mybatis使用注解

代码结构

image.png

其中mybatis-config.xml是配置文件，sql.properties是配置文件，
FileLyMapper.xml中的代码

<?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">
<!--注意,使用Mapper来处理数据时，这个namespace要和Mapper所在包+类名保持一致-->
<mapper namespace="com.ly4.com.mapper.FileLyMapper">
    <select id="getFile" resultType="com.ly4.com.entity.FileLy">
        SELECT * FROM file_ly
    </select>
    <!--简单的mapper映射-->
    <insert id="insert" parameterType="com.ly4.com.entity.FileLy"  useGeneratedKeys="true">
        <!--order 代表[设置entity的id]是在[执行insert语句] 之前还是之后-->
        <selectKey resultType="string" keyProperty="id" order="BEFORE" >
            select uuid()
        </selectKey>
        insert into file_ly(id,name,size,update_time) values(#{id},#{name},#{size},#{updateTime})
    </insert>
</mapper>

FileLyMapper.java类

package com.ly4.com.mapper;

import com.ly4.com.builder.FileLyBuilder;
import com.ly4.com.entity.FileLy;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.InsertProvider;
import org.apache.ibatis.annotations.SelectKey;

public interface FileLyMapper {
    /**
     * 简单的注解
     * @param fileLy
     * @return
     */
    int insert(FileLy fileLy);

    /**
     * 直接在方法上的注解
     * @param fileLy
     * @return
     */
    @Insert("insert into file_ly(id,name,size,update_time) values(#{id},#{name},#{size},#{updateTime})")
    @SelectKey(statement = "select uuid()",keyColumn = "id",keyProperty = "id",before = true,resultType = String.class)
    int insertFileLy(FileLy fileLy);

    /**
     * 使用provider的注解
     * @param fileLy
     * @return
     */
    @SelectKey(statement = "select uuid()",keyColumn = "id",keyProperty = "id",before = true,resultType = String.class)
    @InsertProvider(type = FileLyBuilder.class,method = "buildInsertFileLy")
    int insertFileLyWithProvider(FileLy fileLy);
}

buidler类

public class FileLyBuilder {
    public static String buildInsertFileLy(FileLy fileLy) {
        return new SQL() {{
            INSERT_INTO("file_ly");
            VALUES("id","'"+fileLy.getId()+"'");
            VALUES("name", "'"+fileLy.getName()+"'");
            VALUES("size", "'"+fileLy.getSize() +"'");
            //这里直接用getUpdateTime会报错，日期格式对不上
            VALUES("update_time", "#{updateTime}");
        }}.toString();
    }
}

测试代码如下

private static void insertFileLy() throws IOException{
        InputStream inputStream=Resources.getResourceAsStream("mappings4/mybatis-config.xml");
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        try(SqlSession sqlSession=sqlSessionFactory.openSession()){
            final FileLyMapper mapper = sqlSession.getMapper(FileLyMapper.class);
            mapper.insert(new FileLy("file_name_1",20,new Date()));
            mapper.insertFileLy(new FileLy("file_name2",33,new Date()));
            mapper.insertFileLyWithProvider(new FileLy("file_name3",33,new Date()));
            sqlSession.commit();
        }
    }