package com.lehend.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class HelloServlet extends HttpServlet {
   /*
   从写get和post方法
    */
   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       PrintWriter writer = resp.getWriter(); //获取响应流
       writer.print("hello servlet!");
   }

   @Override
   protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       doGet(req,resp);
   }
}

public class HelloServlet extends HttpServlet {
   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       //this.getInitParameter() 初始化参数
   	//this.getServletConfig() Servlet配置
   	//this.getServletContext() Servlet上下文
       ServletContext servletContext = this.getServletContext();
       String username = "邹文";
       servletContext.setAttribute("username", username);//将一个数据保存在了
   }

   @Override
   protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       doGet(req, resp);
   }
}

public class getServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext servletContext = this.getServletContext();
        resp.setContentType("text/html");
        resp.setCharacterEncoding("utf-8");
        String username = (String) servletContext.getAttribute("username");
//        输出到页面
        resp.getWriter().print("name is " + username);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext servletContext = this.getServletContext();
        String mysqlParam = servletContext.getInitParameter("mysql");
        resp.getWriter().print(mysqlParam);
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext servletContext = this.getServletContext();
//        请求转发
        servletContext.getRequestDispatcher("/GetMysqlParam").forward(req,resp);
    }

public class GetDbProperties extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        InputStream inputStream = this.getServletContext().getResourceAsStream("/WEB-INF/classes/db.properties");
//        InputStream inputStream = this.getServletContext().getResourceAsStream("/WEB-INF/classes/com/lehend/servlet/database.properties");

        Properties properties = new Properties();
        properties.load(inputStream);
        String username = properties.getProperty("username");
        String password = properties.getProperty("password");
        resp.getWriter().print("username:"+username+", password:" + password);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

ServletOutputStream getOutputStream() throws IOException;
PrintWriter getWriter() throws IOException;

void setCharacterEncoding(String var1);
void setContentLength(int var1);
void setContentLengthLong(long var1);
void setContentType(String var1);
void setDateHeader(String var1, long var2);
void addDateHeader(String var1, long var2);
void setHeader(String var1, String var2);
void addHeader(String var1, String var2);
void setIntHeader(String var1, int var2);
void addIntHeader(String var1, int var2);

int SC_CONTINUE = 100;
int SC_SWITCHING_PROTOCOLS = 101;
int SC_OK = 200;
int SC_CREATED = 201;
int SC_ACCEPTED = 202;
int SC_NON_AUTHORITATIVE_INFORMATION = 203;
int SC_NO_CONTENT = 204;
int SC_RESET_CONTENT = 205;
int SC_PARTIAL_CONTENT = 206;
int SC_MULTIPLE_CHOICES = 300;
int SC_MOVED_PERMANENTLY = 301;
int SC_MOVED_TEMPORARILY = 302;
int SC_FOUND = 302;
int SC_SEE_OTHER = 303;
int SC_NOT_MODIFIED = 304;
int SC_USE_PROXY = 305;
int SC_TEMPORARY_REDIRECT = 307;
int SC_BAD_REQUEST = 400;
int SC_UNAUTHORIZED = 401;
int SC_PAYMENT_REQUIRED = 402;
int SC_FORBIDDEN = 403;
int SC_NOT_FOUND = 404;
int SC_METHOD_NOT_ALLOWED = 405;
int SC_NOT_ACCEPTABLE = 406;
int SC_PROXY_AUTHENTICATION_REQUIRED = 407;
int SC_REQUEST_TIMEOUT = 408;
int SC_CONFLICT = 409;
int SC_GONE = 410;
int SC_LENGTH_REQUIRED = 411;
int SC_PRECONDITION_FAILED = 412;
int SC_REQUEST_ENTITY_TOO_LARGE = 413;
int SC_REQUEST_URI_TOO_LONG = 414;
int SC_UNSUPPORTED_MEDIA_TYPE = 415;
int SC_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
int SC_EXPECTATION_FAILED = 417;
int SC_INTERNAL_SERVER_ERROR = 500;
int SC_NOT_IMPLEMENTED = 501;
int SC_BAD_GATEWAY = 502;
int SC_SERVICE_UNAVAILABLE = 503;
int SC_GATEWAY_TIMEOUT = 504;
int SC_HTTP_VERSION_NOT_SUPPORTED = 505;

ServletOutputStream getOutputStream() throws IOException;
PrintWriter getWriter() throws IOException;

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// 1. 要获取下载文件的路径
String realPath = "F:\\班级管理\\西开【19525】\\2、代码\\JavaWeb\\javaweb02-servlet\\response\\target\\classes\\秦疆.png";
System.out.println("下载文件的路径："+realPath);
// 2. 下载的文件名是啥？
String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
// 3. 设置想办法让浏览器能够支持(Content-Disposition)下载我们需要的东西,中文文件
名URLEncoder.encode编码，否则有可能乱码
resp.setHeader("ContentDisposition","attachment;filename="+URLEncoder.encode(fileName,"UTF-8"));
// 4. 获取下载文件的输入流
FileInputStream in = new FileInputStream(realPath);
// 5. 创建缓冲区
int len = 0;
byte[] buffer = new byte[1024];
// 6. 获取OutputStream对象
ServletOutputStream out = resp.getOutputStream();
// 7. 将FileOutputStream流写入到buffer缓冲区,使用OutputStream将缓冲区中的数据
输出到客户端！
while ((len=in.read(buffer))>0){
out.write(buffer,0,len);
}
in.close();
out.close();
}

package com.lehend;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

public class ImageServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
//如何让浏览器3秒自动刷新一次;
        resp.setHeader("refresh","3");
//在内存中创建一个图片
        BufferedImage image = new
                BufferedImage(80,20,BufferedImage.TYPE_INT_RGB);
//得到图片
        Graphics2D g = (Graphics2D) image.getGraphics(); //笔
//设置图片的背景颜色
        g.setColor(Color.white);
        g.fillRect(0,0,80,20);
//给图片写数据
        g.setColor(Color.BLUE);
        g.setFont(new Font(null,Font.BOLD,20));
        g.drawString(makeNum(),0,20);
//告诉浏览器，这个请求用图片的方式打开
        resp.setContentType("image/jpeg");
//网站存在缓存，不让浏览器缓存
        resp.setDateHeader("expires",-1);
        resp.setHeader("Cache-Control","no-cache");
        resp.setHeader("Pragma","no-cache");
//把图片写给浏览器
        ImageIO.write(image,"jpg", resp.getOutputStream());
    }
    //生成随机数
    private String makeNum(){
        Random random = new Random();
        String num = random.nextInt(9999999) + "";
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < 7-num.length() ; i++) {
            sb.append("0");
        }
        num = sb.toString() + num;
        return num;
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        doGet(req, resp);
    }
}

void sendRedirect(String var1) throws IOException;

public class SendRedirect extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws
            ServletException, IOException {
/*
resp.setHeader("Location","/r/img");
resp.setStatus(302);
*/
        resp.sendRedirect("/img");//重定向到验证码页面
    }
}

public class LoginTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("用户开始登录");
        String username = req.getParameter("username");
        String password = req.getParameter("password");

        System.out.println("username: " + username + "password: " + password);
        resp.sendRedirect("/response/success.jsp");

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }
}

package com.lehend;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Arrays;

public class RequestTest extends HttpServlet {
   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       super.doPost(req, resp);
   }

   @Override
   protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {


       req.setCharacterEncoding("UTF-8");
       String username = req.getParameter("username");
       String password = req.getParameter("password");
       String[] hobbies = req.getParameterValues("hobbies");
       System.out.println("username: " + username + "password: " + password);
       System.out.println(Arrays.toString(hobbies));

//        resp.setCharacterEncoding("UTF-8");

       req.getRequestDispatcher("/success.jsp").forward(req, resp);
   }


}

Cookie[] cookies = req.getCookies(); //获得Cookie
cookie.getName(); //获得cookie中的key
cookie.getValue(); //获得cookie中的vlaue
new Cookie("lastLoginTime", System.currentTimeMillis()+""); //新建一个cookie
cookie.setMaxAge(24*60*60); //设置cookie的有效期
resp.addCookie(cookie); //响应给客户端一个cookie

package com.lehend;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Date;

public class CookieTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        解决中文乱码
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");

        PrintWriter out = resp.getWriter();

//        服务器从客户端获取cookie，这里的cookie的客户端的访问服务器的时间
        Cookie[] cookies = req.getCookies();
//        判断cookie是否存在，如果不存在，说明该浏览器的用户之前没有访问过
        if (cookies != null) {
//            如果存在就打印上一次的访问时间
            out.write("你上一次的访问时间:");
            for (int i = 0; i < cookies.length; i++) {
                Cookie cookie = cookies[i];
//                判断cookie数组中的的name是否是之前访问时设置的name
                if (cookie.getName().equals("lastLoginTime")) {
//                    获取cookie的值，这里是访问时间
                    long lastLoginTime = Long.parseLong(cookie.getValue());
                    Date date = new Date(lastLoginTime);
                    out.write(date.toLocaleString());
                }
            }
        }else {
            out.write("这是你第一次访问本网站");
        }
//        服务器给客户端设置一个cookie
        Cookie cookie = new Cookie("lastLoginTime",String.valueOf(System.currentTimeMillis()));
//        设置cookie的有效期为1天
        cookie.setMaxAge(24*60*60);
//        将cookie添加到响应中发送给而客户端
        resp.addCookie(cookie);

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

package com.lehend;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class DeleteCookie extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        创建一个cookie，名字必须和要删除的名字一致
        Cookie cookie = new Cookie("lastLoginTime",String.valueOf(System.currentTimeMillis()));
//        将cookie有效期设置为0
        cookie.setMaxAge(0);
        resp.addCookie(cookie);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }
}

URLEncoder.encode("Lehend邹","utf-8")
URLDecoder.decode(cookie.getValue(),"UTF-8")

package com.lehend;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;
import java.net.URLEncoder;

public class CookieDemo3 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");

        PrintWriter out = resp.getWriter();
        Cookie[] cookies = req.getCookies();
        if (cookies != null) {
            out.write("你上一次的访问时间:");
            for (int i = 0; i < cookies.length; i++) {
                Cookie cookie = cookies[i];
                if (cookie.getName().equals("name")) {
                    out.write(URLDecoder.decode(cookie.getValue(),"utf-8"));
                }
            }
        } else {
            out.write("这是你第一次访问本网站");
        }
        Cookie cookie = new Cookie("name", URLEncoder.encode("Lehend邹","UTF-8"));
        resp.addCookie(cookie);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }
}

package com.lehend.sessiontest;

import com.lehend.pojo.Persion;

import javax.servlet.ServletException;
import javax.servlet.http.*;
import java.io.IOException;

public class SessionTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //    解决乱码问题
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

//        获取session
        HttpSession session = req.getSession();
//        往session中存东西
        session.setAttribute("name",new Persion("Lhend邹",15));
        String sessionId = session.getId();
//        判断当前session是不是新创建的
        if(session.isNew()){
            resp.getWriter().write("session创建成功,is："+sessionId);
        }else {
            resp.getWriter().write("session在服务器中已经存在，不需要再创建");
        }


    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }


}

package com.lehend.sessiontest;

import com.lehend.pojo.Persion;

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 java.io.IOException;

public class DelSession extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");

        HttpSession session = req.getSession();
        Persion persion = (Persion) session.getAttribute("name");
        resp.getWriter().write("session's name :"+persion.toString());
        session.removeAttribute("name");

        //手动注销Session
        session.invalidate();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }
}

package com.lehend.pojo;

public class Persion {
    private String name;
    private int age;

    public Persion(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return super.toString();
    }
}

//        将sessionid添加到cookie中
        Cookie cookie = new Cookie("JSESSIONID",sessionId);
//        将cookie响应给浏览器
        resp.addCookie(cookie);

/*
 * Generated by the Jasper component of Apache Tomcat
 * Version: Apache Tomcat/9.0.46
 * Generated at: 2021-06-20 09:12:53 UTC
 * Note: The last modified time of this file was set to
 *       the last modified time of the source file after
 *       generation to assist with modification tracking.
 */
package org.apache.jsp;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;

public final class index_jsp extends org.apache.jasper.runtime.HttpJspBase
    implements org.apache.jasper.runtime.JspSourceDependent,
                 org.apache.jasper.runtime.JspSourceImports {

  private static final javax.servlet.jsp.JspFactory _jspxFactory =
          javax.servlet.jsp.JspFactory.getDefaultFactory();

  private static java.util.Map<java.lang.String,java.lang.Long> _jspx_dependants;

  private static final java.util.Set<java.lang.String> _jspx_imports_packages;

  private static final java.util.Set<java.lang.String> _jspx_imports_classes;

  static {
    _jspx_imports_packages = new java.util.HashSet<>();
    _jspx_imports_packages.add("javax.servlet");
    _jspx_imports_packages.add("javax.servlet.http");
    _jspx_imports_packages.add("javax.servlet.jsp");
    _jspx_imports_classes = null;
  }

  private volatile javax.el.ExpressionFactory _el_expressionfactory;
  private volatile org.apache.tomcat.InstanceManager _jsp_instancemanager;

  public java.util.Map<java.lang.String,java.lang.Long> getDependants() {
    return _jspx_dependants;
  }

  public java.util.Set<java.lang.String> getPackageImports() {
    return _jspx_imports_packages;
  }

  public java.util.Set<java.lang.String> getClassImports() {
    return _jspx_imports_classes;
  }

  public javax.el.ExpressionFactory _jsp_getExpressionFactory() {
    if (_el_expressionfactory == null) {
      synchronized (this) {
        if (_el_expressionfactory == null) {
          _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory();
        }
      }
    }
    return _el_expressionfactory;
  }

  public org.apache.tomcat.InstanceManager _jsp_getInstanceManager() {
    if (_jsp_instancemanager == null) {
      synchronized (this) {
        if (_jsp_instancemanager == null) {
          _jsp_instancemanager = org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(getServletConfig());
        }
      }
    }
    return _jsp_instancemanager;
  }

  public void _jspInit() {
  }

  public void _jspDestroy() {
  }

  public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response)
      throws java.io.IOException, javax.servlet.ServletException {

    if (!javax.servlet.DispatcherType.ERROR.equals(request.getDispatcherType())) {
      final java.lang.String _jspx_method = request.getMethod();
      if ("OPTIONS".equals(_jspx_method)) {
        response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
        return;
      }
      if (!"GET".equals(_jspx_method) && !"POST".equals(_jspx_method) && !"HEAD".equals(_jspx_method)) {
        response.setHeader("Allow","GET, HEAD, POST, OPTIONS");
        response.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, "JSP 只允许 GET、POST 或 HEAD。Jasper 还允许 OPTIONS");
        return;
      }
    }

    final javax.servlet.jsp.PageContext pageContext;
    javax.servlet.http.HttpSession session = null;
    final javax.servlet.ServletContext application;
    final javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = null;
    final java.lang.Object page = this;
    javax.servlet.jsp.JspWriter _jspx_out = null;
    javax.servlet.jsp.PageContext _jspx_page_context = null;


    try {
      response.setContentType("text/html");
      pageContext = _jspxFactory.getPageContext(this, request, response,
      			null, true, 8192, true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;

      out.write("<html>\n");
      out.write("<body>\n");
      out.write("<h2>Hello World!</h2>\n");
      out.write("</body>\n");
      out.write("</html>\n");
    } catch (java.lang.Throwable t) {
      if (!(t instanceof javax.servlet.jsp.SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
          try {
            if (response.isCommitted()) {
              out.flush();
            } else {
              out.clearBuffer();
            }
          } catch (java.io.IOException e) {}
        if (_jspx_page_context != null) _jspx_page_context.handlePageException(t);
        else throw new ServletException(t);
      }
    } finally {
      _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }
}

//初始化    
public void _jspInit() {
  }
//销毁
  public void _jspDestroy() {
  }
//JSPService
  public void _jspService(final javax.servlet.http.HttpServletRequest request, final javax.servlet.http.HttpServletResponse response){}

final javax.servlet.jsp.PageContext pageContext; //页面上下文
javax.servlet.http.HttpSession session = null; //session
final javax.servlet.ServletContext application; //applicationContext
final javax.servlet.ServletConfig config; //config
javax.servlet.jsp.JspWriter out = null; //out
final java.lang.Object page = this; //page：当前
HttpServletRequest request //请求
HttpServletResponse response //响应

response.setContentType("text/html"); //设置响应的页面类型
pageContext = _jspxFactory.getPageContext(this, request, response,
null, true, 8192, true);
_jspx_page_context = pageContext;
application = pageContext.getServletContext();
config = pageContext.getServletConfig();
session = pageContext.getSession();
out = pageContext.getOut();
_jspx_out = out;

out.write("<html>\r\n");

out.write("\r\n");
      out.write("<html>\r\n");
      out.write("<head>\r\n");
      out.write("    <title>Title</title>\r\n");
      out.write("</head>\r\n");
      out.write("<body>\r\n");

    String name = "Lehend";

      out.write("\r\n");
      out.write("name:");
      out.print(name);
      out.write("\r\n");
      out.write("\r\n");
      out.write("</body>\r\n");
      out.write("</html>\r\n");

    pageContext.setAttribute("name1","Lehend1"); //保存的数据只在一个页面中有效
    request.setAttribute("name2","lehend2");//保存的数据只在一次请求中有效，请求转发会携带这个数据
    session.setAttribute("name3","lehend3");//保存的数据只在一次会话中有效，从打开浏览器到关闭浏览器
    application.setAttribute("name4","lehend4");//保存的数据只在服务器中有效，从打开服务器到关闭服务器

public void setAttribute(String name, Object attribute, int scope) {
        switch(scope) {
        case 1:
            this.mPage.put(name, attribute);
            break;
        case 2:
            this.mRequest.put(name, attribute);
            break;
        case 3:
            this.mSession.put(name, attribute);
            break;
        case 4:
            this.mApp.put(name, attribute);
            break;
        default:
            throw new IllegalArgumentException("Bad scope " + scope);
        }

    }

package com.lehend.pojo;

public class People {
   private int id;
   private String name;
   private int age;
   private String address;

   public People(){

   }
   public People(int id, String name, int age, String address) {
       this.id = id;
       this.name = name;
       this.age = age;
       this.address = address;
   }

   public String getAddress() {
       return address;
   }

   public void setAddress(String address) {
       this.address = address;
   }

   public int getAge() {
       return age;
   }

   public void setAge(int age) {
       this.age = age;
   }

   public String getName() {
       return name;
   }

   public void setName(String name) {
       this.name = name;
   }

   public int getId() {
       return id;
   }

   @Override
   public String toString() {
       return "People{" +
               "id=" + id +
               ", name='" + name + '\'' +
               ", age=" + age +
               ", address='" + address + '\'' +
               '}';
   }
}

package com.lehend.filter;

import javax.servlet.*;
import java.io.IOException;

public class CharacterEncodingFilter implements Filter {
    @Override
    //初始化：web服务器启动，就以及初始化了，随时等待过滤对象出现！
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("Filter 初始化！");
    }
    //Chain : 链
/*
1. 过滤中的所有代码，在过滤特定请求的时候都会执行
2. 必须要让过滤器继续同行
chain.doFilter(request,response);
*/
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        System.out.println("doFilter执行之前");
        chain.doFilter(request,response);
        System.out.println("doFilter执行之后");

    }

    @Override
    //销毁：web服务器关闭的时候，过滤会销毁
    public void destroy() {
        System.out.println("Filter 被销毁！");
    }
}

package com.lehend.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class view extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().write("你好, lehend");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }
}

package com.lehend;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

//统计网站在线人数 ： 通过统计session统计在线人数
public class OnlineCountTotal implements HttpSessionListener {
    @Override
    public void sessionCreated(HttpSessionEvent se) {
//        创建session监听，在创建session时会触发这个监听事件
        ServletContext servletContext = se.getSession().getServletContext();
//        输出当前sessionid个数，也就是在线人数
        System.out.println(se.getSession().getId());
        Integer onlineCount = (Integer) servletContext.getAttribute("OnlineCount");
//        如果OnlineCount为null，那么当前访问的就只有一个，说明在线人数为1
        if (onlineCount == null) {
            onlineCount = new Integer(1);
        } else {
            int count = onlineCount.intValue();
            onlineCount = new Integer(count + 1);
        }
        servletContext.setAttribute("OnlineCount", onlineCount);
    }

    //    当session被销毁的时候就将onlineCount-1
    @Override
    public void sessionDestroyed(HttpSessionEvent se) {
        ServletContext servletContext = se.getSession().getServletContext();
        Integer onlineCount = (Integer) servletContext.getAttribute("OnlineCount");
        if (onlineCount == null) {
            onlineCount = new Integer(0);
        } else {
            int count = onlineCount.intValue();
            onlineCount = new Integer(count - 1);
        }
        servletContext.setAttribute("OnlineCount",onlineCount);
    }
    /*
Session销毁：
1. 手动销毁 getSession().invalidate();
2. 自动销毁
*/
}

public class TestPanel {
public static void main(String[] args) {
Frame frame = new Frame("中秋节快乐"); //新建一个窗体
Panel panel = new Panel(null); //面板
frame.setLayout(null); //设置窗体的布局
frame.setBounds(300,300,500,500);
frame.setBackground(new Color(0,0,255)); //设置背景颜色
panel.setBounds(50,50,300,300);
panel.setBackground(new Color(0,255,0)); //设置背景颜色
frame.add(panel);
    frame.setVisible(true);
//监听事件，监听关闭事件
frame.addWindowListener(new WindowAdapter() {
@Override
public void windowClosing(WindowEvent e) {
super.windowClosing(e);
}
});
}
}

package com.lehend;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

import static com.lehend.util.Constant.USER_SESSION;

public class Login extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        if(username.equals("admin")){
//            登录成功，将sessionID作为USER_SESSION
            req.getSession().setAttribute(USER_SESSION,req.getSession().getId());
            resp.sendRedirect("/sys/success.jsp");
        }else {
//            登录失败
            resp.sendRedirect("/error.jsp");
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

package com.lehend;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

import static com.lehend.util.Constant.USER_SESSION;

public class Logout extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Object userSession = req.getSession().getAttribute(USER_SESSION);
        if (userSession != null) {
//            注销，这里就移除对应用户的session信息
            req.getSession().removeAttribute(USER_SESSION);
            resp.sendRedirect("/login.jsp");
        } else {
            resp.sendRedirect("/login.jsp");
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

package com.lehend;

import com.sun.deploy.net.HttpRequest;
import com.sun.deploy.net.HttpResponse;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

import static com.lehend.util.Constant.USER_SESSION;

public class LoginFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
//
        HttpServletRequest request = (HttpServletRequest)req;
        HttpServletResponse response = (HttpServletResponse)resp;
        if(request.getSession().getAttribute(USER_SESSION) == null){
            response.sendRedirect("/login.jsp");
        }
        chain.doFilter(req,resp);
    }

    @Override
    public void destroy() {

    }
}

package com.lehend.util;

public class Constant {
    public final static String USER_SESSION = "USER_SESSION";
}

package com.lehend;

import java.sql.*;

public class Jdbc_1 {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
//        设置数据库链接的url，用户名、密码
        String url = "jdbc:mysql://localhost:3306/jdbcStudy?useUnicode=true&characterEncoding=utf8&useSSL=true";
        String username = "root";
        String password = "root";
//        加载数据库驱动
        Class.forName("com.mysql.jdbc.Driver");
//        获取与数据库的链接对象
        Connection connection = DriverManager.getConnection(url, username, password);
//       创建数据库操作对象
        Statement statement = connection.createStatement();
//        获取sql语句
        String sql = "select id,name,password,email,birthday from users";

        //向数据库发sql,并获取代表结果集的resultset
        ResultSet resultSet = statement.executeQuery(sql);

//        取出结果集
        while (resultSet.next()) {
            System.out.println("id=" + resultSet.getObject("id"));
            System.out.println("name=" + resultSet.getObject("name"));
            System.out.println("password=" + resultSet.getObject("password"));
            System.out.println("email=" + resultSet.getObject("email"));
            System.out.println("birthday=" + resultSet.getObject("birthday"));
            System.out.println("-----------------------------");
        }
//        关闭数据库链接
        //6.关闭链接，释放资源
        resultSet.close();
        statement.close();
        connection.close();
    }
}

public class TestJDBC2 {
public static void main(String[] args) throws Exception {
//配置信息
//useUnicode=true&characterEncoding=utf-8 解决中文乱码
String url="jdbc:mysql://localhost:3306/jdbc?
useUnicode=true&characterEncoding=utf-8";
String username = "root";
String password = "123456";
//1.加载驱动
Class.forName("com.mysql.jdbc.Driver");
//2.连接数据库,代表数据库
Connection connection = DriverManager.getConnection(url, username,
password);
//3.编写SQL
String sql = "insert into users(id, name, password, email,
birthday) values (?,?,?,?,?);";
//4.预编译
PreparedStatement preparedStatement =
connection.prepareStatement(sql);
preparedStatement.setInt(1,2);//给第一个占位符？ 的值赋值为1；
preparedStatement.setString(2,"狂神说Java");//给第二个占位符？ 的值赋值为狂神说Java；
preparedStatement.setString(3,"123456");//给第三个占位符？ 的值赋值为
123456；
preparedStatement.setString(4,"[email protected]");//给第四个占位符？ 的值赋值为1；
preparedStatement.setDate(5,new Date(new
java.util.Date().getTime()));//给第五个占位符？ 的值赋值为new Date(new
java.util.Date().getTime())；
//5.执行SQL
int i = preparedStatement.executeUpdate();
if (i>0){
System.out.println("插入成功@");
}
//6.关闭连接，释放资源（一定要做） 先开后关
preparedStatement.close();
connection.close();
}
}

@Test
public void test(){
System.out.println("Hello");
}

package com.lehend;

import java.sql.*;

public class JdbcStatement {
    public static void main(String[] args) throws ClassNotFoundException, SQLException {
//        设置数据库链接的url，用户名、密码
        String url = "jdbc:mysql://localhost:3306/jdbcStudy?useUnicode=true&characterEncoding=utf8&useSSL=true";
        String username = "root";
        String password = "root";
//        加载数据库驱动
        Class.forName("com.mysql.jdbc.Driver");
//        获取与数据库的链接对象
        Connection connection = DriverManager.getConnection(url, username, password);
//       创建数据库操作对象
        Statement statement = connection.createStatement();
//        获取sql语句
        String sql = "select id,name,password,email,birthday from users";

        //向数据库发sql,并获取代表结果集的resultset
        ResultSet resultSet = statement.executeQuery(sql);

//        取出结果集
        while (resultSet.next()) {
            System.out.println("id=" + resultSet.getObject("id"));
            System.out.println("name=" + resultSet.getObject("name"));
            System.out.println("password=" + resultSet.getObject("password"));
            System.out.println("email=" + resultSet.getObject("email"));
            System.out.println("birthday=" + resultSet.getObject("birthday"));
            System.out.println("-----------------------------");
        }
//        关闭数据库链接
        //6.关闭链接，释放资源
        resultSet.close();
        statement.close();
        connection.close();
    }
}