在JSP编程中Application的使用方法详解

< jsp:useBean id="cods"
　　class="oracle.jdbc.pool.OracleConnectionCacheImpl"
　　scope="application" />

< event:application_OnStart>
< %
cods.setURL("jdbc:oracle:thin:@HOST:PORT:SID");
cods.setUser("scott");
cods.setPassword("tiger");
cods.setStmtCache (5);
%>
< /event:application_OnStart>

< %@ page import="java.sql.*, javax.sql.*, oracle.jdbc.pool.*" %>
< !----------------------------------------------------------------
* This is a JavaServer Page that uses Connection Caching over
application
* scope. The Cache is created in an application scope in
globals.jsa file.
* Connection is obtained from the Cache and recycled back once
done.

--------------------------------------------------------------------!>
< HTML>
< HEAD>
< TITLE>
ConnCache JSP
< /TITLE>
< /HEAD>
< BODY BGCOLOR=EOFFFO>
< H1> Hello
< %= (request.getRemoteUser() != null? ", " +
request.getRemoteUser() : "") %>
! I am Connection Caching JSP.
< /H1>
< HR>
< B> I get the Connection from the Cache and recycle it back.
< /B>
< P>
< %
try {
Connection conn = cods.getConnection();
Statement stmt = conn.createStatement ();
ResultSet rset = stmt.executeQuery ("SELECT ename, sal " +
"FROM scott.emp ORDER BY ename");
if (rset.next()) {
%>
< TABLE BORDER=1 BGCOLOR="C0C0C0">
< TH WIDTH=200 BGCOLOR="white"> < I>Employee Name< /I> < /TH>
< TH WIDTH=100 BGCOLOR="white"> < I>Salary< /I> < /TH>
< TR> < TD ALIGN=CENTER> < %= rset.getString(1) %> < /TD>
< TD ALIGN=CENTER> $< %= rset.getDouble(2) %> < /TD>
< /TR>
< % while (rset.next()) {
%>
< TR> < TD ALIGN=CENTER> < %= rset.getString(1) %> < /TD>
< TD ALIGN=CENTER> $< %= rset.getDouble(2) %> < /TD>
< /TR>
< % }
%>
< /TABLE>
< % }
else {
%>
< P> Sorry, the query returned no rows! < /P>
< %
}
rset.close();
stmt.close();
conn.close(); // Put the Connection Back into the Pool
} catch (SQLException e) {
out.println("< P>" + "There was an error doing the query:");
out.println ("< PRE>" + e + "< /PRE>
< P>");
}
%>
< /BODY>
< /HTML>

使用application缓存数据库的连接，每次使用时，从缓冲中取出，用完就返回。