CODEWITHSUNDEEP
javaserialization
T.Allen
T.Allen

Reputation: 63

Use Java Serialization to Save Object

I'm planning to use Serialization to save the Bean modified by user--to store the history record. But the ByteArrayOutputStream output a byte array:byte[]. If I convert it to String and convert it back, then it can't be de-serialized. --How to explain this? If I use byte array to store in the oracle, it's complicated.Is there any way to make the String can be de-serialized? Thank you! I'm a Chinese, so forgive me for my bad English. :)

Upvotes: 0

Views: 1147

Answers (4)

code_sniper
code_sniper

Reputation: 61

        static final String SQL_SERIALIZE_OBJECT="insert into serialized_java_objects(serialized_id,object_name,serialized_object) values (ser_id_seq.nextval,?,?)";

        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(baos);
        oos.writeObject(objectToBeSerilize);
        byte[] serializeBytes = baos.toByteArray();

        prepStatement = connection.prepareStatement(SQL_SERIALIZE_OBJECT);
        prepStatement.setString(1, objectToBeSerilize.getClass().getName());
        prepStatement.setBytes(2, serializeBytes);


        prepStatement.executeUpdate();

Upvotes: 0

Peter Lawrey
Peter Lawrey

Reputation: 533880

In byte[] all possible byte values can be used i.e. -128 to 127. However, in text these values and combination of values can be invalid and not convert to text as expected.

I suggest you consider a text based serialization like XML or JSon. These can be read/written as text safely. Text base serialization can be read by a human and possibly edited as text if you want to correct a value.

EDIT: I would look at using XMLEncoder which is crude, but built in or XStream for XML and JSon, which is more flexible and efficient (but requires a couple of extra libraries)

Upvotes: 0

Charles Anthony
Charles Anthony

Reputation: 3155

Brief Answer: encode the byte array as a Base64 string.

Base64 is a way of ensuring that binary data can be stored and transmitted as text - a reasonable explanation can be found on Wikipedia; if you don't encode the byte array, data can easily become "corrupted" by the use of different codepages etc. One thing to be aware of - base64 encoding will take more space than the byte array (so a byte array of 20 bytes may take around 30 characters to be stored)

There are many libraries that can encode/decode Base64 Apache Commons Codec is just one. See this question for more discussions on which library to use (there is a "private" one in the JDK, but use of it may be considered questionable by some developers).

So, in summary, to serialize an object into string, us an ObjectOutputStream and a ByeArrayOutputStream to convert to a byte array, and then use a Base64 encoder to translate that into a string.

To deserialize, use a Base64 decoder to convert the string back into a byte array, and then use a ByteArrayInputStream and a ObjectInputStream to read it back.

Upvotes: 0

Jesper
Jesper

Reputation: 207016

Use ObjectOutputStream to serialize and ObjectInputStream to deserialize objects. The API documentation of those classes has examples that show how to use them to serialize and deserialize objects to and from a file.

Don't try to force a byte[] into a String. (Why would you want to put it in a String?). Serialized objects are binary data, not text characters that you would store in a String.

Upvotes: 2

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