tagutil.java

这是一个mvc模式

package jsp.tags.dapact.util;

import java.util.*;
import javax.servlet.jsp.tagext.TagSupport;
/**
 * Title:        Data Aware Processing And Control Tags
 * Description:  Tag library for the processing and controlling the input and output of data.
 * Copyright:    LGPL (http://www.gnu.org/copyleft/lesser.html)
 * Compile Date: @compile_date@
 * @author Allen M Servedio
 * @amp_sign@version @VERSION@
 */

/**
 * Utility class for the tag library - contains various utility functions.
 */
public class TagUtil
{
  /**
   * This is the character that should appear at the beginning of the attribute name
   * to hide the attribute from the output.
   */
  public static final char HIDE_ATTR_CHAR = '-';

  /**
   * Concatenates all attributes into attribute value pairs (separated by spaces)
   * and returns it as a string. It takes care of converting any double quotes into
   * " and it will not add any attributes that start with a minus sign (so that
   * custom attributes do not show up as attributes of the controls in HTML).
   *
   * @return a string of all attribute and value pairs in the following format:
   *   attr1="value1" attr2="value2"
   */
  protected static final String SPACE = " ";
  protected static final String EQUALS_QUOTE = "=\"";
  protected static final String QUOTE = "\"";
  public static final String getAllAttrAsStr(Enumeration attrNames, TagSupport tag)
  {
    StringBuffer result = new StringBuffer();
    while (attrNames.hasMoreElements())
    {
      // Build the name value pair and write it to the output stream.
      String key = (String)attrNames.nextElement();
      if ((key != null) && (key.length() > 0) && (key.charAt(0) != HIDE_ATTR_CHAR))
      {
        String value = null;
        try
        {
          value = (String)tag.getValue(key);
        }
        catch (ClassCastException e)
        {
          Object objVal = tag.getValue(key);
          value = objVal.toString();
        }
        if (value != null)
        {
          result.append(SPACE);
          result.append(key);
          result.append(EQUALS_QUOTE);
          result.append(makeStringAttrSafe(value));
          result.append(QUOTE);
        }
      }
    }

    return result.toString();
  }

  /**
   * Static function that takes a string and turns all double quotes in it ampersand quot;
   *
   * @param value the string to be converted.
   *
   * @return the string with all double quotes turned into amp quot;
   */
  public static final String makeStringAttrSafe(String value)
  {
    return replace(value, "\"", """);
  }

  /**
   * Static function that takes a string and turns all double quotes in it ampersand quot;
   *
   * @param value the string to be converted.
   *
   * @return the string with all double quotes turned into amp quot;
   */
  public static final String replace(String value, final String stringToMatch, final String replacementString)
  {
    if (value != null)
    {
      StringBuffer buff = null;
      int pos = 0;
      int lastpos = 0;
      while ((pos = value.indexOf(stringToMatch, lastpos)) > -1)
      {
        // Only create the buffer if we get this far...
        if (buff == null)
        {
          buff = new StringBuffer(value.length() + replacementString.length());
        }
        buff.append(value.substring(lastpos, pos));
        buff.append(replacementString);
        lastpos = pos + 1;
      }
      // Append the last part of the string to the return buffer.
      if (buff != null)
      {
        buff.append(value.substring(lastpos));
        value = buff.toString();
      }
    }
    return value;
  }

  /**
   * Examine an object and get one string value out of it.
   *
   * @param obj the object to examine.
   *
   * @return a string representing the object or null if that is what was passed in.
   */
  public static final String getStringFromObj(Object obj)
  {
    String result = null;
    if (obj != null)
    {
      if (obj instanceof String)
      {
        result = (String)obj;
      }
      else if (obj instanceof String[])
      {
        result = ((String[])obj)[0];
      }
      else
      {
        result = obj.toString();
      }
    }
    return result;
  }

  /**
   * For testing purposes....
   */
  public static void main(String[] args)
  {
  }
}