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package com.cdut.math.web.servlet;

import java.util.Iterator;
import java.util.Set;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.io.SAXReader;

import com.cdut.math.utils.PermissionFactory;

public class InitPermissionServlet extends HttpServlet {

	public static final String ADMIN_PERMISSION = "admin_permission";
	public static final String TEACHER_PERMISSION = "teacher_permission";
	public static final String STUDENT_PERMISSION = "student_permission";

	@Override
	public void init() throws ServletException {

		try {
			// 解析document文档
			Document document = new SAXReader().read(Thread.currentThread()
					.getContextClassLoader()
					.getResourceAsStream("permissions.xml"));

			// 获取admin的权限
			Set<String> adminPermissions = new PermissionFactory()
					.readPermission(document
							.selectNodes("//permissions//admin//permission"));
			
			getServletContext()
					.setAttribute(ADMIN_PERMISSION, adminPermissions);

			// 获取teacher的权限
			Set<String> teacherRoles = new PermissionFactory()
					.readPermission(document
							.selectNodes("//permissions//teacher//permission"));
			getServletContext().setAttribute(TEACHER_PERMISSION, teacherRoles);

			// 获取学生的权限
			Set<String> studentPermissions = new PermissionFactory()
					.readPermission(document
							.selectNodes("//permissions//student//permission"));
			getServletContext().setAttribute(STUDENT_PERMISSION,
					studentPermissions);

		} catch (DocumentException e) {
			e.printStackTrace();
		}
		super.init();
	}

}