filetag.java

基于netbeans的java桌面应用程序合集

/*
 * 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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 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
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 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
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 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
 *       "This product includes software developed by the 
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
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 *    Foundation" must not be used to endorse or promote products derived
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package org.apache.taglibs.standard.examples.taglib;

import java.io.*;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;

import org.apache.taglibs.standard.examples.util.*;

/**
 * <p>Tag handler for &lt;file&gt;
 *
 * @author Pierre Delisle
 * @version $Revision: 1.3 $ $Date: 2006/10/12 14:31:26 $
 */
public class FileTag extends TagSupport {
    
    //*********************************************************************
    // Instance variables
    
    private String id;
    private String file;
    
    private Reader reader;
    
    //*********************************************************************
    // Constructors
    
    public FileTag() {
        super();
        init();
    }
    
    private void init() {
        id = null;
        file = null;
    }
    
    //*********************************************************************
    // Tag's properties
    
    /**
     * Tag's 'id' attribute
     */
    public void setId(String id) {
        this.id = id;
    }
    
    /**
     * Tag's 'file' attribute
     */
    public void setfile(String file) {
        this.file = file;
    }
    
    //*********************************************************************
    // TagSupport methods
    
    public int doStartTag() throws JspException {
        reader = getReaderFromFile(file);
        exposeVariable(reader);
        return EVAL_BODY_INCLUDE;
    }
    
    public int doEndTag() throws JspException {
        try {
            reader.close();
        } catch (IOException ex) {}
        reader = null;
        return EVAL_PAGE;
    }
    
    /**
     * Releases any files we may have (or inherit)
     */
    public void release() {
        super.release();
        init();
    }
    
    //*********************************************************************
    // Tag's specific behavior methods
    
    public Reader getReaderFromFile(String name) throws JspException {
        InputStream in = pageContext.getServletContext().
            getResourceAsStream(name);
        if (in == null) {
            throw new JspException("Could not access " + name);
        }

        return new InputStreamReader(in);
    }

    
    //*********************************************************************
    // Utility methods
        
    private void exposeVariable(Reader reader) {
        if (id != null) {
            pageContext.setAttribute(id, reader);
        }
    }
}