Java mysql blob 資料讀寫操作

FH-Admin發表於2021-07-07
JavaMySql

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package com.lw.database;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * CREATE: CREATE TABLE IDCard ( id char(18),pic BLOB);
 * @author fhadmin
 * from www.fhadmin.cn
 */
public class LOBTest {

    protected static final String DEFAULT_URL = "jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf8";
    protected static final String DRIVER_NAME = "com.mysql.jdbc.Driver";

    private Connection connection = null;

    public LOBTest() throws ClassNotFoundException, SQLException {
        Class.forName(DRIVER_NAME);
        connection = DriverManager.getConnection(DEFAULT_URL, "user", "password");
    }

    public void insert(String id,String path) throws SQLException, IOException {
        PreparedStatement preparedStatement = connection.prepareStatement("INSERT INTO IDCard VALUES (?,?)");
        preparedStatement.setString(1, id);
        FileInputStream fileInputStream = new FileInputStream(path);
        preparedStatement.setBlob(2, fileInputStream,fileInputStream.available());
        preparedStatement.execute();
    }

    public void get(String id) throws SQLException, IOException {
        PreparedStatement preparedStatement = connection.prepareStatement("SELECT pic FROM IDCard WHERE id = ?");
        preparedStatement.setString(1, id);
        ResultSet results = preparedStatement.executeQuery();
        while(results.next()) {
            FileOutputStream outputStream = new FileOutputStream("/Users/liuwei/temp.png");
            InputStream inputStream = results.getBinaryStream(1);
            int num = -1;
            while((num=inputStream.read())!=-1) {
                outputStream.write(num);
            }
            outputStream.flush();
            inputStream.close();
            outputStream.close();
        }
    }

    public static void main(String[] args) throws ClassNotFoundException, SQLException, IOException {
        LOBTest test = new LOBTest();
        test.insert("78907656784323", "/Users/liuwei/Documents/bt_next_nor.png");
        test.get("78907656784323");
    }
}

注意：

　　MySQL的四種BLOB型別

　　　　型別 大小(單位：位元組)

　　　 TinyBlob 最大 255B

　　 Blob 最大 65K

　　 MediumBlob 最大 16M

　　　 LongBlob 最大 4G

插入影像的時候，注意下影像大小，影像超過該型別所能容納的最大位元組的時候，會報錯

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