webmappreviewservlet.java

esri的ArcGIS Server超级学习模板程序（for java）

package com.esri.solutions.jitk.web.tasks.mapcomp;

import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.esri.adf.web.data.MapFunctionality;
import com.esri.adf.web.data.WebContext;
import com.esri.adf.web.data.WebMap;
import com.esri.adf.web.data.WebSession;
import com.esri.adf.web.data.geometry.WebExtent;
import com.esri.solutions.jitk.common.export.image.WebMapImageExporter;

/**
 * Generates the Preview for a Map within a WebContext.  This servlet needs
 * to be configured with path-style URL mappings and not extension-style mappings.  This
 * servlet expects the URL to be configured like the following:
 * 
 * <code>http://host/Viewer/maps/current/<Web Context Name>.<format> where
 * 
 * <ul>
 * 	<li>Web Context Name is the name of the Web Context
 *  <li>format is the image encoding (jpg or png)
 * </ul>
 * 
 * In this example, this servlet would need to be mapped to /maps/current/* URL patterns.
 * 
 * <p>
 * This servlet also accepts the following optional parameters:
 * 
 * 	<ul>
 * 		<li>w: width
 * 		<li>h: height
 * 		<li>dpi: Dots Per Inch
 * 		<li>r: ID of GIS Resource to draw.
 * 	</ul>
 * </p>
 * 
 * <p>
 * This servlet will send a 404 (Not Found) response if any of the conditions are met:
 * 	<ul>
 * 		<li>{@link HttpServletRequest#getPathInfo()} is null or zero-length
 *  	<li>Path Info syntax is invalid.
 *  	<li>No HTTP Session
 *  	<li>{@link WebSession} cannot be found within HTTP Session
 *  	<li>WebContext with specified name cannot be found within WebSession
 *  	<li>WebMap within WebContext is null.
 *  	<li>Any unexpected exceptions occur.
 * 	</ul>
 * </p>
 */
 public class WebMapPreviewServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
 
   	private static final int DEFAULT_HEIGHT = 120;
	private static final int DEFAULT_WIDTH = 180;
	private static final int DEFAULT_DPI = 96;

	private static final String VALIDATE_PATH_INFO_RE = "^\\/(\\w[\\w ]*)+\\.(jpg|JPG|png|PNG)$";
   	
	
	private static final long serialVersionUID = 7869517597385668875L;

	/* (non-Java-doc)
	 * @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		String pathInfo = request.getPathInfo();
		if (pathInfo == null || pathInfo.trim().length() == 0 || !pathInfo.toLowerCase().matches(VALIDATE_PATH_INFO_RE)) {
			response.sendError(HttpServletResponse.SC_NOT_FOUND);
			return;
		}
		
		String contentType = this.getServletContext().getMimeType(pathInfo);
		
		Pattern pattern = Pattern.compile(VALIDATE_PATH_INFO_RE);
		Matcher matcher = pattern.matcher(pathInfo);
		if (!matcher.matches()) {
			response.sendError(HttpServletResponse.SC_NOT_FOUND);
			return;
		}
		String webCtxName = matcher.group(1);
		String format = matcher.group(2);
		
		String dpiParam = request.getParameter("dpi");
		if (dpiParam == null) {
			dpiParam = getServletConfig().getInitParameter("dpi");
		}
		int dpi = DEFAULT_DPI;
		if (dpiParam != null) {
			try {
				dpi = Integer.parseInt(dpiParam);
			} catch (NumberFormatException e) {
				dpi = DEFAULT_DPI;
			}
		}
		
		String widthParam = request.getParameter("w");
		if (widthParam == null) {
			widthParam = getServletConfig().getInitParameter("width");
		}
		int width = DEFAULT_WIDTH;
		if (widthParam != null) {
			try {
				width = Integer.parseInt(widthParam);
			} catch (NumberFormatException e) {
				width = DEFAULT_WIDTH;
			}
		}
		
		String heightParam = request.getParameter("h");
		if (heightParam == null) {
			heightParam = getServletConfig().getInitParameter("height");
		}
		int height = DEFAULT_HEIGHT;
		if (heightParam != null) {
			try {
				height = Integer.parseInt(heightParam);
			} catch (NumberFormatException e) {
				height = DEFAULT_HEIGHT;
			}
		}
		
		String exportGraphicsParam = request.getParameter("exportGraphics");
		boolean exportGraphics = true;
		if (exportGraphicsParam == null) {
			exportGraphics = true;
		} else {
			exportGraphics = Boolean.valueOf(exportGraphicsParam).booleanValue();
		}
		
		if (request.getSession(false) == null) {
			response.sendError(HttpServletResponse.SC_NOT_FOUND);
			return;
		}
		
		WebSession webSession = (WebSession) request.getSession(false).getAttribute(WebSession.SESSION_ATTRIBUTE_NAME);
		
		if (webSession == null) {
			response.sendError(HttpServletResponse.SC_NOT_FOUND);
			return;
		}
		
		WebContext ctx = findWebContext(webSession, webCtxName);
		if (ctx == null) {
			response.sendError(HttpServletResponse.SC_NOT_FOUND);
			return;
		}
		
		WebMap webMap = ctx.getWebMap();
		if (webMap == null) {
			response.sendError(HttpServletResponse.SC_NOT_FOUND);
			return;
		}
		
		String resourcesParam = request.getParameter("r");
		List<String> resourceIDList = null;
		Map<MapFunctionality, Boolean> mapFuncStates = null;
		WebExtent extent = null;
		
		if (resourcesParam != null) {
			String[] resourceIDs = resourcesParam.split(",");
			resourceIDList = java.util.Arrays.asList(resourceIDs);
		}
		
		WebMapImageExporter exporter = new WebMapImageExporter();
		exporter.setDpi(dpi);
		exporter.setImageHeight(height);
		exporter.setImageWidth(width);
		exporter.setImageFormatAsString(format);
		exporter.setWebMap(webMap);
		exporter.setExportGraphicsResources(exportGraphics);
		
		if (extent != null) {
			exporter.setExtent(extent);
		} 
		if (resourceIDList != null) {
			exporter.setResourceIDFilter(resourceIDList);
		}
		response.setContentType(contentType);
		exporter.exportImage(response.getOutputStream());
		
		if (mapFuncStates == null) {
			return;
		}
		
		for (Entry<MapFunctionality, Boolean> entry : mapFuncStates.entrySet()) {
			entry.getKey().setDisabled(entry.getValue());
		}
		ctx.refresh();
	}
	
	/**
	 * Finds the WebContext in the WebSession with the specified Name.
	 *
	 * @param webSession		Contains a collection of WebContext objects.
	 * @param webCtxName		Name of WebContext to find.
	 */
	private WebContext findWebContext (WebSession webSession, String webCtxName) {
		List<WebContext> webContexts = webSession.getWebContexts();
		for (WebContext ctx : webContexts) {
			if (webCtxName.equals(ctx.getName())) {
				return ctx;
			}
		}
		return null;
	}
}