InputStreamDataSourceWithHackForSchemaValidation

gistfile1.java

import javax.activation.DataSource;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Vzniklo to, protoze servisa, ktera ma zapnute @SchemaValidation
 * Udela to, ze pri validaci zavola getInputStream a cely ho precte
 * Potom se pri vyplnovani responsu znova zavola getInputStream a chce ho napsat do response, jenomze
 * to umre, protoze ho uz precetla a zavrela validace.
 *
 * Reseni: na prvni volani to nevrati pravy inputStream
 */
public class InputStreamDataSourceWithHackForSchemaValidation implements DataSource {
    private InputStream inputStream;
    private int count = 0;

    public InputStreamDataSourceWithHackForSchemaValidation(InputStream inputStream) {
        this.inputStream = inputStream;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        if (count == 0) {
            //First access to data stream is for @SchemaValidation (and we do not need read stream for validation)
            count++;
            return new ByteArrayInputStream(new byte[]{});
        }
        if (count != 1) {
            throw new IllegalStateException("getInputStream was expected to be called exactly twice");
        }
        //second access is for writing data to response
        count++;
        return inputStream;
    }

    @Override
    public OutputStream getOutputStream() throws IOException {
        throw new UnsupportedOperationException("Not implemented");
    }

    @Override
    public String getContentType() {
        return "*/*";
    }

    @Override
    public String getName() {
        return "InputStreamDataSource";
    }

}