Quick guide for Migration of Commons HttpClient 3.x to HttpComponents HttpClient 4.x

As I agreed in the previous blog post for the migration guide of Commons HttpClient 3.x to HttpComponents HttpClient 4.x. Even I also took time to migrate, let me put my effort here so that someone can reap from it.

HttpComponents HttpClient is a HTTP/1.1 compliant HTTP agent implementation based on HttpCore. It also provides reusable components for client-side authentication, HTTP state management, and HTTP connection management. HttpComponents Client is a successor of and replacement for Commons HttpClient 3.x. Users of Commons HttpClient are strongly encouraged to upgrade.

Below table is the quick reference for the migration.

	Commons HttpClient 3.x	HttpComponents HttpClient 4.x
import	import org.apache.commons.httpclient.Credentials; import org.apache.commons.httpclient.Header; import org.apache.commons.httpclient.HostConfiguration; import org.apache.commons.httpclient.HttpClient; import org.apache.commons.httpclient. MultiThreadedHttpConnectionManager; import org.apache.commons.httpclient. UsernamePasswordCredentials; import org.apache.commons.httpclient.auth.AuthScope; import org.apache.commons.httpclient.methods.DeleteMethod; import org.apache.commons.httpclient.methods.GetMethod; import org.apache.commons.httpclient.methods.PostMethod;	import org.apache.http.Header; import org.apache.http.HttpEntity; import org.apache.http.HttpHost; import org.apache.http.HttpResponse; import org.apache.http.auth.AuthScope; import org.apache.http.auth.Credentials; import org.apache.http.auth.UsernamePasswordCredentials; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.conn.params.ConnRoutePNames; import org.apache.http.entity.ContentType; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.util.EntityUtils;
HttpClient	HttpClient client = new HttpClient(connectionManager);	DefaultHttpClient client = new DefaultHttpClient();
proxy configuration	client.getHostConfiguration().setProxy( proxyHost, proxyPort); client.getState().setAuthenticationPreemptive( true); Credentials cred = new  UsernamePasswordCredentials( proxyUser, proxyPassword); client.getState().setProxyCredentials( AuthScope.ANY_HOST, proxyHost, cred)	client.getCredentialsProvider(). setCredentials(  new AuthScope(proxyHost, proxyPort),  new UsernamePasswordCredentials( proxyUser, proxyPassword)); HttpHost proxy = new HttpHost(proxyHost proxyPort); client.getParams().setParameter( ConnRoutePNames.DEFAULT_PROXY, proxy);
POST	PostMethod post = new PostMethod(); post.setPath(url.getFile());	HttpPost post = new HttpPost(url.getFile());
POST Header	post.setRequestHeader(key, (String) headers.get(key));	post.addHeader(key, (String) headers.get(key));
POST Body	post.setRequestBody(message);	StringEntity messageEntity = new StringEntity( message,  ContentType.create("text/plain", "UTF-8"));       post.setEntity(messageEntity);
Execute POSt	client.executeMethod(post);	HttpHost targetHost = new HttpHost(url.getHost(), url.getPort(), url.getProtocol()); HttpResponse httpResponse = client.execute(targetHost, post);
Response Header	Header[] rspHeaders = post.getResponseHeaders();	Header[] rspHeaders = httpResponse.getAllHeaders();
Response Body	String responseMsg = post.getResponseBodyAsString()	StringBuffer buffer = new StringBuffer();       BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent())); String dataLine = null; while((dataLine = reader.readLine()) != null){             buffer.append(dataLine); } String responseMsg =    buffer.toString();
GET	GetMethod getMethod = new GetMethod(); getMethod.setPath(url.getFile());	HttpGet httpGet = new HttpGet(url.getFile());
GET Header	getMethod.setRequestHeader(key, value);	httpGet.addHeader(key, value);
Execute GET	client.executeMethod(getMethod);	HttpHost targetHost = new HttpHost(url.getHost(), url.getPort(), url.getProtocol()); HttpResponse httpResponse = client.execute( targetHost, httpGet);