Java tutorial
/* * Copyright 2002-2019 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * https://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.web.servlet.support; import javax.servlet.http.HttpServletRequest; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.StringUtils; import org.springframework.web.context.request.RequestAttributes; import org.springframework.web.context.request.RequestContextHolder; import org.springframework.web.context.request.ServletRequestAttributes; import org.springframework.web.util.UriComponentsBuilder; import org.springframework.web.util.UriUtils; import org.springframework.web.util.UrlPathHelper; /** * UriComponentsBuilder with additional static factory methods to create links * based on the current HttpServletRequest. * * <p><strong>Note:</strong> As of 5.1, methods in this class do not extract * {@code "Forwarded"} and {@code "X-Forwarded-*"} headers that specify the * client-originated address. Please, use * {@link org.springframework.web.filter.ForwardedHeaderFilter * ForwardedHeaderFilter}, or similar from the underlying server, to extract * and use such headers, or to discard them. * * @author Rossen Stoyanchev * @since 3.1 */ public class ServletUriComponentsBuilder extends UriComponentsBuilder { @Nullable private String originalPath; /** * Default constructor. Protected to prevent direct instantiation. * @see #fromContextPath(HttpServletRequest) * @see #fromServletMapping(HttpServletRequest) * @see #fromRequest(HttpServletRequest) * @see #fromCurrentContextPath() * @see #fromCurrentServletMapping() * @see #fromCurrentRequest() */ protected ServletUriComponentsBuilder() { } /** * Create a deep copy of the given ServletUriComponentsBuilder. * @param other the other builder to copy from */ protected ServletUriComponentsBuilder(ServletUriComponentsBuilder other) { super(other); this.originalPath = other.originalPath; } // Factory methods based on a HttpServletRequest /** * Prepare a builder from the host, port, scheme, and context path of the * given HttpServletRequest. */ public static ServletUriComponentsBuilder fromContextPath(HttpServletRequest request) { ServletUriComponentsBuilder builder = initFromRequest(request); builder.replacePath(request.getContextPath()); return builder; } /** * Prepare a builder from the host, port, scheme, context path, and * servlet mapping of the given HttpServletRequest. * <p>If the servlet is mapped by name, e.g. {@code "/main/*"}, the path * will end with "/main". If the servlet is mapped otherwise, e.g. * {@code "/"} or {@code "*.do"}, the result will be the same as * if calling {@link #fromContextPath(HttpServletRequest)}. */ public static ServletUriComponentsBuilder fromServletMapping(HttpServletRequest request) { ServletUriComponentsBuilder builder = fromContextPath(request); if (StringUtils.hasText(new UrlPathHelper().getPathWithinServletMapping(request))) { builder.path(request.getServletPath()); } return builder; } /** * Prepare a builder from the host, port, scheme, and path (but not the query) * of the HttpServletRequest. */ public static ServletUriComponentsBuilder fromRequestUri(HttpServletRequest request) { ServletUriComponentsBuilder builder = initFromRequest(request); builder.initPath(request.getRequestURI()); return builder; } /** * Prepare a builder by copying the scheme, host, port, path, and * query string of an HttpServletRequest. */ public static ServletUriComponentsBuilder fromRequest(HttpServletRequest request) { ServletUriComponentsBuilder builder = initFromRequest(request); builder.initPath(request.getRequestURI()); builder.query(request.getQueryString()); return builder; } /** * Initialize a builder with a scheme, host,and port (but not path and query). */ private static ServletUriComponentsBuilder initFromRequest(HttpServletRequest request) { String scheme = request.getScheme(); String host = request.getServerName(); int port = request.getServerPort(); ServletUriComponentsBuilder builder = new ServletUriComponentsBuilder(); builder.scheme(scheme); builder.host(host); if (("http".equals(scheme) && port != 80) || ("https".equals(scheme) && port != 443)) { builder.port(port); } return builder; } // Alternative methods relying on RequestContextHolder to find the request /** * Same as {@link #fromContextPath(HttpServletRequest)} except the * request is obtained through {@link RequestContextHolder}. */ public static ServletUriComponentsBuilder fromCurrentContextPath() { return fromContextPath(getCurrentRequest()); } /** * Same as {@link #fromServletMapping(HttpServletRequest)} except the * request is obtained through {@link RequestContextHolder}. */ public static ServletUriComponentsBuilder fromCurrentServletMapping() { return fromServletMapping(getCurrentRequest()); } /** * Same as {@link #fromRequestUri(HttpServletRequest)} except the * request is obtained through {@link RequestContextHolder}. */ public static ServletUriComponentsBuilder fromCurrentRequestUri() { return fromRequestUri(getCurrentRequest()); } /** * Same as {@link #fromRequest(HttpServletRequest)} except the * request is obtained through {@link RequestContextHolder}. */ public static ServletUriComponentsBuilder fromCurrentRequest() { return fromRequest(getCurrentRequest()); } /** * Obtain current request through {@link RequestContextHolder}. */ protected static HttpServletRequest getCurrentRequest() { RequestAttributes attrs = RequestContextHolder.getRequestAttributes(); Assert.state(attrs instanceof ServletRequestAttributes, "No current ServletRequestAttributes"); return ((ServletRequestAttributes) attrs).getRequest(); } private void initPath(String path) { this.originalPath = path; replacePath(path); } /** * Remove any path extension from the {@link HttpServletRequest#getRequestURI() * requestURI}. This method must be invoked before any calls to {@link #path(String)} * or {@link #pathSegment(String...)}. * <pre> * GET http://www.foo.example/rest/books/6.json * * ServletUriComponentsBuilder builder = ServletUriComponentsBuilder.fromRequestUri(this.request); * String ext = builder.removePathExtension(); * String uri = builder.path("/pages/1.{ext}").buildAndExpand(ext).toUriString(); * assertEquals("http://www.foo.example/rest/books/6/pages/1.json", result); * </pre> * @return the removed path extension for possible re-use, or {@code null} * @since 4.0 */ @Nullable public String removePathExtension() { String extension = null; if (this.originalPath != null) { extension = UriUtils.extractFileExtension(this.originalPath); if (StringUtils.hasLength(extension)) { int end = this.originalPath.length() - (extension.length() + 1); replacePath(this.originalPath.substring(0, end)); } this.originalPath = null; } return extension; } @Override public ServletUriComponentsBuilder cloneBuilder() { return new ServletUriComponentsBuilder(this); } }