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？
LinkedListpatches = // 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 patches3 = (LinkedList ) one; os.close();
OscarRyz.. 264
塞尔吉奥:
你应该使用BLOB.使用JDBC非常简单.
您发布的第二个代码的问题是编码.您还应该对字节进行编码,以确保它们都不会失败.
如果您仍想将其写入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,因为您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,您可以在此处查看原始答案
塞尔吉奥:
你应该使用BLOB.使用JDBC非常简单.
您发布的第二个代码的问题是编码.您还应该对字节进行编码,以确保它们都不会失败.
如果您仍想将其写入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,因为您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,您可以在此处查看原始答案
如何将数据写入ByteArrayOutputStream而不是FileOutputStream？
否则,您可以使用XMLEncoder序列化对象,保留XML,然后通过XMLDecoder反序列化.
感谢您的快速回复.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.
LinkedListpatches1 = 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 restored_patches1 = (LinkedList ) oInputStream.readObject(); // patches1 equals restored_patches1 oInputStream.close(); } catch(Exception ex) { ex.printStackTrace(); }
注意我没有考虑使用JSON,因为效率较低.
注意:我会考虑您的建议,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.
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