MyBatis的增删改查基本操作

MyBatis和Hibernate的使用基本一样，区别在于Hibernate在Java代码中实现数据库操作，集成度高；Mybatis在注解或者xml文件中通过配置实现SQL语句，更加灵活

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创建使用MyBatis的Java项目

1. 创建并配置

• 创建Java项目并引入MyBaits的jar文件
• 配置log4j.properties（用于查看执行的SQL语句，日志等）

log4j.rootLogger=DEBUG,Console

log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d[%t]%-5p[%c]-%m%n

log4j.logger.java.sql.ResultSet=INFO
log4j.logger.org.apache=INFO
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

• 配置MyBaits的配置文件

<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost/mybatis?useSSL=false" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            dataSource>
        environment>
    environments>
    
    <mappers>
        <mapper resource="map/query.xml" />
        <mapper resource="map/insert.xml" />
        <mapper resource="map/update.xml" />
        <mapper resource="map/delete.xml" />
    mappers>
configuration>    

2.实现增删改查操作

• 创建和数据库表对应的JavaBean
• 创建相应的文件
• 通过Java中调用实现相关操作

//加载配置文件并初始化
public class InsertTest {
    public static void main(String[] args) {
        String resource = "map/mybatis.xml";

        Reader reader = null;
        SqlSessionFactory factory = null;
        SqlSession session = null;

        try {
            reader = Resources.getResourceAsReader(resource);
            factory = new SqlSessionFactoryBuilder().build(reader);
            session = factory.openSession();

            /**
            *具体功能实现部分
            **/

            session.commit();
        } catch (IOException e) {
            session.rollback();
            e.printStackTrace();
        } finally {
            session.close();
        }

    }
}

• insert.xml

    
    
    <insert id="insert" parameterType="pojo.User" statementType="PREPARED"
        keyProperty="id" useGeneratedKeys="true">
        insert into mybatis(name,password)
        values(#{name},#{password})
    insert>

• insert实现

    User user = new User(1, "果粒橙", "果粒橙");
    session.insert("insert", user);

• delete.xml

    
    <delete id="deleteByObject" parameterType="pojo.User">
        delete from mybatis
        where id = #{id}
    delete>
    <delete id="deleteByID" parameterType="int">
        delete from mybatis where
        id = #{id}
    delete>

• delete实现

        // 通过对象删除
        User user = new User();
        user.setId(3);
        session.delete("deleteByObject", user);

        // 通过ID删除
        session.delete("deleteByID", 2);

• update.xml

    
    
    <update id="update" parameterType="pojo.User">
        update mybatis set name=#{name},password=#{password}
        where id = #{id}
    update>

• update实现

    User user = new User(3, "益达", "你的益达");
    session.update("update", user);

• query.xml

    
    <select id="queryUser" resultType="pojo.User">
        select * from mybatis where id = #{id}
    select>

    
    <select id="queryUsers" resultType="pojo.User">
        select * from mybatis
    select>

    
    <resultMap type="pojo.User" id="queryResultMap">
        <id column="id" property="id">id>
        <result property="name" column="name" />
        <result property="password" column="password" />
    resultMap>
    <select id="queryMap" resultMap="queryResultMap">
        select * from mybatis
    select>

• query实现

    // 返回一个查询结果,返回resultType
    User user = session.selectOne("queryUser", 1);
    System.out.println(user.getName());

    // 返回多个查询结果,返回resultType
    List results = session.selectList("queryUsers");
    for (User user1 : results) {
        System.out.println(user1.getName() + "---" + user1.getPassword());
    }

    // 返回多个结果,返回resultMap
    List results1 = session.selectList("queryMap");
    for (User user2 : results1) {
        System.out.println(user2.getName() + "---" + user2.getPassword());
    }

• 表
  

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