Apache HttpComponents: org.apache.http.client.ClientProtocolException

问题

So I use apache HttpComponents to handle http request in java. Now I want to reuse the DefaultHttpClient, what should be possible accoarding to this example: http://wiki.apache.org/HttpComponents/QuickStart. The example itselfs give a ssl error so I modefied and simplefied it a bit. Now I always get a org.apache.http.client.ClientProtocolException

Here is my example program, basicly I just request 2 webpages using the same DefaultHttpClient.

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;


public class ClientFormLogin {

    public static void main(String[] args) throws Exception {

        DefaultHttpClient httpclient = new DefaultHttpClient();

        //Handle first request.
        HttpGet httpget = new HttpGet("http://tweakers.net/nieuws/82969/amazon-nederland-opent-digitale-deuren-in-september.html");
        HttpResponse response = httpclient.execute(httpget);
        System.out.println("Execute finished");
        HttpEntity entity = response.getEntity();
        String page = readInput(entity.getContent());
        System.out.println("Request one finished without problems!");

        //Handle second request
        HttpGet httpost = new HttpGet("http://gathering.tweakers.net/forum/list_messages/1506977/last");
        response = httpclient.execute(httpost);
        entity = response.getEntity();
        page = readInput(entity.getContent());
        System.out.println("Request two finished without problems!");
    }

    private static String readInput(InputStream in) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        byte bytes[] = new byte[1024];

        int n = in.read(bytes);

        while (n != -1) {
            out.write(bytes, 0, n);
            n = in.read(bytes);
        }

        return new String(out.toString());
    }
}

When runnig my example I get the folowing error

Request one finished without problems!
Exception in thread "main" org.apache.http.client.ClientProtocolException
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:909)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:805)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:784)
    at ClientFormLogin.main(ClientFormLogin.java:29)
Caused by: org.apache.http.HttpException: Unable to establish route: planned = {}->http://gathering.tweakers.net; current = {}->http://tweakers.net
    at org.apache.http.impl.client.DefaultRequestDirector.establishRoute(DefaultRequestDirector.java:842)
    at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:645)
    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:480)
    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)
    ... 3 more

Any one can give me some pointers how I can solve this problem, except use a new DefaultHttpClient for every request.

Edit

I just found out if I stay on the same domain I have no problems so:

page1: 'http://tweakers.net/nieuws/82969/amazon-nederland-opent-digitale-deuren-in-september.html'
page2: 'http://tweakers.net/nieuws/82973/website-nujij-belandt-op-zwarte-lijst-google-door-malware.html'

I have no problems if I got to:

page1: 'http://tweakers.net/nieuws/82969/amazon-nederland-opent-digitale-deuren-in-september.html'
page2: 'http://gathering.tweakers.net/forum/list_messages/1506076/last'

I get the error.

Ofc I see this one minute after posting my question. Except if someone can tell me how I can go 2 sperate domains with the same DefaultHttpClient my question is already answered.

回答1:

This is likely due to a recent bug in the v4.2 BasicClientConnectionManager affecting cross site redirects. See http://issues.apache.org/jira/browse/HTTPCLIENT-1193.

According to the maintainer, one temporary workaround is to use SingleClientConnManager or PoolingClientConnectionManager. Perhaps something like this:

ClientConnectionManager connManager = new PoolingClientConnectionManager();
DefaultHttpClient httpclient = new DefaultHttpClient(connManager);
...

来源：https://stackoverflow.com/questions/11347635/apache-httpcomponents-org-apache-http-client-clientprotocolexception

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