// Copyright (C) 1998-2001 by Jason Hunter <jhunter_AT_acm_DOT_org>.
// All rights reserved. Use of this class is limited.
// Please see the LICENSE for more information.
package com.oreilly.servlet;
import java.io.*;
import java.net.*;
import java.util.*;
import com.knowgate.misc.Base64Encoder;
/**
* A class to simplify HTTP applet-server communication. It abstracts
* the communication into messages, which can be either GET or POST.
* <p>
* It can be used like this:
* <blockquote><pre>
* URL url = new URL(getCodeBase(), "/servlet/ServletName");
*
* HttpMessage msg = new HttpMessage(url);
*
* // Parameters may optionally be set using java.util.Properties
* Properties props = new Properties();
* props.put("name", "value");
*
* // Headers, cookies, and authorization may be set as well
* msg.setHeader("Accept", "image/png"); // optional
* msg.setCookie("JSESSIONID", "9585155923883872"); // optional
* msg.setAuthorization("guest", "try2gueSS"); // optional
*
* InputStream in = msg.sendGetMessage(props);
* </pre></blockquote>
* <p>
* This class is loosely modeled after the ServletMessage class written
* by Rod McChesney of JavaSoft.
*
* @author <b>Jason Hunter</b>, Copyright © 1998
* @version 1.3, 2000/10/24, fixed headers NPE bug
* @version 1.2, 2000/10/15, changed uploaded object MIME type to
* application/x-java-serialized-object
* @version 1.1, 2000/06/11, added ability to set headers, cookies,
and authorization
* @version 1.0, 1998/09/18
*/
public class HttpMessage {
URL servlet = null;
Hashtable headers = null;
/**
* Constructs a new HttpMessage that can be used to communicate with the
* servlet at the specified URL.
*
* @param servlet the server resource (typically a servlet) with which
* to communicate
*/
public HttpMessage(URL servlet) {
this.servlet = servlet;
}
/**
* Performs a GET request to the servlet, with no query string.
*
* @return an InputStream to read the response
* @exception IOException if an I/O error occurs
*/
public InputStream sendGetMessage() throws IOException {
return sendGetMessage(null);
}
/**
* Performs a GET request to the servlet, building
* a query string from the supplied properties list.
*
* @param args the properties list from which to build a query string
* @return an InputStream to read the response
* @exception IOException if an I/O error occurs
*/
public InputStream sendGetMessage(Properties args) throws IOException {
String argString = ""; // default
if (args != null) {
argString = "?" + toEncodedString(args);
}
URL url = new URL(servlet.toExternalForm() + argString);
// Turn off caching
URLConnection con = url.openConnection();
con.setUseCaches(false);
// Send headers
sendHeaders(con);
return con.getInputStream();
}
/**
* Performs a POST request to the servlet, with no query string.
*
* @return an InputStream to read the response
* @exception IOException if an I/O error occurs
*/
public InputStream sendPostMessage() throws IOException {
return sendPostMessage(null);
}
/**
* Performs a POST request to the servlet, building
* post data from the supplied properties list.
*
* @param args the properties list from which to build the post data
* @return an InputStream to read the response
* @exception IOException if an I/O error occurs
*/
public InputStream sendPostMessage(Properties args) throws IOException {
String argString = ""; // default
if (args != null) {
argString = toEncodedString(args); // notice no "?"
}
URLConnection con = servlet.openConnection();
// Prepare for both input and output
con.setDoInput(true);
con.setDoOutput(true);
// Turn off caching
con.setUseCaches(false);
// Work around a Netscape bug
con.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
// Send headers
sendHeaders(con);
// Write the arguments as post data
DataOutputStream out = new DataOutputStream(con.getOutputStream());
out.writeBytes(argString);
out.flush();
out.close();
return con.getInputStream();
}
/**
* Performs a POST request to the servlet, uploading a serialized object.
* <p>
* The servlet can receive the object in its <tt>doPost()</tt> method
* like this:
* <pre>
* ObjectInputStream objin =
* new ObjectInputStream(req.getInputStream());
* Object obj = objin.readObject();
* </pre>
* The type of the uploaded object can be determined through introspection.
*
* @param obj the serializable object to upload
* @return an InputStream to read the response
* @exception IOException if an I/O error occurs
*/
public InputStream sendPostMessage(Serializable obj) throws IOException {
URLConnection con = servlet.openConnection();
// Prepare for both input and output
con.setDoInput(true);
con.setDoOutput(true);
// Turn off caching
con.setUseCaches(false);
// Set the content type to be application/x-java-serialized-object
con.setRequestProperty("Content-Type",
"application/x-java-serialized-object");
// Send headers
sendHeaders(con);
// Write the serialized object as post data
ObjectOutputStream out = new ObjectOutputStream(con.getOutputStream());
out.writeObject(obj);
out.flush();
out.close();
return con.getInputStream();
}
/**
* Sets a request header with the given name and value. The header
* persists across multiple requests. The caller is responsible for
* ensuring there are no illegal characters in the name and value.
*
* @param name the header name
* @param value the header value
*/
public void setHeader(String name, String value) {
if (headers == null) {
headers = new Hashtable();
}
headers.put(name, value);
}
// Send the contents of the headers hashtable to the server
private void sendHeaders(URLConnection con) {
if (headers != null) {
Enumeration headerenum = headers.keys();
while (headerenum.hasMoreElements()) {
String name = (String) headerenum.nextElement();
String value = (String) headers.get(name);
con.setRequestProperty(name, value);
}
}
}
/**
* Sets a request cookie with the given name and value. The cookie
* persists across multiple requests. The caller is responsible for
* ensuring there are no illegal characters in the name and value.
*
* @param name the header name
* @param value the header value
*/
public void setCookie(String name, String value) {
if (headers == null) {
headers = new Hashtable();
}
String existingCookies = (String) headers.get("Cookie");
if (existingCookies == null) {
setHeader("Cookie", name + "=" + value);
}
else {
setHeader("Cookie", existingCookies + "; " + name + "=" + value);
}
}
/**
* Sets the authorization information for the request (using BASIC
* authentication via the HTTP Authorization header). The authorization
* persists across multiple requests.
*
* @param name the user name
* @param name the user password
*/
public void setAuthorization(String name, String password) {
String authorization = Base64Encoder.encode(name + ":" + password);
setHeader("Authorization", "Basic " + authorization);
}
/*
* Converts a properties list to a URL-encoded query string
*/
private String toEncodedString(Properties args) {
StringBuffer buf = new StringBuffer();
Enumeration names = args.propertyNames();
while (names.hasMoreElements()) {
String name = (String) names.nextElement();
String value = args.getProperty(name);
buf.append(URLEncoder.encode(name) + "=" + URLEncoder.encode(value));
if (names.hasMoreElements()) buf.append("&");
}
return buf.toString();
}
}