/*
* Copyright 2014 Google Inc.
*
* 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.google.gwt.dev.codeserver;
import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.dev.codeserver.Pages.ErrorPage;
import com.google.gwt.dev.json.JsonObject;
import com.google.gwt.thirdparty.guava.common.base.Charsets;
import com.google.gwt.thirdparty.guava.common.base.Preconditions;
import com.google.gwt.thirdparty.guava.common.io.ByteStreams;
import com.google.gwt.thirdparty.guava.common.io.Files;
import com.google.gwt.thirdparty.guava.common.io.Resources;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.Writer;
import java.net.URL;
import java.util.regex.Pattern;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Common HTTP responses other than HTML pages, which are in {@link Pages}.
*/
public class Responses {
private static final Pattern SAFE_CALLBACK =
Pattern.compile("([a-zA-Z_][a-zA-Z0-9_]*\\.)*[a-zA-Z_][a-zA-Z0-9_]*");
/**
* A HTTP response that sends a file.
*/
static Response newFileResponse(final String mimeType, final File file) {
if (!file.isFile()) {
return new ErrorPage("file not found: " + file.toString());
}
return new Response() {
@Override
public void send(HttpServletRequest request, HttpServletResponse response, TreeLogger logger)
throws IOException {
response.setStatus(HttpServletResponse.SC_OK);
response.setContentType(mimeType);
Files.copy(file, response.getOutputStream());
}
};
}
/**
* Returns a JSON response. If the request contains a _callback parameter, it will
* automatically be sent as a JSONP response. Otherwise, it's an AJAX response.
*/
static Response newJsonResponse(final JsonObject json) {
return new Response() {
@Override
public void send(HttpServletRequest request, HttpServletResponse response, TreeLogger logger)
throws IOException {
response.setStatus(HttpServletResponse.SC_OK);
response.setHeader("Cache-control", "no-cache");
PrintWriter out = response.getWriter();
String callbackExpression = request.getParameter("_callback");
if (callbackExpression == null) {
// AJAX
response.setContentType("application/json");
json.write(out);
} else {
// JSONP
response.setContentType("application/javascript");
if (SAFE_CALLBACK.matcher(callbackExpression).matches()) {
out.print("/* API response */ " + callbackExpression + "(");
json.write(out);
out.println(");");
} else {
logger.log(TreeLogger.ERROR, "invalid callback: " + callbackExpression);
// Notice that we cannot execute the callback
out.print("alert('invalid callback parameter');\n");
json.write(out);
}
}
}
};
}
/**
* Sends an entire Js script.
*/
static Response newJavascriptResponse(final String jsScript) {
return new Response() {
@Override
public void send(HttpServletRequest request, HttpServletResponse response, TreeLogger logger)
throws IOException {
response.setStatus(HttpServletResponse.SC_OK);
response.setContentType("application/javascript");
ServletOutputStream outBytes = response.getOutputStream();
Writer out = new OutputStreamWriter(outBytes, "UTF-8");
out.write(jsScript);
out.close();
}
};
}
/**
* Sends a JavaScript file with some JSON data prepended to it.
* @param variableName the global variable where the JSON should be stored.
* @param json the data to include.
* @param resourceName the name of the JavaScript file.
*/
static Response newJavascriptResponse(final String variableName, final JsonObject json,
final String resourceName) {
final URL resource = WebServer.class.getResource(resourceName);
if (resource == null) {
return new ErrorPage("resource not found: " + resourceName);
}
return new Response() {
@Override
public void send(HttpServletRequest request, HttpServletResponse response, TreeLogger logger)
throws IOException {
response.setStatus(HttpServletResponse.SC_OK);
response.setContentType("application/javascript");
ServletOutputStream outBytes = response.getOutputStream();
Writer out = new OutputStreamWriter(outBytes, "UTF-8");
out.append("window." + variableName + " = ");
json.write(out);
out.append(";\n");
out.flush();
Resources.copy(resource, outBytes);
}
};
}
/**
* Sends a text file, substituting one variable. (Doesn't preserve line endings.)
* @param templateVariable the string to replace
* @param replacement the replacement
*/
static Response newTextTemplateResponse(final String mimeType, final File file,
final String templateVariable, final String replacement) {
if (!file.isFile()) {
return new ErrorPage("file not found: " + file.toString());
}
return new Response() {
@Override
public void send(HttpServletRequest request, HttpServletResponse response, TreeLogger logger)
throws IOException {
BufferedReader reader = Files.newReader(file, Charsets.UTF_8);
try {
response.setStatus(HttpServletResponse.SC_OK);
response.setContentType(mimeType);
PrintWriter out = response.getWriter();
while (true) {
String line = reader.readLine();
if (line == null) {
break;
}
line = line.replace(templateVariable, replacement);
out.println(line);
}
} finally {
reader.close();
}
}
};
}
/**
* Creates a page that sends the given stream of bytes.
* The response will close the stream after sending it.
* (Beware that if the page is never sent, the file handle will leak.)
* TODO: fix the callers and get rid of this.
*/
static Response newBinaryStreamResponse(final String mimeType, final InputStream pageBytes) {
return new Response() {
boolean sent = false;
@Override
public void send(HttpServletRequest request, HttpServletResponse response, TreeLogger logger)
throws IOException {
Preconditions.checkState(!sent);
try {
response.setStatus(HttpServletResponse.SC_OK);
response.setContentType(mimeType);
ByteStreams.copy(pageBytes, response.getOutputStream());
} finally {
pageBytes.close();
}
sent = true;
}
};
}
/**
* Wraps another response in order to log how long it takes to send it.
*/
static Response newTimedResponse(final Response barePage, final String message) {
return new Response() {
@Override
public void send(HttpServletRequest request, HttpServletResponse response, TreeLogger logger)
throws IOException {
long startTime = System.currentTimeMillis();
barePage.send(request, response, logger);
long elapsedTime = System.currentTimeMillis() - startTime;
logger.log(TreeLogger.INFO, message + " in " + elapsedTime + " ms");
}
};
}
}