Servlet中的技术

1.防盗链

 

String referer = request.getHeader("referer"); if(referer==null || !referer.startsWith("http://localhost")){ response.sendRedirect("/jsp/index.jsp"); return; } response.setContentType("text/html;charset=UTF-8"); 

2.request获取头相关的方法

String value = request.getHeader("Accept-Encoding"); System.out.println(value); Enumeration e = request.getHeaders("Accept-Encoding"); e = request.getHeaderNames(); while(e.hasMoreElements()){ String name = (String) e.nextElement(); value = request.getHeader(name); System.out.println(name + "=" + value); } 

3.将请求的类封装到实体，用到Beanutils类

Map map = request.getParameterMap(); //beanutils User user = new User(); try { ConvertUtils.register(new Converter(){ public Object convert(Class type, Object value) { if(value==null || value.equals("")){ return null; } if(!(value instanceof String)){ throw new ConversionException("只支持string类型的转换！！"); } String s = (String) value; //9943-348u492 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); try { return sdf.parse(s); } catch (ParseException e) { throw new ConversionException(s + "不是一个合法的日期值"); } } }, Date.class); BeanUtils.populate(user, map); //birthday=1980-09-09 } catch (Exception e) { e.printStackTrace(); }  

4.获取客户端提交的表单数据，如select

String likes[] = request.getParameterValues("like"); for(int i=0;likes!=null && i<likes.length;i++){ System.out.println(likes[i]); } 

 

5.//提交数据的中文乱码问题

//request.setCharacterEncoding("UTF-8"); //解决post提交的问题 //解决get提交的问题 /*String username = request.getParameter("username"); username = new String(username.getBytes("iso8859-1"),"UTF-8"); System.out.println(username);*/ request.setCharacterEncoding("UTF-8"); String username = request.getParameter("username"); response.setCharacterEncoding("gb2312"); response.setContentType("text/html;charset=gb2312"); response.getWriter().write(username); //不会乱码 

6//用response的outputStream输出中文

//注意事项2 private void test4(HttpServletResponse response) throws UnsupportedEncodingException, IOException { response.setHeader("content-type", "text/html;charset=UTF-8"); response.getOutputStream().write((2+"").getBytes("UTF-8")); } //注意事项1 private void test3(HttpServletResponse response) throws UnsupportedEncodingException, IOException { response.setHeader("content-type", "text/html,charset=UTF-8"); String data = "中国"; byte b[] = data.getBytes("UTF-8"); response.getOutputStream().write(b); } //用meta标签模似一个http响应头，控制浏览器以u8打开 private void test2(HttpServletResponse response) throws UnsupportedEncodingException, IOException { //response.setHeader("content-type", "text/html;charset=UTF-8"); String data = "中国"; byte b[] = data.getBytes("UTF-8"); response.getOutputStream().write("<meta http-equiv='content-type' content='text/html;charset=UTF-8'>".getBytes()); response.getOutputStream().write(b); } private void test1(HttpServletResponse response) throws UnsupportedEncodingException, IOException { response.setHeader("content-type", "text/html;charset=UTF-8"); String data = "中国"; byte b[] = data.getBytes("UTF-8"); response.getOutputStream().write(b); } 

 

7.//实现文件下载（如果是中文文件名的话，在输出给客户机下载时，要记得url编码）

String path = this.getServletContext().getRealPath("/download/日本妞.jpg"); String filename = path.substring(path.lastIndexOf("//")+1); response.setHeader("content-disposition","attachment;filename=" + URLEncoder.encode(filename, "UTF-8")); FileInputStream in = new FileInputStream(path); int len = 0; byte buffer[] = new byte[1024]; OutputStream out = response.getOutputStream(); while((len=in.read(buffer))>0){ out.write(buffer, 0, len); } in.close(); 

8.//控制浏览器定时刷新

response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=UTF-8"); System.out.println("登陆成功！！"); this.getServletContext().setAttribute("message", "登陆成功！！本浏览器将在3秒后跳到首页，如果没有跳转，请点。。。。。<meta http-equiv='refresh' content='3;url=/day05/index.jsp'>"); this.getServletContext().getRequestDispatcher("/message.jsp").forward(request, response); /*response.getWriter().write("登陆成功！！<br/>"); response.getWriter().write("本浏览器将在3秒后跳到首页，如果没有跳转，请点。。。。。"); response.getWriter().write("<meta http-equiv='refresh' content='3;url=/day05/index.jsp'>");*/ 

9.//控制浏览器缓存

 

response.setDateHeader("expires", System.currentTimeMillis()+1000*3600);//缓存时间1小时 String data = "xxxxx"; response.getWriter().write(data); 

 

10.验证码的技术

1.

package cn.itcast.checkcode; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.IOException; import java.io.OutputStream; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ImageServlet extends HttpServlet { private static final int WIDTH = 130; private static final int HEIGHT = 30; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB); Graphics g = image.getGraphics(); setBackground(g); setBorder(g); drawRandomLine(g); String random = drawRandomNum((Graphics2D) g); request.getSession().setAttribute("checkcode", random); //把验证码作为session传递 //response.setHeader("content-type", "image/jpeg"); //Expires: -1 //Cache-Control: no-cache //Pragma: no-cache //下面的代码一定不能少 response.setDateHeader("Expires", -1); response.setHeader("Cache-Control", "no-cache"); response.setHeader("Pragma", "no-cache"); response.setContentType("image/jpeg"); OutputStream out = response.getOutputStream(); ImageIO.write(image, "jpg", out); } private void setBackground(Graphics g) { g.setColor(Color.WHITE); g.fillRect(0, 0, WIDTH, HEIGHT); } private void setBorder(Graphics g) { g.setColor(Color.BLUE); g.drawRect(1, 1, WIDTH-2, HEIGHT-2); } private void drawRandomLine(Graphics g) { g.setColor(Color.GREEN); for(int i=0;i<5;i++){ int x1 = new Random().nextInt(WIDTH); int y1 = new Random().nextInt(HEIGHT); int x2 = new Random().nextInt(WIDTH); int y2 = new Random().nextInt(HEIGHT); g.drawLine(x1, y1, x2, y2); } } //[/u4e00-/u9fa5] 30*3.14/180 private String drawRandomNum(Graphics2D g) { g.setColor(Color.RED); g.setFont(new Font("宋体",Font.BOLD,20)); String base = "/u7684/u4e00/u4e86/u662f/u6211/u4e0d/u5728/u4eba/u4eec/u6709/u6765/u4ed6/u8fd9/u4e0a/u7740/u4e2a/u5730/u5230/u5927/u91cc/u8bf4/u5c31/u53bb/u5b50/u5f97/u4e5f/u548c/u90a3/u8981/u4e0b/u770b/u5929/u65f6/u8fc7/u51fa/u5c0f/u4e48/u8d77/u4f60/u90fd/u628a/u597d/u8fd8/u591a/u6ca1/u4e3a/u53c8/u53ef/u5bb6/u5b66/u53ea/u4ee5/u4e3b/u4f1a/u6837/u5e74/u60f3/u751f/u540c/u8001/u4e2d/u5341/u4ece/u81ea/u9762/u524d/u5934/u9053/u5b83/u540e/u7136/u8d70/u5f88/u50cf/u89c1/u4e24/u7528/u5979/u56fd/u52a8/u8fdb/u6210/u56de/u4ec0/u8fb9/u4f5c/u5bf9/u5f00/u800c/u5df1/u4e9b/u73b0/u5c71/u6c11/u5019/u7ecf/u53d1/u5de5/u5411/u4e8b/u547d/u7ed9/u957f/u6c34/u51e0/u4e49/u4e09/u58f0/u4e8e/u9ad8/u624b/u77e5/u7406/u773c/u5fd7/u70b9/u5fc3/u6218/u4e8c/u95ee/u4f46/u8eab/u65b9/u5b9e/u5403/u505a/u53eb/u5f53/u4f4f/u542c/u9769/u6253/u5462/u771f/u5168/u624d/u56db/u5df2/u6240/u654c/u4e4b/u6700/u5149/u4ea7/u60c5/u8def/u5206/u603b/u6761/u767d/u8bdd/u4e1c/u5e2d/u6b21/u4eb2/u5982/u88ab/u82b1/u53e3/u653e/u513f/u5e38/u6c14/u4e94/u7b2c/u4f7f/u5199/u519b/u5427/u6587/u8fd0/u518d/u679c/u600e/u5b9a/u8bb8/u5feb/u660e/u884c/u56e0/u522b/u98de/u5916/u6811/u7269/u6d3b/u90e8/u95e8/u65e0/u5f80/u8239/u671b/u65b0/u5e26/u961f/u5148/u529b/u5b8c/u5374/u7ad9/u4ee3/u5458/u673a/u66f4/u4e5d/u60a8/u6bcf/u98ce/u7ea7/u8ddf/u7b11/u554a/u5b69/u4e07/u5c11/u76f4/u610f/u591c/u6bd4/u9636/u8fde/u8f66/u91cd/u4fbf/u6597/u9a6c/u54ea/u5316/u592a/u6307/u53d8/u793e/u4f3c/u58eb/u8005/u5e72/u77f3/u6ee1/u65e5/u51b3/u767e/u539f/u62ff/u7fa4/u7a76/u5404/u516d/u672c/u601d/u89e3/u7acb/u6cb3/u6751/u516b/u96be/u65e9/u8bba/u5417/u6839/u5171/u8ba9/u76f8/u7814/u4eca/u5176/u4e66/u5750/u63a5/u5e94/u5173/u4fe1/u89c9/u6b65/u53cd/u5904/u8bb0/u5c06/u5343/u627e/u4e89/u9886/u6216/u5e08/u7ed3/u5757/u8dd1/u8c01/u8349/u8d8a/u5b57/u52a0/u811a/u7d27/u7231/u7b49/u4e60/u9635/u6015/u6708/u9752/u534a/u706b/u6cd5/u9898/u5efa/u8d76/u4f4d/u5531/u6d77/u4e03/u5973/u4efb/u4ef6/u611f/u51c6/u5f20/u56e2/u5c4b/u79bb/u8272/u8138/u7247/u79d1/u5012/u775b/u5229/u4e16/u521a/u4e14/u7531/u9001/u5207/u661f/u5bfc/u665a/u8868/u591f/u6574/u8ba4/u54cd/u96ea/u6d41/u672a/u573a/u8be5/u5e76/u5e95/u6df1/u523b/u5e73/u4f1f/u5fd9/u63d0/u786e/u8fd1/u4eae/u8f7b/u8bb2/u519c/u53e4/u9ed1/u544a/u754c/u62c9/u540d/u5440/u571f/u6e05/u9633/u7167/u529e/u53f2/u6539/u5386/u8f6c/u753b/u9020/u5634/u6b64/u6cbb/u5317/u5fc5/u670d/u96e8/u7a7f/u5185/u8bc6/u9a8c/u4f20/u4e1a/u83dc/u722c/u7761/u5174/u5f62/u91cf/u54b1/u89c2/u82e6/u4f53/u4f17/u901a/u51b2/u5408/u7834/u53cb/u5ea6/u672f/u996d/u516c/u65c1/u623f/u6781/u5357/u67aa/u8bfb/u6c99/u5c81/u7ebf/u91ce/u575a/u7a7a/u6536/u7b97/u81f3/u653f/u57ce/u52b3/u843d/u94b1/u7279/u56f4/u5f1f/u80dc/u6559/u70ed/u5c55/u5305/u6b4c/u7c7b/u6e10/u5f3a/u6570/u4e61/u547c/u6027/u97f3/u7b54/u54e5/u9645/u65e7/u795e/u5ea7/u7ae0/u5e2e/u5566/u53d7/u7cfb/u4ee4/u8df3/u975e/u4f55/u725b/u53d6/u5165/u5cb8/u6562/u6389/u5ffd/u79cd/u88c5/u9876/u6025/u6797/u505c/u606f/u53e5/u533a/u8863/u822c/u62a5/u53f6/u538b/u6162/u53d4/u80cc/u7ec6"; StringBuffer sb = new StringBuffer(); int x = 10; for(int i=0;i<4;i++){ String ch = base.charAt(new Random().nextInt(base.length()))+""; sb.append(ch); //写入字之前，设置好旋转 int degree = new Random().nextInt()%30; g.rotate(degree*Math.PI/180, x, 20); g.drawString(ch, x, 20); g.rotate(-degree*Math.PI/180, x, 20); x = x+30; } return sb.toString(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }  

2.

request.setCharacterEncoding("UTF-8"); //处理注册请求之前，校验认证码是否有效 String c_checkcode = request.getParameter("checkcode"); String s_checkcode = (String) request.getSession().getAttribute("checkcode"); if(c_checkcode!=null && s_checkcode!=null && c_checkcode.equals(s_checkcode)){ System.out.println("处理注册请求！！"); }else{ System.out.println("认证码错误！！"); } 

 

11.首页显示上次访问时间

 

response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=UTF-8"); PrintWriter out = response.getWriter(); //输出用户上次访问时间 out.write("您上次访问时间是："); Cookie cookies[] = request.getCookies(); for(int i=0;cookies!=null && i<cookies.length;i++){ Cookie cookie = cookies[i]; if(cookie.getName().equals("lastAccessTime")){ String value = cookie.getValue(); Date d = new Date(Long.parseLong(value)); out.write(d.toLocaleString()); } } //输出本次访问时间(lastAccessTime) Cookie cookie = new Cookie("lastAccessTime",System.currentTimeMillis()+""); cookie.setMaxAge(60*60); cookie.setPath("/day06"); response.addCookie(cookie); 

 

12.判断表单是否有效（是否重复提交）

1.//判断表单号是否有效 private boolean isTokenValid(HttpServletRequest request) { String client_token = request.getParameter("token"); if(client_token==null){ return false; } String server_token = (String) request.getSession().getAttribute("token"); if(server_token==null){ return false; } if(!client_token.equals(server_token)){ return false; } return true; }  

2..产生加密的令牌

//产生表单 public class FormServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //产生随机数（表单号） TokenProcessor tp = TokenProcessor.getInstance(); String token = tp.generateToken(); request.getSession().setAttribute("token", token); request.getRequestDispatcher("/form.jsp").forward(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } } class TokenProcessor{ //令牌 /* * 1.把构造方法私有 * 2.自己创建一个 * 3.对外暴露一个方法，允许获取上面创建的对象 */ private TokenProcessor(){} private static final TokenProcessor instance = new TokenProcessor(); public static TokenProcessor getInstance(){ return instance; } public String generateToken(){ //12121212 232323i23238923892 121232323232323239928392839283829382 String token = System.currentTimeMillis() + new Random().nextInt() + ""; try { MessageDigest md = MessageDigest.getInstance("md5"); byte[] md5 = md.digest(token.getBytes()); //base64编码 BASE64Encoder encoder = new BASE64Encoder(); return encoder.encode(md5); } catch (NoSuchAlgorithmException e) { throw new RuntimeException(e); } } } 

 

13..加上这段把Session提升为cookie级别，这样关闭浏览器也能浏览购买的商品

 

/*Cookie cookie = new Cookie("JSESSIONID",request.getSession().getId()); cookie.setMaxAge(60*60); cookie.setPath("/Mybabe"); response.addCookie(cookie);*/ 

14..对象访问其他的域

 

 

<title>pageContext对象访问其它域</title> </head> <body> <% request.setAttribute("data","aaa"); String data = (String)pageContext.getAttribute("data",PageContext.REQUEST_SCOPE); out.write(data); pageContext.findAttribute("data"); //page request session application 重点 %>