servlet redirect/forward/session/cookie 与 HTTP 协议的测试

 本文直接展示servlet的测试结果。

servlet的代码中使用sendRedirect：

public class SessionTest extends HttpServlet {
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
...
response.sendRedirect("http://localhost:8080/web/");
...}

查看浏览器交互过程，先是请求该servlet：

1. Request URL:

   http://localhost:8080/web/SessionTest

2. Request Method:

   GET

3. Status Code:

   302 Found

4. Request Headersview source
   1. Accept:

      text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

   2. Accept-Encoding:

      gzip,deflate,sdch

   3. Accept-Language:

      en-US,en;q=0.8,zh;q=0.6,ko;q=0.4,ja;q=0.2

   4. Cache-Control:

      max-age=0

   5. Connection:

      keep-alive

   6. Host:

      localhost:8080

   7. User-Agent:

      Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.94 Safari/537.36

5. Response Headersview source
   1. Content-Length:

      0

   2. Content-Type:

      text/html;charset=UTF-8

   3. Date:

      Thu, 06 Jun 2013 07:16:55 GMT

   4. Location:

      http://localhost:8080/web/

   5. Server:

      Apache-Coyote/1.1

   6. Set-Cookie:

      JSESSIONID=8C8DCD7355CC62C75C9BD154B2ADEDD0; Path=/web/; HttpOnly

可以看到response返回了302，并带上了location, 指示浏览器做第二次跳转请求，浏览器得到提示后进行第二次请求。

同样的servlet，将代码改为forward，实现了在servlet容器内部的跳转，对浏览器实际上是不可见得。

request.getRequestDispatcher("/index.jsp").forward(request, response);

看一下tomcat服务器的响应，一个200  OK之后，直接返回了内容，很直接

1. Request URL:

   http://localhost:8080/web/SessionTest

2. Request Method:

   GET

3. Status Code:

   200 OK

4. Request Headersview source
   1. Accept:

      text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

   2. Accept-Encoding:

      gzip,deflate,sdch

   3. Accept-Language:

      en-US,en;q=0.8,zh;q=0.6,ko;q=0.4,ja;q=0.2

   4. Connection:

      keep-alive

   5. Cookie:

      JSESSIONID=4D4C34D45462707E53A475C060E2D2A2; test=test

   6. DNT:

      1

   7. Host:

      localhost:8080

   8. User-Agent:

      Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.94 Safari/537.36

5. Response Headersview source
   1. Content-Length:

      218

   2. Content-Type:

      text/html;charset=UTF-8

   3. Date:

      Thu, 06 Jun 2013 09:12:04 GMT

   4. Server:

      Apache-Coyote/1.1

   5. Set-Cookie:

      JSESSIONID=0FE64A4D2D1777BD44F08F2F8186384B; Path=/web/; HttpOnly

再看cookie的保存，将以上代码改为将cookie加入response：

        Cookie cookie = new Cookie("test","test");
        response.addCookie(cookie);
        PrintWriter out = response.getWriter();

再看HTTP head：

1. Request URL:

   http://localhost:8080/web/SessionTest

2. Request Method:

   GET

3. Status Code:

   200 OK

4. Request Headersview source
   1. Accept:

      text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

   2. Accept-Encoding:

      gzip,deflate,sdch

   3. Accept-Language:

      en-US,en;q=0.8,zh;q=0.6,ko;q=0.4,ja;q=0.2

   4. Cache-Control:

      max-age=0

   5. Connection:

      keep-alive

   6. Cookie:

      JSESSIONID=FB43328EF48C78B7122454F84B57F164

   7. DNT:

      1

   8. Host:

      localhost:8080

   9. User-Agent:

      Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.94 Safari/537.36

5. Response Headersview source
   1. Content-Length:

      186

   2. Content-Type:

      text/html;charset=UTF-8

   3. Date:

      Thu, 06 Jun 2013 07:47:13 GMT

   4. Server:

      Apache-Coyote/1.1

   5. Set-Cookie:

      JSESSIONID=BC3FDA2D942F2F4B50757D9C436D21A9; Path=/web/; HttpOnly

   6. Set-Cookie:

      test=test

Tomcat通过HTTP协议的Set-Cookie将servlet的cookie放入了响应头，查看浏览器的cookie，除了jsessionid，又加了一个test/test的cookie进来。