Apache HttpComponents Custom protocol interceptors通过拦截器自定义压缩

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package org.apache.http.examples.client;

import java.io.IOException;

import org.apache.http.Header;
import org.apache.http.HeaderElement;
import org.apache.http.HttpEntity;
import org.apache.http.HttpException;
import org.apache.http.HttpRequest;
import org.apache.http.HttpRequestInterceptor;
import org.apache.http.HttpResponse;
import org.apache.http.HttpResponseInterceptor;
import org.apache.http.client.entity.GzipDecompressingEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.protocol.HttpContext;
import org.apache.http.util.EntityUtils;

/**
* Demonstration of the use of protocol interceptors to transparently
* modify properties of HTTP messages sent / received by the HTTP client.
* <p/>
* In this particular case HTTP client is made capable of transparent content
* GZIP compression by adding two protocol interceptors: a request interceptor
* that adds 'Accept-Encoding: gzip' header to all outgoing requests and
* a response interceptor that automatically expands compressed response
* entities by wrapping them with a uncompressing decorator class. The use of
* protocol interceptors makes content compression completely transparent to
* the consumer of the {@link org.apache.http.client.HttpClient HttpClient}
* interface.
*/
public class ClientGZipContentCompression {

public final static void main(String[] args) throws Exception {
DefaultHttpClient httpclient = new DefaultHttpClient();
try {
httpclient.addRequestInterceptor(new HttpRequestInterceptor() {

public void process(
final HttpRequest request,
final HttpContext context) throws HttpException, IOException {
if (!request.containsHeader("Accept-Encoding")) {
request.addHeader("Accept-Encoding", "gzip");
}
}

});

httpclient.addResponseInterceptor(new HttpResponseInterceptor() {

public void process(
final HttpResponse response,
final HttpContext context) throws HttpException, IOException {
HttpEntity entity = response.getEntity();
if (entity != null) {
Header ceheader = entity.getContentEncoding();
if (ceheader != null) {
HeaderElement[] codecs = ceheader.getElements();
for (int i = 0; i < codecs.length; i++) {
if (codecs[i].getName().equalsIgnoreCase("gzip")) {
response.setEntity(
new GzipDecompressingEntity(response.getEntity()));
return;
}
}
}
}
}

});

HttpGet httpget = new HttpGet("http://www.apache.org/");

// Execute HTTP request
System.out.println("executing request " + httpget.getURI());
HttpResponse response = httpclient.execute(httpget);

System.out.println("----------------------------------------");
System.out.println(response.getStatusLine());
System.out.println(response.getLastHeader("Content-Encoding"));
System.out.println(response.getLastHeader("Content-Length"));
System.out.println("----------------------------------------");

HttpEntity entity = response.getEntity();

if (entity != null) {
String content = EntityUtils.toString(entity);
System.out.println(content);
System.out.println("----------------------------------------");
System.out.println("Uncompressed size: "+content.length());
}

} finally {
// When HttpClient instance is no longer needed,
// shut down the connection manager to ensure
// immediate deallocation of all system resources
httpclient.getConnectionManager().shutdown();
}
}

}