问题
我能够将一个对象序列化为一个文件然后再次恢复它，如下一个代码片段所示。我想将对象序列化为字符串并存储到数据库中。谁能帮我？
LinkedList<Diff_match_patch.Patch> patches = // whatever...
FileOutputStream fileStream = new FileOutputStream("foo.ser");
ObjectOutputStream os = new ObjectOutputStream(fileStream);
os.writeObject(patches1);
os.close();
FileInputStream fileInputStream = new FileInputStream("foo.ser");
ObjectInputStream oInputStream = new ObjectInputStream(fileInputStream);
Object one = oInputStream.readObject();
LinkedList<Diff_match_patch.Patch> patches3 = (LinkedList<Diff_match_patch.Patch>) one;
os.close();
#1 热门回答(251 赞)
塞尔吉奥：
你应该使用BLOB。使用JDBC非常简单。
你发布的第二个代码的问题是编码。你还应该对字节进行编码，以确保它们都不会失败。
如果你仍想将其写入String，则可以使用java.util.Base64对字节进行编码。
仍然应该使用CLOB作为数据类型，因为你不知道序列化数据将会持续多长时间。
以下是如何使用它的示例。
import java.util.*;
import java.io.*;
/**
* Usage sample serializing SomeClass instance
*/
public class ToStringSample {
public static void main( String [] args ) throws IOException,
ClassNotFoundException {
String string = toString( new SomeClass() );
System.out.println(" Encoded serialized version " );
System.out.println( string );
SomeClass some = ( SomeClass ) fromString( string );
System.out.println( "\n\nReconstituted object");
System.out.println( some );
}
/**Read the object from Base64 string. */
private static Object fromString( String s ) throws IOException ,
ClassNotFoundException {
byte [] data = Base64.getDecoder().decode( s );
ObjectInputStream ois = new ObjectInputStream(
new ByteArrayInputStream( data ) );
Object o = ois.readObject();
ois.close();
return o;
}
/**Write the object to a Base64 string. */
private static String toString( Serializable o ) throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream( baos );
oos.writeObject( o );
oos.close();
return Base64.getEncoder().encodeToString(baos.toByteArray());
}
}
/**Test subject. A very simple class. */
class SomeClass implements Serializable {
private final static long serialVersionUID = 1; // See Nick's comment below
int i = Integer.MAX_VALUE;
String s = "ABCDEFGHIJKLMNOP";
Double d = new Double( -1.0 );
public String toString(){
return "SomeClass instance says: Don't worry, "
+ "I'm healthy. Look, my data is i = " + i
+ ", s = " + s + ", d = " + d;
}
}
输出：
C:\samples>javac *.java
C:\samples>java ToStringSample
Encoded serialized version
rO0ABXNyAAlTb21lQ2xhc3MAAAAAAAAAAQIAA0kAAWlMAAFkdAASTGphdmEvbGFuZy9Eb3VibGU7T
AABc3QAEkxqYXZhL2xhbmcvU3RyaW5nO3hwf////3NyABBqYXZhLmxhbmcuRG91YmxlgLPCSilr+w
QCAAFEAAV2YWx1ZXhyABBqYXZhLmxhbmcuTnVtYmVyhqyVHQuU4IsCAAB4cL/wAAAAAAAAdAAQQUJ
DREVGR0hJSktMTU5PUA==
Reconstituted object
SomeClass instance says: Don't worry, I'm healthy. Look, my data is i = 2147483647, s = ABCDEFGHIJKLMNOP, d = -1.0
注意：对于Java 7及更早版本，你可以看到原始的889103979
#2 热门回答(11 赞)
如何将数据写入ByteArrayOutputStream而不是FileOutputStream？
否则，你可以使用XMLEncoder序列化对象，保留XML，然后通过XMLDecoder反序列化。
#3 热门回答(7 赞)
感谢你的快速回复。我会立即给予一些投票，以表示你的帮助。我根据你的答案在我看来编写了最好的解决方案。
LinkedList<Patch> patches1 = diff.patch_make(text2, text1);
try {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream os = new ObjectOutputStream(bos);
os.writeObject(patches1);
String serialized_patches1 = bos.toString();
os.close();
ByteArrayInputStream bis = new ByteArrayInputStream(serialized_patches1.getBytes());
ObjectInputStream oInputStream = new ObjectInputStream(bis);
LinkedList<Patch> restored_patches1 = (LinkedList<Patch>) oInputStream.readObject();
// patches1 equals restored_patches1
oInputStream.close();
} catch(Exception ex) {
ex.printStackTrace();
}
注意i未考虑使用JSON，因为效率较低。
**注意：**我将考虑你的建议，即不将序列化对象存储为数据库中的字符串，而是将byte []替换为。