request對象和response對象

Web服務器收到客戶端的http請求，會針對每一次請求，分別建立一個用於表明請求的request對象、和表明響應的response對象

HttpServletResponse

HttpServletResponse對象表明服務器的響應。這個對象中封裝了向客戶端發送數據、發送響應頭，發送響應狀態碼的方法。

1.向客戶端輸出中文數據（字節）

package cn.lsl.response;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ResponseDemo1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        test5(response);
    }
    
    //輸出整數：最好轉換成字符串輸出
    private void test5(HttpServletResponse response) throws IOException{
        int i = 98;
        response.getOutputStream().write((i+"").getBytes());
    }
    
    //以字節流用默認編碼向客戶端輸出中文數據：沒有亂碼
    //默認的是GBK
    private void test1(HttpServletResponse response) throws IOException{
        String s = "你好！一";
        ServletOutputStream out = response.getOutputStream();
        out.write(s.getBytes());
    }
    
    //以字節流用utf-8編碼向客戶端輸出中文數據
    //以UTF-8編碼發送數據，瀏覽器(默認用GB2312)會出現亂碼
    private void test2(HttpServletResponse response) throws IOException{
        String s = "你好！二";
        //通知客戶端查看UTF-8碼錶
        response.setHeader("Content-Type", "text/html;charset=UTF-8");
        ServletOutputStream out = response.getOutputStream();
        out.write(s.getBytes("UTF-8"));
    }
    
    //以字節流用utf-8編碼向客戶端輸出中文數據
    private void test3(HttpServletResponse response) throws IOException{
        String s = "你好！三";
        ServletOutputStream out = response.getOutputStream();
        out.write("<meta http-equiv='Content-Type' content='text/html;charset=UTF-8'>".getBytes("UTF-8"));
        out.write(s.getBytes("UTF-8"));
    }
    
    //以字節流用utf-8編碼向客戶端輸出中文數據
    private void test4(HttpServletResponse response) throws IOException{
        String s = "你好！四";
        response.setContentType("text/html;charset=UTF-8");
        ServletOutputStream out = response.getOutputStream();
        out.write(s.getBytes("UTF-8"));
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}

分析：出現亂碼的圖解

 

解決辦法：

1)經過更改瀏覽器的編碼方式：IE/」查看」/」編碼」/」UTF-8」(不可取)

2)經過設置響應頭告知客戶端編碼方式：response.setHeader(「Content-type」, 「text/html;charset=UTF-8」);//告知瀏覽器數據類型及編碼

3)經過meta標籤模擬請求頭:out.write("<meta http-equiv='Content-Type' content='text/html; charset=utf-8' />".getBytes());

4)經過如下方法：response.setContentType("text/html;charset=UTF-8");

2.向客戶端輸出中文數據（字符）

package cn.lsl.response;

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 ResponseDemo2 extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        test3(response);
    }

    //字符流輸出中文數據
    private void test1(HttpServletResponse response) throws IOException{
        String s = "你好！一";
        response.setCharacterEncoding("UTF-8");    //設置查的UTF-8（對內容進行編碼，查utf-8）
        response.setHeader("Content-Type", "text/html;charset=UTF-8");//通知瀏覽器以utf-8打開
        PrintWriter out = response.getWriter();
        out.write(s);//默認查的是ISO-8859-1碼錶
    }
    //字符流輸出中文數據
    private void test2(HttpServletResponse response) throws IOException{
        String s = "你好！二";
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        out.write(s);
    }
    //字符流輸出中文數據
    private void test3(HttpServletResponse response) throws IOException{
        String s = "你好！三";
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        out.write(s);
    }

    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}

分析：

亂碼緣由：以默認編碼發送數據 ISO-8859-1（沒有中國二字編碼），此時會發生亂碼

解決辦法：

1）

setCharacterEncoding(「UTF-8」);//更改編碼爲UTF-8

response.setHead(「Context-type」,」text/html;charset=UTF-8」);//告訴客戶端編碼方式

2）response.setContentType("text/html;charset=utf-8");

在字符流輸出中文數據時:

response.setContentType("text/html;charset=utf-8");有兩個做用：

通知字符流以UTF-8編碼輸出

通知客戶端以UTF-8解碼顯示

3.輸出隨機驗證碼

package cn.lsl.response;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
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;

public class ResponseDemo3 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //通知瀏覽器不要緩存
        response.setHeader("Expires", "-1");
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "no-cache");
        
        int width = 120;
        int height = 25;
        //建立一副內存圖像BufferedImage
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        //獲得屬於該圖片的畫筆：Graphics();
        Graphics g = image.getGraphics();
        //畫邊框
        g.setColor(Color.BLUE);
        g.drawRect(0, 0, width, height);
        //填充背景色
        g.setColor(Color.YELLOW);
        g.fillRect(1, 1, width-2, height-2);
        //畫干擾線
        g.setColor(Color.GRAY);
        Random r = new Random();
        for(int i=0; i<10; i++)
            g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height));
        //隨機數字
        g.setColor(Color.RED);
        g.setFont(new Font("宋體",Font.BOLD|Font.ITALIC,20));
        int x = 23;
        for(int i=0; i<4; i++){
            g.drawString(r.nextInt(10)+"", x, 20);
            x = x+20;
        }
        //輸出到瀏覽器的頁面上：ImageIO
        ImageIO.write(image, "jpg", response.getOutputStream());
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}

4.定時刷新

package cn.lsl.response;

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

public class ResponseDemo4 extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        test2(response);
    }
    
    //定時刷新到本身
    private void test1(HttpServletResponse response) throws IOException{
        Random r = new Random();
        int i = r.nextInt();
        response.setIntHeader("Refresh", 1);
        response.getOutputStream().write((i+"").getBytes());
    }
    
    //刷到別的頁面
    private void test2(HttpServletResponse response) throws IOException{
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        response.setHeader("Refresh", "2;URL=/Response/index.jsp");
        out.write("登錄成功！2秒後將跳轉到主頁！若沒有跳轉，請猛點<a href='/Response/index.jsp'>這裏</a>");
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}

5.控制緩存時間

package cn.lsl.response;

 

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 ResponseDemo5 extends HttpServlet {

 

    public void doGet(HttpServletRequest request, HttpServletResponse response)

           throws ServletException, IOException {

       //緩存一小時

       response.setDateHeader("Expires", System.currentTimeMillis()+60*60*1000);

       response.getWriter().write("hello");

    }

 

    public void doPost(HttpServletRequest request, HttpServletResponse response)

           throws ServletException, IOException {

       doGet(request,response);

    }

}

6.請求重定向

請求重定向：一個web資源收到客戶端請求後，通知客戶端去訪問另一個web資源，這稱之         爲請求重定向。

地址欄會連，併發送2次請求，增長服務器負擔。

實現方式：response.sendRedirect();

原理：302/307狀態碼和location頭便可實現重定向

package cn.lsl.response;
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 ResponseDemo6 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
//        response.setStatus(302);
//        response.setHeader("Location", "/Response/index.jsp");
        response.sendRedirect("/Response/index.jsp");
    }

    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}

7.getOutputStream和getWriter方法分別用於獲得輸出二進制數據、輸出文本數據的ServletOuputStream、Printwriter對象。

getOutputStream和getWriter這兩個方法互相排斥，調用了其中的任何一個方法後，就不能再調用另外一方法。會拋異常。

異常爲：getOutputStream() has already been called for this response

package cn.lsl.response;

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;

//字節流和字符流同時使用，報錯
//getOutputStream() has already been called for this response
public class ResponseDemo7 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String s1 = "a";
        response.getOutputStream().write(s1.getBytes());
        String s2 = "b";
        response.getWriter().write(s2);
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }

}

注：經過字符流或字節流輸出的數據並非直接打給瀏覽器的。而是把數據寫到response對象的緩存中的。服務器從緩存中取出數據，按照HTTP協議的響應格式輸出給瀏覽器。若是你調用的response的輸出流沒有主動關閉，服務器會替你關的。

 

HttpServletRequest

HttpServletRequest對象表明客戶端的請求，當客戶端經過HTTP協議訪問服務器時，HTTP請求頭中的全部信息都封裝在這個對象中，經過這個對象的方法，能夠得到客戶這些信息。

1.獲取客戶機信息的方法

getRequestURL方法返回客戶端發出請求時的完整URL。

getRequestURI方法返回請求行中的資源名部分。

getQueryString 方法返回請求行中的參數部分。

getRemoteAddr方法返回發出請求的客戶機的IP地址

getRemoteHost方法返回發出請求的客戶機的完整主機名

getRemotePort方法返回客戶機所使用的網絡端口號

getLocalAddr方法返回WEB服務器的IP地址。

getLocalName方法返回WEB服務器的主機名

getMethod獲得客戶機請求方式

eg：

package cn.lsl.request;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

//獲取客戶機信息
public class RequestDemo1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //獲取URL和URI
        //url:http://localhost:8080/Request/servlet/RequestDemo1
        //uri:/Request/servlet/RequestDemo1
        System.out.println("url:"+request.getRequestURL());
        System.out.println("uri:"+request.getRequestURI());
        
        //經過getQueryString能夠得到get方式提交查詢串url中？後面部分
        System.out.println("queryString:"+request.getQueryString());
        //得到客戶端ip
        System.out.println("ip:"+request.getRemoteAddr());
        //經過getContextPath得到工程虛擬目錄名稱
        System.out.println("工程虛擬目錄名稱:"+request.getContextPath());
        //經過getMethod得到請求方式
        System.out.println("請求方式："+request.getMethod());
        //得到當前訪問資源路徑 ----/servlet/RequestDemo1
        System.out.println("當前訪問資源路徑:"+request.getRequestURI().substring(request.getContextPath().length()));
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}

注：

1)URL和URI的區別

URL: http://localhost:8080/Request/servlet/RequestDemo1

URI: /Request/servlet/RequestDemo1

URI 包含 URL的 ，URL 必定完成路徑，URI能夠相對路徑

http://localhost:8080/Request/servlet/RequestDemo1

是一個URL 同時也是 URI

/Request/servlet/RequestDemo1 ---- 都是URI 不是URL

2)得到當前訪問資源路徑 ：

request.getRequestURI().substring(request.getContextPath().length());

2.獲取請求頭信息

getHeader 得到頭信息的值，轉換一個字符串

getHeaders 得到頭信息值 ，得到Enumeration

getHeaderNames 得到全部頭信息名稱  返回 Enumeration

eg:

package cn.lsl.request;

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

public class RequestDemo2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //獲取指定頭信息字段
        String value = request.getHeader("Accept-Encoding");
        System.out.println(value);
        System.out.println("---------------");
        //得到全部頭信息內容
        Enumeration<String> enumeration = request.getHeaderNames();
        while(enumeration.hasMoreElements()){
            String name = enumeration.nextElement();
            System.out.println(name+":"+request.getHeader(name));
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }

}

3.防盜鏈程序

referer.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>referer.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">
  </head>
  
  <body>
    <h1>經過連接訪問RequestDemo3 不是盜鏈</h1>
    <a href="/Request/servlet/RequestDemo3">link</a>
  </body>
</html>

package cn.lsl.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 RequestDemo3 extends HttpServlet {

    //防盜鏈
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //經過getHeader得到referer頭信息
        String referer = request.getHeader("referer");
        //判斷頭信息能夠知道是否是盜鏈
        response.setContentType("text/html;charset=utf-8");
        if(referer == null || !referer.startsWith("http://localhost")){
            //盜鏈
            response.getWriter().println("是盜鏈");
        }else{
            //不是盜鏈
            response.getWriter().println("真不是盜鏈");
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}

4.獲取客戶機請求參數

經常使用API四個

getParameter

getParameterValues

getParameterNames

getParameterMap

eg：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>request.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">
  </head>
  
  <body>
    <h1>分別以get和post方式提交數據</h1>
    <h1>第一種：經過超連接提交數據以？方式</h1>
    <a href="/Request/servlet/RequestDemo4?name=zhangsan&city=shenzhen">超連接提交數據</a>
    <h1>第二種：經過form的post方式提交數據</h1>
    <form action="/Request/servlet/RequestDemo4" method="post">
        姓名<input type="text" name="name" /><br/>
        城市<input type="text" name="city" /><br/>
        <input type="submit" value="提交">
    </form>
  </body>
</html>

package cn.lsl.request;

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 RequestDemo4 extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String name = request.getParameter("name");
        System.out.println(name);
        String city = request.getParameter("city");
        System.out.println(city);
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}

5.獲取複雜表單的數據及解決中文亂碼問題

regist.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <title>regist.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">
    </head>

    <body>
        <form action="/Request/servlet/RequestDemo5" method="post">
            <table>
                <tr>
                    <td>
                        用戶名
                    </td>
                    <td>
                        <input type="text" name="username" />
                    </td>
                </tr>
                <tr>
                    <td>
                        密碼
                    </td>
                    <td>
                        <input type="password" name="password" />
                    </td>
                </tr>
                <tr>
                    <td>
                        性別
                    </td>
                    <td>
                        <input type="radio" name="gender" value="male" />
                        男
                        <input type="radio" name="gender" value="female" />
                        女
                    </td>
                </tr>
                <tr>
                    <td>
                        愛好
                    </td>
                    <td>
                        <input type="checkbox" name="hobby" value="sport" />
                        運動
                        <input type="checkbox" name="hobby" value="music" />
                        音樂
                        <input type="checkbox" name="hobby" value="game" />
                        遊戲
                    </td>
                </tr>
                <tr>
                    <td>
                        城市
                    </td>
                    <td>
                        <select name="city">
                            <option value="beijing">
                                北京
                            </option>
                            <option value="shanghai">
                                上海
                            </option>
                            <option value="shenzhen">
                                深圳
                            </option>
                        </select>
                    </td>
                </tr>
                <tr>
                    <td>
                        我的簡介
                    </td>
                    <td>
                        <textarea rows="5" cols="60" name="introduce"></textarea>
                    </td>
                </tr>
                <tr>
                    <td colspan="2">
                        <input type="submit" value="註冊" />
                    </td>
                </tr>
            </table>
        </form>
    </body>
</html>

package cn.lsl.request;

import java.io.IOException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;

import javax.activation.URLDataSource;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class RequestDemo5 extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //解決post亂碼
        request.setCharacterEncoding("utf-8");
        
        
        
        
        //經過getParameter得到指定數據
        String username = request.getParameter("username");
        System.out.println(username);
        
        //解決get亂碼
//        username = URLEncoder.encode(username, "ISO-8859-1");    //用ISO-8859-1編碼
//        username = URLDecoder.decode(username, "utf-8");    //用utf-8解碼
        
        
//        username = new String(username.getBytes("ISO-8859-1"),"UTF-8");
        
//        System.out.println(username);
        
        
        
        String gender = request.getParameter("gender");
        System.out.println(gender);
        
        //獲取checkbox全部提交數據 --- getParameterValues
        String[] hobbies = request.getParameterValues("hobby");
        System.out.println(Arrays.toString(hobbies));
        
        //打印全部請求提交的參數
        //方式一
        Enumeration<String> names = request.getParameterNames();
        while(names.hasMoreElements()){
            String name = names.nextElement();    //獲取每個參數的名稱
            System.out.println(name + ":" +Arrays.toString(request.getParameterValues(name)));
        }
        System.out.println("----------------");
        Map<String, String[]> parameterMap = request.getParameterMap();
        Set<String> keys = parameterMap.keySet();
        for (String key : keys) {
            System.out.println(key + ":" + Arrays.toString(parameterMap.get(key)));
        }
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }

}

注：解決中文亂碼問題

//解決post亂碼

request.setCharacterEncoding("utf-8");

//解決get亂碼（手動編碼）

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

username = URLDecoder.decode(username, "utf-8"); //用utf-8解碼

或    

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

 

6.請求轉發

1)request對象實現請求轉發：請求轉發指一個web資源收到客戶端請求後，通知服務器調用另一個web資源進行處理。

2)request對象提供了一個getRequestDispatcher方法，該方法返回一個RequestDispatcher對象，調用這個對象的forward方法能夠實現請求轉發。

3)request對象同時也是一個域對象，開發人員經過request對象在實現轉發時，把數據經過request對象帶給其它web資源處理。

eg:AServlet轉發到BServlet

package cn.lsl.request;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AServlet extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //經過request對象傳遞
        //向request域對象保存一個屬性
        request.setAttribute("name", "lsl");
        //傳遞數據給BServlet
        RequestDispatcher dispatcher = request.getRequestDispatcher("/servlet/BServlet");
        dispatcher.forward(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }

}

package cn.lsl.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 BServlet extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        System.out.println(request.getAttribute("name"));
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }

}

注：一、ServletContext對象的getRequestDispather(String path1)

    path1必須用絕對路徑，即以」/」開頭，若用相對路徑會拋出異常     IllegalArgumentException

    二、ServletRequest對象的getRequestDispatcher(String path2)           path2能夠用絕對路徑也能夠用相對路徑

 

 

拓展：轉發與重定向區別

1).轉發一次請求、一次響應。重定向兩次請求，兩次響應

2).轉發只能跳轉到站內程序，重定向可定向任何站點

3).轉發URL地址不變，重定向URL地址改變

4).轉發對客戶端不可見，重定向對客戶度可見

5).轉發共享一個Request中數據，重定向兩次請求，不一樣Request對象，不能共享Request數據

 

7.包含

logo.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>logo.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">
  </head>
  
  <body>
    <h1>LOGO</h1>
  </body>
</html>

footer.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>footer.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">
  </head>
  
  <body>
    <h1>@COPY</h1>
  </body>
</html>

package cn.lsl.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 MainServlet1 extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.getRequestDispatcher("/logo.html").include(request, response);
        response.getOutputStream().write("<h1>Main 1</h1>".getBytes());
        request.getRequestDispatcher("/footer.html").include(request, response);
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }

}

package cn.lsl.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 MainServlet2 extends HttpServlet {
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.getRequestDispatcher("/logo.html").include(request, response);
        response.getOutputStream().write("<h1>Main 2</h1>".getBytes());
        request.getRequestDispatcher("/footer.html").include(request, response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);
    }
}