breadcrumbsinterceptor.java

一个很好的开源项目管理系统源代码

package net.java.workeffort.webapp.support;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Enumeration;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
import org.springframework.web.util.UrlPathHelper;

/**
 * Manages the bread crumbs of the user.
 * @author Antony Joseph
 */

public class BreadCrumbsInterceptor extends HandlerInterceptorAdapter {
    protected static final Log logger = LogFactory
            .getLog(BreadCrumbsInterceptor.class);

    public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {

        if (logger.isInfoEnabled())
            logger.info("preHandle() invoked");

        BreadCrumbs breadCrumbs = null;
        if (request.getParameter("fromMenu") != null) {
            // navigating from main menu. clear the bread crumbs
            breadCrumbs = (BreadCrumbs) request.getSession().getAttribute(
                    WebConstants.BREAD_CRUMBS);
            breadCrumbs.clear();
            // set session attribute for the case where the http session is
            // being replicated in a cluster
            request.getSession().setAttribute(WebConstants.BREAD_CRUMBS,
                    breadCrumbs);
        }

        String dispatch = request.getParameter("dispatch");

        if (logger.isInfoEnabled())
            logger.info("dispatch=" + dispatch);

        if (!hasParentFlow(request)
                && ("newSearch".equals(dispatch) || "query".equals(dispatch) || request
                        .getParameter("crumbsEnabled") != null)) {
            Crumb crumb = new Crumb(getKey(request, dispatch),
                    createUrlWithParameters(request, response));

            breadCrumbs = (BreadCrumbs) request.getSession().getAttribute(
                    WebConstants.BREAD_CRUMBS);
            breadCrumbs.put(crumb);
            // set session attribute for the case where the http session is
            // being replicated in a cluster
            request.getSession().setAttribute(WebConstants.BREAD_CRUMBS,
                    breadCrumbs);
        }
        return true;
    }

    /**
     * The crumb key. Example: mapping path '/requirmentSearch.do' and suffix is
     * 'newSearch' then the key is 'requirmentSearch.newSearch.crumb'
     * @param request The request
     * @param suffix The suffix
     * @return
     */
    private String getKey(HttpServletRequest request, String suffix) {
        UrlPathHelper helper = new UrlPathHelper();
        String mappingPath = helper.getLookupPathForRequest(request);
        if (suffix == null)
            return mappingPath.substring(1, mappingPath.indexOf("."))
                    + ".crumb";
        else
            return mappingPath.substring(1, mappingPath.indexOf(".")) + "."
                    + suffix + ".crumb";
    }

    /**
     * Creates the full url for the bread crumb using the request url and
     * parameters. The url is encoded.
     * @param request The request
     * @param response The response
     * @return The encoded full url
     */
    private String createUrlWithParameters(HttpServletRequest request,
            HttpServletResponse response) {
        StringBuffer sb = request.getRequestURL();

        boolean isFirst = true;
        Enumeration enum = request.getParameterNames();
        while (enum.hasMoreElements()) {
            String name = (String) enum.nextElement();
            String values[] = request.getParameterValues(name);
            String val = null;
            if (values != null) {
                for (int i = 0; i < values.length; i++) {
                    addParameter(sb, name, values[i], isFirst);
                    isFirst = false;
                }
            }
            else {
                addParameter(sb, name, null, isFirst);
            }
            isFirst = false;
        }
        return (response.encodeURL(sb.toString()));
    }

    /**
     * Adds the name/value pair to the url. The value is encoded.
     * @param sb String buffer
     * @param name The parameter name
     * @param value The value of the parameter
     * @param isFirst Whether the first parameter
     */
    private void addParameter(StringBuffer sb, String name, String value,
            boolean isFirst) {
        if (isFirst)
            sb.append("?");
        else
            sb.append("&");

        sb.append(name);
        if (value != null) {
            sb.append("=");
            try {
                value = URLEncoder.encode(value, "UTF-8");
            }
            catch (UnsupportedEncodingException e) {
                throw new RuntimeException(e);
            }
            sb.append(value);
        }
    }

    private boolean hasParentFlow(HttpServletRequest request) {
        if (request.getParameter("parentFlow") == null
                || request.getParameter("parentFlow").length() == 0)
            return false;
        else
            return true;
    }

}