#{id}
    </delete>
    <select id="findUserById" parameterType="int" resultMap="UserMap">
    select * from user where id=#{id}
    </select>
    <update id="updateUser" parameterType="User">
        update  user set  username=#{User.userName},pwd=#{User.userPwd},state=#{User.state} where id=#{User.id}
    </update>
    
    <select id="FindAllUser" resultMap="UserMap">
        select * from user
    </select>
    
    <select id="findUserCount" resultType="int">
        select count(*) from user
    
    </select>
    <select id="FindUserByState" resultMap="UserMap">
        select * from user where state=#{state}
    
    </select>
    <select id="sumOfState" resultType="int">
        select sum(state) from user
    </select>

</mapper>

接口如下：

public interface UserMapper {
    public int addUser(@Param("User") User user);
    public int delUserById(@Param("id") int id);
    public int updateUser(@Param("User") User user);
    public User findUserById(@Param("id") int id);
    public List<User> FindAllUser();
    public int findUserCount();
    public List<User> FindUserByState(@Param("state") int state);
    public int sumOfState();
}

这里的@param("User")为别名，除参数只有单个，且为基本数据类型外，都需要给于别名。

最后在建立service层

如：

public class UserServiceImpl implements UserService {
    SqlSession sqlSession=DbUtil.getSession();
    UserMapper mapper=sqlSession.getMapper(UserMapper.class);
    @Override
    public int addUser(User user) {
        // TODO Auto-generated method stub
        int num=0;
        num=mapper.addUser(user);
        sqlSession.commit();
        return num;
    }