Mybatis（一），使用三种方式实现对数据库表的增删改查

心已赠人 2022-05-28 09:40 116阅读 0赞

MyBatis实现对数据库表的增删改查主要有三种方式，分别为“基于配置文件方式”、“基于接口方式”和“基于注解方式”，下面主要介绍一下这三种方式是如何实现的。推荐使用接口方式。

**（一）基于配置文件方式**

涉及三个文件：核心配置文件，映射文件和测试类。核心配置文件主要是配置与数据库相关的信息和注册映射文件；映射文件中涉及SQL语句；测试类是SQL真正执行的地方。

1.核心配置文件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>
    	<environments default="development">
    		<environment id="development">
    			
    			<transactionManager type="JDBC"></transactionManager>
    			
    			<dataSource type="POOLED">
    				<property name="driver" value="com.mysql.jdbc.Driver"/>
    				<property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
    				<property name="username" value="root"/>
    				<property name="password" value="123"/>
    			</dataSource>
    		</environment>
    	</environments>
    	
    	<mappers>
    		<mapper resource="mapper/BlogMapper1.xml"/>
    	</mappers>
    </configuration>

2.映射文件BlogMapper1.xml，放置于mapper包下

<?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">
    <mapper namespace="BlogMapper">
    	
    	<select id="selectOne" parameterType="int" resultType="entity.Blog">
    		select * from blog where id = #{id}
    	</select>
    	
    	 
    	<insert id="insert" parameterType="entity.Blog">
    		INSERT INTO blog(id,title,author_id) VALUES(#{id},#{title},#{author_id})
    	</insert>
    	
    	
    	<delete id="delete" parameterType="int">
    		delete from blog where id = #{id}
    	</delete>
    	
    	
    	<update id="update" parameterType="entity.Blog">
    		update blog set title = #{title} where id = #{id}
    	</update>
    </mapper>

3.测试类test1.java

package test;
    
    import java.io.InputStream;
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import com.mysql.jdbc.Blob;
    
    import entity.Blog;
    
    /**
     * 通过配置文件实现对blog表的增删改查
     * @author baka
     *
     */
    public class test1 {
    
    	public static void main(String[] args) {
    		//1.获取配置文件名
    		String resource = "SqlMapConfig.xml";
    		
    		//2.得到数据源
    		InputStream is = test1.class.getClassLoader().getResourceAsStream(resource);
    		
    		//3.提供连接，建立工厂
    		SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
    		
    		//4.得到真正的连接
    		SqlSession session = factory.openSession();
    		
    		//5.执行SQL语句
    		
    		//查询
    		String statement = "BlogMapper.selectOne";
    		Blog blog = session.selectOne(statement, 2);
    		System.out.println(blog);
    		
    		//插入
    		String statement2 = "BlogMapper.insert";
    		Blog blog2 = new Blog(8, "wawa", 1);
    		session.insert(statement2, blog2);
    		
    		//修改
    		String statement3 = "BlogMapper.update";
    		Blog blog3 = new Blog(8, "wawahh", 2);
    		session.update(statement3, blog3);
    		
    		//删除
    		String statement4 = "BlogMapper.delete";
    		session.update(statement4, 8);
    		
    		//6、提交事务，关闭连接
    		session.commit();
    		session.close();
    	}
    }

**(二)基于接口方式，涉及四个文件，核心配置文件、映射文件、测试类和接口类**

1.核心配置文件

2.接口类BlogDao2.java

package dao;
    
    import java.util.List;
    
    import entity.Blog;
    
    public interface BlogDao2 {
    	public Blog selectOne(int id);
    	public int insert(Blog blog);
    	public int delete(int id);
    	public int update(Blog blog);
    }

3.映射文件BlogMapper2.xml，使用的是上面的映射文件，但有两点需要注意

（1）命名空间必须是接口所在的位置

我的接口类是“BlogDao.java”，位于"dao"包下

（2）命名空间中的id必须和接口中的方法同名

（3）完整代码

<?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="dao.BlogDao2">
    	
    	<select id="selectOne" parameterType="int" resultType="entity.Blog">
    		select * from blog where id = #{id}
    	</select>
    	
    	 
    	<insert id="insert" parameterType="entity.Blog">
    		INSERT INTO blog(id,title,author_id) VALUES(#{id},#{title},#{author_id})
    	</insert>
    	
    	
    	<delete id="delete" parameterType="int">
    		delete from blog where id = #{id}
    	</delete>
    	
    	
    	<update id="update" parameterType="entity.Blog">
    		update blog set title = #{title} where id = #{id}
    	</update>
    </mapper>

4.测试类test2.java

package test;
    
    import java.io.InputStream;
    import java.util.List;
    
    import javax.naming.spi.ObjectFactory;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import dao.BlogDao2;
    import entity.Blog;
    
    /**
     * 基于接口方式实现blog表的增删改查
     * @author baka
     *
     */
    public class test2 {
    	public static void main(String[] args) {
    		//1.获得配置文件名
    		String resource = "SqlMapConfig.xml";
    		
    		//2.获得数据流
    		InputStream is = test2.class.getClassLoader().getResourceAsStream(resource);
    		
    		//3.提供连接，建立工厂
    		SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
    		
    		//4.获得真正的连接
    		SqlSession session = factory.openSession();
    		
    		//5.实例化接口
    		BlogDao2 blogDao = session.getMapper(BlogDao2.class);
    		
    		//6.执行SQL语句
    		
    		//查询
    		Blog blog = blogDao.selectOne(2);
    		System.out.println(blog);
    		
    		//插入
    		Blog blog2 = new Blog(9, "xxx", 4);
    		blogDao.insert(blog2);
    		
    		//修改
    		Blog blog3 = new Blog(9, "xxxL", 4);
    		blogDao.update(blog3);
    		
    		//删除
    		blogDao.delete(9);
    		
    		//7.提交事务，关闭连接
    		session.commit();
    		session.close();
    	}
    }

**（三）基于注解方式**

涉及三个文件，核心配置文件，接口类和测试类，没有映射文件，SQL语句注解写在接口方法中

1.核心配置文件

2.接口类BlogDao3.java

package dao;
    
    import java.util.List;
    
    import org.apache.ibatis.annotations.Delete;
    import org.apache.ibatis.annotations.Insert;
    import org.apache.ibatis.annotations.Select;
    import org.apache.ibatis.annotations.Update;
    
    import entity.Blog;
    
    /**
     * 注解方式
     * @author baka
     *
     */
    
    public interface BlogDao3 {
    	@Select("select * from blog where id = #{id}")
    	public Blog selectOne(int id);
    	
    	@Insert("INSERT INTO blog(id,title,author_id) VALUES(#{id},#{title},#{author_id})")
    	public int insert(Blog blog);
    	
    	@Delete("delete from blog where id = #{id}")
    	public int delete(int id);
    	
    	@Update("update blog set title = #{title} where id = #{id}")
    	public int update(Blog blog);
    }

3.测试类test3.java

package test;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import dao.BlogDao2;
    import dao.BlogDao3;
    import entity.Blog;
    
    /**
     * 基于注解方式实现对blog表的增删改查
     * 
     * @author baka
     *
     */
    public class test3 {
    
    	public static void main(String[] args) throws IOException {
    		// 1.获得配置文件名
    		String resource = "SqlMapConfig.xml";
    
    		// 2.获得数据流
    		InputStream is = test3.class.getClassLoader().getResourceAsStream(resource);
    
    		// 3.提供连接，建立工厂
    		SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
    
    		// 4.获得真正的连接
    		SqlSession session = factory.openSession();
    
    		// 5.实例化接口
    		BlogDao3 blogDao = session.getMapper(BlogDao3.class);
    
    		// 6.执行SQL语句
    		
    		//查询
    		Blog blog = blogDao.selectOne(1);
    		System.out.println(blog);
    		
    		//增加
    		Blog blog1 = new Blog(9, "xxx", 4);
    		blogDao.insert(blog1);
    		
    		//修改
    		Blog blog3 = new Blog(9, "xxxL", 4);
    		blogDao.update(blog3);
    		
    		//删除
    		blogDao.delete(9);
    		
    		// 7.提交事务，关闭连接
    		session.commit();
    		session.close();
    	}
    
    }