MyBatis(3.2.3) - Handling the CLOB/BLOB types

MyBatis provides built-in support for mapping CLOB/BLOB type columns.

Assume we have the following table to store the Students and Tutors photographs and their biodata:

CREATE TABLE USER_PICS (
    ID INT(11) NOT NULL AUTO_INCREMENT,
    NAME VARCHAR(50) DEFAULT NULL,
    PIC BLOB,
    BIO LONGTEXT,
    PRIMARY KEY (ID)
) ENGINE=INNODB AUTO_INCREMENT=1 DEFAULT CHARSET=LATIN1;

Here, the photograph can be an image of type PNG, JPG, and so on, and the biodata can be a lengthy history about the student/tutor.

By default, MyBatis maps CLOB type columns to the java.lang.String type and BLOB type columns to the byte[] type.

public class UserPic {
    private int id;
    private String name;
    private byte[] pic;
    private String bio;
    //setters & getters
}

Create the UserPicMapper.xml file and configure the mapped statements as follows:

<insert id="insertUserPic" parameterType="UserPic">
    INSERT INTO USER_PICS(NAME, PIC, BIO) VALUES(#{name}, #{pic}, #{bio})
</insert>
<select id="getUserPic" parameterType="int" resultType="UserPic">
    SELECT * FROM USER_PICS WHERE ID = #{id}
</select>

The following method insertUserPic() shows how to insert data into CLOB/BLOB type columns:

public void insertUserPic() {
    byte[] pic = null;
    try {
        File file = new File("C:\\Images\\UserImg.jpg");
        InputStream is = new FileInputStream(file);
        pic = new byte[is.available()];
        is.read(pic);
        is.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    String name = "UserName";
    String bio = "put some lenghty bio here";
    UserPic userPic = new UserPic(0, name, pic, bio);
    SqlSession sqlSession = MyBatisUtil.openSession();
    try {
        UserPicMapper mapper = sqlSession.getMapper(UserPicMapper.class);
        mapper.insertUserPic(userPic);
        sqlSession.commit();
    } finally {
        sqlSession.close();
    }
}

The following method getUserPic() shows how to read CLOB type data into String and BLOB type data into byte[] properties:

public void getUserPic() {
    UserPic userPic = null;
    SqlSession sqlSession = MyBatisUtil.openSession();
    try {
        UserPicMapper mapper = sqlSession.getMapper(UserPicMapper.class);
        userPic = mapper.getUserPic(1);
    } finally {
        sqlSession.close();
    }
    byte[] pic = userPic.getPic();
    try {
        OutputStream os = new FileOutputStream(new File("C:\\Images\\UserImage_FromDB.jpg"));
        os.write(pic);
        os.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}