sampledatatag1.java

这是一个mvc模式

package jsp.tags.dapact.samples;

import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.jsp.JspException;
import jsp.tags.dapact.BaseBodyTagSupport;
import jsp.tags.dapact.lookup.DefaultSelectOption;
import jsp.tags.dapact.tags.data.RetrieveValueByNameInf;
/**
 * 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@
 */

/**
 * Simple data tag used to demonstrate use of data tags with other tags in the system.
 * It does not retrieve its data from anywhere useful (it is all hard coded), other
 * tags will demonstrate more robust data retrieval. This tag responds to the same
 * keys as SampleDataTag2, but returns different values.
 *
 * <p>Supports the following names:<br />
 *   <ul>
 *     <li><b>test1</b> - returns a single string.</li>
 *     <li><b>test2</b> - returns a single string.</li>
 *     <li><b>optionlist1</b> - returns an array of DefaultSelectOption.</li>
 *     <li><b>optionlist2</b> - returns an ArrayList of DefaultSelectOption.</li>
 *     <li>Default string - if the name is not reconized, it returns a single default string.
 *     Please note, that you should never really do this (there is a great example in the
 *     select tag that demonstrates why). You should return null if you do not understand
 *     what is being asked for so that another tag or data source can respond.</li>
 *   </ul>
 * </p>
 */
public class SampleDataTag1 extends BaseBodyTagSupport implements RetrieveValueByNameInf
{
  /**
   * Default constructor...
   */
  public SampleDataTag1()
  {
  }

  /**
   * Called by objects that want to request a value by its name.
   *
   * @param requestor the object requesting the value or the object that the value
   *   is being requested for (like with a lookup: you would pass the TagSupport
   *   object, not the lookup which is what actually calls this function).
   * @param name the name of the value to retrieve.
   *
   * @return the value that was found by the name supplied.
   */
  public Object retrieveValueByName(Object requestor, String name)
  {
    Object result = null;
    if (name != null)
    {
      if (name.equals("test1"))
      {
        result = "test one found - from data 1";
      }
      else if (name.equals("test2"))
      {
        result = "test two found - from data 1";
      }
      else if (name.equals("optionlist1"))
      {
        DefaultSelectOption[] list = new DefaultSelectOption[10];
        for (int i=0; i < 10; i++)
        {
          list[i] = (new DefaultSelectOption("val" + i, "Text List 1 - Data 1 - Option " + i));
        }
        result = list;
      }
      else if (name.equals("optionlist2"))
      {
        ArrayList list = new ArrayList();
        for (int i=0; i < 10; i++)
        {
          list.add(new DefaultSelectOption("val" + i, "Text List 2 - Data 1 - Option " + i));
        }
        result = list;
      }
      else
      {
        result = "test default";
      }
    }
    return result;
  }

  /**
   * Called at the end of the tag. Will output the end body tag text and return that
   * it wants to have the rest of the page processed.
   *
   * @exception JspException general JSP exception.
   *
   * @return EVAL_PAGE so that it continues to process the rest of the page.
   */
  public int doEndTag() throws JspException
  {
    // Write out the result of the body tags.
    try
    {
      try
      {
        getBodyContent().writeOut(getPreviousOut());
      }
      catch (NullPointerException e)
      {}
    }
    catch (IOException e)
    {
      e.printStackTrace();
      throw new JspException(e.toString());
    }
    return super.doEndTag();
  }

  /*=============================================================================*/
  /*                           PROPERTIES/ATTRIBUTES                             */
  /*=============================================================================*/
  /**
   * @return Get the name of the object to see if we should use it to look up values.
   */
  public String getName()
  {
    return name;
  }
  /**
   * Set the name of the object to see if we should use it to look up values.
   */
  public void setName(String name)
  {
    this.name = name;
  }
  private String name;
}