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JspServlet.javaAPI DocApache Tomcat 6.0.1412336Fri Jul 20 04:20:32 BST 2007org.apache.jasper.servlet

JspServlet

public class JspServlet extends HttpServlet implements org.apache.PeriodicEventListener
The JSP engine (a.k.a Jasper). The servlet container is responsible for providing a URLClassLoader for the web application context Jasper is being used in. Jasper will try get the Tomcat ServletContext attribute for its ServletContext class loader, if that fails, it uses the parent class loader. In either case, it must be a URLClassLoader.
author
Anil K. Vijendran
author
Harish Prabandham
author
Remy Maucherat
author
Kin-man Chung
author
Glenn Nielsen

Fields Summary
private org.apache.juli.logging.Log
log
private ServletContext
context
private ServletConfig
config
private org.apache.jasper.Options
options
private org.apache.jasper.compiler.JspRuntimeContext
rctxt
Constructors Summary
Methods Summary
public voiddestroy()

        if (log.isDebugEnabled()) {
            log.debug("JspServlet.destroy()");
        }

        rctxt.destroy();
public intgetJspCount()
Returns the number of JSPs for which JspServletWrappers exist, i.e., the number of JSPs that have been loaded into the webapp with which this JspServlet is associated.

This info may be used for monitoring purposes.

return
The number of JSPs that have been loaded into the webapp with which this JspServlet is associated

        return this.rctxt.getJspCount();
public intgetJspReloadCount()
Gets the number of JSPs that have been reloaded.

This info may be used for monitoring purposes.

return
The number of JSPs (in the webapp with which this JspServlet is associated) that have been reloaded

        return this.rctxt.getJspReloadCount();
public voidinit(javax.servlet.ServletConfig config)



    /*
     * Initializes this JspServlet.
     */
          
        
        super.init(config);
        this.config = config;
        this.context = config.getServletContext();
        
        // Initialize the JSP Runtime Context
        // Check for a custom Options implementation
        String engineOptionsName = 
            config.getInitParameter("engineOptionsClass");
        if (engineOptionsName != null) {
            // Instantiate the indicated Options implementation
            try {
                ClassLoader loader = Thread.currentThread()
                        .getContextClassLoader();
                Class engineOptionsClass = loader.loadClass(engineOptionsName);
                Class[] ctorSig = { ServletConfig.class, ServletContext.class };
                Constructor ctor = engineOptionsClass.getConstructor(ctorSig);
                Object[] args = { config, context };
                options = (Options) ctor.newInstance(args);
            } catch (Throwable e) {
                // Need to localize this.
                log.warn("Failed to load engineOptionsClass", e);
                // Use the default Options implementation
                options = new EmbeddedServletOptions(config, context);
            }
        } else {
            // Use the default Options implementation
            options = new EmbeddedServletOptions(config, context);
        }
        rctxt = new JspRuntimeContext(context, options);
        
        if (log.isDebugEnabled()) {
            log.debug(Localizer.getMessage("jsp.message.scratch.dir.is",
                    options.getScratchDir().toString()));
            log.debug(Localizer.getMessage("jsp.message.dont.modify.servlets"));
        }
public voidperiodicEvent()

        rctxt.checkCompile();
booleanpreCompile(javax.servlet.http.HttpServletRequest request)

Look for a precompilation request as described in Section 8.4.2 of the JSP 1.2 Specification. WARNING - we cannot use request.getParameter() for this, because that will trigger parsing all of the request parameters, and not give a servlet the opportunity to call request.setCharacterEncoding() first.

param
request The servlet requset we are processing
exception
ServletException if an invalid parameter value for the jsp_precompile parameter name is specified


        String queryString = request.getQueryString();
        if (queryString == null) {
            return (false);
        }
        int start = queryString.indexOf(Constants.PRECOMPILE);
        if (start < 0) {
            return (false);
        }
        queryString =
            queryString.substring(start + Constants.PRECOMPILE.length());
        if (queryString.length() == 0) {
            return (true);             // ?jsp_precompile
        }
        if (queryString.startsWith("&")) {
            return (true);             // ?jsp_precompile&foo=bar...
        }
        if (!queryString.startsWith("=")) {
            return (false);            // part of some other name or value
        }
        int limit = queryString.length();
        int ampersand = queryString.indexOf("&");
        if (ampersand > 0) {
            limit = ampersand;
        }
        String value = queryString.substring(1, limit);
        if (value.equals("true")) {
            return (true);             // ?jsp_precompile=true
        } else if (value.equals("false")) {
	    // Spec says if jsp_precompile=false, the request should not
	    // be delivered to the JSP page; the easiest way to implement
	    // this is to set the flag to true, and precompile the page anyway.
	    // This still conforms to the spec, since it says the
	    // precompilation request can be ignored.
            return (true);             // ?jsp_precompile=false
        } else {
            throw new ServletException("Cannot have request parameter " +
                                       Constants.PRECOMPILE + " set to " +
                                       value);
        }
public voidservice(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)


        String jspUri = null;

        String jspFile = (String) request.getAttribute(Constants.JSP_FILE);
        if (jspFile != null) {
            // JSP is specified via <jsp-file> in <servlet> declaration
            jspUri = jspFile;
        } else {
            /*
             * Check to see if the requested JSP has been the target of a
             * RequestDispatcher.include()
             */
            jspUri = (String) request.getAttribute(Constants.INC_SERVLET_PATH);
            if (jspUri != null) {
                /*
		 * Requested JSP has been target of
                 * RequestDispatcher.include(). Its path is assembled from the
                 * relevant javax.servlet.include.* request attributes
                 */
                String pathInfo = (String) request.getAttribute(
                                    "javax.servlet.include.path_info");
                if (pathInfo != null) {
                    jspUri += pathInfo;
                }
            } else {
                /*
                 * Requested JSP has not been the target of a 
                 * RequestDispatcher.include(). Reconstruct its path from the
                 * request's getServletPath() and getPathInfo()
                 */
                jspUri = request.getServletPath();
                String pathInfo = request.getPathInfo();
                if (pathInfo != null) {
                    jspUri += pathInfo;
                }
            }
        }

        if (log.isDebugEnabled()) {	    
            log.debug("JspEngine --> " + jspUri);
            log.debug("\t     ServletPath: " + request.getServletPath());
            log.debug("\t        PathInfo: " + request.getPathInfo());
            log.debug("\t        RealPath: " + context.getRealPath(jspUri));
            log.debug("\t      RequestURI: " + request.getRequestURI());
            log.debug("\t     QueryString: " + request.getQueryString());
            log.debug("\t  Request Params: ");
            Enumeration e = request.getParameterNames();
            while (e.hasMoreElements()) {
                String name = (String) e.nextElement();
                log.debug("\t\t " + name + " = " 
                          + request.getParameter(name));
            }
        }

        try {
            boolean precompile = preCompile(request);
            serviceJspFile(request, response, jspUri, null, precompile);
        } catch (RuntimeException e) {
            throw e;
        } catch (ServletException e) {
            throw e;
        } catch (IOException e) {
            throw e;
        } catch (Throwable e) {
            throw new ServletException(e);
        }
private voidserviceJspFile(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, java.lang.String jspUri, java.lang.Throwable exception, boolean precompile)


        JspServletWrapper wrapper =
            (JspServletWrapper) rctxt.getWrapper(jspUri);
        if (wrapper == null) {
            synchronized(this) {
                wrapper = (JspServletWrapper) rctxt.getWrapper(jspUri);
                if (wrapper == null) {
                    // Check if the requested JSP page exists, to avoid
                    // creating unnecessary directories and files.
                    if (null == context.getResource(jspUri)) {
                        response.sendError(HttpServletResponse.SC_NOT_FOUND,
                                           request.getRequestURI());
                        return;
                    }
                    boolean isErrorPage = exception != null;
                    wrapper = new JspServletWrapper(config, options, jspUri,
                                                    isErrorPage, rctxt);
                    rctxt.addWrapper(jspUri,wrapper);
                }
            }
        }

        wrapper.service(request, response, precompile);
public voidsetJspReloadCount(int count)
Resets the JSP reload counter.

param
count Value to which to reset the JSP reload counter

        this.rctxt.setJspReloadCount(count);