com.github.matthesrieke.jprox.JProxViaParameterServlet.java Source code

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Here is the source code for com.github.matthesrieke.jprox.JProxViaParameterServlet.java

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/**
 * Copyright (C) 2013
 * by Matthes Rieke
 *
 * Contact: http://matthesrieke.github.io
 *
 * 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 com.github.matthesrieke.jprox;

import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.entity.ByteArrayEntity;
import org.apache.http.entity.ContentType;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.ByteArrayBuffer;
import org.apache.http.util.EntityUtils;

public class JProxViaParameterServlet extends HttpServlet {

    /**
     * 
     */
    private static final long serialVersionUID = -3762618215346245527L;
    private String parameterKey = "targetUrl";

    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);

        if (config != null) {
            String parameterKey = config.getInitParameter("parameterKey");
            if (parameterKey != null) {
                this.parameterKey = parameterKey;
            }
        }

    }

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        executeRequest(req, resp);
    }

    private void executeRequest(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        String target = resolveTargetUrl(req);
        HttpClient client = new DefaultHttpClient();
        HttpResponse response = client.execute(prepareRequest(req, target));
        try {
            String contentType = response.getEntity().getContentType().getValue();

            resp.setContentLength((int) response.getEntity().getContentLength());
            resp.setStatus(response.getStatusLine().getStatusCode());
            resp.setContentType(contentType);

            copyStream(response.getEntity().getContent(), resp.getOutputStream());
        } finally {
            EntityUtils.consume(response.getEntity());
        }
    }

    private HttpUriRequest prepareRequest(HttpServletRequest req, String target) throws IOException {
        String method = req.getMethod();
        if (method.equals(HttpGet.METHOD_NAME)) {
            return new HttpGet(target);
        } else if (method.equals(HttpPost.METHOD_NAME)) {
            HttpPost post = new HttpPost(target);
            post.setEntity(new ByteArrayEntity(readInputStream(req.getInputStream(), req.getContentLength()),
                    ContentType.parse(req.getContentType())));
            return post;
        }
        throw new UnsupportedOperationException("Only GET and POST are supported by this proxy.");
    }

    private byte[] readInputStream(InputStream inputStream, int estimateLength) throws IOException {
        ByteArrayBuffer bb = new ByteArrayBuffer(estimateLength);
        int b;
        while ((b = inputStream.read()) != -1) {
            bb.append(b);
        }
        inputStream.close();
        return bb.toByteArray();
    }

    private String resolveTargetUrl(HttpServletRequest req) {
        String[] values = req.getParameterValues(this.parameterKey);
        if (values != null && values.length > 0) {
            try {
                return URLDecoder.decode(values[0], "UTF-8");
            } catch (UnsupportedEncodingException e) {
                throw new RuntimeException(e);
            }
        }
        throw new RuntimeException(this.parameterKey + " request key not specified!");
    }

    private void copyStream(InputStream content, ServletOutputStream outputStream) throws IOException {
        ReadableByteChannel ci = Channels.newChannel(content);
        WritableByteChannel co = Channels.newChannel(outputStream);

        copyChannel(ci, co);
    }

    private void copyChannel(final ReadableByteChannel src, final WritableByteChannel dest) throws IOException {
        final ByteBuffer buffer = ByteBuffer.allocateDirect(16 * 1024);

        while (src.read(buffer) != -1) {
            buffer.flip();
            dest.write(buffer);
            buffer.compact();
        }

        buffer.flip();

        while (buffer.hasRemaining()) {
            dest.write(buffer);
        }
    }

}