技术开发 频道

运用类反射机制简化Struts应用程序开发

【IT168 技术文档】1、 先定义Action FormBean:

package com.bhsky.webis.system; import org.apache.struts.action.*; import javax.servlet.http.*; public class UsersActionForm extends ActionForm { private String usr_id; private String usr_name; public void setUsr_id(String usr_id) { this.usr_id = usr_id; } public String getUsr_id() { return usr_id; } public String getUsr_memo() { return usr_memo; } public void setUsr_name(String usr_name) { this.usr_name = usr_name; } }

2、 编写通用的为ActionFormBean赋值的方法:

//Function: 完成ResultSet对象向ArrayList对象为集合的对象的转化 //Para:sql,指定的查询Sql //Para:className,Sql相对应得JavaBean/FormBean类的名字 //Return:以类className为一条记录的结果集, //完成ResultSet对象向ArrayList对象为集合的className对象的转化 public ArrayList Select(String sql,String className){ ArrayList paraList=new ArrayList(); try{ if (conn == null){ Connection(); } PreparedStatement stmt = conn.prepareStatement(sql); ResultSet rs = stmt.executeQuery(); String recordValue=""; Object c1=null; paraList=new ArrayList(); ResultSetMetaData rsmd = rs.getMetaData(); int columnCount = rsmd.getColumnCount(); while (rs.next()){ c1=Class.forName(className).newInstance(); for (int i=1; i<=columnCount; i++) { if(rs.getString(rsmd.getColumnName(i))!=null){ recordValue=rs.getString(rsmd.getColumnName(i)); }else{ recordValue=""; } Method m=c1.getClass().getMethod(getSetMethodName(rsmd.getColumnName(i)), new Class[]{recordValue.getClass()}); m.invoke (c1, new Object[]{recordValue}); } paraList.add(c1); } }catch(SQLException ex){ }catch(ClassNotFoundException e){ }catch(NoSuchMethodException e) { }catch(InvocationTargetException e){ }catch (IllegalAccessException e){ }catch(InstantiationException e){ } finaly{ closeConnection(); return paraList; } }

3、 在JavaBean封装的商业逻辑中调用Select 方法,然后在JSP页面上显示出来:

//Function:取得用户列表 //Para: //Return:返回用户列表 public ArrayList getUsers(){ ArrayList ret=null; DatabaseManage db=new DatabaseManage(); String sql=" select usr_id,usr_name " +" from users " ; ret=db.Select(sql," com.bhsky. webis.system.UsersActionForm"); return ret; }


 

4、 在Action的execute方法中调用getUsers()方法:

public ActionForward execute(ActionMapping actionMapping, ActionForm actionForm, HttpServletRequest request, HttpServletResponse httpServletResponse) { /**@todo: complete the business logic here, this is just a skeleton.*/ UsersActionForm uaf=(UsersActionForm)actionForm; SystemService ubb=new SystemService(); ArrayList userList=ubb.getUsers(); request.setAttribute("userList",userList); ActionForward actionForward=actionMapping.findForward(url); return actionForward; }

 

5、 在JSP中显示:

<table width="700" class="1" border="1" cellspacing="1" align="center"> <tr> <td class="list" >用户ID</td> <td class="list" >&#160&#160名</td> </tr> <logic:present name="userList" scope="request"> <logic:iterate name="userList" id="userList" type="com.bhsky.webis.system.UsersActionForm"> <tr> <td class="cell1" height="22"><bean:write name="userList" property="usr_id"/></td> <td class="cell1" height="22"><bean:write name="userList" property="usr_name"/></td> </tr> </logic:iterate> </logic:present> </table>
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