怎样运用servlet
制作登陆界面
login.html
<!DOCTYPE html><html> <head> <title>login.html</title> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="this is my page"> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <!--<link rel="stylesheet" type="text/css" href="./styles.css">--> </head> <body > <div style="text-align: center;"> <form action="./servlet/DemoServlet" enctype="application/x-www-form-urlencoded"> 用户名：<input type="text" name="username"/><br/><br/> 密 码: <input type="password" name="userpass"/><br/><br/> <input type="submit" name="" value="登陆"> </div> </form> </body></html>
user.html
<!DOCTYPE html><html> <head> <title>user.html</title> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="this is my page"> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <!--<link rel="stylesheet" type="text/css" href="./styles.css">--> </head> <body> <a href="#">查询用户信息</a> </body></html>
DemoServlet.java
package www.csdn.net.servlet;import java.io.IOException;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 DemoServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { //请求中带有的参数值String uName=request.getParameter("username");String uPass=request.getParameter("userpass");System.out.println("用户名"+uName);System.out.println("密码"+uPass);System.out.println(request.getRemoteAddr()+"------"+request.getRemoteHost());//响应response.setContentType("text/html;charset=UTF-8");response.setCharacterEncoding("UTF-8");/*PrintWriter out = response.getWriter();out.println("欢迎"+"----"+request.getRemoteAddr()+uName+"登陆此系统");out.flush();out.close();*///用户名密码存在302临时重定向response.setStatus(302);//状态码System.out.println(request.getContextPath());response.sendRedirect(request.getContextPath()+"/user.html");//跳转另一个界面}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { this.doGet(request, response);}}
Demo1Servlet.java怎样写入图片
package www.csdn.net.servlet;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.ServletInputStream;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class Demo1Servlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{downImg(request, response);}public void showImg(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { //响应的数据是图片response.setContentType("image/jpeg");//写出图片//获取项目的绝对路径String path=this.getServletContext().getRealPath("/");//图片路径File file=new File(path+"/image/150CA0R1YPM.jpg");System.out.println(file);//创建文件的输入流FileInputStream is=new FileInputStream(file);//响应的输出流ServletOutputStream out=response.getOutputStream();//读取的缓冲区byte buffer[]=new byte[1024];//记录读取的长度int len=0;//读取 如果len=-1读取完毕while((len=is.read(buffer))!=-1){//写入out.write(buffer, 0, len);}//释放资源操作is.close();out.flush();out.close();}/** * 下载图片 * @param request * @param response * @throws ServletException * @throws IOException */public void downImg(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//写出图片//获取项目的绝对路径String path=this.getServletContext().getRealPath("/");//图片路径File file=new File(path+"/image/小婷.jpg");System.out.println(file.getName());//创建文件的输入流FileInputStream is=new FileInputStream(file);response.setHeader("Content-Disposition", "attachment;filename="+file.getName());//响应的输出流ServletOutputStream out=response.getOutputStream();//读取的缓冲区byte buffer[]=new byte[1024];//记录读取的长度int len=0;//读取 如果len=-1读取完毕while((len=is.read(buffer))!=-1){//写入out.write(buffer, 0, len);}//释放资源操作is.close();out.flush();out.close();}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {this.doGet(request, response);}}
web.xml
<?xml version="1.0" encoding="UTF-8"?><web-app version="3.0" 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_3_0.xsd"> <display-name></display-name> <servlet> <servlet-name>DemoServlet</servlet-name> <servlet-class>www.csdn.net.servlet.DemoServlet</servlet-class> </servlet> <servlet> <servlet-name>Demo1Servlet</servlet-name> <servlet-class>www.csdn.net.servlet.Demo1Servlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>DemoServlet</servlet-name> <url-pattern>/servlet/DemoServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>Demo1Servlet</servlet-name> <url-pattern>/servlet/Demo1Servlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list></web-app>