jspsecuritytag.java

J2EE独立开发制作

package com.presentation.viewhelper;
import javax.servlet.jsp.tagext.*;
import javax.servlet.jsp.*;
import java.util.*;
import org.xml.sax.*;
import org.xml.sax.helpers.*;
import org.w3c.dom.*;
import java.io.*;
import javax.xml.parsers.*;
public class JspSecurityTag extends BodyTagSupport {

  //保存从XML文件中取到角色和页面元素的对应集合
private static ArrayList roleList;

  //页面元素的名称

  private String elementName;
  public void setElementName(String str)
{
  this.elementName=str;
}

public int doAfterBody() throws JspException{
if(roleList==null)
{
  roleList=getList();
}

    try{

        //如果认证通过就显示标签正文，否则跳过标签正文，就这么简单

        if(isAuthentificated(elementName))

        {

          if(bodyContent != null){

            JspWriter out=bodyContent.getEnclosingWriter();

            bodyContent.writeOut(out);

          }else

          {

          }

        }

    }catch(Exception e){

      throw new JspException();

    }

    return SKIP_BODY;

  }

  //从XML配置文件中取到角色和页面元素的对应，保存到静态的ArrayList

  private ArrayList getList()

  {

    DocumentBuilderFactory dbf =

        DocumentBuilderFactory.newInstance();

    DocumentBuilder db = null;

    Document doc=null;

    NodeList childlist = null;

    String elementName;

    String roleName;

    int index;

    ArrayList theList = new ArrayList();


    try{

      db = dbf.newDocumentBuilder();

    }catch(Exception e)

    {

      e.printStackTrace();

    }

    try{

      doc = db.parse(new File("webapps/securitytag/security.xml"));

    }catch(Exception e)

    {

      e.printStackTrace();
      System.out.println(e);

    }

    //读取页面元素列表

    NodeList elementList = doc.getElementsByTagName("htmlElement");

    for(int i=0;i<elementList.getLength();i++)

    {

      Element name = ((Element)elementList.item(i));

      //页面元素的名称

      elementName = name.getAttribute("name");

      //该页面元素对应的有权限的角色的列表

      NodeList rolNodeList = ((NodeList)name.getElementsByTagName("roleName"));

      for(int j=0;j<rolNodeList.getLength();j++)

      {

        //有权限的角色的名称

        //roleName = ((Element)rolNodeList.item(j)).getNodeValue();

        roleName = ((Element)rolNodeList.item(j)).getAttribute("name");

        theList.add(new ElementAndRole(elementName,roleName));

      }

    }

    return theList;

  }


  //检查该角色是否有该页面元素的权限

  private boolean isAuthentificated(String elementName)

  {

String roleName = "";

//在用户登陆时把该用户的角色保存到SESSION中，这里只是直接从SESSION中取用//户角色。

roleName=(String)this.pageContext.getSession().getAttribute("rolename"); 
// roleList包含elementName属性为elementName，roleName属性为roleName的//ElementAndRole对象，则该角色有该页面元素的权限

     if(roleList.contains(new ElementAndRole(elementName,roleName)))

          {

               return true;

          }

    

    return  false;

  }

  //表示角色和页面元素的对应的关系的内部类

  class ElementAndRole{

    String elementName;

    String roleName;

    public ElementAndRole(String elementName,String roleName)

    {

      this.elementName=elementName;

      this.roleName=roleName;

    }

    public boolean equals(Object obj)

    {

      return(((ElementAndRole)obj).elementName.equals(this.elementName)&&((ElementAndRole)obj).roleName.equals(this.roleName));

    }

  }

}