JAVAWEB开发之HttpServletResponse和HttpServletRequest详解(下)（各种乱码、验证码、重定向和转发）

HttpServletRequest获取请求头信息

 （1）获取客户机请求头

String getHeader(String name)

Enumeration<String> getHeaders(String name)

Enumeration<String> getHeaderNames()

（2）获取具体类型客户机请求头

int  getIntHead（String name）

long getDateHead(String name) 日期对应毫秒

（3）常见的请求头

   referer  记住当前网页的内容，用于防盗链

   User-Agent   判断浏览器（MSIE IE浏览器，Firefox 火狐浏览器，Chrome 谷歌浏览器）

   if-modified-since   控制缓存

 防盗链案例

 // 遍历所有请求头信息Enumeration<String> names = request.getHeaderNames();while (names.hasMoreElements()) {String name = names.nextElement();System.out.println(name + ":" + request.getHeader(name));}System.out.println("-----------------------------------------");System.out.println("您使用浏览器：" + request.getHeader("user-agent"));String referer = request.getHeader("referer");// 判断referer是否存在和有效if (referer != null && referer.startsWith("http://localhost/day6")) {// 不属于盗链response.setContentType("text/html;charset=utf-8");response.getWriter().println("机密信息");} else {// 盗链response.setContentType("text/html;charset=utf-8");response.getWriter().println("您的请求是盗链");}

HttpServletRequest获取请求参数(以及POST或GET请求乱码解决方法)

String getParameter(String name)  通过name获取一个值

String[] getParameterValues(String name) 通过name获取多个值 checkbox

Enumeration getParameterNames() 获取所有请求参数的名称

Map<String,String[]> getParameterMap()   

可以提交请求的两种方式
1>.使用<form>
执行form的submit，提交form表单。
常用表单元素
<input type=[text | password | radio | checkbox | submit ]>
<select>…<option>
<textarea>
2>.使用URL链接
<a href="http://www.163.com?name=abc&password=123"> 点击链接 </a>
这样通过？可以提交参数，&用来分隔多个参数，
效果和<form>的GET方式相同
解决乱码问题：

（1）POST请求乱码

     request.setCharacterEncoding("UTF-8");

（2）GET请求乱码

   解决方案一：修改tomcat/conf/server.xml 
<Connector port="80" protocol="HTTP/1.1" 
 connectionTimeout="20000" 
 redirectPort="8443" URIEncoding="utf-8"/>
                                 * 必须有修改tomcat服务器配置文件权限
  解决方案二：逆向编码解码

      username = URLEncoder.encode(username,"ISO-8859-1");

      username = URLDecoder.decode(username,"UTF-8");

  解决方案三：简写的方式（推荐使用）

      username = new String(username.getBytes("ISO-8859-1"),"UTF-8");

  request获取中文数据乱码（总结：）
  post提交 设置request缓冲区的编码  request.setCharacterEncoding("utf-8"); 
  get提交  * String构造方法   username = new String(username.getBytes("ISO-8859-1"),"utf-8");
非空有效校验
if (username != null && username.trim().length() > 0) {
System.out.println("username 有效");
}else{
   // username 无效
}

URL特殊字符转义规则：

常用转义规则
空格换成加号(+) 
+换成%2B
正斜杠(/)分隔目录和子目录 换成%2F 
问号(?)分隔URL和查询 换成%3F 
百分号(%)制定特殊字符 换成%25 
#号指定书签  换成%23 
&号分隔参数  换成%26
java.net.URLEncoder和 java.net.URLDecoder

  

URL编码和解码
1) 浏览器提交一次请求，请求中中文字符，自动进行URL编码 （由浏览器完成）
2) web服务器接收到内容之后，自动URL解码 
URLEncoder 完成URL编码 ， URLDecoder 完成URL解码 

服务器端接收请求，请求url : http://localhost/day6/request3?name=aaa+bbb
问题：在服务器端执行 request.getParameter("name"); 值 aaa bbb

HttpServletRequest利用请求域传递对象

域对象：所知道的已经有两个域对象了

ServletContext：服务器一启动，为每个web应用创建一个ServletContext对象，所有servlet实例共享对象。
request：一次请求的范围。

request对象同时也是一个域对象，开发人员通过request对象在实现转发时，把数据通过request对象带给其它web资源处理
setAttribute方法 
getAttribute方法  
removeAttribute方法
getAttributeNames方法
request对象提供了一个getRequestDispatcher方法，该方法返回一个RequestDispatcher对象，调用这个对象的forward方法可以实现请求转发，从而共享请求中的数据

请求转发传递数据 
请求转发forward 和 请求重定向redirect 区别 ？？？ 
1) 转发一次请求 一次响应； 重定向两次请求 两次响应
2) 转发URL地址 不变，重定向URL地址改变第二个资源地址
3) 转发只能转发给同一个网站内部资源，重定向可以定向到任何网站 
4) 转发中/属于服务器内部路径 不写工程名，重定向/来自客户端必须要写工程名

创建RequestServlet4 RequestServlet5 
* 使两个Servlet连续执行 1) 重定向 2) 转发 
最佳应用：Servlet处理数据得到数据处理结果，通过请求转发，将处理结果传递JSP显示 
* Servlet处理数据获得结果，JSP负责数据显示 
request.setAttribute传递数据，必须要结合 request.getRequestDispatcher().forward 转发一起使用！！！

 请求重定向和请求转发的具体区别：

• RequestDispatcher.forward方法只能将请求转发给同一个WEB应用中的组件；而HttpServletResponse.sendRedirect方法还可以重定向到同一个站点上的其它应用程序中的资源，甚至是使用绝对URL重定向到其它站点的资源。
• 如果传递给HttpServletResponse.sendRedirect方法的相对URL以"/"开头，它相对于服务器的根目录；如果创建ResquestDispatcher对象时指定的相对URL以"/"开头，它是相对于当前WEB应用程序的根目录。
• 调用HttpServletResponse.sendRedirect方法重定向的访问过程结束后，浏览器地址栏中显示的URL会发生变化，由初始的URL地址变成重定向的目的URL；调用RequestDispatcher.forward方法的请求转发过程结束后，浏览器地址栏保持初始的URL地址不变。
• HttpServletResponse.sendRedirect方法对浏览器的请求直接作出响应，响应的结果就是告诉浏览器去重新发出对另外一个URL的访问请求；RequestDispatcher.forward方法在服务器端内部将请求转发给另外一个资源，浏览器只知道发出了请求并得到了响应结果，并不知道在服务器程序内部发生了转发行为。 
• RequestDispatcher.forward方法的调用者与被调用者之间共享相同的request对象和response对象，它们属于同一个访问请求和响应过程；而HttpServletResponse.sendRedirect方法调用者与被调用者使用各自的request对象和response对象，它们属于两个独立的访问请求和响应过程。 

代码案例：

项目的整体目录如下：

web.xml

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  <display-name></display-name>  <servlet>    <servlet-name>ErrorServlet</servlet-name>    <servlet-class>cn.itcast.servlet.ErrorServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>LoginServlet</servlet-name>    <servlet-class>cn.itcast.response.LoginServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>RefreshServlet</servlet-name>    <servlet-class>cn.itcast.response.RefreshServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>CEPServlet</servlet-name>    <servlet-class>cn.itcast.response.CEPServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>OutServlet</servlet-name>    <servlet-class>cn.itcast.response.OutServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>DownloadServlet</servlet-name>    <servlet-class>cn.itcast.response.DownloadServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>TestServlet</servlet-name>    <servlet-class>cn.itcast.response.TestServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>CheckcodeServlet</servlet-name>    <servlet-class>cn.itcast.response.CheckcodeServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>RequestServlet1</servlet-name>    <servlet-class>cn.itcast.request.RequestServlet1</servlet-class>  </servlet>  <servlet>    <servlet-name>RegServlet</servlet-name>    <servlet-class>cn.itcast.request.RegServlet</servlet-class>  </servlet>  <servlet>    <servlet-name>RequestDemo3</servlet-name>    <servlet-class>cn.itcast.request.RequestDemo3</servlet-class>  </servlet>  <servlet>    <servlet-name>RequestDemo4</servlet-name>    <servlet-class>cn.itcast.request.RequestDemo4</servlet-class>  </servlet>  <servlet>    <servlet-name>Login2Servlet</servlet-name>    <servlet-class>cn.itcast.request.Login2Servlet</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>ErrorServlet</servlet-name>    <url-pattern>/error</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>LoginServlet</servlet-name>    <url-pattern>/login</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>RefreshServlet</servlet-name>    <url-pattern>/refresh</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>CEPServlet</servlet-name>    <url-pattern>/cep</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>OutServlet</servlet-name>    <url-pattern>/out</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>DownloadServlet</servlet-name>    <url-pattern>/download</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>TestServlet</servlet-name>    <url-pattern>/test1</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>CheckcodeServlet</servlet-name>    <url-pattern>/checkcode</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>RequestServlet1</servlet-name>    <url-pattern>/request1</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>RegServlet</servlet-name>    <url-pattern>/reg</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>RequestDemo3</servlet-name>    <url-pattern>/request3</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>RequestDemo4</servlet-name>    <url-pattern>/request4</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>Login2Servlet</servlet-name>    <url-pattern>/login2</url-pattern>  </servlet-mapping>  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list></web-app>

login.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body><form action="/day10/login" method="post"><table border="1" width="50%"><tr><td>输入姓名</td><td><input type="text" name="username" /></td></tr><tr><td>输入密码</td><td><input type="password" name="password" /></td></tr><tr><td colspan="2"><input type="submit" value="登陆"/></td></tr></table></form></body></html>

refresh.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><!-- 5秒后跳转  --><meta http-equiv="refresh" content="5;url=/day10/response/login.html"><title>页面定时跳转（读秒）</title></head><body onload="run()"><h2>页面将在<span id="spanId">5</span>秒后跳转</h2></body><script type="text/javascript">/* 读秒的操作页面一加载，加载事件onload执行读秒的操作，每隔一秒变一次。每隔一秒，js的定时器*/var x = 5;function run(){var span = document.getElementById("spanId");span.innerHTML = x;x--;window.setTimeout("run()", 1000);}</script></html>

checkcode.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body><form action="/day10/login" method="post"><table border="1" width="70%"><tr><td>输入姓名</td><td><input type="text" name="username" /></td></tr><tr><td>输入密码</td><td><input type="password" name="password" /></td></tr><tr><td>验证码</td><td><input type="text" name="code" /><img id="imgId" src="/day10/checkcode"><a href="#" onclick="run()">看不清，换一张</a></td></tr><tr><td colspan="2"><input type="submit" value="登陆"/></td></tr></table></form></body><script type="text/javascript">// 看不清，换一张，时间戳function run(){// 获取图片var image = document.getElementById("imgId");image.src = "/day10/checkcode?"+new Date().getTime();}</script></html>

reg.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body><form action="/day10/reg" method="get"><table border="1" width="50%"><tr><td>输入姓名</td><td><input type="text" name="username" /></td></tr><tr><td>输入密码</td><td><input type="password" name="password" /></td></tr><tr><td>选择性别</td><td><input type="radio" name="sex" value="nan" />男<input type="radio" name="sex" value="nv" />女</td></tr><tr><td>选择爱好</td><td><input type="checkbox" name="love" value="lq" />篮球<input type="checkbox" name="love" value="zq" />足球<input type="checkbox" name="love" value="pq" />排球</td></tr><tr><td>选择城市</td><td><select name="city"><option value="none">--请选择--</option><option value="bj">北京</option><option value="sh">上海</option><option value="gz">广州</option></select></td></tr><tr><td colspan="2"><input type="submit" value="登陆"/></td></tr></table></form></body></html>

login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body>${msg}<form action="/day10/login2" method="post"><table border="1" width="50%"><tr><td>输入姓名</td><td><input type="text" name="username" /></td></tr><tr><td>输入密码</td><td><input type="password" name="password" /></td></tr><tr><td colspan="2"><input type="submit" value="登陆"/></td></tr></table></form></body></html>

CEPServlet.java （禁用浏览器缓存）

package cn.itcast.response;import java.io.IOException;import java.text.SimpleDateFormat;import java.util.Date;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 禁用浏览器的缓存 * @author Administrator * */public class CEPServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/** * Cache-Control : no-cacheExpires: -1值是日期类型（setDateHeader()）Pragma : no-cache */// 设置三个头信息response.setHeader("Cache-Control","no-cache");response.setHeader("Pragma","no-cache");response.setDateHeader("Expires", -1);// 向页面输出当前的时间// 获取当前时间Date date = new Date();// 修改格式yyyy-MM-dd HH:mm:ssSimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String str = sdf.format(date);// 输出response.getWriter().write(str);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

TestServlet.java (验证码热身)

package cn.itcast.response;import java.awt.Color;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import javax.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 验证码热身 * @author Administrator * */public class TestServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {// 在内存中生成图片BufferedImage image = new BufferedImage(300, 500, BufferedImage.TYPE_INT_RGB);// 获取画笔对象Graphics g = image.getGraphics();// 设置颜色g.setColor(Color.RED);// 画一个矩形g.drawRect(100, 100, 150, 100);g.setColor(Color.YELLOW);// 定义字符串String str = "abc";g.drawString(str, 80, 80);// 把内存中的图片输出到浏览器端ImageIO.write(image, "jpg", response.getOutputStream());}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

CheckcodeServlet.java（实现验证码流程）

package cn.itcast.response;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.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;/** * 验证码 * @author Administrator * */public class CheckcodeServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/** * 在内存中生成图片（纸），没有设置背景颜色，画填充的矩形，并且和纸的大小相同，矩形有颜色。 * 获取笔的对象（设置颜色，设置字体，画字符串，画矩形） * 先准备好数据，随机生成4个字符，把字符画到纸上 * 画干扰线 * 把内存中的图片输出到客户端上 */int width = 120;int height = 30;// 在内存中生成图片BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);// 先获取画笔对象Graphics2D g = (Graphics2D) image.getGraphics();// 设置灰色g.setColor(Color.GRAY);// 画填充的矩形g.fillRect(0, 0, width, height);// 设置颜色g.setColor(Color.BLUE);// 画边框g.drawRect(0, 0, width-1, height-1);// 准备数据，随机获取4个字符// String words = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";String words = "\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";// 设置颜色g.setColor(Color.YELLOW);// 设置字体g.setFont(new Font("隶书", Font.BOLD, 20));Random random = new Random();int x = 20;int y = 20;for(int i=0;i<4;i++){// void rotate(double theta, double x, double y)  // theta 弧度// hudu = jiaodu * Math.PI / 180;// 获取正负30之间的角度int jiaodu = random.nextInt(60)-30;double hudu = jiaodu * Math.PI / 180;g.rotate(hudu, x, y);// 获取下标int index = random.nextInt(words.length());// 返回指定下标位置的字符，随机获取下标char ch = words.charAt(index);// 写字符串g.drawString(""+ch, x, y);g.rotate(-hudu, x, y);x += 20;}// 设置颜色g.setColor(Color.GREEN);int x1,x2,y1,y2;// 画干扰线for(int i=0;i<4;i++){x1 = random.nextInt(width);y1 = random.nextInt(height);x2 = random.nextInt(width);y2 = random.nextInt(height);g.drawLine(x1, y1, x2, y2);}// 输出到客户端ImageIO.write(image, "jpg", response.getOutputStream());}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}public static void main(String[] args) {System.out.println("\u9fa5");System.out.println("\u9fa4");System.out.println("\u9fa3");System.out.println("\u9fa2");}}

DownloadServlet.java  简单实现文件下载（中文名乱码）

package cn.itcast.response;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.URLEncoder;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 文件下载 * @author Administrator * */public class DownloadServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {// 先获取到文件，读入输入流中// 获取文件的绝对磁盘路径String path = getServletContext().getRealPath("/img/外国美女.jpg");// 包含文件的名称c:\tomcat\webapps\day10\img\girl7.jpg// 截取文件的名称girl7.jpgString filename = null;// 获取最后一个\的位置int index = path.lastIndexOf("\\");if(index != -1){filename = path.substring(index+1);}// 判断是什么浏览器// 解决各浏览器的中文乱码问题String agent = request.getHeader("User-Agent");// 处理safari的乱码问题byte[] bytes = agent.contains("MSIE") ? filename.getBytes() : filename.getBytes("UTF-8");filename = new String(bytes, "ISO-8859-1");// 各浏览器基本都支持ISO编码if(filename != null){// 设置头信息response.setHeader("Content-Disposition", "attachment;filename="+filename);System.out.println(request.getRemoteAddr());System.out.println(path);InputStream in = new FileInputStream(path);// 通过response读出到客户端OutputStream os = response.getOutputStream();// io的拷贝byte [] b = new byte[1024];int len = 0;while((len =  in.read(b)) != -1){os.write(b, 0, len);}in.close();// os.close();服务器管理流}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

OutServlet.java (处理HttpServletResponse 响应输出中文的乱码问题 包括字节和字符)

package cn.itcast.response;import java.io.IOException;import java.io.OutputStream;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 输出中文的乱码的问题 * @author Administrator * */public class OutServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {run2(response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}/** * 字符输出中文是否乱码呢？ * * 肯定乱码 * response缓冲区的编码，默认值ISO-8859-1 * * 设置response缓冲编码 * response.setCharacterEncoding("UTF-8"); *  * 设置浏览器打开文件所采用的编码 *  response.setHeader("Content-Type", "text/html;charset=UTF-8"); *  * 简写方式 *  response.setContentType("text/html;charset=UTF-8"); *  * @param response * @throws IOException */public void run2(HttpServletResponse response) throws IOException{// 设置response缓冲区的编码//response.setCharacterEncoding("UTF-8");// 设置浏览器打开文件所采用的编码//response.setHeader("Content-Type", "text/html;charset=UTF-8");// 简写的形式（等于上面两句）response.setContentType("text/html;charset=UTF-8");response.getWriter().write("哈罗卧得");}/** * 字节的输出中文的乱码 * * 输出哈罗我的是否乱码呢？ * * 不一定乱码。 * * 解决办法 * * 设置浏览器打开文件时所采用的编码 * response.setHeader("Content-Type", "text/html;charset=UTF-8"); * * 获取字符串byte数组时编码和打开文件时编码一致。 * "哈罗我的".getBytes("UTF-8") * @throws IOException  */public void run1(HttpServletResponse response) throws IOException{// 设置浏览器打开文件时编码response.setHeader("Content-Type", "text/html;charset=UTF-8");// 获取字节输出流OutputStream os = response.getOutputStream();// 输出中文os.write("哈罗我的".getBytes("UTF-8"));}}

RefreshServlet.java  (页面自动定时跳转)

package cn.itcast.response;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 页面的定时跳转 * @author Administrator * */public class RefreshServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {// 读秒操作response.setContentType("text/html;charset=UTF-8");response.getWriter().write("<h1>页面将在5秒后跳转</h1>");// 通过refresh头完成页面刷新response.setHeader("refresh", "5;url=/day10/response/login.html");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

LoginServlet.java

package cn.itcast.response;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 重定向到登陆页面 * @author Administrator * */public class LoginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/** * 先获取用户输入的内容（request对象） * 判断姓名和密码是否都是admin，如果有一个不是，重定向到登陆页面，如果都是，就登陆成功。 */// 获取用户输入的内容String username = request.getParameter("username");// 程序入口// 获取密码String password = request.getParameter("password");// 判断if("admin".equals(username) && "admin".equals(password)){// 登陆成功// 重定向到登陆页面// response.getWriter().write("success");response.sendRedirect("/day10/response/refresh.html");}else{// 重定向到登陆页面// 设置302的状态码//response.setStatus(302);// 设置地址//response.setHeader("location", "/day10/response/login.html");// 重定向response.sendRedirect("/day10/response/login.html");}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

RequestServlet1.java  （获取客户机内容）

package cn.itcast.request;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 获取客户机的内容 * @author Administrator * */public class RequestServlet1 extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {// 获取IPString ip = request.getRemoteAddr();// 获取请求方式String method = request.getMethod();// 获取虚拟路径String path = request.getContextPath();System.out.println("IP地址："+ip);System.out.println("请求方式："+method);System.out.println("虚拟路径名称："+path);// 获取请求头记住来源(防盗链)String referer = request.getHeader("referer");// 判断浏览器（文件下载）String agent = request.getHeader("user-agent");// 做操作}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

RegServlet.java  (解决请求乱码 GET和POST请求乱码)

package cn.itcast.request;import java.io.IOException;import java.util.Arrays;import java.util.Map;import java.util.Set;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 获取请求参数 * @author Administrator * */public class RegServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/** * request获取中文的乱码 * post请求（经常使用） * setCharacterEncoding(String env) 设置request的缓冲区的编码 * get请求 * username = new String(username.getBytes("ISO-8859-1"),"UTF-8"); */// 设置request缓冲区的编码（一定要在request.getParameter("username");之前）// request.setCharacterEncoding("UTF-8");// 获取内容，做其他操作// 获取姓名String username = request.getParameter("username");// 解析get方式乱码的问题username = new String(username.getBytes("ISO-8859-1"),"UTF-8");// 获取密码String password = request.getParameter("password");// 获取性别String sex = request.getParameter("sex");// 获取城市String city = request.getParameter("city");// 获取爱好返回是String数组String [] loves = request.getParameterValues("love");System.out.println("用户名："+username);System.out.println("密码："+password);System.out.println("性别："+sex);System.out.println("城市："+city);System.out.println("爱好："+Arrays.toString(loves));System.out.println("===================================================================");// 获取map集合Map<String, String []> map = request.getParameterMap();// 循环遍历Set<String> keys = map.keySet();for (String key : keys) {String [] values = map.get(key);System.out.println(Arrays.toString(values));}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

RequestDemo3.java  (转发和重定向)

package cn.itcast.request;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 重定向和转发 * @author Administrator * */public class RequestDemo3 extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {// request域设置内容request.setAttribute("name", "凤姐");// 完成重定向的工作（客户端端绝对路径）// response.sendRedirect("/day10/request4");// 转发（路径服务器的绝对路径）request.getRequestDispatcher("/request4").forward(request, response);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

RequestDemo4.java (测试request域)

package cn.itcast.request;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class RequestDemo4 extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {// 获取String value = (String) request.getAttribute("name");// 输出中文response.setContentType("text/html;charset=UTF-8");response.getWriter().write("访问到了demo4... "+value);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

使用转发效果如下：能获取request域中的值

使用重定向效果如下：是不能获取到request域中的值的

Login2Servlet.java  (使用request域属性和转发 实现登录的错误信息提示)

package cn.itcast.request;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 使用转发到登陆页面 * @author Administrator * */public class Login2Servlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {/** * 先获取用户输入的内容（request对象） * 判断姓名和密码是否都是admin，如果有一个不是，重定向到登陆页面，如果都是，就登陆成功。 */// 获取用户输入的内容String username = request.getParameter("username");// 程序入口// 获取密码String password = request.getParameter("password");// 判断if("admin".equals(username) && "admin".equals(password)){// 登陆成功// 重定向到登陆页面response.sendRedirect("/day10/response/refresh.html");}else{// 在request域存入内容request.setAttribute("msg", "用户名或者密码错误！");// 重定向到登陆页面// 重定向// response.sendRedirect("/day10/response/login.html");request.getRequestDispatcher("/request/login.jsp").forward(request, response);}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}