struts的一个简单的包含select下拉框的例子-JSP教程,资料/其它

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</p> <p>
*@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.mainet.core.spreadsheet.db.menustreetable;
import com.mainet.core.spreadsheet.projectfactory;

/**
*  copyright: copyright (c) 2002</p> <p>
*@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("success");
  }
}

———————————————–

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
*  <tt><html:select></tt> and <tt><html:option></tt> tags.</p> <p>
*@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:)
<html:select property="type">
  <html:options collection="appnames" property="id"
                   labelproperty="displayname"/>
</html:select>

搞定！