权限校验

<%@ page pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<title>Insert title here</title>
</head>
<body>
	<form action="${pageContext.request.contextPath}/login" method="post"> 
		<h2>登陆页面</h2>
		用户名：<input name="name" value="磨时间"/> <br/><br/>
		密 码：<input name="pwd" type="password" value="123456"/> <br/><br/>
		<input value="提交" type="submit"/> <br/><br/>
	</form>
</body>
</html>

欢迎大家来到IT世界,在知识的湖畔探索吧!

欢迎大家来到IT世界,在知识的湖畔探索吧!@SuppressWarnings("serial")
@WebServlet(urlPatterns= {"/login","/logout"})
public class LoginServlet extends HttpServlet{
	@Override
	protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		String path = req.getServletPath();
		if("/login".equals(path)) {
			doLogin(req,resp);
		}else if("/logout".equals(path)){
			doLogout(req,resp);
		}
	}
	
	private void doLogout(HttpServletRequest req, HttpServletResponse resp) throws IOException {
		req.getSession().invalidate();
		resp.sendRedirect("index.html");
		
	}

	protected void doLogin(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//获取请求参数方法1
		String name = req.getParameter("name");
		String pwd = req.getParameter("pwd");
		//获取请求参数方法2
		Map<String, String[]> map = req.getParameterMap();
		for(Entry<String, String[]> entry : map.entrySet()) {
			System.out.println(entry.getKey() + " -- " + entry.getValue()[0]);
		}
		//获取请求参数方法3
		Enumeration<String> names = req.getParameterNames();
		System.out.println(names.nextElement());
		
    //  这就是演示 可以自己改  随意写的
		if("磨时间".equals(name) && "123456".equals(pwd)) {
			req.getSession().setAttribute("name", name);
			resp.sendRedirect("admin/success.jsp");
		}else {
			resp.sendRedirect("login.jsp");
		}
		
//		resp.getWriter().print("<h1>请求参数：" + name + " -- " + pwd + "</h1>");
	
	}

}

过滤器添加权限

public class LoginFilter implements Filter{
	
	@Override
	public void destroy() {
	}

	@Override
	public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
			throws IOException, ServletException {
		//1.获取Session
		HttpServletRequest req = (HttpServletRequest)arg0;
		HttpServletResponse resp = (HttpServletResponse)arg1;
		
		HttpSession session = req.getSession();
		//2.通过Session获取name绑定值
		Object obj = session.getAttribute("name");
		//3.判断name是否为null，为空跳转到登陆页面
		if(obj==null) {
			resp.sendRedirect("/login.jsp");
			return;
		}
		//4.判断name是否不为null，放行
		arg2.doFilter(arg0, arg1);
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
	}

}

配置 web.xml

欢迎大家来到IT世界,在知识的湖畔探索吧!  <filter>
  	<filter-name>EncodingFilter</filter-name>
  	<filter-class>cn.xxxx.filter.EncodingFilter</filter-class>
  	<init-param>
  		<param-name>encoding</param-name>
  		<param-value>UTF-8</param-value>
  	</init-param>
  </filter>
  <filter-mapping>
  	<filter-name>EncodingFilter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>
     <filter>
  	<filter-name>LoginFilter</filter-name>
  	<filter-class>cn.xxxx.filter.LoginFilter</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>LoginFilter</filter-name>
  	<url-pattern>/admin/*</url-pattern><!-- 约定大于配置，那些路径下才过滤，那些不过滤 -->
  </filter-mapping>

这里要多加注意

字符编码

@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)
			throws IOException, ServletException {
	String encoding = config.getInitParameter("encoding");
	req.setCharacterEncoding(encoding);
	resp.setContentType("text/html;charset=UTF-8");
	chain.doFilter(req, resp);
}
@Override
public void init(FilterConfig config) throws ServletException {
	this.config = config;
}

web.xml

<filter>
  	<filter-name>encodingFilter</filter-name>
  	<filter-class>cn.laonian.filter.EncodingFilter</filter-class>
  	<init-param>
  		<param-name>encoding</param-name>
  		<param-value>UTF-8</param-value>
  	</init-param>
</filter>
<filter-mapping>
  	<filter-name>encodingFilter</filter-name>
  	<url-pattern>/*</url-pattern>
</filter-mapping>

字符过滤

//接收前端数据的功能增强
public class MyHttpServletRequest extends HttpServletRequestWrapper{
	private HttpServletRequest req;

	public MyHttpServletRequest(HttpServletRequest req) {
		super(req);
		this.req = req;
	}
	
//到时在Servlet获取请求参数的时候实际上调用的是这个方法，名字可以自定义，但是最好一样，方便理解
	@Override
	public String getParameter(String name) {//常用
		Map<String, String[]> map = getParameterMap();
		String[] values = map.get(name);
		return values == null?null:values[0];
	}
	
//到时在Servlet获取请求参数的时候实际上调用的是这个方法，名字可以自定义，但是最好一样，方便理解
	@Override
	public Map<String, String[]> getParameterMap() {//用的比较少
		//获取请求参数
		Map<String, String[]> map = req.getParameterMap();
		//将敏感数据替换掉
		for(Entry<String, String[]> set : map.entrySet()) {
			String[] values = set.getValue();
//			for(String str : values) {//不能用这个，否则替换不了
//				str = str.replaceAll("傻逼", "***");
//			}
			for(int i = 0 ; i < values.length;i++ ) {
				//返回值是被替换的值
				values[i] = values[i].replaceAll("傻逼", "***");
			}
		}
		return map;
	}
	
//到时在Servlet获取请求参数的时候实际上调用的是这个方法，名字可以自定义，但是最好一样，方便理解
	@Override
	public String[] getParameterValues(String name) {//复选框
		return getParameterMap().get(name);
	}
}

过滤器

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
	MyHttpServletRequest req = new MyHttpServletRequest((HttpServletRequest) request);
	chain.doFilter(req, response);
}

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