org.opendatakit.sync.aggregate.SimpleJSONMessageReaderWriter.java Source code

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Here is the source code for org.opendatakit.sync.aggregate.SimpleJSONMessageReaderWriter.java

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/*
 * Copyright (C) 2012-2013 University of Washington
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package org.opendatakit.sync.aggregate;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.math.BigInteger;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;

import org.apache.commons.lang3.CharEncoding;
import org.opendatakit.aggregate.odktables.rest.ApiConstants;

import com.fasterxml.jackson.databind.ObjectMapper;

@Consumes({ MediaType.APPLICATION_JSON })
@Produces({ MediaType.APPLICATION_JSON })
@Provider
public class SimpleJSONMessageReaderWriter<T> implements MessageBodyReader<T>, MessageBodyWriter<T> {

    private static final ObjectMapper mapper = new ObjectMapper();
    private static final String DEFAULT_ENCODING = "utf-8";

    @Override
    public boolean isReadable(Class<?> type, Type genericType, Annotation annotations[], MediaType mediaType) {
        return mediaType.getType().equals(MediaType.APPLICATION_JSON_TYPE.getType())
                && mediaType.getSubtype().equals(MediaType.APPLICATION_JSON_TYPE.getSubtype());
    }

    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation annotations[], MediaType mediaType) {
        return mediaType.getType().equals(MediaType.APPLICATION_JSON_TYPE.getType())
                && mediaType.getSubtype().equals(MediaType.APPLICATION_JSON_TYPE.getSubtype());
    }

    @Override
    public T readFrom(Class<T> aClass, Type genericType, Annotation[] annotations, MediaType mediaType,
            MultivaluedMap<String, String> map, InputStream stream) throws IOException, WebApplicationException {
        String encoding = getCharsetAsString(mediaType);
        try {
            if (!encoding.equalsIgnoreCase(DEFAULT_ENCODING)) {
                throw new IllegalArgumentException("charset for the request is not utf-8");
            }

            InputStreamReader r = new InputStreamReader(stream, CharEncoding.UTF_8);
            return mapper.readValue(r, aClass);
        } catch (Exception e) {
            throw new IOException(e);
        }
    }

    @Override
    public void writeTo(T o, Class<?> aClass, Type type, Annotation[] annotations, MediaType mediaType,
            MultivaluedMap<String, Object> map, OutputStream rawStream)
            throws IOException, WebApplicationException {
        String encoding = getCharsetAsString(mediaType);
        try {
            if (!encoding.equalsIgnoreCase(DEFAULT_ENCODING)) {
                throw new IllegalArgumentException("charset for the response is not utf-8");
            }
            // write it to a byte array
            ByteArrayOutputStream bas = new ByteArrayOutputStream(8192);
            OutputStreamWriter w = new OutputStreamWriter(bas, Charset.forName(ApiConstants.UTF8_ENCODE));
            mapper.writeValue(w, o);
            // get the array and compute md5 hash
            byte[] bytes = bas.toByteArray();
            String eTag;
            try {
                MessageDigest md = MessageDigest.getInstance("MD5");
                md.update(bytes);

                byte[] messageDigest = md.digest();

                BigInteger number = new BigInteger(1, messageDigest);
                String md5 = number.toString(16);
                while (md5.length() < 32)
                    md5 = "0" + md5;
                eTag = "md5_" + md5;
            } catch (NoSuchAlgorithmException e) {
                throw new IllegalStateException("Unexpected problem computing md5 hash", e);
            }
            map.putSingle(HttpHeaders.ETAG, eTag);

            rawStream.write(bytes);
            rawStream.flush();

        } catch (Exception e) {
            throw new IOException(e);
        }
    }

    @Override
    public long getSize(T arg0, Class<?> arg1, Type arg2, Annotation[] arg3, MediaType arg4) {
        return -1;
    }

    protected static String getCharsetAsString(MediaType m) {
        if (m == null) {
            return DEFAULT_ENCODING;
        }
        String result = m.getParameters().get("charset");
        return (result == null) ? DEFAULT_ENCODING : result;
    }
}