字符过滤器CharacterEncodingFilter和后端页面过滤器PageFilter

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 CharacterEncodingFilter在web容器中的注册：

<!-- 处理请求编码过滤器 配置和servlet一样 -->
  	<filter>
		<filter-name>CharacterEncodingFilter</filter-name>  	
		<filter-class>com.lin.linframework.sysmanage.filter.CharacterEncodingFilter</filter-class>
		<!-- 配置初始化参数 -->
		<init-param>
			<param-name>encoding</param-name>
			<param-value>UTF-8</param-value>
		</init-param>
  	</filter>
  	<!--  映射对应路径的java类 -->
  	<filter-mapping>
  		<filter-name>CharacterEncodingFilter</filter-name>
  		<!-- 匹配的servlet的别名   /* 表示对所有servlet起作用  /servlet表示对url-pattern 为servlet的起作用 -->
  		<url-pattern>/*</url-pattern>
  	</filter-mapping>

CharacterEncodingFilter的实现：

public class CharacterEncodingFilter implements Filter {
	
	//初始化私有变量FilterConfig 
	private FilterConfig filterConfig;
    @Override
	public void init(FilterConfig config) throws ServletException {
		this.filterConfig = config;
		System.out.println("filter....创建");
	}
	//ServletRequest 为HttpServletRequest 父类 重写子类重写
	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		//得到是配置在xml中的filter-param中的encoding值为UTF-8
		String encoding = filterConfig.getInitParameter("encoding");
		if(null != encoding && !encoding.equals("")){
			request.setCharacterEncoding(encoding);
			response.setCharacterEncoding(encoding);
			response.setContentType("text/html;charset=" + encoding);
		}
		System.out.println("filter....等待处理..");
		//把请求和响应继续带到下一个filter，如果没有就进入请求的servlet(下一步) 当前页所要跳转的页面	
		chain.doFilter(request,response);
	}
    @Override
	public void destroy() {
	}
}

后端页面过滤器PageFilter，即登入验证，在web容器中注册：

<!-- 过滤未登入请求后台 -->
  	<filter>
  		<description>未登入页面请求拦截</description>
  		<filter-name>pagesFilter</filter-name>
  		<filter-class>com.lin.linframework.sysmanage.filter.PagesFilter</filter-class>
  	</filter>
  	<!--  映射对应filter类  注意url-pattern 所有后台页面-->
  	<filter-mapping>
  		<filter-name>pagesFilter</filter-name>
  		<url-pattern>/pages/*</url-pattern>
  	</filter-mapping>

PageFilter的实现：

public class PagesFilter implements Filter {
	private FilterConfig filterConfig;
	
    @Override
	public void init(FilterConfig config) throws ServletException {
		this.filterConfig = config;
	}
	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		//得到httpservletrequest 只有子类HttpServlet 有getSession方法
		HttpServletRequest httpServletRequest = (HttpServletRequest) request;
		HttpServletResponse httpServletReponse = (HttpServletResponse) response;
		//得到session对象中设置的值
		String username = (String) httpServletRequest.getSession().getAttribute("userName");
		
		if( !StringUtils.isEmpty(username)){
			System.out.println("通过session验证.........");
			chain.doFilter(request, response);
		}else{
			System.out.println("未通过session验证........返回登入页面.....");
			//重定向路径  上一级 下的index.html
			httpServletReponse.sendRedirect("../login.jsp");
		}
	}
	
    @Override
	public void destroy() {

	}
}