javax.servlet.http
Class HttpUtils

java.lang.Object
  |
  +--javax.servlet.http.HttpUtils

public class HttpUtils

extends java.lang.Object

Provides a collection of methods that are useful in writing HTTP servlets.

Version:

$Version$

Author:

Various

Constructor Summary

HttpUtils()
Constructs an empty HttpUtils object.

Method Summary

static java.lang.StringBuffer	getRequestURL(HttpServletRequest req) Reconstructs the URL the client used to make the request, using information in the HttpServletRequest object.
static java.util.Hashtable	parsePostData(int len, ServletInputStream in) Parses data from an HTML form that the client sends to the server using the HTTP POST method and the application/x-www-form-urlencoded MIME type.
static java.util.Hashtable	parseQueryString(java.lang.String s) Parses a query string passed from the client to the server and builds a HashTable object with key-value pairs.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HttpUtils

public HttpUtils()

Constructs an empty HttpUtils object.

Method Detail

parseQueryString

public static java.util.Hashtable parseQueryString(java.lang.String s)

Parses a query string passed from the client to the server and builds a HashTable object with key-value pairs. The query string should be in the form of a string packaged by the GET or POST method, that is, it should have key-value pairs in the form key=value, with each pair separated from the next by a & character.

A key can appear more than once in the query string with different values. However, the key appears only once in the hashtable, with its value being an array of strings containing the multiple values sent by the query string.

The keys and values in the hashtable are stored in their decoded form, so any + characters are converted to spaces, and characters sent in hexadecimal notation (like %xx) are converted to ASCII characters.

Parameters:

s - a string containing the query to be parsed

Returns:

a HashTable object built from the parsed key-value pairs

Throws:

java.lang.IllegalArgumentException - if the query string is invalid

parsePostData

public static java.util.Hashtable parsePostData(int len,
                                                ServletInputStream in)

Parses data from an HTML form that the client sends to the server using the HTTP POST method and the application/x-www-form-urlencoded MIME type.

The data sent by the POST method contains key-value pairs. A key can appear more than once in the POST data with different values. However, the key appears only once in the hashtable, with its value being an array of strings containing the multiple values sent by the POST method.

The keys and values in the hashtable are stored in their decoded form, so any + characters are converted to spaces, and characters sent in hexadecimal notation (like %xx) are converted to ASCII characters.

Parameters:

len - an integer specifying the length, in characters, of the ServletInputStream object that is also passed to this method

in - the ServletInputStream object that contains the data sent from the client

Returns:

a HashTable object built from the parsed key-value pairs

Throws:

java.lang.IllegalArgumentException - if the data sent by the POST method is invalid

getRequestURL

public static java.lang.StringBuffer getRequestURL(HttpServletRequest req)

Reconstructs the URL the client used to make the request, using information in the HttpServletRequest object. The returned URL contains a protocol, server name, port number, and server path, but it does not include query string parameters.

Because this method returns a StringBuffer, not a string, you can modify the URL easily, for example, to append query parameters.

This method is useful for creating redirect messages and for reporting errors.

Parameters:

req - a HttpServletRequest object containing the client's request

Returns:

a StringBuffer object containing the reconstructed URL