org.ocpsoft.rewrite.servlet.config.proxy

Class ProxyServlet

java.lang.Object

org.ocpsoft.rewrite.servlet.config.proxy.ProxyServlet

public class ProxyServlet
extends Object

An HTTP reverse proxy/gateway servlet. It is designed to be extended for customization if desired. Most of the work is handled by Apache HttpClient.

There are alternatives to a servlet based proxy such as Apache mod_proxy if that is available to you. However this servlet is easily customizable by Java, secure-able by your web application's security (e.g. spring-security), portable across servlet engines, and is embeddable into another web application.

Inspiration: http://httpd.apache.org/docs/2.0/mod/mod_proxy.html

Author:

David Smiley dsmiley@mitre.org

Field Summary

Fields

Modifier and Type	Field and Description
protected static BitSet	asciiQueryChars
protected boolean	doLog
protected static org.apache.http.message.HeaderGroup	hopByHopHeaders These are the "hop-by-hop" headers that should not be copied.
static String	P_LOG A boolean parameter name to enable logging of input and target URLs to the servlet log.
protected org.apache.http.client.HttpClient	proxyClient
protected String	targetUri
protected URI	targetUriObj

Constructor Summary

Constructors

Constructor and Description
ProxyServlet()

Method Summary

Methods

Modifier and Type	Method and Description
protected void	closeQuietly(Closeable closeable)
protected void	copyRequestHeaders(HttpServletRequest servletRequest, org.apache.http.HttpRequest proxyRequest) Copy request headers from the servlet client to the proxy request.
protected void	copyResponseEntity(org.apache.http.HttpResponse proxyResponse, HttpServletResponse servletResponse) Copy response body data (the entity) from the proxy to the servlet client.
protected void	copyResponseHeaders(org.apache.http.HttpResponse proxyResponse, HttpServletResponse servletResponse) Copy proxied response headers back to the servlet client.
protected org.apache.http.client.HttpClient	createHttpClient(org.apache.http.params.HttpParams hcParams) Called from init(javax.servlet.ServletConfig).
void	destroy()
protected boolean	doResponseRedirectOrNotModifiedLogic(HttpServletRequest servletRequest, HttpServletResponse servletResponse, org.apache.http.HttpResponse proxyResponse, int statusCode)
protected static CharSequence	encodeUriQuery(CharSequence in) Encodes characters in the query or fragment part of the URI.
ServletConfig	getServletConfig()
void	init(ServletConfig servletConfig)
protected void	readConfigParam(org.apache.http.params.HttpParams hcParams, String hcParamName, Class type)
protected String	rewriteUrlFromResponse(HttpServletRequest servletRequest, String theUrl) For a redirect response from the target server, this translates theUrl to redirect to and translates it to one the original client can use.
protected void	service(HttpServletRequest servletRequest, HttpServletResponse servletResponse)

Methods inherited from class java.lang.Object

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

Field Detail

P_LOG

public static final String P_LOG

A boolean parameter name to enable logging of input and target URLs to the servlet log.

See Also:

Constant Field Values

doLog

protected boolean doLog

targetUriObj

protected URI targetUriObj

targetUri

protected String targetUri

proxyClient

protected org.apache.http.client.HttpClient proxyClient

hopByHopHeaders

protected static final org.apache.http.message.HeaderGroup hopByHopHeaders

These are the "hop-by-hop" headers that should not be copied. http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html I use an HttpClient HeaderGroup class instead of Set because this approach does case insensitive lookup faster.

asciiQueryChars

protected static final BitSet asciiQueryChars

Constructor Detail

ProxyServlet

public ProxyServlet()

Method Detail

getServletConfig

public ServletConfig getServletConfig()

init

public void init(ServletConfig servletConfig)
          throws ServletException

Throws:

ServletException

createHttpClient

protected org.apache.http.client.HttpClient createHttpClient(org.apache.http.params.HttpParams hcParams)

Called from init(javax.servlet.ServletConfig). HttpClient offers many opportunities for customization.

readConfigParam

protected void readConfigParam(org.apache.http.params.HttpParams hcParams,
                   String hcParamName,
                   Class type)

destroy

public void destroy()

service

protected void service(HttpServletRequest servletRequest,
           HttpServletResponse servletResponse)
                throws ServletException,
                       IOException

Throws:

ServletException

IOException

doResponseRedirectOrNotModifiedLogic

protected boolean doResponseRedirectOrNotModifiedLogic(HttpServletRequest servletRequest,
                                           HttpServletResponse servletResponse,
                                           org.apache.http.HttpResponse proxyResponse,
                                           int statusCode)
                                                throws ServletException,
                                                       IOException

Throws:

ServletException

IOException

closeQuietly

protected void closeQuietly(Closeable closeable)

copyRequestHeaders

protected void copyRequestHeaders(HttpServletRequest servletRequest,
                      org.apache.http.HttpRequest proxyRequest)

Copy request headers from the servlet client to the proxy request.

copyResponseHeaders

protected void copyResponseHeaders(org.apache.http.HttpResponse proxyResponse,
                       HttpServletResponse servletResponse)

Copy proxied response headers back to the servlet client.

copyResponseEntity

protected void copyResponseEntity(org.apache.http.HttpResponse proxyResponse,
                      HttpServletResponse servletResponse)
                           throws IOException

Copy response body data (the entity) from the proxy to the servlet client.

Throws:

IOException

rewriteUrlFromResponse

protected String rewriteUrlFromResponse(HttpServletRequest servletRequest,
                            String theUrl)

For a redirect response from the target server, this translates theUrl to redirect to and translates it to one the original client can use.

encodeUriQuery

protected static CharSequence encodeUriQuery(CharSequence in)

Encodes characters in the query or fragment part of the URI.

Unfortunately, an incoming URI sometimes has characters disallowed by the spec. HttpClient insists that the outgoing proxied request has a valid URI because it uses Java's URI. To be more forgiving, we must escape the problematic characters. See the URI class for the spec.

Parameters:

in - example: name=value&foo=bar#fragment