struts的一個容易的包含select下拉框的例子
發(fā)表時間:2023-07-23 來源:明輝站整理相關(guān)軟件相關(guān)文章人氣:
[摘要]首先,當(dāng)然是需要你先對struts有一定的了解:)1. 定義相應(yīng)頁面(client.jsp)的form bean,這里假設(shè)為ClientForm;注意在struts_config.xml中定義映射關(guān)...
首先,當(dāng)然是需要你先對struts有一定的了解:)
1. 定義相應(yīng)頁面(client.jsp)的form bean,這里假設(shè)為ClientForm;注意在struts_config.xml中定義映射關(guān)系;client.jsp中包含了你需要的html form內(nèi)容,比如一個select下拉框;
這里是form bean的代碼(其實就是一個java bean,繼承了ActionForm,然后需要重載reset和validate方法):
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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
*@created2003年6月4日
*@version1.0
*/
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;
}
}
-----------------------------------------------
這里是ActionServlet代碼,繼承Action:
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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
*@created2003年6月4日
*@version1.0
*/
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邏輯
...
HttpSession session = request.getSession();
...
return mapping.findForward("success");
}
}
-----------------------------------------------
2. 寫一個bean,專門用來保存select的option集合。代碼如下:
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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
*@created2003年6月4日
*@version1.0
*/
public class HtmlSelectOption implements Serializable {
private String id;
private String displayName;
/**
*Constructor for the HtmlSelectOption object
*/
public HtmlSelectOption() { }
/**
*Constructor for the HtmlSelectOption object
*
*@paramid Description of the Parameter
*@paramdisplayNameDescription 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,接下來從db或者其它地方去取下拉列表中的具體內(nèi)容;
java.util.Iterator iter = ....;//這里假設(shè)從數(shù)據(jù)庫中取得數(shù)據(jù)
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:這段邏輯也可以寫在ClienetForm中通過javabean的方式在頁面上獲得這個集合。
4. 然后就是頁面上使用啦:)
<html:select property="type">
<html:options collection="appNames" property="id"
labelProperty="displayName"/>
</html:select>
搞定!