[Java知识库]MyBatis第一章

目录

1.首先上来就给你一个错位的信息：

2.配置MyBatis环境其实是比较简单，我们第一步选择使用MAVEN来搭建项目。

3.第三部就是在资源下创建配置信息的文件 (resources下的)mybatis-config.xml

4.在test包下面：进行测试

5.创建domain 以及我的创建：

下面是我的类里面的具体实现：我使用了 lombok

我在接口中实现的方法（dao或者是mapper）

工具类：utils 因为使用sqlSessonfactory 太麻烦?

测试：

sql语句：

1.首先上来就给你一个错位的信息：

### Error querying database.? Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for com.csi.smbms.domain.User.class.findCount
### Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for com.csi.smbms.domain.User.class.findCount

大家很好奇这是什么原因吧？

哈哈哈哈

这是因为没在配置信息（mybatis-config.xml）里 进行mapper映射！所以就会产生的错误信息

2.配置MyBatis环境其实是比较简单，我们第一步选择使用MAVEN来搭建项目。

进去项目后就是配置maven环境，以及在pom.xml文件中导入依赖------->下面是我的pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.csi</groupId>
    <artifactId>two</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    导入依赖

    <dependencies>

      mybatis的依赖

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.7</version>
        </dependency>

       和数据库连接

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.30</version>
        </dependency>

       测试类中TEST
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>

     日志  和对应的日志
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

     这个是domain下使用  可以使用DATA  GET  SET 和构造函数等
      非常好用
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.24</version>
        </dependency>



    </dependencies>









</project>

3.第三部就是在资源下创建配置信息的文件 (resources下的)mybatis-config.xml

下面是mybatis-config.xml 的具体信息? 在mybatis的中文网中也可以找到：MyBatis中文网

?

<?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>
    <!--属性配置文件-->
    <properties resource="jdbc.properties" />
    <!--给对象做别名-->
    <typeAliases>
        <!--给某一个类做别名-->
        <!--<typeAlias type="com.csi.smbms.domain.User" alias="User" />-->
        <!--扫描某一个包，将包中所有类全部自动化命名。规则是将首字母大写！-->
        <package name="com.csi.smbms.domain"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <!--事务的管理-->
            <transactionManager type="JDBC"/>
            <!--数据连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/smbms"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>

    </environments>

    <mappers>
            <!--加载对应的映射文件-->
        <mapper resource="com/csi/smbms/domain/UserMapper.xml" />
        <mapper resource="com/csi/smbms/domain/ProviderMapper.xml" />

    </mappers>
</configuration>

4.在test包下面：进行测试

?在这个类中进行测试 sqlSession 是否能用！

package com.csi.test;

import com.csi.smbms.domain.Provider;
import com.csi.smbms.domain.User;
import com.csi.smbms.utils.MyBatisUtils;
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.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class MyBatisTest {

    @Test
    public void testUserCount1() throws IOException {

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        System.out.println("sqlSession测试："+sqlSession);

        int result = sqlSession.selectOne("com.csi.smbms.domain.User.findCount");

        System.out.println("user的人数：" + result);

        //关闭SqlSession
        MyBatisUtils.close();
    }

    @Test
    public void testUserTianjia() throws IOException {
        //步骤1：读取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml") ;
        //步骤2：通过API对应的功能实现数据库链接
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is) ;

        //步骤2-1：创建链接
        //SqlSession:提供的是一套完整的针对数据库的CRUD操作
        SqlSession sqlSession = factory.openSession() ;

        User user = new User();
        user.setUserCode("hahahha");
        user.setUserName("xiaojie");
        user.setUserPassword("123456");

        //关闭SqlSession
        sqlSession.close();
    }

    @Test
    public void testProviderList() throws IOException {
        //步骤1：读取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml") ;
        //步骤2：通过API对应的功能实现数据库链接
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is) ;
        //步骤2-1：创建链接
        //SqlSession:提供的是一套完整的针对数据库的CRUD操作
        SqlSession sqlSession = factory.openSession() ;

        List<Provider> Providers = sqlSession.selectList("com.csi.smbms.domain.Provider.list");

        System.out.println("provider的list集合展示所有人的信息：");

        Providers.forEach(System.out::println);

        //关闭SqlSession
        sqlSession.close();
    }

    @Test
    public void testProviderCount() throws IOException {
        //步骤1：读取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml") ;
        //步骤2：通过API对应的功能实现数据库链接
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is) ;

        //步骤2-1：创建链接
        //SqlSession:提供的是一套完整的针对数据库的CRUD操作
        SqlSession sqlSession = factory.openSession() ;

        int result = sqlSession.selectOne("com.csi.smbms.domain.Provider.findCount");

        System.out.println("Provider的人数：" + result);
        //关闭SqlSession
        sqlSession.close();
    }


    @Test
    public void testUserList() throws IOException {
        //步骤1：读取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml") ;
        //步骤2：通过API对应的功能实现数据库链接
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is) ;
        //步骤2-1：创建链接
        //SqlSession:提供的是一套完整的针对数据库的CRUD操作
        SqlSession sqlSession = factory.openSession() ;

        List<User> users = sqlSession.selectList("com.csi.smbms.domain.User.list");

        System.out.println("user的list集合展示所有人的信息：");

        users.forEach(System.out::println);

        //关闭SqlSession
        sqlSession.close();
    }

    @Test
    public void testUserCount() throws IOException {
        //步骤1：读取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml") ;
        //步骤2：通过API对应的功能实现数据库链接
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is) ;

        //步骤2-1：创建链接
        //SqlSession:提供的是一套完整的针对数据库的CRUD操作
        SqlSession sqlSession = factory.openSession() ;

        int result = sqlSession.selectOne("com.csi.smbms.domain.User.findCount");

        System.out.println("user的人数：" + result);
        //关闭SqlSession
        sqlSession.close();
    }


    这个测试下就是第一次测试看看sqlsession是否能用！
    @Test
    public void testInit() throws IOException {
        //步骤1：读取配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml") ;
        //步骤2：通过API对应的功能实现数据库链接
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is) ;

        System.out.println("factory:"+factory);
        //步骤2-1：创建链接
        //SqlSession:提供的是一套完整的针对数据库的CRUD操作
        SqlSession sqlSession = factory.openSession() ;

        System.out.println("测试："+sqlSession);
        //关闭SqlSession
        sqlSession.close();
    }



}

5.创建domain 以及我的创建：

?这样简单的MyBatis 就弄好了：

下面是我的类里面的具体实现：我使用了 lombok

package com.csi.smbms.domain;

import lombok.Data;

import java.io.Serializable;
import java.util.Date;

@Data
public class User implements Serializable {
    private Long id ;

    private String userCode ;

    private String userName ;

    private String userPassword ;

    private int gender ;

    private Date birthday ;

    private String phone ;

    private String address ;

    private long userRole ;

    private long createdBy ;

    private Date creationDate ;

    private long modifyBy ;

    private Date modifyDate ;


}

我在接口中实现的方法（dao或者是mapper）

package com.csi.smbms.mapper;

import com.csi.smbms.domain.User;
import java.util.List;
import java.util.Map;

public interface UserMapper {

    int findCount() ;

    List<User> list() ;

    int save(User user) ;

    User findById(long id) ;

    List<User> findLike(String userName) ;

    User findCondition(User user) ;

    User findByMap(Map<String,Object> map) ;

    User login(String userCode , String userPassword) ;

    User login1(User user) ;

    User login2(Map<String,Object> map) ;

}

工具类：utils 因为使用sqlSessonfactory 太麻烦?

package com.csi.smbms.utils;

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 java.io.IOException;
import java.io.InputStream;
/**
 * MyBatis的工具类
 */
public class MyBatisUtils {

    private static SqlSessionFactory factory ;

    private static ThreadLocal<SqlSession> tl = new ThreadLocal<>() ;

    static{
        InputStream is = null;
        try {
            is = Resources.getResourceAsStream("mybatis-config.xml");
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        //步骤2：通过API对应的功能实现数据库链接
        factory = new SqlSessionFactoryBuilder().build(is) ;
    }


    public static SqlSession getSqlSession() {
        SqlSession sqlSession = tl.get();    /*
         * 创建SqlSession对象
         */
        //判断本地线程中是否已经存在SqlSession
        if(sqlSession == null) {
            System.out.println("创建了SqlSession对象");
            //如果不存在则构建一个新的SqlSession，同时存放在ThreadLocal中
            sqlSession = factory.openSession() ;
            tl.set(sqlSession);
        }
        return sqlSession ;
    }

    /**
     * 资源关闭
     */
    public static void close() {
        SqlSession sqlSession = tl.get();
        if(sqlSession != null) {
            System.out.println("关闭了SqlSession对象");
            sqlSession.close();
            tl.set(null);
        }
    }

}

测试：

package com.csi.test;

import com.csi.smbms.mapper.UserMapper;
import com.csi.smbms.domain.User;
import com.csi.smbms.utils.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MyBatisMapperTest {

    @Test
    public void testUserLogin2(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        Map<String,Object> map = new HashMap<>() ;

        map.put("userCode","admin") ;
        map.put("userPassword","1234657");

        User user  = userMapper.login2(map);

        System.out.println(user);

        MyBatisUtils.close();
    }


    @Test
    public void testUserLogin1(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        User user = new User();
        user.setUserCode("admin");
        user.setUserPassword("1234567");
        System.out.println(user);

        MyBatisUtils.close();
    }

    @Test
    public void testUserLogin(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        User user = userMapper.login("admin", "1234567");

        System.out.println(user);

        MyBatisUtils.close();
    }


    @Test
    public void testUserFindByMap(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        Map<String,Object> map = new HashMap<>() ;

        map.put("userRole","1") ;
        map.put("userCode","admin") ;

        User user  = userMapper.findByMap(map);

        System.out.println(user);

        MyBatisUtils.close();
    }

    @Test
    public void testUserFindCondition(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        User  user= new User() ;
        user.setUserCode("admin");
        user.setUserRole(1);

        user= userMapper.findCondition(user);

        System.out.println("对象查询："+user);

        MyBatisUtils.close();
    }

    @Test
    public void testUserSave(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        int save = 0;
        try {
            User user = new User();
            user.setUserCode("wangde");
            user.setUserName("王德");
            user.setUserPassword("123456");
            user.setAddress("tianjin");
            user.setUserRole(2L);
            user.setBirthday(new Date());
            user.setCreatedBy(1L);
            user.setGender(2);
            user.setPhone("2132165156");
            user.setCreationDate(new Date());

            save = userMapper.save(user);
            sqlSession.commit();
        } catch (Exception e) {
            sqlSession.rollback();
            throw new RuntimeException() ;
        }finally {
            MyBatisUtils.close();
        }




    }

    @Test
    public void testUserFindLike(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        List<User> users = userMapper.findLike("孙");

        users.forEach(System.out::println);

        MyBatisUtils.close();
    }


    @Test
    public void testUserFindById(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        User user = userMapper.findById(1L);

        System.out.println("user duixiang :："+user);

        MyBatisUtils.close();
    }

    @Test
    public void testUserCount(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        int num = userMapper.findCount();

        System.out.println("userMapper count 个数是："+num);

        MyBatisUtils.close();
    }


    @Test
    public void testUserList(){

        SqlSession sqlSession = MyBatisUtils.getSqlSession();

        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);

        List<User> list = userMapper.list();

        System.out.println("userMapper count 个数是：");

        list.forEach(System.out::println);

        MyBatisUtils.close();
    }



}

sql语句：

<?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.csi.smbms.mapper.UserMapper">


    <select id="findLike" resultType="User" parameterType="String">
        select * from smbms_user where userName Like CONCAT('%',#{userName},'%')
    </select>

    <select id="findById" resultType="com.csi.smbms.domain.User" parameterType="long">
        select * from smbms_user where id = #{id}
    </select>

    <select id="findCount" resultType="int">
        select count(*) from smbms_user
    </select>

    <select id="list" resultType="com.csi.smbms.domain.User">
        select * from smbms_user
    </select>

    <insert id="save" parameterType="User">
        insert into smbms_user
        (userCode,userName,userPassword,gender,birthday,phone,address,userRole,createdBy,creationDate)
        values
        (#{userCode},#{userName},#{userPassword},#{gender},#{birthday},#{phone},#{address},#{userRole},#{createdBy},#{creationDate})
    </insert>

    <select id="findCondition"  parameterType="User" resultType="User">
        select * from smbms_user where userCode = #{userCode} AND userRole = #{userRole}
    </select>


    <select id="findByMap"  parameterType="map" resultType="User">
        select * from smbms_user where userCode = #{userCode} AND userRole = #{userRole}
    </select>

    <select id="login" resultType="User" parameterType="String">
        select *
        from smbms_user
        where userCode = #{userCode} AND userPassword = #{userPassword};
    </select>

    <select id="login1" resultType="User" parameterType="User">
        select *
        from smbms_user
        where userCode = #{userCode} AND userPassword = #{userPassword};
    </select>

    <select id="login2" resultType="User" parameterType="map">
        select *
        from smbms_user
        where userCode = #{userCode} AND userPassword = #{userPassword};
    </select>






</mapper>