struts的一个简单的包含select下拉框的例子

首先，当然是需要你先对struts有一定的了解：）

1. 定义相应页面(client.jsp)的form bean，这里假设为ClientForm；注意在struts_config.xml中定义映射关系；client.jsp中包含了你需要的html form内容，比如一个select下拉框；

这里是form bean的代码（其实就是一个java bean，继承了ActionForm，然后需要重载reset和validate方法）：
-----------------------------------------------
package com.egi.core.ioblock.form;

import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;

/**
*  Copyright: Copyright (c) 2002

*@author     sjoy
*@created    2003年6月4日
*@version    1.0
*/

public class LoginForm extends ActionForm {

  //-----------------------------Instance Variable
  private String appName = null;
  private String type = null;

  public String getAppName() {
    return appName;
  }

  public void setAppName(String appName) {
    this.appName = appName;
  }

  public String getType() {
    return type;
  }

  public void setType(String type) {
    this.type = type;
  }

  public void reset(ActionMapping mapping, HttpServletRequest request) {
    appName = null;
    type = null;
  }

  public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) {

    ActionErrors errors = new ActionErrors();
    if (appName == null || appName.length() < 1) {
      errors.add("application name", new ActionError("error.appname.required"));
    }
    return errors;
  }
}
-----------------------------------------------


这里是ActionServlet代码，继承Action：
-----------------------------------------------
package com.egi.core.ioblock.action;

import java.io.IOException;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionForward;
import com.egi.core.ioblock.form.LoginForm;
import com.ma.net.core.spreadsheet.db.MenusTreeTable;
import com.mainet.core.spreadsheet.ProjectFactory;

/**
*  Copyright: Copyright (c) 2002

*@author     sjoy
*@created    2003年6月4日
*@version    1.0
*/

public class LoginAction extends Action {

  public ActionForward perform(ActionMapping mapping,
      ActionForm form,
      HttpServletRequest request,
      HttpServletResponse response)
   throws IOException, ServletException {

    ActionErrors errors = new ActionErrors();
    String appName = ((LoginForm) form).getAppName();
    
    //下面是你所需要的一些逻辑
    ...
    HttpSession session = request.getSession();
    ...
    
    return mapping.findForward("suclearcase/" target="_blank" >ccess");
  }
}

-----------------------------------------------


2. 写一个bean，专门用来保存select的option集合。代码如下：
-----------------------------------------------
package com.egi.core.ioblock.util;

import java.io.Serializable;

/**
*  Description: This class is a bean, used to represent one option in an HTML
*  drop-down ''select'' list. It contains two properties - see {@link
*  getDisplayName()} and {@link getInternalId()} for a description. Useful in a
*  struts Form class for constructing a select list to pass to the jsp with the
*   and tags.

*@author     sjoy
*@created    2003年6月4日
*@version    1.0
*/

public class HtmlSelectOption implements Serializable {
  private String id;
  private String displayName;

  /**
   *  Constructor for the HtmlSelectOption object
   */
  public HtmlSelectOption() { }

  /**
   *  Constructor for the HtmlSelectOption object
   *
   *@param  id           Description of the Parameter
   *@param  displayName  Description of the Parameter
   */
  public HtmlSelectOption(String id, String displayName) {
    this.id = id;
    this.displayName = displayName;
  }

  public String getDisplayName() {
    return displayName;
  }

  public void setDisplayName(String displayName) {
    this.displayName = displayName;
  }

  public String getId() {
    return id;
  }

  public void setId(String id) {
    this.id = id;
  }
}
-----------------------------------------------

3. ok，接下来从db或者其它地方去取下拉列表中的具体内容；
java.util.Iterator iter = ....;//这里假设从数据库中取得数据
java.util.ArrayList list = new java.util.ArrayList();
String obj;
while(iter.hasNext()){
  obj = (String)iter.next();
  list.add(new com.egi.core.ioblock.util.HtmlSelectOption(obj,obj));
}
pageContext.setAttribute("appNames", list);

注意：这段逻辑也可以写在ClienetForm中通过javabean的方式在页面上获得这个集合。

4. 然后就是页面上使用啦:)

                     labelProperty="displayName"/>


搞定！

原文转自：http://www.ltesting.net