www.pudn.com > RFID_98798798698698.rar > SetCharacterEncodingFilter.java


/* 
 * $Header: /cvsfile/RFID/src/com/rfid/filters/SetCharacterEncodingFilter.java,v 1.1 2006/10/29 10:27:45 Administrator Exp $ 
 * $Revision: 1.1 $ 
 * $Date: 2006/10/29 10:27:45 $ 
 * 
 * ==================================================================== 
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 * The Apache Software License, Version 1.1 
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 * reserved. 
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 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
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package com.rfid.filters; 
 
 
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; 
import javax.servlet.UnavailableException; 
 
 
/** 
 * 
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:
 
 *  
 * 
 * 
Although this filter can be used unchanged, it is also easy to 
 * subclass it and make the selectEncoding() method more 
 * intelligent about what encoding to choose, based on characteristics of 
 * the incoming request (such as the values of the Accept-Language 
 * and User-Agent headers, or a value stashed in the current 
 * user's session.
 
 * 
 * @author Craig McClanahan 
 * @version $Revision: 1.1 $ $Date: 2006/10/29 10:27:45 $ 
 */ 
 
public class SetCharacterEncodingFilter 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 
     * null. 
     * 
 
     * The default implementation unconditionally returns the value configured 
     * by the encoding initialization parameter for this 
     * filter. 
     * 
     * @param request The servlet request we are processing 
     */ 
    protected String selectEncoding(ServletRequest request) { 
 
        return (this.encoding); 
 
    } 
 
 
}