Jackson: ObjectMapper closes stream after writing value

Currently the ObjectMapper closes the stream which means that you can’t write two values to the underlying stream which mean that the following fails because the stream has been closed

PipedOutputStream pipedOutputStream = new PipedOutputStream();
PipedInputStream pipedInputStream = new PipedInputStream();
pipedInputStream.connect(pipedOutputStream);

ArrayList<Object> list = new ArrayList<>();
ObjectMapper objectMapper = new ObjectMapper(new MessagePackFactory());
objectMapper.writeValue(pipedOutputStream, list);
objectMapper.writeValue(pipedOutputStream, list);

with an IOException saying the pipe closed (same happens with socket)

java.io.IOException: Pipe closed
    at java.io.PipedInputStream.checkStateForReceive(PipedInputStream.java:260)
    at java.io.PipedInputStream.receive(PipedInputStream.java:226)
    at java.io.PipedOutputStream.write(PipedOutputStream.java:149)
    at org.msgpack.core.buffer.OutputStreamBufferOutput.flush(OutputStreamBufferOutput.java:46)
    at org.msgpack.core.MessagePacker.flush(MessagePacker.java:134)
    at org.msgpack.core.MessagePacker.close(MessagePacker.java:143)
    at org.msgpack.jackson.dataformat.MessagePackGenerator.close(MessagePackGenerator.java:344)
    at com.fasterxml.jackson.databind.ObjectMapper._configAndWriteValue(ObjectMapper.java:2883)
    at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:2304)

For now I’m writing to a temporary array and then writing that value to the stream, but that seems inefficient.

byte[] buffer = objectMapper.writeValueAsBytes(packet);

OutputStream output = <from somewhere>
output.write(buffer);
output.flush();

Would it be possible to leave the stream open after writing the value?

[borice]

Leaving a comment for future Googlers looking for a solution to the auto-closed stream:

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectMapper;

JsonFactory jsonFactory = new JsonFactory();
jsonFactory.configure(JsonGenerator.Feature.AUTO_CLOSE_TARGET, false);
ObjectMapper mapper = new ObjectMapper(jsonFactory);

// use mapper as needed... it won't automatically close your stream anymore.

[AaronSharp5]

Adding to @borice comment to address @Sergey123456 issue, which I also encountered: In addition to JsonGenerator.Feature.AUTO_CLOSE_TARGET, which controls OutputStreams when serializing Object to JSON, there is another feature, JsonParser.Feature.AUTO_CLOSE_SOURCE, which controls InputStreams when deserializing JSON to Object. So if you want to handle closing both Input- and OutputStreams yourself:

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.ObjectMapper;

JsonFactory jsonFactory = new JsonFactory();
jsonFactory.configure(JsonGenerator.Feature.AUTO_CLOSE_TARGET, false);
jsonFactory.configure(JsonParser.Feature.AUTO_CLOSE_SOURCE, false);
ObjectMapper mapper = new ObjectMapper(jsonFactory);

// use mapper as needed... it won't automatically close output OR input streams anymore.