Mysql存储二进制对象数据问题

吾爱主题阅读：192 2023-03-15 16:56:00 评论：0

Mysql存储二进制对象数据

首先数据库存储一个Object对象

需要在数据库表中定义一个blob类型的字段

与数据库对应的实体类

编写一个操作二进制的工具类

import java.io.*;
/**
* byte[]类型操作类
*/
public class BlobUtil {
/**
* 把object对象序列化为二进制字节数组
* @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();
}
/**
* 把二进制字节数组反序列化为object对象
* object当中的每个javaBean对象都必须实现序列化
* 最外层的类必须生成一个序列化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;
}
}

需要转换为byte[]的对象必须实现序列化和生成一个序列化ID，生成一个序列化ID是为了解决类当中一但有修改，反序列化时序列化ID就会对应不上，如下图：

类中如果有其他类为变量也需要实现序列化，否则从数据库中取出数据然后反序列化成Object对象的时候会直接报错

对user的数据进行操作

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;
}
}

调用二进制工具类来转换数据然后进行存取就可以了。

测试功能

public class TestMain {
public static void main(String[] args) {
UserVO user = new UserVO();
user.setUserId("123456");
user.setUserName("张三");
byte[] dataValue = BlobUtil.setObject(user);
System.out.println("=====对象转换成blob类型数据====="+Arrays.toString(dataValue));
UserVO userVO = (UserVO) BlobUtil.getObject(dataValue);
System.out.println("=====blob类型数据转换成对象====="+ JSONObject.toJSONString(userVO));
}
}

打印输出

=====对象转换成blob类型数据=====[-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类型数据转换成对象====={"userId":"123456","userName":"张三"}