Mybatis的应用，直接访问数据库

1.引入jar包：pom.xml

<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.jareny.it.mybatis</groupId>
  <artifactId>mybatis-demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  
  <properties>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
	<java.version>1.8</java.version>
</properties>
  
  
 <dependencies>
	 <dependency>
	    <groupId>mysql</groupId>
	    <artifactId>mysql-connector-java</artifactId>
	    <version>5.1.9</version>
	</dependency> 
	
	<dependency>
	    <groupId>org.mybatis</groupId>
	    <artifactId>mybatis</artifactId>
	    <version>3.2.8</version>
	</dependency>
	
	<dependency>
	    <groupId>org.slf4j</groupId>
	    <artifactId>slf4j-log4j12</artifactId>
	    <version>1.7.5</version>
	</dependency>
	
	<dependency>
	    <groupId>junit</groupId>
	    <artifactId>junit</artifactId>
	    <version>4.12</version>
	</dependency>
	
 </dependencies> 
 

</project>

2.在/mybatis-demo/src/main/resources下创建

MyBatis的全局配置：mybatis-config.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">
<!-- 根标签 -->
<configuration>

	<settings>	
		<!-- 开启延时加载这是总开关 -->
		<setting name="LazyLoadingEnabled" value="true"/>
		<!-- 关闭侵入式延时加载：延时加载就从表查询侵入到主表查询  -->
		<setting name="aggressiveLazyLoading" value="false"/>
	</settings>
   <!-- 环境，可以配置多个，default：指定采用哪个环境 -->
   <environments default="test">
      <!-- id：唯一标识 -->
      <environment id="test">
         <!-- 事务管理器，JDBC类型的事务管理器 -->
         <transactionManager type="JDBC" />
         <!-- 数据源，池类型的数据源 -->
         <dataSource type="POOLED">
            <property name="driver" value="com.mysql.jdbc.Driver" />
            <property name="url" value="jdbc:mysql://127.0.0.1:3306/test??useUnicode=true&characterEncoding=utf-8&allowMultiQueries=true" />
            <property name="username" value="root" />                   
            <property name="password" value="123456" />
         </dataSource>
      </environment>
   </environments>
   <mappers>
     <mapper resource="mappers/MyMapper.xml" />
     <mapper resource="mappers/UserDaoMapper.xml" />
     <mapper resource="mappers/ICountryMapper.xml" />
     <mapper resource="mappers/ICountryMapper2.xml" />
     <mapper resource="mappers/INewsLabelMapper.xml" />
     <mapper resource="mappers/INewsLabelMapper2.xml" />
     <mapper resource="mappers/INewsLabelMapper3.xml" />
   </mappers>
</configuration>

3.在/mybatis-demo/src/main/resources下创建

日志配置文件：log4j.properties

log4j.rootLogger=DEBUG,A1
log4j.logger.org.apache=DEBUG
log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss,SSS} [%t] [%c]-[%p] %m%n

log4j.logger.com.jareny.it.mybatis.dao.ICountryDao=trace,console

#log4j.logger.com.jareny.it.mybatis.entity.Country=trace,console

4.创建实体类

com.jareny.it.mybatis.entity.Country

package com.jareny.it.mybatis.entity;

import java.util.Set;

public class Country {
	
	private Integer cid;
	private String cname;
	//关联属性 一对多的查询
	private Set<Minister> ministers;
	
	public Integer getCid() {
		return cid;
	}
	public void setCid(Integer cid) {
		this.cid = cid;
	}
	public String getCname() {
		return cname;
	}
	public void setCname(String cname) {
		this.cname = cname;
	}
	public Set<Minister> getMinisters() {
		return ministers;
	}
	public void setMinisters(Set<Minister> ministers) {
		this.ministers = ministers;
	}
	@Override
	public String toString() {
		return "Country [cid=" + cid + ", cname=" + cname + ", ministers=" + ministers + "]";
	}
	
	

}

　com.jareny.it.mybatis.entity.Country2

package com.jareny.it.mybatis.entity;

import java.util.Set;

public class Country2 {
	
	private Integer cid;
	private String cname;
	
	public Integer getCid() {
		return cid;
	}
	public void setCid(Integer cid) {
		this.cid = cid;
	}
	public String getCname() {
		return cname;
	}
	public void setCname(String cname) {
		this.cname = cname;
	}
	

	public String toString() {
		return "Country2 [cid=" + cid + ", cname=" + cname + "]";
	}
	
	
	

}

　

com.jareny.it.mybatis.entity.Minister

package com.jareny.it.mybatis.entity;



public class Minister {
	
	private Integer mid;
	private String mname;
	
	public Integer getMid() {
		return mid;
	}
	public void setMid(Integer mid) {
		this.mid = mid;
	}
	public String getMname() {
		return mname;
	}
	public void setMname(String mname) {
		this.mname = mname;
	}
	@Override
	public String toString() {
		return "Minister [mid=" + mid + ", mname=" + mname + "]";
	}
	
	
	
}

　com.jareny.it.mybatis.entity.Minister2

package com.jareny.it.mybatis.entity;



public class Minister2 {
	
	private Integer mid;
	private String mname;
	//关联属性 多对一查询
	private Country country;
	
	public Integer getMid() {
		return mid;
	}
	public void setMid(Integer mid) {
		this.mid = mid;
	}
	public String getMname() {
		return mname;
	}
	public void setMname(String mname) {
		this.mname = mname;
	}
	public Country getCountry() {
		return country;
	}
	public void setCountry(Country country) {
		this.country = country;
	}
	public String toString() {
		return "Minister2 [mid=" + mid + ", mname=" + mname + ", country=" + country + "]";
	}

	
	
	
}

　　com.jareny.it.mybatis.entity.NewsLabel

package com.jareny.it.mybatis.entity;

import java.util.Set;

public class NewsLabel {
	
	private Integer id;
	private String name;
	
	private Set<NewsLabel> childent;
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Set<NewsLabel> getChildent() {
		return childent;
	}
	public void setChildent(Set<NewsLabel> childent) {
		this.childent = childent;
	}
	@Override
	public String toString() {
		return "NewsLabel [id=" + id + ", name=" + name + ", childents=" + childent + "]";
	}
	
	
	

}

　　com.jareny.it.mybatis.entity.NewsLabel2

package com.jareny.it.mybatis.entity;

import java.util.Set;

public class NewsLabel2 {
	
	private Integer id;
	private String name;
	private Set<NewsLabel2> childents;
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Set<NewsLabel2> getChildents() {
		return childents;
	}
	public void setChildents(Set<NewsLabel2> childents) {
		this.childents = childents;
	}
	@Override
	public String toString() {
		return "NewsLabel2 [id=" + id + ", name=" + name + ", childents=" + childents + "]";
	}
	

}

　　com.jareny.it.mybatis.entity.NewsLabel3

package com.jareny.it.mybatis.entity;

import java.util.Set;

//子目录查询父目录
public class NewsLabel3 {
	
	private Integer id;
	private String name;
	private NewsLabel3 parent;
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public NewsLabel3 getParent() {
		return parent;
	}
	public void setParent(NewsLabel3 parent) {
		this.parent = parent;
	}
	@Override
	public String toString() {
		return "NewsLabel3 [id=" + id + ", name=" + name + ", parent=" + parent + "]";
	}
	
	

}

　　com.jareny.it.mybatis.entity.NewsLabel4

package com.jareny.it.mybatis.entity;

import java.util.List;
import java.util.Set;

//子目录查询父目录
public class NewsLabel4 {
	
	private Integer id;
	private String name;
	private NewsLabel4 parent;
	private List<NewsLabel4> childents;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public NewsLabel4 getParent() {
		return parent;
	}
	public void setParent(NewsLabel4 parent) {
		this.parent = parent;
	}
	public List<NewsLabel4> getChildents() {
		return childents;
	}
	public void setChildents(List<NewsLabel4> childents) {
		this.childents = childents;
	}
	@Override
	public String toString() {
		return "NewsLabel4 [id=" + id + ", name=" + name + ", parent=" + parent + ", childents=" + childents + "]";
	}
	

}

　　com.jareny.it.mybatis.entity.User

package com.jareny.it.mybatis.entity;

import java.text.SimpleDateFormat;
import java.util.Date;

public class User {
	
	private String id;
    private String userName;
    private String password;
    private String name;
    private Integer age;
    private Integer sex;
    private Date birthday;
    private String created;
    private String updated;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Integer getSex() {
        return sex;
    }

    public void setSex(Integer sex) {
        this.sex = sex;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getCreated() {
        return created;
    }

    public void setCreated(String created) {
        this.created = created;
    }

    public String getUpdated() {
        return updated;
    }

    public void setUpdated(String updated) {
        this.updated = updated;
    }

    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", userName='" + userName + '\'' +
                ", password='" + password + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex=" + sex +
                ", birthday='" + new SimpleDateFormat("yyyy-MM-dd").format(birthday) + '\'' +
                ", created='" + created + '\'' +
                ", updated='" + updated + '\'' +
                '}';
    }

}

　　com.jareny.it.mybatis.test.MybatisTest

package com.jareny.it.mybatis.test;

import java.io.InputStream;

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 com.jareny.it.mybatis.entity.User;


public class MybatisTest {
	public static void main(String[] args) throws Exception {
	      // 指定全局配置文件 
	      String resource = "mybatis-config.xml";
	      // 读取配置文件
	      InputStream inputStream = Resources.getResourceAsStream(resource);
	      // 构建sqlSessionFactory
	      SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
	      // 获取sqlSession
	      SqlSession sqlSession = sqlSessionFactory.openSession();
	      try {
	         // 操作CRUD，第一个参数：指定statement，规则：命名空间+“.”+statementId
	         // 第二个参数：指定传入sql的参数：这里是用户id
	         User user = sqlSession.selectOne("MyMapper.selectUser", 1);
	         System.out.println(user);
	      } finally {
	         sqlSession.close();
	      }
	   }
}

　　com.jareny.it.mybatis.dao.impl.UserDaoImpl

package com.jareny.it.mybatis.dao.impl;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import com.jareny.it.mybatis.dao.UserDao;
import com.jareny.it.mybatis.entity.User;

public class UserDaoImpl implements UserDao {
	
	 public SqlSession sqlSession;

	    public UserDaoImpl(SqlSession sqlSession) {
	        this.sqlSession = sqlSession;
	    }

	    public User queryUserById(String id) {
	        return this.sqlSession.selectOne("UserDao.queryUserById", id);
	    }

	    public List<User> queryUserAll() {
	        return this.sqlSession.selectList("UserDao.queryUserAll");
	    }
 
	    public void insertUser(User user) {
	        this.sqlSession.insert("UserDao.insertUser", user);
	    }

	    public void updateUser(User user) {
	        this.sqlSession.update("UserDao.updateUser", user);
	    }

	    public void deleteUser(String id) {
	        this.sqlSession.delete("UserDao.deleteUser", id);
	    }


}

　　5.创建dao层

package com.jareny.it.mybatis.dao;

import com.jareny.it.mybatis.entity.Country;

public interface ICountryMapper {
	
	Country selectCountryById(Integer cid);

}

　　com.jareny.it.mybatis.dao.ICountryMapper2

package com.jareny.it.mybatis.dao;

import com.jareny.it.mybatis.entity.Country;

public interface ICountryMapper2 {
	
	Country selectCountryById(Integer cid);

}

　　com.jareny.it.mybatis.dao.INewsLabelMapper

package com.jareny.it.mybatis.dao;

import java.util.List;

import com.jareny.it.mybatis.entity.Country;
import com.jareny.it.mybatis.entity.NewsLabel;

public interface INewsLabelMapper {
	
	List<NewsLabel> selectChildrenByParent(int pid);

}

　　com.jareny.it.mybatis.dao.INewsLabelMapper2

package com.jareny.it.mybatis.dao;

import java.util.List;

import com.jareny.it.mybatis.entity.Country;
import com.jareny.it.mybatis.entity.NewsLabel;
import com.jareny.it.mybatis.entity.NewsLabel2;

public interface INewsLabelMapper2 {
	
	NewsLabel2 selectChildrenById(int id);

}

　　com.jareny.it.mybatis.dao.INewsLabelMapper3

package com.jareny.it.mybatis.dao;

import java.util.List;

import com.jareny.it.mybatis.entity.Country;
import com.jareny.it.mybatis.entity.NewsLabel;
import com.jareny.it.mybatis.entity.NewsLabel2;
import com.jareny.it.mybatis.entity.NewsLabel3;

public interface INewsLabelMapper3 {
	
	NewsLabel3 selectChildrenById(int id);

}

　　com.jareny.it.mybatis.dao.UserDao

package com.jareny.it.mybatis.dao;

import java.util.List;

import com.jareny.it.mybatis.entity.User;



public interface UserDao {
	
    /**
     * 根据id查询用户信息
     *
     * @param id
     * @return
     */
    public User queryUserById(String id);
    
    /**
     * 查询所有用户信息
     *
     * @return
     */
    public List<User> queryUserAll();

    /**
     * 新增用户
     *
     * @param user
     */
    public void insertUser(User user);

    /**
     * 更新用户信息
     *
     * @param user
     */
    public void updateUser(User user);

    /**
     * 根据id删除用户信息
     *
     * @param id
     */
    public void deleteUser(String id);

}

6.创建Mybatis映射文件：/mybatis-demo/src/main/resources/mappers/ICountryMapper.xml

<?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:根标签，namespace：命名空间，随便写，一般保证命名空间唯一 ，为了使用接口动态代理，这里必须是接口的全路径名-->
<mapper namespace="com.jareny.it.mybatis.dao.ICountryMapper">
	
	<!-- 一对多查询 -->			 
	<resultMap type="com.jareny.it.mybatis.entity.Country" id="countryMapper">
		<id column="cid" property="cid"/>
		<result column="cname" property="cname"/>
		<collection property="ministers" ofType="com.jareny.it.mybatis.entity.Minister">
			<id column="mid" property="mid"/>
			<result column="mname" property="mname"/>
		</collection>
	</resultMap>

    <!--
       1.#{},预编译的方式preparedstatement，使用占位符替换，防止sql注入，一个参数的时候，任意参数名可以接收
       2.${},普通的Statement，字符串直接拼接，不可以防止sql注入，一个参数的时候，必须使用${value}接收参数
     -->
    <select id="selectCountryById" resultMap="countryMapper">
        select cid,cname,mid,mname
        from country ,minister 
		where countryId=cid and cid=#{cid}
    </select>
    
    
    

</mapper>

　/mybatis-demo/src/main/resources/mappers/ICountryMapper2.xml

<?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:根标签，namespace：命名空间，随便写，一般保证命名空间唯一 ，为了使用接口动态代理，这里必须是接口的全路径名-->
<mapper namespace="com.jareny.it.mybatis.dao.ICountryMapper2">
				 
	<resultMap type="com.jareny.it.mybatis.entity.Country" id="countryMapper">
		<id column="cid" property="cid"/>
		<result column="cname" property="cname"/>
		<collection property="ministers" 
					ofType="com.jareny.it.mybatis.entity.Minister"
			        column="cid" 
			        select="selectMiniSterByCountry">
		</collection>
	</resultMap>

    <!--
       1.#{},预编译的方式preparedstatement，使用占位符替换，防止sql注入，一个参数的时候，任意参数名可以接收
       2.${},普通的Statement，字符串直接拼接，不可以防止sql注入，一个参数的时候，必须使用${value}接收参数
     -->
    <select id="selectCountryById" resultMap="countryMapper">
        select cid,cname
        from country 
		where cid=#{cid}
    </select>
    
    <select id="selectMiniSterByCountry" 
    resultType="com.jareny.it.mybatis.entity.Minister">
        select mid,mname
        from minister 
		where countryId=#{cid}
    </select>
    
    

</mapper>

　　/mybatis-demo/src/main/resources/mappers/INewsLabelMapper.xml

<?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:根标签，namespace：命名空间，随便写，一般保证命名空间唯一 ，为了使用接口动态代理，这里必须是接口的全路径名-->
<mapper namespace="com.jareny.it.mybatis.dao.ICountryMapper2">
				 
	<resultMap type="com.jareny.it.mybatis.entity.Country" id="countryMapper">
		<id column="cid" property="cid"/>
		<result column="cname" property="cname"/>
		<collection property="ministers" 
					ofType="com.jareny.it.mybatis.entity.Minister"
			        column="cid" 
			        select="selectMiniSterByCountry">
		</collection>
	</resultMap>

    <!--
       1.#{},预编译的方式preparedstatement，使用占位符替换，防止sql注入，一个参数的时候，任意参数名可以接收
       2.${},普通的Statement，字符串直接拼接，不可以防止sql注入，一个参数的时候，必须使用${value}接收参数
     -->
    <select id="selectCountryById" resultMap="countryMapper">
        select cid,cname
        from country 
		where cid=#{cid}
    </select>
    
    <select id="selectMiniSterByCountry" 
    resultType="com.jareny.it.mybatis.entity.Minister">
        select mid,mname
        from minister 
		where countryId=#{cid}
    </select>
    
    

</mapper>

　　/mybatis-demo/src/main/resources/mappers/INewsLabelMapper2.xml

<?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:根标签，namespace：命名空间，随便写，一般保证命名空间唯一 ，为了使用接口动态代理，这里必须是接口的全路径名-->
<mapper namespace="com.jareny.it.mybatis.dao.INewsLabelMapper2">
				 
	<!--自关联的递归查询，查询父目录下的所有子目录 -->	
	
			 
	<resultMap type="com.jareny.it.mybatis.entity.NewsLabel2" id="NewsLabelMapper2">
		<id column="id" property="id"/>
		<result column="name" property="name"/>
		<collection property="childents" 
					ofType="com.jareny.it.mybatis.entity.NewsLabel2"
			        column="id" 
			        select="selectChildrenByParent2">
		</collection>
	</resultMap>

    <!--
       1.#{},预编译的方式preparedstatement，使用占位符替换，防止sql注入，一个参数的时候，任意参数名可以接收
       2.${},普通的Statement，字符串直接拼接，不可以防止sql注入，一个参数的时候，必须使用${value}接收参数
     -->
    <!-- 这里里父目录  -->
    <select id="selectChildrenById" resultMap="NewsLabelMapper2">
        select id,name
        from newslabel
		where id=#{id}
    </select>
     
    <!-- 这里里递归  -->
    <select id="selectChildrenByParent2" resultMap="NewsLabelMapper2">
        select id,name
        from newslabel
		where pid=#{id}
    </select>
    
    
    
</mapper>

　　/mybatis-demo/src/main/resources/mappers/INewsLabelMapper3.xml

<?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:根标签，namespace：命名空间，随便写，一般保证命名空间唯一 ，为了使用接口动态代理，这里必须是接口的全路径名-->
<mapper namespace="com.jareny.it.mybatis.dao.INewsLabelMapper3">
				 
	<!--自关联的递归查询，查询子目录的所父目录 -->	
	<resultMap type="com.jareny.it.mybatis.entity.NewsLabel3" id="NewsLabelMapper3">
		<id column="id" property="id"/>
		<result column="name" property="name"/>
		<association property="parent" 
					javaType="com.jareny.it.mybatis.entity.NewsLabel3"
			        column="pid" 
			        select="selectChildrenById" />
	</resultMap>

    <!--
       1.#{},预编译的方式preparedstatement，使用占位符替换，防止sql注入，一个参数的时候，任意参数名可以接收
       2.${},普通的Statement，字符串直接拼接，不可以防止sql注入，一个参数的时候，必须使用${value}接收参数
     -->
    <!-- 这里递归查询父目录  -->
    <select id="selectChildrenById" resultMap="NewsLabelMapper3">
        select id,name,pid
        from newslabel
		where id=#{id}
    </select>

</mapper>

　　/mybatis-demo/src/main/resources/mappers/MyMapper.xml

<?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:根标签，namespace：命名空间，随便写，一般保证命名空间唯一 -->
<mapper namespace="MyMapper">
   <!-- statement，内容：sql语句。id：唯一标识，随便写，在同一个命名空间下保持唯一
      resultType：sql语句查询结果集的封装类型,tb_user即为数据库中的表
    -->
   <select id="selectUser" resultType="com.jareny.it.mybatis.entity.User">
      select * from tb_user where id = #{id}
   </select>
   
</mapper>

　　/mybatis-demo/src/main/resources/mappers/UserDaoMapper.xml

<?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:根标签，namespace：命名空间，随便写，一般保证命名空间唯一 -->
<mapper namespace="com.jareny.it.mybatis.dao.UserDao">
    <!-- statement，内容：sql语句。id：唯一标识，随便写，在同一个命名空间下保持唯一
       resultType：sql语句查询结果集的封装类型,tb_user即为数据库中的表
     -->
    <!--<select id="queryUserById" resultType="com.jareny.it.mybatis.entity.User">-->
    <!--select * from tb_user where id = #{id}-->
    <!--</select>-->  

    <!--使用别名-->
    <select id="queryUserById" resultType="com.jareny.it.mybatis.entity.User">
      select
       tuser.id as id,
       tuser.user_name as userName,
       tuser.password as password,
       tuser.name as name,
       tuser.age as age,
       tuser.birthday as birthday,
       tuser.sex as sex,
       tuser.created as created,
       tuser.updated as updated
       from
       tb_user tuser
       where tuser.id = #{id};
   </select>

    <select id="queryUserAll" resultType="com.jareny.it.mybatis.entity.User">
        select * from tb_user;
    </select>

    <!--插入数据-->
    <insert id="insertUser" parameterType="com.jareny.it.mybatis.entity.User">
        INSERT INTO tb_user (
        user_name,
        password,
        name,
        age,
        sex,
        birthday,
        created,
        updated
        )
        VALUES
        (
        #{userName},
        #{password},
        #{name},
        #{age},
        #{sex},
        #{birthday},
        now(),
        now()
        );
    </insert>

    <update id="updateUser" parameterType="com.jareny.it.mybatis.entity.User">
        UPDATE tb_user
        <trim prefix="set" suffixOverrides=",">
            <if test="userName!=null">user_name = #{userName},</if>
            <if test="password!=null">password = #{password},</if>
            <if test="name!=null">name = #{name},</if>
            <if test="age!=null">age = #{age},</if>
            <if test="sex!=null">sex = #{sex},</if>
            <if test="birthday!=null">birthday = #{birthday},</if>
            updated = now(),
        </trim>
        WHERE
        (id = #{id});
    </update>

    <delete id="deleteUser">
        delete from tb_user where id=#{id}
    </delete>
</mapper>

　

7.　创建测试类com.jareny.it.test.MybatisTest

package com.jareny.it.test;

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

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.Before;
import org.junit.Test;

import com.jareny.it.mybatis.dao.ICountryMapper;
import com.jareny.it.mybatis.dao.ICountryMapper2;
import com.jareny.it.mybatis.dao.INewsLabelMapper;
import com.jareny.it.mybatis.dao.INewsLabelMapper2;
import com.jareny.it.mybatis.dao.INewsLabelMapper3;
import com.jareny.it.mybatis.entity.Country;
import com.jareny.it.mybatis.entity.NewsLabel;
import com.jareny.it.mybatis.entity.NewsLabel2;
import com.jareny.it.mybatis.entity.NewsLabel3;

public class MybatisTest {
	
	public ICountryMapper countryMapper;
	public ICountryMapper2 countryMapper2;
	public INewsLabelMapper newsLabelMapper;
	public INewsLabelMapper2 newsLabelMapper2;
	public INewsLabelMapper3 newsLabelMapper3;
	
    public SqlSession sqlSession;

    @Before
    public void setUp() throws Exception {
        // mybatis-config.xml
        String resource = "mybatis-config.xml";
        // 读取配置文件
        InputStream is = Resources.getResourceAsStream(resource);
        // 构建SqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
        // 获取sqlSession
        sqlSession = sqlSessionFactory.openSession();
        this.countryMapper = sqlSession.getMapper(ICountryMapper.class);
        this.countryMapper2 = sqlSession.getMapper(ICountryMapper2.class);
        this.newsLabelMapper = sqlSession.getMapper(INewsLabelMapper.class);
        this.newsLabelMapper2 = sqlSession.getMapper(INewsLabelMapper2.class);
        this.newsLabelMapper3 = sqlSession.getMapper(INewsLabelMapper3.class);
    }

    /**
     * 这是联表查询的，两张表一起去查询
     * <p>Title: testSelectCountryById</p>
     * <p>Description: </p>
     * @throws Exception
     */
    @Test
    public void testSelectCountryById() throws Exception {
    	Country country = this.countryMapper.selectCountryById(2);
    	System.out.println(country.toString());
    }
    
    /**
     * 这是延时加载查询，分开一张表一张表查询
     * <p>Title: testSelectCountryById2</p>
     * <p>Description: </p>
     * @throws Exception
     */
    @Test
    public void testSelectCountryById2() throws Exception {
    	Country country = this.countryMapper2.selectCountryById(2);
    	System.out.println(country.toString());
    }
    
    
    /**
     * 这里自关联的递归查询
     * <p>Title: testSelectCountryById3</p>
     * <p>Description: </p>
     * @throws Exception
     */
    @Test
    public void testNewsLabelMapper() throws Exception {
    	List<NewsLabel> list = this.newsLabelMapper.selectChildrenByParent(4);
    	System.out.println(list.toString());
    }
    
    /**
     * 这里自关联的父目录查询子目录
     * <p>Title: testSelectCountryById3</p>
     * <p>Description: </p>
     * @throws Exception
     */
    @Test
    public void testNewsLabelMapper2() throws Exception {
    	NewsLabel2 newNsLabel2 = this.newsLabelMapper2.selectChildrenById(2);
    	System.out.println(newNsLabel2.toString());
    }
    
    /**
     * 子目录查询父目录
     * <p>Title: testSelectCountryById3</p>
     * <p>Description: </p>
     * @throws Exception
     */
    @Test
    public void testNewsLabelMapper3() throws Exception {
    	NewsLabel3 newNsLabel3 = this.newsLabelMapper3.selectChildrenById(7);
    	System.out.println(newNsLabel3.toString());
    }
    
    
    
    
    
}

　com.jareny.it.test.UserDaoTest

package com.jareny.it.test;



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

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.Before;
import org.junit.Test;

import com.jareny.it.mybatis.dao.UserDao;
import com.jareny.it.mybatis.entity.User;

public class UserDaoTest {
	 
	 public UserDao userDao;
	    public SqlSession sqlSession;

	    @Before
	    public void setUp() throws Exception {
	        // mybatis-config.xml
	        String resource = "mybatis-config.xml";
	        // 读取配置文件
	        InputStream is = Resources.getResourceAsStream(resource);
	        // 构建SqlSessionFactory
	        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
	        // 获取sqlSession
	        sqlSession = sqlSessionFactory.openSession();
	        this.userDao = sqlSession.getMapper(UserDao.class);
	        //this.userDao = new UserDaoImpl(sqlSession);
	    }

	    @Test
	    public void queryUserById() throws Exception {
	        System.out.println(this.userDao.queryUserById("1"));
	    }

	    @Test
	    public void queryUserAll() throws Exception {
	        List<User> userList = this.userDao.queryUserAll();
	        for (User user : userList) {
	            System.out.println(user);
	        }
	    }

	    @Test
	    public void insertUser() throws Exception {
	        User user = new User();
	        user.setAge(16);
	        user.setBirthday(new Date("1990/09/02"));
	        user.setName("大鹏");
	        user.setPassword("123456");
	        user.setSex(1);
	        user.setUserName("evan");
	        this.userDao.insertUser(user);
	        this.sqlSession.commit();
	    }

	    @Test
	    public void updateUser() throws Exception {
	        User user = new User();
	        user.setBirthday(new Date());
	        user.setName("静鹏");
	        user.setPassword("654321");
	        user.setSex(1);
	        user.setUserName("evanjin");
	        user.setId("1");
	        this.userDao.updateUser(user);
	        this.sqlSession.commit();
	    }

	    @Test
	    public void deleteUser() throws Exception {
	        this.userDao.deleteUser("4");
	        this.sqlSession.commit();
	    }

}

　　

8.运行sql语句 test.sql

/*
Navicat MySQL Data Transfer

Source Server         : localhost
Source Server Version : 80015
Source Host           : localhost:3306
Source Database       : test

Target Server Type    : MYSQL
Target Server Version : 80015
File Encoding         : 65001

Date: 2019-08-05 00:17:55
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for country
-- ----------------------------
DROP TABLE IF EXISTS `country`;
CREATE TABLE `country` (
  `cid` int(5) NOT NULL AUTO_INCREMENT,
  `cname` varchar(20) NOT NULL,
  PRIMARY KEY (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of country
-- ----------------------------
INSERT INTO `country` VALUES ('1', 'USA');
INSERT INTO `country` VALUES ('2', 'England');

-- ----------------------------
-- Table structure for course
-- ----------------------------
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course` (
  `cid` int(5) NOT NULL AUTO_INCREMENT,
  `cname` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

-- ----------------------------
-- Records of course
-- ----------------------------
INSERT INTO `course` VALUES ('1', 'JAVASE');
INSERT INTO `course` VALUES ('2', 'JAVAEE');
INSERT INTO `course` VALUES ('3', 'Android');

-- ----------------------------
-- Table structure for minister
-- ----------------------------
DROP TABLE IF EXISTS `minister`;
CREATE TABLE `minister` (
  `mid` int(5) NOT NULL AUTO_INCREMENT,
  `mname` varchar(20) NOT NULL,
  `countryId` int(5) DEFAULT NULL,
  PRIMARY KEY (`mid`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of minister
-- ----------------------------
INSERT INTO `minister` VALUES ('1', 'aaa', '1');
INSERT INTO `minister` VALUES ('2', 'bbb', '1');
INSERT INTO `minister` VALUES ('3', 'ccc', '1');
INSERT INTO `minister` VALUES ('4', 'ddd', '2');
INSERT INTO `minister` VALUES ('5', 'eee', '2');

-- ----------------------------
-- Table structure for newslabel
-- ----------------------------
DROP TABLE IF EXISTS `newslabel`;
CREATE TABLE `newslabel` (
  `id` int(20) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) DEFAULT NULL,
  `pid` int(5) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=12 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

-- ----------------------------
-- Records of newslabel
-- ----------------------------
INSERT INTO `newslabel` VALUES ('1', '娱乐新闻', '0');
INSERT INTO `newslabel` VALUES ('2', '体育新闻', '0');
INSERT INTO `newslabel` VALUES ('3', 'NBA', '2');
INSERT INTO `newslabel` VALUES ('4', 'CBA', '2');
INSERT INTO `newslabel` VALUES ('5', '火箭', '3');
INSERT INTO `newslabel` VALUES ('6', '湖人', '3');
INSERT INTO `newslabel` VALUES ('7', '东莞银行', '4');
INSERT INTO `newslabel` VALUES ('8', '北京金隅', '4');
INSERT INTO `newslabel` VALUES ('9', '青岛双星', '4');
INSERT INTO `newslabel` VALUES ('10', '港台明星', '1');
INSERT INTO `newslabel` VALUES ('11', '内地明星', '1');

-- ----------------------------
-- Table structure for student
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
  `sid` int(11) NOT NULL AUTO_INCREMENT,
  `sname` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`sid`)
) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

-- ----------------------------
-- Records of student
-- ----------------------------
INSERT INTO `student` VALUES ('1', 'zhangsan');
INSERT INTO `student` VALUES ('2', 'lisi');
INSERT INTO `student` VALUES ('3', 'wangwu');

-- ----------------------------
-- Table structure for stu_cou
-- ----------------------------
DROP TABLE IF EXISTS `stu_cou`;
CREATE TABLE `stu_cou` (
  `id` int(5) NOT NULL AUTO_INCREMENT,
  `studentId` int(5) NOT NULL,
  `courseId` int(5) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

-- ----------------------------
-- Records of stu_cou
-- ----------------------------
INSERT INTO `stu_cou` VALUES ('1', '1', '1');
INSERT INTO `stu_cou` VALUES ('2', '1', '2');
INSERT INTO `stu_cou` VALUES ('3', '2', '1');
INSERT INTO `stu_cou` VALUES ('4', '2', '3');

-- ----------------------------
-- Table structure for tb_user
-- ----------------------------
DROP TABLE IF EXISTS `tb_user`;
CREATE TABLE `tb_user` (
  `id` char(32) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `user_name` varchar(32) DEFAULT NULL,
  `password` varchar(32) DEFAULT NULL,
  `name` varchar(32) DEFAULT NULL,
  `age` int(10) DEFAULT NULL,
  `sex` int(2) DEFAULT NULL,
  `birthday` date DEFAULT NULL,
  `created` datetime DEFAULT NULL,
  `updated` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of tb_user
-- ----------------------------
INSERT INTO `tb_user` VALUES ('1', 'aaa', '123456', 'zhangsan', '22', '1', '1990-01-04', '2019-08-04 17:44:22', '2019-08-04 17:44:24');