Servet一些东西

Servlet 写控制语句

JSP显示页面

 

Servlet 主要是 Contyol控制—控制用Contyol做~~ 用View显示给用户看。用JSP做-

MVC模型视图控制

RequestDispatcher rd = Request.getRequestDispatcher(“”)；

Rd.fo

 

对话用request保存 对话 一次 结束

发送响应 返回响应 则结束

 

Session会话 会话关闭socket才会结束

 

 

   <servlet>

      <servlet-name>BookListServlet</servlet-name>

      <servlet-class>

        com.softeem.books.servlet.BookListServlet

      </servlet-class>

   </servlet>

   <servlet-mapping>

      <servlet-name>BookListServlet</servlet-name>

      <url-pattern>/booklist</url-pattern>

   </servlet-mapping>

 

 

   <servlet>

      <servlet-name>Bookservletupdate</servlet-name>

      <servlet-class>

        com.softeem.books.servlet.Bookservletupdate

      </servlet-class>

   </servlet>

   <servlet-mapping>

      <servlet-name>Bookservletupdate</servlet-name>

      <url-pattern>/bookupdate</url-pattern>

   </servlet-mapping>

 

 

XML的配置

 

 

 

JSP    是一个特殊的sevlet

 

JSP 调用–jspservlet方法

 

Servlet调用 doGet（）或dopost（）方法

 

反射机制

通过Class.forName() 变成对象

Class.forName() 返回 object

 

JSP 先解析在编译  然后执行

 

Tomcat 是当JSP 有修改后。则在解析编译在执行否则执行上一次的.class

doGet()

<form>

数据需要提交。有两种选择一 doGet() . dopost()

</form>

超连接使用doGet()提交

数据过多使用dopost()提交多次发送数据

 

doPost()

 

Servlet里的方法

doGet()

doPost()

init() 当用户访问的第一次访问时被调用。（以后不调用，只调用一次）

Destyor()当服务器关闭时调用

response.sendRedirect("booklist"); 一次对话。一次请求一次响应。返回null

RequestDispatcher rs = request.getRequestDispatcher("Book.jsp");

rs.forward(request, response); 多次会话

 

 

MVC 核心C。

<load-on-startup>1</load-on-startup> //服务器启动则加载init()不然当第用户访问加载init()

初始化参数 

 

<init-param>
<param-name>driverName</param-name>
<param-value>com.softeem.books
</init-param>
       <servlet>
              <init-param>
              <param-name>DriverName</param-name>
       <param-value>com.softeem.microsoft.sqlserver.SQLServerDriver</param-value>
              </init-param>
              <init-param>
              <param-name>URL</param-name>       <param-value>jdbc:microsoft:sqlserver://locahost:1433;DatebaseName="basicInfo"</param-value>
       </init-param>
       <init-param>
       <param-name>User</param-name>
       <param-value>sa</param-value>
       </init-param>
     </init-param>
 
              <init-param>
              <param-name>Password</param-name>
              <param-value>123</param-value>
              </init-param>
              <servlet-name>BookListServlet</servlet-name>
              <servlet-class>
                     com.softeem.books.servlet.BookListServlet
              </servlet-class>
              <load-on-startup>1</load-on-startup> //服务器启动则加载init()不然当第用户访问加载init()
       </servlet>
           <init-param>
              <param-name>Password</param-name>
              <param-value>123</param-value>
              </init-param>
              <servlet-name>BookListServlet</servlet-name>
              <servlet-class>
                     com.softeem.books.servlet.BookListServlet
              </servlet-class>
              <load-on-startup>1</load-on-startup>
       </servlet>

 

 

Web – inf 里面所有的东西都不能访问。

 

文件下载 

<a href=”文件名.txt” >文件下载</a>

 

String path = this.getServletContext().getRealPath(“/”);获取到这个目录

 

 

文件下载实现

protectedvoid Press(HttpServletRequest request,

       HttpServletResponse response) throws ServletException, IOException {

       String filename = request.getParameter("filename");

       String path = this.getServletContext().getRealPath("/");//获取当前tomcat路劲

       response.setContentType("application/pdf");

       File file = new File(path + "//Web-inf//" + filename); //文件路劲

       InputStream in = new FileInputStream(file);

       response.addHeader("Content-Disposition", "attachment;filename="

              +filename); //给文件名字

       response.setContentLength((int)(file.length())); //给文件长度

       OutputStream out = response.getOutputStream();

      

       byte[] buff = newbyte[1024];

       int len = 0;

       while ((len = in.read(buff)) != -1) {

           out.write(buff, 0, len);

       }

       out.flush();

       in.close();

 

    }

}

 

 

压缩文件的下载

protectedvoid Press(HttpServletRequest request,

           HttpServletResponse response) throws ServletException, IOException {

       // String filename = request.getParameter("filename");

       String path = this.getServletContext().getRealPath("/");// 获取当前tomcat路劲

       response.setContentType("application/zip");

       File file = new File(path + "//Web-inf//" + "SCSJ004-jSP-SERVLET.pdf"); // 文件路劲

       InputStream in = new FileInputStream(file);

       response.addHeader("Content-Disposition", "attachment;filename="

              + "z.zip"); // 给文件名字

//     response.setContentLength((int)(file.length())); //给文件长度

       OutputStream out = response.getOutputStream();

       ZipOutputStream zout = new ZipOutputStream(out);

       zout.putNextEntry(new ZipEntry("SCSJ004-jSP-SERVLET.pdf"));

       byte[] buff = newbyte[1024];

       int len = 0;

       while ((len = in.read(buff)) != -1) {

           zout.write(buff, 0, len);

       }

       zout.flush();

       in.close();

       File file1 = new File(path + "//Web-inf//" + "oracle.txt");

       InputStream in1 = new FileInputStream(file1);

       zout.putNextEntry(new ZipEntry("oracle.txt"));

       byte[] buff1 = newbyte[1024];

       int len1 = 0;

       while ((len1 = in1.read(buff1)) != -1) {

           zout.write(buff1, 0, len1);

       }

       zout.flush();

       in1.close();

       zout.close();

    }

}

 

会话

Session 用来记录 用户信息 

不要过量使用，大量数据放到Session

 

<%@taglib 标签 

“/Web-INF/下放着

<%@taglib uri=“标签所在路劲”

 

 

 

request.setCharacterEncoding("UTF-8");// 解决乱码取出来时候使用 UTF-8解决中日韩问题

 

 

request.getSession().setAttribute("user", dto); //使用session()存取判断用户

UserDTO dto = (UserDTO) request.getSession().getAttribute("user");

       if (dto == null) {

           RequestDispatcher rs1 = request

           .getRequestDispatcher("login.jsp");

           rs1.forward(request, response);

           return;

       }

 

 

request.getRequestDispatcher()是请求转发，前后页面共享一个request

response.sendRedirect()是重新定向 前后页面不是一个request