implicitobjectelresolver.java

业界著名的tomcat服务器的最新6.0的源代码。

                                }
                            }
                        }
                        return null;
                    }

                };
            }
            return this.cookie;
        }

        public Map getHeader() {
            if (this.header == null) {
                this.header = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        return ((HttpServletRequest) page.getRequest())
                                .getHeaderNames();
                    }

                    protected Object getAttribute(String name) {
                        return ((HttpServletRequest) page.getRequest())
                                .getHeader(name);
                    }
                };
            }
            return this.header;
        }

        public Map getHeaderValues() {
            if (this.headerValues == null) {
                this.headerValues = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        return ((HttpServletRequest) page.getRequest())
                                .getHeaderNames();
                    }

                    protected Object getAttribute(String name) {
                        Enumeration e = ((HttpServletRequest) page.getRequest())
                                .getHeaders(name);
                        if (e != null) {
                            List list = new ArrayList();
                            while (e.hasMoreElements()) {
                                list.add(e.nextElement().toString());
                            }
                            return (String[]) list.toArray(new String[list
                                    .size()]);
                        }
                        return null;
                    }

                };
            }
            return this.headerValues;
        }

        public Map getInitParam() {
            if (this.initParam == null) {
                this.initParam = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        return page.getServletContext().getInitParameterNames();
                    }

                    protected Object getAttribute(String name) {
                        return page.getServletContext().getInitParameter(name);
                    }
                };
            }
            return this.initParam;
        }

        public PageContext getPageContext() {
            return this.page;
        }

        public Map getPageScope() {
            if (this.pageScope == null) {
                this.pageScope = new ScopeMap() {
                    protected void setAttribute(String name, Object value) {
                        page.setAttribute(name, value);
                    }

                    protected void removeAttribute(String name) {
                        page.removeAttribute(name);
                    }

                    protected Enumeration getAttributeNames() {
                        return page
                                .getAttributeNamesInScope(PageContext.PAGE_SCOPE);
                    }

                    protected Object getAttribute(String name) {
                        return page.getAttribute(name);
                    }
                };
            }
            return this.pageScope;
        }

        public Map getParam() {
            if (this.param == null) {
                this.param = new ScopeMap() {
                    protected Enumeration getAttributeNames() {
                        return page.getRequest().getParameterNames();
                    }

                    protected Object getAttribute(String name) {
                        return page.getRequest().getParameter(name);
                    }
                };
            }
            return this.param;
        }

        public Map getParamValues() {
            if (this.paramValues == null) {
                this.paramValues = new ScopeMap() {
                    protected Object getAttribute(String name) {
                        return page.getRequest().getParameterValues(name);
                    }

                    protected Enumeration getAttributeNames() {
                        return page.getRequest().getParameterNames();
                    }
                };
            }
            return this.paramValues;
        }

        public Map getRequestScope() {
            if (this.requestScope == null) {
                this.requestScope = new ScopeMap() {
                    protected void setAttribute(String name, Object value) {
                        page.getRequest().setAttribute(name, value);
                    }

                    protected void removeAttribute(String name) {
                        page.getRequest().removeAttribute(name);
                    }

                    protected Enumeration getAttributeNames() {
                        return page.getRequest().getAttributeNames();
                    }

                    protected Object getAttribute(String name) {
                        return page.getRequest().getAttribute(name);
                    }
                };
            }
            return this.requestScope;
        }

        public Map getSessionScope() {
            if (this.sessionScope == null) {
                this.sessionScope = new ScopeMap() {
                    protected void setAttribute(String name, Object value) {
                        ((HttpServletRequest) page.getRequest()).getSession()
                                .setAttribute(name, value);
                    }

                    protected void removeAttribute(String name) {
                        HttpSession session = page.getSession();
                        if (session != null) {
                            session.removeAttribute(name);
                        }
                    }

                    protected Enumeration getAttributeNames() {
                        HttpSession session = page.getSession();
                        if (session != null) {
                            return session.getAttributeNames();
                        }
                        return null;
                    }

                    protected Object getAttribute(String name) {
                        HttpSession session = page.getSession();
                        if (session != null) {
                            return session.getAttribute(name);
                        }
                        return null;
                    }
                };
            }
            return this.sessionScope;
        }
    }

    private abstract static class ScopeMap extends AbstractMap {

        protected abstract Enumeration getAttributeNames();

        protected abstract Object getAttribute(String name);

        protected void removeAttribute(String name) {
            throw new UnsupportedOperationException();
        }

        protected void setAttribute(String name, Object value) {
            throw new UnsupportedOperationException();
        }

        public final Set entrySet() {
            Enumeration e = getAttributeNames();
            Set set = new HashSet();
            if (e != null) {
                while (e.hasMoreElements()) {
                    set.add(new ScopeEntry((String) e.nextElement()));
                }
            }
            return set;
        }

        private class ScopeEntry implements Map.Entry {

            private final String key;

            public ScopeEntry(String key) {
                this.key = key;
            }

            public Object getKey() {
                return (Object) this.key;
            }

            public Object getValue() {
                return getAttribute(this.key);
            }

            public Object setValue(Object value) {
                if (value == null) {
                    removeAttribute(this.key);
                } else {
                    setAttribute(this.key, value);
                }
                return null;
            }

            public boolean equals(Object obj) {
                return (obj != null && this.hashCode() == obj.hashCode());
            }

            public int hashCode() {
                return this.key.hashCode();
            }

        }

        public final Object get(Object key) {
            if (key != null) {
                return getAttribute(key.toString());
            }
            return null;
        }

        public final Object put(Object key, Object value) {
            if (key == null) {
                throw new NullPointerException();
            }
            if (value == null) {
                this.removeAttribute(key.toString());
            } else {
                this.setAttribute(key.toString(), value);
            }
            return null;
        }

        public final Object remove(Object key) {
            if (key == null) {
                throw new NullPointerException();
            }
            this.removeAttribute(key.toString());
            return null;
        }

    }

}