Mysql儲存二進位制物件資料問題

2023-03-15 06:01:00

Mysql儲存二進位制物件資料

首先資料庫儲存一個Object物件

需要在資料庫表中定義一個blob型別的欄位

與資料庫對應的實體類

編寫一個操作二進位制的工具類

import java.io.*;
 
/**
 * byte[]型別操作類
 */
public class BlobUtil {
 
    /**
     * 把object物件序列化為二進位制位元組陣列
     * @param object
     * @return
     */
    public static byte[] setObject(Object object) {
        ByteArrayOutputStream baos = null;
        ObjectOutputStream out = null;
        try {
            baos = new ByteArrayOutputStream();
            out = new ObjectOutputStream(baos);
            out.writeObject(object);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (baos != null) {
                try {
                    baos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return baos.toByteArray();
    }
 
    /**
     * 把二進位制位元組陣列反序列化為object物件
     * object當中的每個javaBean物件都必須實現序列化
	 * 最外層的類必須生成一個序列化ID
     * @param bytes
     * @return
     */
    public static Object getObject(byte[] bytes) {
        Object obj = null;
        ByteArrayInputStream bais = null;
        ObjectInputStream in = null;
        try {
            bais = new ByteArrayInputStream(bytes);
            in = new ObjectInputStream(bais);
            obj = in.readObject();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (bais != null) {
                try {
                    bais.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return obj;
    }
}

需要轉換為byte[]的物件必須實現序列化和生成一個序列化ID，生成一個序列化ID是為了解決類當中一但有修改，反序列化時序列化ID就會對應不上，如下圖：

類中如果有其他類為變數也需要實現序列化，否則從資料庫中取出資料然後反序列化成Object物件的時候會直接報錯

對user的資料進行操作

import java.io.Serializable;
 
/**
 * @author
 * @description
 * @date
 */
public class UserVO implements Serializable {
 
    private static final long serialVersionUID = 1L;
 
    private String userId;
 
    private String userName;
 
    private String password;
 
    public String getUserId() {
        return userId;
    }
 
    public void setUserId(String userId) {
        this.userId = userId;
    }
 
    public String getUserName() {
        return userName;
    }
 
    public void setUserName(String userName) {
        this.userName = userName;
    }
 
    public String getPassword() {
        return password;
    }
 
    public void setPassword(String password) {
        this.password = password;
    }
}

呼叫二進位制工具類來轉換資料然後進行存取就可以了。

測試功能

public class TestMain {
 
    public static void main(String[] args) {
        UserVO user = new UserVO();
        user.setUserId("123456");
        user.setUserName("張三");
        byte[] dataValue = BlobUtil.setObject(user);
        System.out.println("=====物件轉換成blob型別資料====="+Arrays.toString(dataValue));
        UserVO userVO = (UserVO) BlobUtil.getObject(dataValue);
        System.out.println("=====blob型別資料轉換成物件====="+ JSONObject.toJSONString(userVO));
    }
}

列印輸出

=====物件轉換成blob型別資料=====[-84, -19, 0, 5, 115, 114, 0, 53, 99, 111, 109, 46, 100, 111, 108, 112, 104, 105, 110, 46, 109, 111, 100, 117, 108, 101, 115, 46, 116, 109, 115, 46, 100, 111, 109, 97, 105, 110, 46, 99, 117, 115, 116, 111, 109, 101, 114, 115, 101, 114, 118, 105, 99, 101, 46, 85, 115, 101, 114, 86, 79, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 3, 76, 0, 8, 112, 97, 115, 115, 119, 111, 114, 100, 116, 0, 18, 76, 106, 97, 118, 97, 47, 108, 97, 110, 103, 47, 83, 116, 114, 105, 110, 103, 59, 76, 0, 6, 117, 115, 101, 114, 73, 100, 113, 0, 126, 0, 1, 76, 0, 8, 117, 115, 101, 114, 78, 97, 109, 101, 113, 0, 126, 0, 1, 120, 112, 112, 116, 0, 6, 49, 50, 51, 52, 53, 54, 116, 0, 6, -27, -68, -96, -28, -72, -119]
=====blob型別資料轉換成物件====={"userId":"123456","userName":"張三"}