wcshttpclientbase.java

esri的ArcGIS Server超级学习模板程序（for java）

/**
 * 
 */
package com.esri.solutions.jitk.datasources.ogc.wcs;

import java.io.IOException;
import java.net.MalformedURLException;
import java.util.Iterator;

import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;

import com.esri.solutions.jitk.datasources.exceptions.ParserNotFoundException;
import com.esri.solutions.jitk.datasources.exceptions.ResponseParsingException;
import com.esri.solutions.jitk.datasources.exceptions.WCSException;
import com.esri.solutions.jitk.datasources.ogc.wcs.info.WCSCapabilities;
import com.esri.solutions.jitk.datasources.ogc.wcs.parsing.IWCSCapabilitiesParser;
import com.esri.solutions.jitk.datasources.ogc.wcs.parsing.WCSCapabilitiesParserFactory;

/**
 * @author vlad2928
 *
 */
public class WCSHTTPClientBase {
	
	protected static Logger logger = LogManager.getLogger(WCSHTTPClientBase.class.getName());
	
	protected GetMethod method;
	protected String version;
	
	public String getVersion() {
		return this.version;
	}
	
	protected void doGET(IURL url) throws HttpException, IOException {
		
		// Release previously opened connection if any 
		releaseConnection();
		
		// Create an instance of HttpClient.
		HttpClient client = new HttpClient();

	    // Create a method instance.
		method = new GetMethod(url.toString());
	    
	    // Provide custom retry handler is necessary
	    method.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(3, false));

	    // Execute the method.
	    if(client.executeMethod(method) != HttpStatus.SC_OK) {
	    	logger.error("HTTP request failed for '" + url + "': " + method.getStatusLine());
	    	throw new HttpException("HTTP request failed for '" + url + "': " + method.getStatusLine());
	    }
	}
	
	protected boolean isConnectionOpen() {
		return (method != null);
	}
	
	protected String getResponseContentType() {
		if(isConnectionOpen()) {
			return method.getResponseHeader("Content-Type").getValue();
		}
		return "";
	}
	
	protected void releaseConnection() {
		if(isConnectionOpen()) {
			method.releaseConnection();
		}
	}
	
	public WCSCapabilities getCapabilities(String getCapabilitiesURL) throws WCSException {

		WCSCapabilities wcsCapabilities = null;
		String version = "";
			
		try {
			IURL url = new URLBuilder(getCapabilitiesURL);
			if(url.isValid()) {
				url.setParam("request", "GetCapabilities");
				url.setParam("service", "WCS");
				
				for(Iterator<String> i = WCSCapabilitiesParserFactory.getSupportedVersions().iterator(); i.hasNext();) {
					version = i.next();
					
					if(WCSClientFactory.isSupportedVersion(version)) {
						IWCSCapabilitiesParser parser = WCSCapabilitiesParserFactory.getInstance(version);
						url.setParam("version", version);
						
						try {
							doGET(url);
							if(isConnectionOpen()) {
								wcsCapabilities = parser.parse(method.getResponseBodyAsStream());
							}
						
						} catch(ResponseParsingException e) {
						
						} finally {
							releaseConnection();
						}
					
						if(wcsCapabilities != null) {
							break;
						}
					}
				}
				
			} else {
				throw new MalformedURLException(url.getErrorMessage());
			}
		
		} catch(MalformedURLException e) {
			logger.error("Malformed url " + getCapabilitiesURL + " provided.");
			logger.error(e.getMessage());
			throw new WCSException("Malformed url " + getCapabilitiesURL + " provided.");
			
		} catch(ParserNotFoundException e) {
			logger.error("GetCapabilities parser ver. " + version + " not found.");
			logger.error(e.getMessage());
			throw new WCSException("GetCapabilities parser ver. " + version + " not found.");
			
		} catch(HttpException e) {
			logger.error("Fatal protocol violation: " + e.getMessage());
			throw new WCSException("Fatal protocol violation.");
		    
		} catch(IOException e) {
			logger.error("Fatal transport error: " + e.getMessage());
			throw new WCSException("Fatal transport error.");
		}
		
		return wcsCapabilities;
	}
}