myBatis之Clob & Blob

1. 表结构

1.1 在Mysql中的数据类型，longblob  -->  blob, longtext --> clob

2. 配置文件， 请参考  myBatis之入门示例

3. LOB.java

package com.blueStarWei.entity;

public class LOB {

    private Integer id;

    private byte[] picture;//BLOb  --> byte[]

    private String remark;//CLOB --> String

    //getter & setter method

   //toString{No picture}

}

3.1 在Java中数据类型：  byte[]   -->  BLOb ,  String -->  CLOB

4. LOBMapper.java

package com.blueStarWei.mappers;

import com.blueStarWei.entity.LOB;

public interface LOBMapper {

    void insert(LOB lob);

    LOB getLOBByID(Integer id);
}

5. LOBMapper.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 namespace="com.blueStarWei.mappers.LOBMapper">

    <insert id="insert" parameterType="LOB">
        insert into t_lob values(null,#{picture},#{remark});
    </insert>

    <select id="getLOBByID" parameterType="Integer" resultMap="LobResult">
        select * from t_lob where id = #{id};
    </select>

    <resultMap type="LOB" id="LobResult">
        <id property="id" column="id"/>
        <result property="picture" column="picture"/>
        <result property="remark" column="remark"/>
    </resultMap>

</mapper> 

6. TestLOB.java

package com.blueStarWei.test;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import com.blueStarWei.entity.LOB;
import com.blueStarWei.mappers.LOBMapper;
import com.blueStarWei.utils.SqlSessionFactoryUtil;

public class TestLOB {

    @Test
    public void testInsert() {
        SqlSession session = SqlSessionFactoryUtil.openSession();
        LOBMapper mapper = session.getMapper(LOBMapper.class);

        LOB lob = new LOB();
        lob.setRemark("long text for clob...");
        try {
            FileInputStream in = new FileInputStream(new File("C:/Users/msi/Pictures/Camera Roll/Happy.png"));
            byte[] picture = new byte[in.available()];
            in.read(picture);
            in.close();
            lob.setPicture(picture);
        } catch (Exception e) {
            e.printStackTrace();
        }

        mapper.insert(lob);
        session.commit();
        session.close();
    }

    @Test
    public void testGetLob() {
        SqlSession session = SqlSessionFactoryUtil.openSession();
        LOBMapper mapper = session.getMapper(LOBMapper.class);
        LOB lob = mapper.getLOBByID(6);
        System.out.println(lob);

        byte[] picture = lob.getPicture();
        File file = new File("C:/Users/msi/Pictures/Camera Roll/Happy_copy.png");
        try {
            FileOutputStream out = new FileOutputStream(file);
            out.write(picture);
            out.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

7.日志

7.1 表数据

7.2 TestLOB输出

7.3 生成图片

8.总结：

Blob & Clob 就是通过流进行读写操作

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