Java tutorial
/** * Code copied from foursquared project * Licensed under Apache License 2.0 * * Copyright 2009 Joe LaPenna */ package org.cogsurv.cogsurver.http; import org.cogsurv.cogsurver.CogSurver; import org.cogsurv.cogsurver.error.CogSurvCredentialsException; import org.cogsurv.cogsurver.error.CogSurvException; import org.cogsurv.cogsurver.error.CogSurvParseException; import org.cogsurv.cogsurver.parsers.AbstractParser; import org.cogsurv.cogsurver.parsers.Parser; import org.cogsurv.cogsurver.types.CogSurvType; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.ParseException; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.methods.HttpRequestBase; import org.apache.http.client.params.HttpClientParams; import org.apache.http.client.utils.URLEncodedUtils; import org.apache.http.conn.ClientConnectionManager; import org.apache.http.conn.scheme.PlainSocketFactory; import org.apache.http.conn.scheme.Scheme; import org.apache.http.conn.scheme.SchemeRegistry; import org.apache.http.conn.scheme.SocketFactory; import org.apache.http.conn.ssl.SSLSocketFactory; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager; import org.apache.http.params.BasicHttpParams; import org.apache.http.params.HttpConnectionParams; import org.apache.http.params.HttpParams; import org.apache.http.protocol.HTTP; import org.apache.http.util.EntityUtils; import java.io.IOException; import java.io.InputStream; import java.io.UnsupportedEncodingException; import java.util.ArrayList; import java.util.List; import java.util.logging.Level; import java.util.logging.Logger; /** * @author Joe LaPenna (joe@joelapenna.com) */ abstract public class AbstractHttpApi implements HttpApi { protected static final Logger LOG = Logger.getLogger(AbstractHttpApi.class.getCanonicalName()); protected static final boolean DEBUG = CogSurver.DEBUG; private static final String DEFAULT_CLIENT_VERSION = "org.cogsurv.droid.v1"; private static final String CLIENT_VERSION_HEADER = "User-Agent"; private static final int TIMEOUT = 10; private final DefaultHttpClient mHttpClient; private final String mClientVersion; public AbstractHttpApi(DefaultHttpClient httpClient, String clientVersion) { mHttpClient = httpClient; if (clientVersion != null) { mClientVersion = clientVersion; } else { mClientVersion = DEFAULT_CLIENT_VERSION; } } public CogSurvType executeHttpRequest(HttpRequestBase httpRequest, Parser<? extends CogSurvType> parser) throws CogSurvCredentialsException, CogSurvParseException, CogSurvException, IOException { if (DEBUG) LOG.log(Level.FINE, "doHttpRequest: " + httpRequest.getURI()); HttpResponse response = executeHttpRequest(httpRequest); if (DEBUG) LOG.log(Level.FINE, "executed HttpRequest for: " + httpRequest.getURI().toString()); int statusCode = response.getStatusLine().getStatusCode(); switch (statusCode) { case 200: InputStream is = response.getEntity().getContent(); try { return parser.parse(AbstractParser.createXmlPullParser(is)); } finally { is.close(); } case 201: is = response.getEntity().getContent(); try { return parser.parse(AbstractParser.createXmlPullParser(is)); } finally { is.close(); } case 401: response.getEntity().consumeContent(); if (DEBUG) LOG.log(Level.FINE, "HTTP Code: 401"); throw new CogSurvCredentialsException(response.getStatusLine().toString()); case 404: response.getEntity().consumeContent(); throw new CogSurvException(response.getStatusLine().toString()); case 500: response.getEntity().consumeContent(); if (DEBUG) LOG.log(Level.FINE, "HTTP Code: 500"); throw new CogSurvException("Foursquare is down. Try again later."); default: if (DEBUG) LOG.log(Level.FINE, "Default case for status code reached: " + response.getStatusLine().toString()); response.getEntity().consumeContent(); throw new CogSurvException("Error connecting to Foursquare: " + statusCode + ". Try again later."); } } public String doHttpPost(String url, NameValuePair... nameValuePairs) throws CogSurvCredentialsException, CogSurvParseException, CogSurvException, IOException { if (DEBUG) LOG.log(Level.FINE, "doHttpPost: " + url); HttpPost httpPost = createHttpPost(url, nameValuePairs); HttpResponse response = executeHttpRequest(httpPost); if (DEBUG) LOG.log(Level.FINE, "executed HttpRequest for: " + httpPost.getURI().toString()); switch (response.getStatusLine().getStatusCode()) { case 200: try { return EntityUtils.toString(response.getEntity()); } catch (ParseException e) { throw new CogSurvParseException(e.getMessage()); } case 401: response.getEntity().consumeContent(); throw new CogSurvCredentialsException(response.getStatusLine().toString()); case 404: response.getEntity().consumeContent(); throw new CogSurvException(response.getStatusLine().toString()); default: response.getEntity().consumeContent(); throw new CogSurvException(response.getStatusLine().toString()); } } /** * execute() an httpRequest catching exceptions and returning null instead. * * @param httpRequest * @return * @throws IOException */ public HttpResponse executeHttpRequest(HttpRequestBase httpRequest) throws IOException { if (DEBUG) LOG.log(Level.FINE, "executing HttpRequest for: " + httpRequest.getURI().toString()); try { mHttpClient.getConnectionManager().closeExpiredConnections(); return mHttpClient.execute(httpRequest); } catch (IOException e) { httpRequest.abort(); throw e; } } public HttpGet createHttpGet(String url, NameValuePair... nameValuePairs) { if (DEBUG) LOG.log(Level.FINE, "creating HttpGet for: " + url); String query = URLEncodedUtils.format(stripNulls(nameValuePairs), HTTP.UTF_8); HttpGet httpGet = new HttpGet(url + "?" + query); httpGet.addHeader(CLIENT_VERSION_HEADER, mClientVersion); if (DEBUG) LOG.log(Level.FINE, "Created: " + httpGet.getURI()); return httpGet; } public HttpPost createHttpPost(String url, NameValuePair... nameValuePairs) { if (DEBUG) LOG.log(Level.FINE, "creating HttpPost for: " + url); HttpPost httpPost = new HttpPost(url); httpPost.addHeader(CLIENT_VERSION_HEADER, mClientVersion); try { httpPost.setEntity(new UrlEncodedFormEntity(stripNulls(nameValuePairs), HTTP.UTF_8)); } catch (UnsupportedEncodingException e1) { throw new IllegalArgumentException("Unable to encode http parameters."); } if (DEBUG) LOG.log(Level.FINE, "Created: " + httpPost); return httpPost; } private List<NameValuePair> stripNulls(NameValuePair... nameValuePairs) { List<NameValuePair> params = new ArrayList<NameValuePair>(); for (int i = 0; i < nameValuePairs.length; i++) { NameValuePair param = nameValuePairs[i]; if (param.getValue() != null) { if (DEBUG) LOG.log(Level.FINE, "Param: " + param); params.add(param); } } return params; } /** * Create a thread-safe client. This client does not do redirecting, to allow us to capture * correct "error" codes. * * @return HttpClient */ public static final DefaultHttpClient createHttpClient() { // Sets up the http part of the service. final SchemeRegistry supportedSchemes = new SchemeRegistry(); // Register the "http" protocol scheme, it is required // by the default operator to look up socket factories. final SocketFactory sf = PlainSocketFactory.getSocketFactory(); supportedSchemes.register(new Scheme("http", sf, 80)); supportedSchemes.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 443)); // Set some client http client parameter defaults. final HttpParams httpParams = createHttpParams(); HttpClientParams.setRedirecting(httpParams, false); final ClientConnectionManager ccm = new ThreadSafeClientConnManager(httpParams, supportedSchemes); return new DefaultHttpClient(ccm, httpParams); } /** * Create the default HTTP protocol parameters. */ private static final HttpParams createHttpParams() { final HttpParams params = new BasicHttpParams(); // Turn off stale checking. Our connections break all the time anyway, // and it's not worth it to pay the penalty of checking every time. HttpConnectionParams.setStaleCheckingEnabled(params, false); HttpConnectionParams.setConnectionTimeout(params, TIMEOUT * 1000); HttpConnectionParams.setSoTimeout(params, TIMEOUT * 1000); HttpConnectionParams.setSocketBufferSize(params, 8192); return params; } }