Examples of javax.servlet.jsp.PageContext

javax.servlet.jsp.PageContext
A PageContext instance provides access to all the namespaces associated with a JSP page, provides access to several page attributes, as well as a layer above the implementation details. Implicit objects are added the pageContext automatically.
The PageContext class is an abstract class, designed to be extended to provide implementation dependent implementations thereof, by conformant JSP engine runtime environments. A PageContext instance is obtained by a JSP implementation class by calling the JspFactory.getPageContext() method, and is released by calling JspFactory.releasePageContext().
An example of how PageContext, JspFactory, and other classes can be used within a JSP Page Implementation object is given elsewhere.
The PageContext provides a number of facilities to the page/component author and page implementor, including:
- a single API to manage the various scoped namespaces
- a number of convenience API's to access various public objects
- a mechanism to obtain the JspWriter for output
- a mechanism to manage session usage by the page
- a mechanism to expose page directive attributes to the scripting environment
- mechanisms to forward or include the current request to other active components in the application
- a mechanism to handle errorpage exception processing
Methods Intended for Container Generated Code
Some methods are intended to be used by the code generated by the container, not by code written by JSP page authors, or JSP tag library authors.
The methods supporting lifecycle are initialize() and release()
The following methods enable the management of nested JspWriter streams to implement Tag Extensions: pushBody() and popBody()
Methods Intended for JSP authors
Some methods provide uniform access to the diverse objects representing scopes. The implementation must use the underlying Servlet machinery corresponding to that scope, so information can be passed back and forth between Servlets and JSP pages. The methods are: setAttribute(), getAttribute(), findAttribute(), removeAttribute(), getAttributesScope() and getAttributeNamesInScope() .
The following methods provide convenient access to implicit objects:

    }


    protected void doRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


        // save the old PageContext
        PageContext oldPageContext = ServletActionContext.getPageContext();


        // create a new PageContext
        JspFactory jspFactory = JspFactory.getDefaultFactory();


        PageContext pageContext = jspFactory.getPageContext(this, request, response, null, true, 8192, true);


        // put the new PageContext into ActionContext
        ActionContext actionContext = ActionContext.getContext();


        actionContext.put(ServletActionContext.PAGE_CONTEXT, pageContext);


        /*
         * Must put the stack into HttpServletRequest, because the WebWork JSP
         * Taglib will use it to judge whether there are some errors in stack.
         */
        OgnlValueStack stack = ActionContext.getContext().getValueStack();


        //request.setAttribute(ServletActionContext.WEBWORK_VALUESTACK_KEY,
        // stack);
        //Moved to WebWorkPortlet doService()


        VelocityManager velocityManager = VelocityManager.getInstance();
        Context resultContext = velocityManager.createContext(stack, request, response);


        response.setContentType("text/html");


        try {
            String location = (String) ActionContext.getContext().get("template");
            Template template = velocityManager.getVelocityEngine().getTemplate(location);


            Writer writer = pageContext.getOut();
            template.merge(resultContext, writer);
            writer.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {

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    JspFactory factory = JspFactory.getDefaultFactory();
    String errorPageURL = null;
    int bufferSize = (JspWriter.DEFAULT_BUFFER <= 0) ? 1024 : JspWriter.DEFAULT_BUFFER;
    boolean needsSession = false;
    boolean autoFlush = true;
    PageContext pageContext = null;
    try {
      req.setCharacterEncoding("UTF-8");
      pageContext = factory.getPageContext(this, req, resp,
        errorPageURL, needsSession, bufferSize, autoFlush);
    
      // Create a shared wrapper
      PageRequest request = new JspPageRequest(pageContext);
      PageResponse response = new JspPageResponse(pageContext);


      // Extract the file name
      String encoding = "utf-8"; // We use utf-8 in our JSPs
      String fileUrl = SearchToolkit.extractFileUrl(req.getRequestURI(), encoding);


      // Check the file
      try {
        if (SearchToolkit.allowFileAccess(request, fileUrl)) {
          // Access allowed -> Send the file
          SearchToolkit.sendFile(request, response, RegainToolkit.urlToFile(fileUrl));
        } else {
          // Access not allowed -> Send 403 Forbidden
          resp.sendError(403);
        }
      }
      catch (RegainException exc) {
        throw new ServletException("Checking file access failed: " + fileUrl, exc);
      }
    }
    catch (Exception exc) {
      pageContext.handlePageException(exc);
    } finally {
      factory.releasePageContext(pageContext);
    }
  }

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     * Returns a variable resolver that will resolve variables by searching through
     * the page scope, request scope, session scope and application scope for an
     * attribute with a matching name.
     */
    public VariableResolver getVariableResolver() {
        final PageContext ctx = this;


        return new VariableResolver() {
            public Object resolveVariable(String name) throws ELException {
                return ctx.findAttribute(name);
            }
        };
    }

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     * Returns a variable resolver that will resolve variables by searching through
     * the page scope, request scope, session scope and application scope for an
     * attribute with a matching name.
     */
    public VariableResolver getVariableResolver() {
        final PageContext ctx = this;


        return new VariableResolver() {
            public Object resolveVariable(String name) throws ELException {
                return ctx.findAttribute(name);
            }
        };
    }

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    /**
     * Creates the Map that "wraps" page-scoped attributes
     */
    public static Map createPageScopeMap(PageContext pContext)
    {
        final PageContext context = pContext;


        return new EnumeratedMap()
        {
            public Enumeration enumerateKeys()
            {
                return context.getAttributeNamesInScope
                        (PageContext.PAGE_SCOPE);
            }


            public Object getValue(Object pKey)
            {
                if (pKey instanceof String) {
                    return context.getAttribute
                            ((String) pKey,
                                    PageContext.PAGE_SCOPE);
                } else {
                    return null;
                }

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    /**
     * Creates the Map that "wraps" request-scoped attributes
     */
    public static Map createRequestScopeMap(PageContext pContext)
    {
        final PageContext context = pContext;


        return new EnumeratedMap()
        {
            public Enumeration enumerateKeys()
            {
                return context.getAttributeNamesInScope
                        (PageContext.REQUEST_SCOPE);
            }


            public Object getValue(Object pKey)
            {
                if (pKey instanceof String) {
                    return context.getAttribute
                            ((String) pKey,
                                    PageContext.REQUEST_SCOPE);
                } else {
                    return null;
                }

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    /**
     * Creates the Map that "wraps" session-scoped attributes
     */
    public static Map createSessionScopeMap(PageContext pContext)
    {
        final PageContext context = pContext;


        return new EnumeratedMap()
        {
            public Enumeration enumerateKeys()
            {
                return context.getAttributeNamesInScope
                        (PageContext.SESSION_SCOPE);
            }


            public Object getValue(Object pKey)
            {
                if (pKey instanceof String) {
                    return context.getAttribute
                            ((String) pKey,
                                    PageContext.SESSION_SCOPE);
                } else {
                    return null;
                }

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    /**
     * Creates the Map that "wraps" application-scoped attributes
     */
    public static Map createApplicationScopeMap(PageContext pContext)
    {
        final PageContext context = pContext;


        return new EnumeratedMap()
        {
            public Enumeration enumerateKeys()
            {
                return context.getAttributeNamesInScope
                        (PageContext.APPLICATION_SCOPE);
            }


            public Object getValue(Object pKey)
            {
                if (pKey instanceof String) {
                    return context.getAttribute
                            ((String) pKey,
                                    PageContext.APPLICATION_SCOPE);
                } else {
                    return null;
                }

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     * Returns null if the variable is not found.
     */
    public Object resolveVariable(String pName,
                                  Object pContext)
            throws ELException {
        PageContext ctx = (PageContext) pContext;


        // Check for implicit objects
        if ("pageContext".equals(pName)) {
            return ctx;
        } else if ("pageScope".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getPageScopeMap();
        } else if ("requestScope".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getRequestScopeMap();
        } else if ("sessionScope".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getSessionScopeMap();
        } else if ("applicationScope".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getApplicationScopeMap();
        } else if ("param".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getParamMap();
        } else if ("paramValues".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getParamsMap();
        } else if ("header".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getHeaderMap();
        } else if ("headerValues".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getHeadersMap();
        } else if ("initParam".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getInitParamMap();
        } else if ("cookie".equals(pName)) {
            return ImplicitObjects.
                    getImplicitObjects(ctx).
                    getCookieMap();
        }


        // Otherwise, just look it up in the page context
        else {
            return ctx.findAttribute(pName);
        }
    }

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  // Logger
  private static Logger logger = LoggerFactory.getLogger(JstlMessageResolver.class);


  public String getResource(String messageKey, String defaultValue, Object... params) {


    PageContext pageContext = (PageContext) params[0];
    String message = null;
    ResourceBundle bundle = null;


    LocalizationContext localizationContext = BundleSupport.getLocalizationContext(pageContext);

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