注 : 该 .Java 文件与 .Jsp 文件不在同一目录 , 可以引用吗 ?
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import java.sql.*;public class SQLTest{
public static void DBconnect(){
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
String url = "jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=Tests";
String user = "sa";
String password = "";
Connection conn = DriverManager.getConnection(url,user,password);
Statement stmt = conn.createStatement();
String sql = "select * from Test";
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()){
System.out.println("Your frist field is " + rs.getString("Name"));
}
rs.close();
stmt.close();
conn.close();
}
catch(Exception e){
System.err.println(e);
}
}
}
将类SQLTest在页面中引用,
在jsp页面中加入语句<% SQLTest.DBconnect();%>即可
提示 :HTTP Status 500 - --------------------------------------------------------------------------------type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: Unable to compile class for JSPAn error occurred at line: 4 in the jsp file: /DBTest.jspGenerated servlet error:
[javac] Compiling 1 source fileC:\Program Files\Apache Group\Tomcat 4.1\work\Standalone\localhost\_\DBTest_jsp.java:46: cannot resolve symbol
symbol : variable jt
location: class org.apache.jsp.DBTest_jsp
jt.DBconnect();
^
1 error
at org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:130)
at org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:293)
at org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:340)
at org.apache.jasper.compiler.Compiler.compile(Compiler.java:352)
at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:474)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:184)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:260)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2415)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:170)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:223)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:432)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:386)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:534)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:530)
at java.lang.Thread.run(Thread.java:534)--------------------------------------------------------------------------------Apache Tomcat/4.1.18(已经编译了 jt.java)
<%@ page import="java.sql.*"%>
<html>
<body>
<% jt.DBconnect();%>
</body>
</html>-------------------------
Java 文件(同目录下 , 已编译为 jt.class)import java.sql.*;public class jt{
public static void DBconnect(){
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
String url = "jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=Tests";
String user = "sa";
String password = "";
Connection conn = DriverManager.getConnection(url,user,password);
Statement stmt = conn.createStatement();
String sql = "select * from Test";
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()){
System.out.println("Your frist field is " + rs.getString("Name"));
}
rs.close();
stmt.close();
conn.close();
}
catch(Exception e){
System.err.println(e);
}
}
}
import java.sql.*;public class jt{
public static void DBconnect(){
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
String url = "jdbc:microsoft:sqlserver://localhost:1433;DatabaseName=Tests";
String user = "sa";
String password = "";
Connection conn = DriverManager.getConnection(url,user,password);
Statement stmt = conn.createStatement();
String sql = "select * from Test";
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()){
System.out.println("Your frist field is " + rs.getString("Name"));
}
rs.close();
stmt.close();
conn.close();
}
catch(Exception e){
System.err.println(e);
}
}
public static void main(String args[])
{
jt.DBconnect();
}
}
看结果显示是否正确??
如果你想在页面中显示数据库字段内容,
则jt类中添加一方法,返回ResultSet!!!
则jt类中添加一方法,返回ResultSet!!!_______________________
能详细说说吗 ? 我不会啊
的目录下。
如写一个CONN.JAVA,编译后是CONN.CLASS,放在WEB-INF/CLASSES/里面
然后在JSP页面中调用这个BEAN就是了