Spring Framework example source code file (RedirectView.java)

This example Spring Framework source code file (RedirectView.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

default_encoding_scheme, http, httpservletrequest, httpservletresponse, io, ioexception, ioexception, iterator, map, map, redirectview, redirectview, request, response, servlet, string, string, stringbuffer, unsupportedencodingexception, util

The Spring Framework RedirectView.java source code

/*
 * Copyright 2002-2007 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
 *
 *      http://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.view;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.util.ClassUtils;

/**
 * <p>View that redirects to an absolute, context relative, or current request
 * relative URL, by default exposing all model attributes as HTTP query
 * parameters.
 *
 * <p>A URL for this view is supposed to be a HTTP redirect URL, i.e.
 * suitable for HttpServletResponse's <code>sendRedirect method, which
 * is what actually does the redirect if the HTTP 1.0 flag is on, or via sending
 * back an HTTP 303 code - if the HTTP 1.0 compatibility flag is off.
 *
 * <p>Note that while the default value for the "contextRelative" flag is off,
 * you will probably want to almost always set it to true. With the flag off,
 * URLs starting with "/" are considered relative to the web server root, while
 * with the flag on, they are considered relative to the web application root.
 * Since most web applications will never know or care what their context path
 * actually is, they are much better off setting this flag to true, and
 * submitting paths which are to be considered relative to the web application
 * root.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Colin Sampaleanu
 * @author Sam Brannen
 * @see #setContextRelative(boolean)
 * @see #setHttp10Compatible(boolean)
 * @see #setExposeModelAttributes(boolean)
 * @see javax.servlet.http.HttpServletResponse#sendRedirect
 */
public class RedirectView extends AbstractUrlBasedView {

	/** The default encoding scheme: UTF-8 */
	public static final String DEFAULT_ENCODING_SCHEME = "UTF-8";


	private boolean contextRelative = false;

	private boolean http10Compatible = true;

	private boolean exposeModelAttributes = true;

	private String encodingScheme = DEFAULT_ENCODING_SCHEME;


	/**
	 * Constructor for use as a bean.
	 */
	public RedirectView() {
	}

	/**
	 * Create a new RedirectView with the given URL.
	 * <p>The given URL will be considered as relative to the web server,
	 * not as relative to the current ServletContext.
	 * @param url the URL to redirect to
	 * @see #RedirectView(String, boolean)
	 */
	public RedirectView(String url) {
		super(url);
	}

	/**
	 * Create a new RedirectView with the given URL.
	 * @param url the URL to redirect to
	 * @param contextRelative whether to interpret the given URL as
	 * relative to the current ServletContext
	 */
	public RedirectView(String url, boolean contextRelative) {
		super(url);
		this.contextRelative = contextRelative;
	}

	/**
	 * Create a new RedirectView with the given URL.
	 * @param url the URL to redirect to
	 * @param contextRelative whether to interpret the given URL as
	 * relative to the current ServletContext
	 * @param http10Compatible whether to stay compatible with HTTP 1.0 clients
	 */
	public RedirectView(String url, boolean contextRelative, boolean http10Compatible) {
		super(url);
		this.contextRelative = contextRelative;
		this.http10Compatible = http10Compatible;
	}

	/**
	 * Create a new RedirectView with the given URL.
	 * @param url the URL to redirect to
	 * @param contextRelative whether to interpret the given URL as
	 * relative to the current ServletContext
	 * @param http10Compatible whether to stay compatible with HTTP 1.0 clients
	 * @param exposeModelAttributes whether or not model attributes should be
	 * exposed as query parameters
	 */
	public RedirectView(String url, boolean contextRelative, boolean http10Compatible, boolean exposeModelAttributes) {
		super(url);
		this.contextRelative = contextRelative;
		this.http10Compatible = http10Compatible;
		this.exposeModelAttributes = exposeModelAttributes;
	}

	/**
	 * Set whether to interpret a given URL that starts with a slash ("/")
	 * as relative to the current ServletContext, i.e. as relative to the
	 * web application root.
	 * <p>Default is "false": A URL that starts with a slash will be interpreted
	 * as absolute, i.e. taken as-is. If true, the context path will be
	 * prepended to the URL in such a case.
	 * @see javax.servlet.http.HttpServletRequest#getContextPath
	 */
	public void setContextRelative(boolean contextRelative) {
		this.contextRelative = contextRelative;
	}

	/**
	 * Set whether to stay compatible with HTTP 1.0 clients.
	 * <p>In the default implementation, this will enforce HTTP status code 302
	 * in any case, i.e. delegate to <code>HttpServletResponse.sendRedirect.
	 * Turning this off will send HTTP status code 303, which is the correct
	 * code for HTTP 1.1 clients, but not understood by HTTP 1.0 clients.
	 * <p>Many HTTP 1.1 clients treat 302 just like 303, not making any
	 * difference. However, some clients depend on 303 when redirecting
	 * after a POST request; turn this flag off in such a scenario.
	 * @see javax.servlet.http.HttpServletResponse#sendRedirect
	 */
	public void setHttp10Compatible(boolean http10Compatible) {
		this.http10Compatible = http10Compatible;
	}

	/**
	 * Set the <code>exposeModelAttributes flag which denotes whether
	 * or not model attributes should be exposed as HTTP query parameters.
	 * <p>Defaults to true.
	 */
	public void setExposeModelAttributes(final boolean exposeModelAttributes) {
		this.exposeModelAttributes = exposeModelAttributes;
	}

	/**
	 * Set the encoding scheme for this view. Default is UTF-8.
	 */
	public void setEncodingScheme(String encodingScheme) {
		this.encodingScheme = encodingScheme;
	}


	/**
	 * Convert model to request parameters and redirect to the given URL.
	 * @see #appendQueryProperties
	 * @see #sendRedirect
	 */
	protected final void renderMergedOutputModel(
			Map model, HttpServletRequest request, HttpServletResponse response) throws IOException {

		// Prepare target URL.
		StringBuffer targetUrl = new StringBuffer();
		if (this.contextRelative && getUrl().startsWith("/")) {
			// Do not apply context path to relative URLs.
			targetUrl.append(request.getContextPath());
		}
		targetUrl.append(getUrl());
		if (this.exposeModelAttributes) {
			appendQueryProperties(targetUrl, model, this.encodingScheme);
		}

		sendRedirect(request, response, targetUrl.toString(), this.http10Compatible);
	}

	/**
	 * Append query properties to the redirect URL.
	 * Stringifies, URL-encodes and formats model attributes as query properties.
	 * @param targetUrl the StringBuffer to append the properties to
	 * @param model Map that contains model attributes
	 * @param encodingScheme the encoding scheme to use
	 * @throws UnsupportedEncodingException if string encoding failed
	 * @see #queryProperties
	 */
	protected void appendQueryProperties(StringBuffer targetUrl, Map model, String encodingScheme)
			throws UnsupportedEncodingException {

		// Extract anchor fragment, if any.
		String fragment = null;
		int anchorIndex = targetUrl.indexOf("#");
		if (anchorIndex > -1) {
			fragment = targetUrl.substring(anchorIndex);
			targetUrl.delete(anchorIndex, targetUrl.length());
		}

		// If there aren't already some parameters, we need a "?".
		boolean first = (getUrl().indexOf('?') < 0);
		Iterator entries = queryProperties(model).entrySet().iterator();
		while (entries.hasNext()) {
			if (first) {
				targetUrl.append('?');
				first = false;
			}
			else {
				targetUrl.append('&');
			}
			Map.Entry entry = (Map.Entry) entries.next();
			String encodedKey = urlEncode(entry.getKey().toString(), encodingScheme);
			String encodedValue =
					(entry.getValue() != null ? urlEncode(entry.getValue().toString(), encodingScheme) : "");
			targetUrl.append(encodedKey).append('=').append(encodedValue);
		}

		// Append anchor fragment, if any, to end of URL.
		if (fragment != null) {
			targetUrl.append(fragment);
		}
	}

	/**
	 * Determine name-value pairs for query strings, which will be stringified,
	 * URL-encoded and formatted by {@link #appendQueryProperties}.
	 * <p>This implementation filters the model through checking
	 * {@link #isEligibleProperty(String, Object)} for each element,
	 * by default accepting Strings, primitives and primitive wrappers only.
	 * @param model the original model Map
	 * @return the filtered Map of eligible query properties
	 * @see #isEligibleProperty(String, Object)
	 */
	protected Map queryProperties(Map model) {
		Map result = new LinkedHashMap();
		for (Iterator it = model.entrySet().iterator(); it.hasNext();) {
			Map.Entry entry = (Map.Entry) it.next();
			if (isEligibleProperty(entry.getKey().toString(), entry.getValue())) {
				result.put(entry.getKey().toString(), entry.getValue().toString());
			}
		}
		return result;
	}

	/**
	 * Determine whether the given model element should be exposed
	 * as a query property.
	 * @param key the key of the model element
	 * @param value the value of the model element
	 * @return whether the element is eligible as query property
	 */
	protected boolean isEligibleProperty(String key, Object value) {
		return (value != null &&
				(value instanceof String || ClassUtils.isPrimitiveOrWrapper(value.getClass())));
	}

	/**
	 * URL-encode the given input String with the given encoding scheme.
	 * <p>Default implementation uses URLEncoder.encode(input, enc).
	 * @param input the unencoded input String
	 * @param encodingScheme the encoding scheme
	 * @return the encoded output String
	 * @throws UnsupportedEncodingException if thrown by the JDK URLEncoder
	 * @see java.net.URLEncoder#encode(String, String)
	 * @see java.net.URLEncoder#encode(String)
	 */
	protected String urlEncode(String input, String encodingScheme) throws UnsupportedEncodingException {
		return (input != null ? URLEncoder.encode(input, encodingScheme) : null);
	}

	/**
	 * Send a redirect back to the HTTP client
	 * @param request current HTTP request (allows for reacting to request method)
	 * @param response current HTTP response (for sending response headers)
	 * @param targetUrl the target URL to redirect to
	 * @param http10Compatible whether to stay compatible with HTTP 1.0 clients
	 * @throws IOException if thrown by response methods
	 */
	protected void sendRedirect(
			HttpServletRequest request, HttpServletResponse response, String targetUrl, boolean http10Compatible)
			throws IOException {

		if (http10Compatible) {
			// Always send status code 302.
			response.sendRedirect(response.encodeRedirectURL(targetUrl));
		}
		else {
			// Correct HTTP status code is 303, in particular for POST requests.
			response.setStatus(303);
			response.setHeader("Location", response.encodeRedirectURL(targetUrl));
		}
	}

}