Java tutorial
/* * Copyright 2000-2018 Vaadin Ltd. * * 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 com.vaadin.server; import java.io.IOException; import java.io.OutputStream; import java.io.PrintWriter; import java.io.Serializable; import javax.portlet.MimeResponse; import javax.portlet.PortletResponse; import javax.portlet.ResourceResponse; import javax.servlet.ServletResponse; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServletResponse; import com.vaadin.util.CurrentInstance; /** * A generic response from the server, wrapping a more specific response type, * e.g. HttpServletResponse or PortletResponse. * * @since 7.0 */ public interface VaadinResponse extends Serializable { /** * Sets the (http) status code for the response. If you want to include an * error message along the status code, use {@link #sendError(int, String)} * instead. * * @param statusCode * the status code to set * @see HttpServletResponse#setStatus(int) * * @see ResourceResponse#HTTP_STATUS_CODE */ public void setStatus(int statusCode); /** * Sets the content type of this response. If the content type including a * charset is set before {@link #getWriter()} is invoked, the returned * PrintWriter will automatically use the defined charset. * * @param contentType * a string specifying the MIME type of the content * * @see ServletResponse#setContentType(String) * @see MimeResponse#setContentType(String) */ public void setContentType(String contentType); /** * Sets the value of a generic response header. If the header had already * been set, the new value overwrites the previous one. * * @param name * the name of the header * @param value * the header value. * * @see HttpServletResponse#setHeader(String, String) * @see PortletResponse#setProperty(String, String) */ public void setHeader(String name, String value); /** * Properly formats a timestamp as a date header. If the header had already * been set, the new value overwrites the previous one. * * @param name * the name of the header * @param timestamp * the number of milliseconds since epoch * * @see HttpServletResponse#setDateHeader(String, long) */ public void setDateHeader(String name, long timestamp); /** * Returns a <code>OutputStream</code> for writing binary data in the * response. * <p> * Either this method or getWriter() may be called to write the response, * not both. * * @return a <code>OutputStream</code> for writing binary data * @throws IOException * if an input or output exception occurred * * @see #getWriter() * @see ServletResponse#getOutputStream() * @see MimeResponse#getPortletOutputStream() */ public OutputStream getOutputStream() throws IOException; /** * Returns a <code>PrintWriter</code> object that can send character text to * the client. The PrintWriter uses the character encoding defined using * setContentType. * <p> * Either this method or getOutputStream() may be called to write the * response, not both. * * @return a <code>PrintWriter</code> for writing character text * @throws IOException * if an input or output exception occurred * * @see #getOutputStream() * @see ServletResponse#getWriter() * @see MimeResponse#getWriter() */ public PrintWriter getWriter() throws IOException; /** * Sets cache time in milliseconds, -1 means no cache at all. All required * headers related to caching in the response are set based on the time. * * @param milliseconds * Cache time in milliseconds */ public void setCacheTime(long milliseconds); /** * Sends an error response to the client using the specified status code and * clears the buffer. In some configurations, this can cause a predefined * error page to be displayed. * * @param errorCode * the HTTP status code * @param message * a message to accompany the error * @throws IOException * if an input or output exception occurs * * @see HttpServletResponse#sendError(int, String) */ public void sendError(int errorCode, String message) throws IOException; /** * Gets the vaadin service for the context of this response. * * @return the vaadin service * * @see VaadinService */ public VaadinService getService(); /** * Adds the specified cookie to the response. This method can be called * multiple times to set more than one cookie. * * @param cookie * the Cookie to return to the client * * @see HttpServletResponse#addCookie(Cookie) * @see PortletResponse#addProperty(Cookie) */ public void addCookie(Cookie cookie); /** * Sets the length of the content body in the response In HTTP servlets, * this method sets the HTTP Content-Length header. For some portlet * responses, this method sets the content-length header, for others this * method does nothing. * * @param len * an integer specifying the length of the content being returned * to the client * @since 7.3.8 */ public void setContentLength(int len); /** * Sets all conceivable headers that might prevent a response from being * stored in any caches. * * @since 8.3.2 */ public default void setNoCacheHeaders() { // no-store to disallow storing even if cache would be revalidated // must-revalidate to not use stored value even if someone asks for it setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // Also set legacy values in case of old proxies in between setHeader("Pragma", "no-cache"); setHeader("Expires", "0"); } /** * Gets the currently processed Vaadin response. The current response is * automatically defined when the request is started. The current response * can not be used in e.g. background threads because of the way server * implementations reuse response instances. * * @return the current Vaadin response instance if available, otherwise * <code>null</code> * @since 8.1 */ public static VaadinResponse getCurrent() { return CurrentInstance.get(VaadinResponse.class); } }