补充-servlet基础

一、获取客户端信息

1.建立一个动态web (Dynamic Web project)ServletTest的项目

2 在工程.ServletTest中创建一个BookInformationServlet.java的Servlet。

package com;

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;


/**
 * Servlet implementation class bookinformation
 */
public class BookInformationServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
      
    /**
     * @see HttpServlet#HttpServlet()
     */
    public BookInformationServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out=response.getWriter();
        request.setCharacterEncoding("UTF-8");
        String price=request.getParameter("price");
        out.println("<html>");
        out.println("价格："+price+"<br>");
        out.println("</html>");
    }

}

3.建立一个JSP显示页面 bookInformation.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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
    <form name="form1" method="post" action="BookInformationServlet">
      <table>
       <tr>
          <td> 价格：<input name="price" type="text" id="name">
          </td>
       </tr>
       </table>
    </form>

</body>
</html>

4.部署用于描述文件web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>ServletTest</display-name>
  <servlet>
    <servlet-name>SampleServlet</servlet-name>
    <servlet-class>com.SampleServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>SampleServlet</servlet-name>
    <url-pattern>/SampleServlet</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>BookInformationServlet</display-name>
    <servlet-name>BookInformationServlet</servlet-name>
    <servlet-class>com.BookInformationServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>BookInformationServlet</servlet-name>
    <url-pattern>/BookInformationServlet</url-pattern>
  </servlet-mapping>

</web-app>

5.结果如图

二、Servlet之间通信

出现在同一个web服务器上的servlet可皮此通信，也可共享资源。可用RequestDispatcher接口来实现Servlet之间的通信。即当前页面所要转

发的目标页或servlet对象可用request获取用户提交的数据

实现转发步骤：
1、得到RequestDispatcher引用：
public abstract RequestDispatcher getRequestDispatcher(String urlpath)
其中urlpath为要转发Jsp页面或Servlet地址。
RequestDispatcher dispatcher=request. getRequestDispatcher(a.jsp);
或
RequestDispatcher dispatcher;
dispatcher =getSeveltContext().

getRequestDispatcher(/SecondServlet);

2、转发：

public abstract void forward(ServletRequest request,SevletResponse response)
throws ServletException,IOException
该方法用来把一个Jsp或Servlet请求提交到另一个。当其输出完全由第二个Servlet或被调用Servlet生成时，必须用此方法。若第一个Servlet已访问了PrintWriter对象，则由此方法引发异常
dispatcher.forward（request, response）;

例6-7 Servlet之间通信

<%@ page contentType="text/html;charset=GB2312" %>
<HTML>
<BODY ><Font size=4>
    <form action="Verify" method="post">
         输入姓名:<Input Type=text name=name>
     <BR>输入分数:<Input Type=text name=score>
     <BR><Input Type=submit value="提交">
    </form>
    </Font>
</BODY>
</HTML>

Verity.java

package com;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class Verify extends HttpServlet
{  public void init(ServletConfig config) throws ServletException
    {super.init(config);
    }
   public  void  doPost(HttpServletRequest request,HttpServletResponse response) 
                        throws ServletException,IOException
    {   String name=request.getParameter("name");      //获取客户提交的信息
        String score=request.getParameter("score");        
        if(name.length()==0||name==null)
         { response.sendRedirect("sixth_example5.jsp");          //重定向
         }
        else if(score.length()==0)
         { response.sendRedirect("sixth_example5.jsp");          //重定向
         }
        else if(score.length()>0)
         { try { int numberScore=Integer.parseInt(score);
                 if(numberScore<0||numberScore>100)
                  { response.sendRedirect("sixth_example5.jsp");
                  }
                 else
                 {  RequestDispatcher dispatcher= 
                    request.getRequestDispatcher("ShowMessage");
                    dispatcher.forward(request, response);      // 转发
                  }  
               }
            catch(NumberFormatException e)
              {  response.sendRedirect("input.jsp");
              }
         }
    } 
   public  void  doGet(HttpServletRequest request,HttpServletResponse response) 
                        throws ServletException,IOException
    {   doPost(request,response);
    }
}

ShowMessage.java

package com;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ShowMessage extends HttpServlet
{  public void init(ServletConfig config) throws ServletException
    {super.init(config);
    }
   public  void  doPost(HttpServletRequest request,HttpServletResponse response) 
                        throws ServletException,IOException
    {   response.setContentType("text/html;charset=utf-8");
        PrintWriter out=response.getWriter();
        String name=request.getParameter("name");      //获取客户提交的信息
        String score=request.getParameter("score");        //获取客户提交的信息
        try{ byte bb[]=name.getBytes("utf-8");
             name=new String(bb,"utf-8");
           }
        catch(Exception exp){}
        out.print("<Font color=blue size=4>你的姓名是：");
        out.print(name);
        out.print("<BR><Font color=pink size=4>你的成绩是:");
        out.print(score);
    } 
   public  void  doGet(HttpServletRequest request,HttpServletResponse response) 
                        throws ServletException,IOException
    {  doPost(request,response);
    }
}