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();

    }

}

巴特西

MyBatis(3.2.3) - Handling the CLOB/BLOB types

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