HttpServletRequest学习

package cn.request;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.InvocationTargetException;
import java.util.Enumeration;
import java.util.Map;

import javax.servlet.Servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.apache.commons.beanutils.BeanUtils;

import cn.response.com.ResDemo2;

public class ReqDemo1 extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

			test8(request,response);
	}

	//利用requset 设置请求头 referer 放盗链
	private void test8(HttpServletRequest request, HttpServletResponse response) throws IOException {
		String data = "aaaa";
		String referer = request.getHeader("referer");
		
		if (referer == null || !referer.startsWith("http://localhost")) {
			response.sendRedirect("/Test/index.jsp");  // 如果不是从我的网站来请求的资源，那就跳到主页， 然胡再在主页提供连接再回来请求
		} else {
			response.getWriter().print(data);
		}
	}

	//跳转之前数据不能写给客户端     java.lang.IllegalStateException: Cannot forward after response has been committed
	//forward会清空response中的数据
	//请求转发特点： 1： 客户端只发送一次请求，而服务端会产生多个资源的调用 2：客户机地址栏没有变化
				
	private void test7(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
		String data = "aa";
		PrintWriter pw = response.getWriter();
		pw.write(data);
		pw.close();
		
		request.getRequestDispatcher("/Test/index.jsp").forward(request, response);
		
	}

	//request的请求转发   实现MVC框架的设计思想
	private void test6(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String data = "aaa";
		HttpSession session = request.getSession();
		session.setAttribute("data", data);
		request.getRequestDispatcher("index.jsp").forward(request, response);
	}


	//解决中文乱码问题
	private void test5(HttpServletRequest request) throws UnsupportedEncodingException {
		/*request.setCharacterEncoding("UTF-8");  //只对post提交有效
		String name = request.getParameter("name");
		System.out.println("name = " + name);*/
		
		//手工解决都get post 都可以..   
		String name = request.getParameter("name");
		String myName = new String(name.getBytes("ISO-8859-1"),"UTF-8");
		System.out.println("myName = " + myName);
	}
	
	//利用request收集用户提交的数据
	private void test4(HttpServletRequest request) {
		String username = request.getParameter("username");
		System.out.println("username = " + username);
		
		String password = request.getParameter("password");
		System.out.println("password = " + password);
		
		String gender = request.getParameter("gender");
		System.out.println("gender = " + gender);
		
		String address = request.getParameter("address");
		System.out.println("address = " + address);
		
		String[] likes = request.getParameterValues("likes");
		for (int i = 0; likes != null && i < likes.length; ++i) {
			System.out.println("likes :" + likes[i]);
		}
		
		String des = request.getParameter("des");
		System.out.println("des = " + des);
		
		
		String id = request.getParameter("id");
		System.out.println("id = " + id);
	}
	
	//获得请求数据
    private void test3(HttpServletRequest request) {
		String name1 = request.getParameter("name");
		
		Enumeration<String> e = request.getParameterNames();
		while (e.hasMoreElements()) {
			String name = e.nextElement();
			String value = request.getParameter(name);
			System.out.println("name = " + name + " value = " + value);
		}
		String[] v = request.getParameterValues("name");
		for (int i = 0; v != null && i < v.length; ++i) {
			System.out.println(v[i]);
		}
		Map<String, String[]> entity = request.getParameterMap();
		User u = new User();
		//这样可以利用BeanUtils 简单操作
		try {
			BeanUtils.populate(u, entity);
		} catch (IllegalAccessException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		} catch (InvocationTargetException e1) {
			// TODO Auto-generated catch block
			e1.printStackTrace();
		}
	}
    
	//获取请求头
	private void test2(HttpServletRequest request) {
		String headValue = request.getHeader("Accept-Encoding");
		System.out.println(headValue);
		
		Enumeration<String> e = request.getHeaders("Accept-Encoding");
		while (e.hasMoreElements()) {
			String value = e.nextElement();
			System.out.println(value);
		}
		
		e = request.getHeaderNames();
		while (e.hasMoreElements()) {
			String name = e.nextElement();
			String value = request.getHeader(name);
			System.out.println("name = " + name + "   value = " + value);
		}
	}

	//获得用户请求的URI和URL 可以实现用户权限的控制， 统计某个web资源被访问的次数
	private void test1(HttpServletRequest request) {
		System.out.println("URI : " + request.getRequestURI());
		System.out.println("URL : " + request.getRequestURL());
		http://localhost:8080/Test/ReqDemo1?name=gbx
		System.out.println("查询参数:　" + request.getQueryString());
		System.out.println("IP :" + request.getRemoteAddr());
		System.out.println("Port :" + request.getRemotePort());
		System.out.println("Host :" + request.getRemoteHost());
		System.out.println("客户机请求方式 ：" + request.getMethod());
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}

class User{
	
}

　　

这里是测试request手机数据时的jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <meta http-equiv="content-tyoe"  content="text/html; charset=UTF-8">
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
    	<form action="/Test/ReqDemo1" method="post">
    		用户名： <input type="text" name="username"> <br/>
    		密码： <input type="password" name="password"> <br/>
    		性别 : <input type="radio" name="gender" value="男"><br/>
    			  <input type="radio" name="gender" value="女"><br/>
    	           住址： <select name="address">
    	            <option value="bj">北京</option>
    	           	<option value="sd">山东</option>
    	          </select> <br/>
    	    
    	          爱好： <input type="checkbox" name="likes" value="bas">篮球
    	          <input type="checkbox" name="likes" value="sing">唱歌
    	          <input type="checkbox" name="likes" value="dance">跳舞
    	    	  <br/>
    	    	  <input type="hidden" name = "id" value="123"> <br/>
    	    	  
    	         简介：<textarea rows="6" cols="60" name="des"></textarea><br/>	  
    	         照片: <input type="file" name="image"><br/>
    	             
    	         <input type="submit" value="提交">
    	</form>
  </body>
  
</html>

　　

利用Http头的referer 实现图片的防盗链， 不是本网张的不给显示

jsp

 <body>
  		<img alt="" src="/Test/ImgServlet?filename=1.jpg">
  </body>

　　

Servlet

package cn.request;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;

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

public class ImgServlet extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String referer = request.getParameter("referer");
		//如果非法就不给资源
		if (referer == null || !referer.startsWith("http://localhost")) {
			return ;
			
		} else  {  //合法
			String filename = request.getParameter("filename");
			System.out.println(referer + " " + filename);
			String path = this.getServletContext().getRealPath("/download/" + filename);
			System.out.println("path : " + path);
			InputStream in = new FileInputStream(path);
			OutputStream out = response.getOutputStream();
			int len = 0;
			byte[] buf = new byte[1024];
			while ((len = in.read(buf)) > 0){
				out.write(buf, 0, len);
			}
		}
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

}