001// Copyright 2019 Google LLC 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package com.google.cloud.functions; 016 017import java.io.BufferedWriter; 018import java.io.IOException; 019import java.io.OutputStream; 020import java.util.List; 021import java.util.Map; 022import java.util.Optional; 023 024/** 025 * Represents the contents of an HTTP response that is being sent by a Cloud Function in response 026 * to an HTTP request. 027 */ 028public interface HttpResponse { 029 /** 030 * Sets the numeric HTTP 031 * <a href="https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml">status 032 * code</a> to use in the response. Most often this will be 200, which is the OK status. 033 */ 034 void setStatusCode(int code); 035 036 /** 037 * Sets the numeric HTTP 038 * <a href="https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml">status 039 * code</a> and reason message to use in the response. For example<br> 040 * {@code setStatusCode(400, "Something went wrong")}. 041 */ 042 void setStatusCode(int code, String message); 043 044 /** 045 * Sets the value to use for the {@code Content-Type} header in the response. This may include 046 * a character encoding, for example {@code setContentType("text/plain; charset=utf-8")}. 047 */ 048 void setContentType(String contentType); 049 050 /** 051 * Returns the {@code Content-Type} that was previously set by {@link #setContentType}, or by 052 * {@link #appendHeader} with a header name of {@code Content-Type}. If no {@code Content-Type} 053 * has been set, returns {@code Optional.empty()}. 054 */ 055 Optional<String> getContentType(); 056 057 /** 058 * Includes the given header name with the given value in the response. This method may be called 059 * several times for the same header, in which case the response will contain the header the same 060 * number of times. 061 */ 062 void appendHeader(String header, String value); 063 064 /** 065 * Returns the headers that have been defined for the response so far. This will contain at least 066 * the headers that have been set via {@link #appendHeader} or {@link #setContentType}, and may 067 * contain additional headers such as {@code Date}. 068 */ 069 Map<String, List<String>> getHeaders(); 070 071 /** 072 * Returns an {@link OutputStream} that can be used to write the body of the response. 073 * This method is typically used to write binary data. If the body is text, the 074 * {@link #getWriter()} method is more appropriate. 075 * 076 * @throws IOException if a valid {@link OutputStream} cannot be returned for some reason. 077 * @throws IllegalStateException if {@link #getWriter} has already been called on this instance. 078 */ 079 OutputStream getOutputStream() throws IOException; 080 081 /** 082 * Returns a {@link BufferedWriter} that can be used to write the text body of the response. 083 * If the written text will not be US-ASCII, you should specify a character encoding by calling 084 * {@link #setContentType setContentType("text/foo; charset=bar")} or 085 * {@link #appendHeader appendHeader("Content-Type", "text/foo; charset=bar")} 086 * before calling this method. 087 * 088 * @throws IOException if a valid {@link BufferedWriter} cannot be returned for some reason. 089 * @throws IllegalStateException if {@link #getOutputStream} has already been called on this 090 * instance. 091 */ 092 BufferedWriter getWriter() throws IOException; 093}