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<HEAD><TITLE>FAQ汇萃 >> Servlet >> 有关servlet和servlet之间通信的问题</title>
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<a href=http://www.jsp001.com/list_thread.php?int_attribute=1>FAQ汇萃</a>
>> <a href=http://www.jsp001.com/list_thread.php?forumid=9&int_attribute=1>Servlet</a>
>> 有关servlet和servlet之间通信的问题 [<a href=http://www.jsp001.com/forum/showthread.php?goto=newpost&threadid=112>查看别人的评论</a>]<br>

<hr><p>由 webmaster 发布于: 2001-01-21 11:13</p><p> </p><p>以下是几种常调用的方法<br>　　 Servlet to Servlet Communication<br>　　<br>　　 Listing 1: ServletBase<br>　　 public class ServletBase extends HttpServlet{<br>　　 static Connection databaseConnection = null;<br>　　 public void init(ServletConfig _config) throws ServletException{<br>　　 super.init(_config);<br>　　 if ( databaseConnection == null )<br>　　 //- Open up the database connection<br>　　 }<br>　　 protected boolean isLoggedOn( String _username ){<br>　　 return true;<br>　　 }<br>　　 protected boolean logUserOn( String _username ){<br>　　 return true;<br>　　 }<br>　　 }<br>　　 Listing 2: Using the NewSerletBase Class<br>　　 public class logonServlet extends ServletBase{<br>　　 public void service(HttpServletRequest _req, HttpServletRe-<br>　　 sponse _res) throws ServletException{<br>　　 if ( isLoggedOn( _req.getParameter(襏SERNAME? ){<br>　　 //- Display a message indicating they are already logged on<br>　　 }else{<br>　　 logUserOn( _req.getParameter(襏SERNAME? );<br>　　 }<br>　　 }<br>　　 }<br>　　 Listing 3: Storing an Object<br>　　 public class logonServlet extends HttpServlet{<br>　　 public void service(HttpServletRequest _req, HttpServletRe-<br>　　 sponse _res) throws ServletException{<br>　　 ServletContext thisContext = getServletContext();<br>　　 //-- Assume some method creates a new connection class<br>　　 Connection newConnection = createConnection();<br>　　 thisContext.setAttribute( database.connection? newConnection );<br>　　 //-- Return some output to the client<br>　　 }<br>　　 }<br>　　 Listing 4: retrieving an Object<br>　　 public class logoffServlet extends HttpServlet{<br>　　 public void service(HttpServletRequest _req, HttpServletRe-<br>　　 sponse _res) throws ServletException{<br>　　 ServletContext thisContext = getServletContext();<br>　　 //-- Assume some method creates a new connection class<br>　　 Connection newConnection = thisContext.getAttribute(<br>　　 database.connection?;<br>　　 if ( newConnection == null )<br>　　 //- Database has not been opened yet<br>　　 //-- Return some output to the client<br>　　 }<br>　　 }<br>　　 Listing 5: Looking at All the Objects<br>　　 public class allServlet extends HttpServlet{<br>　　 public void service(HttpServletRequest _req, HttpServletRe-<br>　　 sponse _res) throws ServletException{<br>　　 ServletContext thisContext = getServletContext();<br>　　 //-- Assume some method creates a new Connection class<br>　　 Enumeration E = thisContext.getAttributeNames();<br>　　 while ( E.hasMoreElements() ){<br>　　 String name = (String)E.nextElement();<br>　　 System.out.println( "Object: " + name );<br>　　 }<br>　　 }<br>　　 }<br>　　 Listing 6: Retrieving Remote Contexts<br>　　 public class otherServlet extends HttpServlet{<br>　　 public void service(HttpServletRequest _req, HttpServletRe-<br>　　 sponse _res) throws ServletException{<br>　　 ServletContext otherContext =<br>　　 getServletContext(http://&lt;otherdomain&gt;/servlet/allServlet?;<br>　　 //-- Assume some method creates a new Connection class<br>　　 Enumeration E = otherContext.getAttributeNames();<br>　　 while ( E.hasMoreElements() ){<br>　　 String name = (String)E.nextElement();<br>　　 System.out.println( "Object: " + name );<br>　　 }<br>　　 }<br>　　 }<br>　　 Listing 7: Forwarding a Request<br>　　 public class forwardServlet extends HttpServlet{<br>　　 public void service(HttpServletRequest _req, HttpServletRe-<br>　　 sponse _res) throws ServletException{<br>　　 ServletContext xt = getServletContext();<br>　　 RequestDispatcher xyzServlet =<br>　　 xt.getRequestDispatcher(http://&lt;domain&gt;/servlet/xyzServlet?;<br>　　 //- Do any preliminary processing<br>　　 _req.setAttribute( database.results? new Results() );<br>　　 xyzServlet.forward( _req, _res );<br>　　 }<br>　　 }<br>　　 Listing 8: Inserting Content<br>　　 public class insertServlet extends HttpServlet{<br>　　 public void service(HttpServletRequest _req, HttpServletRe-<br>　　 sponse _res) throws ServletException{<br>　　 ServletContext xt = getServletContext();<br>　　 RequestDispatcher xyzServlet =<br>　　 xt.getRequestDispatcher(http://&lt;domain&gt;/servlet/xyzServlet?;<br>　　 PrintWriter Out = _res.getWriter();<br>　　 Out.println( this is from the insertServlet ?);<br>　　 for(int x=0; x &lt; 10; x++ )<br>　　 xyzServlet.insert( _req, _res );<br>　　 Out.println( this is the end of the print servlet ?);<br>　　 }<br>　　 }<br><br></p></td>
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<p>该文章总得分是 <font color=red>0</font> 分，你认为它对你有帮助吗？
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