generator.java

业界著名的tomcat服务器的最新6.0的源代码。

            } else {
                pageParam = attributeValue(page, false, String.class);
            }

            // If any of the params have their values specified by
            // jsp:attribute, prepare those values first.
            Node jspBody = findJspBody(n);
            if (jspBody != null) {
                prepareParams(jspBody);
            } else {
                prepareParams(n);
            }

            out.printin("_jspx_page_context.forward(");
            out.print(pageParam);
            printParams(n, pageParam, page.isLiteral());
            out.println(");");
            if (isTagFile || isFragment) {
                out.printil("throw new SkipPageException();");
            } else {
                out.printil((methodNesting > 0) ? "return true;" : "return;");
            }
            out.popIndent();
            out.printil("}");

            n.setEndJavaLine(out.getJavaLine());
            // XXX Not sure if we can eliminate dead codes after this.
        }

        public void visit(Node.GetProperty n) throws JasperException {
            String name = n.getTextAttribute("name");
            String property = n.getTextAttribute("property");

            n.setBeginJavaLine(out.getJavaLine());

            if (beanInfo.checkVariable(name)) {
                // Bean is defined using useBean, introspect at compile time
                Class bean = beanInfo.getBeanType(name);
                String beanName = JspUtil.getCanonicalName(bean);
                java.lang.reflect.Method meth = JspRuntimeLibrary
                        .getReadMethod(bean, property);
                String methodName = meth.getName();
                out
                        .printil("out.write(org.apache.jasper.runtime.JspRuntimeLibrary.toString("
                                + "((("
                                + beanName
                                + ")_jspx_page_context.findAttribute("
                                + "\""
                                + name + "\"))." + methodName + "())));");
            } else {
                // The object could be a custom action with an associated
                // VariableInfo entry for this name.
                // Get the class name and then introspect at runtime.
                out
                        .printil("out.write(org.apache.jasper.runtime.JspRuntimeLibrary.toString"
                                + "(org.apache.jasper.runtime.JspRuntimeLibrary.handleGetProperty"
                                + "(_jspx_page_context.getAttribute(\""
                                + name
                                + "\", PageContext.PAGE_SCOPE), \""
                                + property
                                + "\")));");
            }

            n.setEndJavaLine(out.getJavaLine());
        }

        public void visit(Node.SetProperty n) throws JasperException {
            String name = n.getTextAttribute("name");
            String property = n.getTextAttribute("property");
            String param = n.getTextAttribute("param");
            Node.JspAttribute value = n.getValue();

            n.setBeginJavaLine(out.getJavaLine());

            if ("*".equals(property)) {
                out
                        .printil("org.apache.jasper.runtime.JspRuntimeLibrary.introspect("
                                + "_jspx_page_context.findAttribute("
                                + "\""
                                + name + "\"), request);");
            } else if (value == null) {
                if (param == null)
                    param = property; // default to same as property
                out
                        .printil("org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper("
                                + "_jspx_page_context.findAttribute(\""
                                + name
                                + "\"), \""
                                + property
                                + "\", request.getParameter(\""
                                + param
                                + "\"), "
                                + "request, \""
                                + param
                                + "\", false);");
            } else if (value.isExpression()) {
                out
                        .printil("org.apache.jasper.runtime.JspRuntimeLibrary.handleSetProperty("
                                + "_jspx_page_context.findAttribute(\""
                                + name
                                + "\"), \"" + property + "\",");
                out.print(attributeValue(value, false, null));
                out.println(");");
            } else if (value.isELInterpreterInput()) {
                // We've got to resolve the very call to the interpreter
                // at runtime since we don't know what type to expect
                // in the general case; we thus can't hard-wire the call
                // into the generated code. (XXX We could, however,
                // optimize the case where the bean is exposed with
                // <jsp:useBean>, much as the code here does for
                // getProperty.)

                // The following holds true for the arguments passed to
                // JspRuntimeLibrary.handleSetPropertyExpression():
                // - 'pageContext' is a VariableResolver.
                // - 'this' (either the generated Servlet or the generated tag
                // handler for Tag files) is a FunctionMapper.
                out
                        .printil("org.apache.jasper.runtime.JspRuntimeLibrary.handleSetPropertyExpression("
                                + "_jspx_page_context.findAttribute(\""
                                + name
                                + "\"), \""
                                + property
                                + "\", "
                                + quote(value.getValue())
                                + ", "
                                + "_jspx_page_context, "
                                + value.getEL().getMapName() + ");");
            } else if (value.isNamedAttribute()) {
                // If the value for setProperty was specified via
                // jsp:attribute, first generate code to evaluate
                // that body.
                String valueVarName = generateNamedAttributeValue(value
                        .getNamedAttributeNode());
                out
                        .printil("org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper("
                                + "_jspx_page_context.findAttribute(\""
                                + name
                                + "\"), \""
                                + property
                                + "\", "
                                + valueVarName
                                + ", null, null, false);");
            } else {
                out
                        .printin("org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper("
                                + "_jspx_page_context.findAttribute(\""
                                + name
                                + "\"), \"" + property + "\", ");
                out.print(attributeValue(value, false, null));
                out.println(", null, null, false);");
            }

            n.setEndJavaLine(out.getJavaLine());
        }

        public void visit(Node.UseBean n) throws JasperException {

            String name = n.getTextAttribute("id");
            String scope = n.getTextAttribute("scope");
            String klass = n.getTextAttribute("class");
            String type = n.getTextAttribute("type");
            Node.JspAttribute beanName = n.getBeanName();

            // If "class" is specified, try an instantiation at compile time
            boolean generateNew = false;
            String canonicalName = null; // Canonical name for klass
            if (klass != null) {
                try {
                    Class bean = ctxt.getClassLoader().loadClass(klass);
                    if (klass.indexOf('$') >= 0) {
                        // Obtain the canonical type name
                        canonicalName = JspUtil.getCanonicalName(bean);
                    } else {
                        canonicalName = klass;
                    }
                    int modifiers = bean.getModifiers();
                    if (!Modifier.isPublic(modifiers)
                            || Modifier.isInterface(modifiers)
                            || Modifier.isAbstract(modifiers)) {
                        throw new Exception("Invalid bean class modifier");
                    }
                    // Check that there is a 0 arg constructor
                    bean.getConstructor(new Class[] {});
                    // At compile time, we have determined that the bean class
                    // exists, with a public zero constructor, new() can be
                    // used for bean instantiation.
                    generateNew = true;
                } catch (Exception e) {
                    // Cannot instantiate the specified class, either a
                    // compilation error or a runtime error will be raised,
                    // depending on a compiler flag.
                    if (ctxt.getOptions()
                            .getErrorOnUseBeanInvalidClassAttribute()) {
                        err.jspError(n, "jsp.error.invalid.bean", klass);
                    }
                    if (canonicalName == null) {
                        // Doing our best here to get a canonical name
                        // from the binary name, should work 99.99% of time.
                        canonicalName = klass.replace('$', '.');
                    }
                }
                if (type == null) {
                    // if type is unspecified, use "class" as type of bean
                    type = canonicalName;
                }
            }

            String scopename = "PageContext.PAGE_SCOPE"; // Default to page
            String lock = "_jspx_page_context";

            if ("request".equals(scope)) {
                scopename = "PageContext.REQUEST_SCOPE";
                lock = "request";
            } else if ("session".equals(scope)) {
                scopename = "PageContext.SESSION_SCOPE";
                lock = "session";
            } else if ("application".equals(scope)) {
                scopename = "PageContext.APPLICATION_SCOPE";
                lock = "application";
            }

            n.setBeginJavaLine(out.getJavaLine());

            // Declare bean
            out.printin(type);
            out.print(' ');
            out.print(name);
            out.println(" = null;");

            // Lock while getting or creating bean
            out.printin("synchronized (");
            out.print(lock);
            out.println(") {");
            out.pushIndent();

            // Locate bean from context
            out.printin(name);
            out.print(" = (");
            out.print(type);
            out.print(") _jspx_page_context.getAttribute(");
            out.print(quote(name));
            out.print(", ");
            out.print(scopename);
            out.println(");");

            // Create bean
            /*
             * Check if bean is alredy there
             */
            out.printin("if (");
            out.print(name);
            out.println(" == null){");
            out.pushIndent();
            if (klass == null && beanName == null) {
                /*
                 * If both class name and beanName is not specified, the bean
                 * must be found locally, otherwise it's an error
                 */
                out
                        .printin("throw new java.lang.InstantiationException(\"bean ");
                out.print(name);
                out.println(" not found within scope\");");
            } else {
                /*
                 * Instantiate the bean if it is not in the specified scope.
                 */
                if (!generateNew) {
                    String binaryName;
                    if (beanName != null) {
                        if (beanName.isNamedAttribute()) {
                            // If the value for beanName was specified via
                            // jsp:attribute, first generate code to evaluate
                            // that body.
                            binaryName = generateNamedAttributeValue(beanName
                                    .getNamedAttributeNode());
                        } else {
                            binaryName = attributeValue(beanName, false,
                                    String.class);
                        }
                    } else {
                        // Implies klass is not null
                        binaryName = quote(klass);
                    }
                    out.printil("try {");
                    out.pushIndent();
                    out.printin(name);
                    out.print(" = (");
                    out.print(type);
                    out.print(") java.beans.Beans.instantiate(");
                    out.print("this.getClass().getClassLoader(), ");
                    out.print(binaryName);
                    out.println(");");
                    out.popIndent();
                    /*
                     * Note: Beans.instantiate throws ClassNotFoundException if
                     * the bean class is abstract.
                     */
                    out.printil("} catch (ClassNotFoundException exc) {");
                    out.pushIndent();
                    out
                            .printil("throw new InstantiationException(exc.getMessage());");
                    out.popIndent();
                    out.printil("} catch (Exception exc) {");
                    out.pushIndent();
                    out.printin("throw new ServletException(");
                    out.print("\"Cannot create bean of class \" + ");
                    out.print(binaryName);
                    out.println(", exc);");
                    out.popIndent();
                    out.printil("}"); // close of try
                } else {
                    // Implies klass is not null
                    // Generate codes to instantiate the bean class
                    out.printin(name);
                    out.print(" = new ");
                    out.print(canonicalName);
                    out.println("();");
                }
                /*
                 * Set attribute for bean in the specified scope
                 */
                out.printin("_jspx_page_context.setAttribute(");
                out.print(quote(name));
                out.print(", ");
                out.print(name);
                out.print(", ");
                out.print(scopename);
                out.println(");");

                // Only visit the body when bean is instantiated
                visitBody(n);
            }
            out.popIndent();
            out.printil("}");