pt.sapo.pai.vip.VipServlet.java Source code

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Here is the source code for pt.sapo.pai.vip.VipServlet.java

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package pt.sapo.pai.vip;

import java.io.IOException;
import java.io.OutputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collections;
import java.util.Optional;
import java.util.Random;
import java.util.function.Supplier;
import javaslang.Tuple;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.io.IOUtils;
import org.apache.http.HttpHeaders;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.*;
import org.apache.http.entity.InputStreamEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 *
 * @author brsantos
 */
@WebServlet(name = "VipServlet", urlPatterns = { "/*" })
public class VipServlet extends HttpServlet {

    private static final Logger log = LoggerFactory.getLogger(VipServlet.class);
    private static final Random rand = new Random();
    private static final long serialVersionUID = -2011159554763671377L;
    private final HttpClientBuilder builder = HttpClientBuilder.create();
    private String[] servers;

    @Override
    public String getServletInfo() {
        return "Server VIP";
    }

    @Override
    public void init() throws ServletException {
        super.init();
        try {
            servers = ((String) new InitialContext().lookup("java:comp/env/servers")).split(",");
        } catch (NamingException ex) {
            throw new ServletException(ex);
        }
    }

    private void processRequest(HttpServletRequest request, HttpServletResponse response,
            Supplier<HttpRequestBase> supplier) throws ServletException, IOException {
        try (OutputStream out = response.getOutputStream(); CloseableHttpClient http = builder.build()) {
            Optional.ofNullable(servers[rand.nextInt(2)]).map(server -> server.split(":"))
                    .map(parts -> Tuple.of(parts[0], Integer.valueOf(parts[1]))).ifPresent(server -> {
                        try {
                            HttpRequestBase method = supplier.get();
                            method.setURI(new URI(request.getScheme(), null, server._1, server._2,
                                    request.getRequestURI(), request.getQueryString(), null));
                            HttpResponse rsp = http.execute(method);
                            Collections.list(request.getHeaderNames())
                                    .forEach(name -> Collections.list(request.getHeaders(name))
                                            .forEach(value -> method.setHeader(name, value)));
                            response.setStatus(rsp.getStatusLine().getStatusCode());
                            response.setContentType(rsp.getFirstHeader(HttpHeaders.CONTENT_TYPE).getValue());
                            IOUtils.copy(rsp.getEntity().getContent(), out);
                        } catch (IOException | URISyntaxException ex) {
                            log.error(null, ex);
                        }
                    });
        }
    }

    private Supplier<HttpRequestBase> withEntity(HttpEntityEnclosingRequestBase method,
            HttpServletRequest request) {
        try {
            method.setEntity(new InputStreamEntity(request.getInputStream()));
        } catch (IOException ex) {
            log.warn(null, ex);
        }
        return () -> method;
    }

    @Override
    protected void doDelete(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response, () -> new HttpDelete());
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response, () -> new HttpGet());
    }

    @Override
    protected void doHead(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response, () -> new HttpHead());
    }

    @Override
    protected void doOptions(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response, () -> new HttpOptions());
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response, withEntity(new HttpPost(), request));
    }

    @Override
    protected void doPut(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response, withEntity(new HttpPut(), request));
    }

    @Override
    protected void doTrace(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response, () -> new HttpTrace());
    }

}