encoding

/**
*
*/
package com.huawei.cloud.util.encondFilter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

/**
* <p>
* Example filter that sets the character encoding to be used in parsing the
* incoming request, either unconditionally or only if the client did not
* specify a character encoding. Configuration of this filter is based on
* the following initialization parameters:
* </p>
* <ul>
* <li><strong>encoding</strong> - The character encoding to be configured
* for this request, either conditionally or unconditionally based on the
* <code>ignore</code> initialization parameter. This parameter is
* required, so there is no default.</li>
* <li><strong>ignore</strong> - If set to "true", any character encoding
* specified by the client is ignored, and the value returned by the
* <code>selectEncoding()</code> method is set. If set to "false,
* <code>selectEncoding()</code> is called <strong>only</strong> if the
* client has not already specified an encoding. By default, this parameter
* is set to "true".</li>
* </ul>
*
* <p>
* Although this filter can be used unchanged, it is also easy to subclass
* it and make the <code>selectEncoding()</code> method more intelligent
* about what encoding to choose, based on characteristics of the incoming
* request (such as the values of the <code>Accept-Language</code> and
* <code>User-Agent</code> headers, or a value stashed in the current
* user's session.
* </p>
*
* @author Craig McClanahan
* @version $Revision: 1.1 $ $Date: 2008/04/23 14:24:22 $
*/

public class EncondFilter implements Filter {

// ----------------------------------------------------- Instance
// Variables

/**
* The default character encoding to set for requests that pass through
* this filter.
*/
protected String encoding = null;

/**
* The filter configuration object we are associated with. If this value
* is null, this filter instance is not currently configured.
*/
protected FilterConfig filterConfig = null;

/**
* Should a character encoding specified by the client be ignored?
*/
protected boolean ignore = true;

// --------------------------------------------------------- Public
// Methods

/**
* Take this filter out of service.
*/
public void destroy() {

this.encoding = null;

this.filterConfig = null;

}

/**
* Select and set (if specified) the character encoding to be used to
* interpret request parameters for this request.
*
* @param request
*            The servlet request we are processing
* @param result
*            The servlet response we are creating
* @param chain
*            The filter chain we are processing
*
* @exception IOException
*                if an input/output error occurs
* @exception ServletException
*                if a servlet error occurs
*/
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {

// Conditionally select and set the character encoding to be used

if (ignore || (request.getCharacterEncoding() == null)) {

String encoding = selectEncoding(request);

if (encoding != null)

request.setCharacterEncoding(encoding);

}

// Pass control on to the next filter

chain.doFilter(request, response);

}

/**
* Place this filter into service.
*
* @param filterConfig
*            The filter configuration object
*/
public void init(FilterConfig filterConfig) throws ServletException {

this.filterConfig = filterConfig;

this.encoding = filterConfig.getInitParameter("encoding");

String value = filterConfig.getInitParameter("ignore");

if (value == null)

this.ignore = true;

else if (value.equalsIgnoreCase("true"))

this.ignore = true;

else if (value.equalsIgnoreCase("yes"))

this.ignore = true;

else

this.ignore = false;

}

// ------------------------------------------------------ Protected
// Methods

/**
* Select an appropriate character encoding to be used, based on the
* characteristics of the current request and/or filter initialization
* parameters. If no character encoding should be set, return
* <code>null</code>.
* <p>
* The default implementation unconditionally returns the value
* configured by the <strong>encoding</strong> initialization parameter
* for this filter.
*
* @param request
*            The servlet request we are processing
*/
protected String selectEncoding(ServletRequest request) {

return (this.encoding);

}

}