好久没来,问个问题,帮忙看一下代码:)

javawriter 2003-06-23 06:05:28
package com.syj.data;

import java.sql.*;

public class DataBase {

Connection conn=null;
Statement st=null;
ResultSet rs=null;

public ResultSet getRs(String query){
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
String url="jdbc:microsoft:sqlserver://172.16.244.206:1433;DatabaseName=syj";

String user="sa";
String password="";
Connection conn= DriverManager.getConnection(url,user,password);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
rs=st.executeQuery(query);
}catch(Exception e){
e.printStackTrace();
}
return rs;
}
}


错误提示:
java.lang.NullPointerException
at com.syjzw.data.DataBase.getRs(DataBase.java:24)
at org.apache.jsp.index_jsp._jspService(index_jsp.java:96)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:210)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:2
95)
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(Appl
icationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a: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.j
ava:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatche
rValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:22
3)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java
:594)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.proce
ssConnection(Http11Protocol.java:392)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java
:565)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadP
ool.java:619)
at java.lang.Thread.run(Thread.java:534)
java.lang.NullPointerException
at org.apache.jsp.index_jsp._jspService(index_jsp.java:98)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:137)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper
.java:210)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:2
95)
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(Appl
icationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a: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.j
ava:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatche
rValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContex
t.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.jav
a:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)

at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:22
3)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java
:594)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.proce
ssConnection(Http11Protocol.java:392)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java
:565)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadP
ool.java:619)
at java.lang.Thread.run(Thread.java:534)
...全文
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javawriter 2003-06-24
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up
javawriter 2003-06-24
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改完后出现下面错误:
java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC]Error establis
hing socket.
at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source
)
at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSConnection.<init>(Unknown Source)

at com.microsoft.jdbc.sqlserver.SQLServerImplConnection.open(Unknown Sou
rce)
at com.microsoft.jdbc.base.BaseConnection.getNewImplConnection(Unknown S
ource)
at com.microsoft.jdbc.base.BaseConnection.open(Unknown Source)
at com.microsoft.jdbc.base.BaseDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:512)
at java.sql.DriverManager.getConnection(DriverManager.java:171)
at com.syjzw.data.DataBase.getRs(DataBase.java:18)
at _index__jsp._jspService(_index__jsp.java:51)
at com.caucho.jsp.JavaPage.service(JavaPage.java:75)
at com.caucho.jsp.Page.subservice(Page.java:497)
at com.caucho.server.http.FilterChainPage.doFilter(FilterChainPage.java:
182)
at com.caucho.server.http.Invocation.service(Invocation.java:312)
at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:1
35)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:244
)
at com.caucho.server.http.HttpRequest.handleConnection(HttpRequest.java:
163)
at com.caucho.server.TcpConnection.run(TcpConnection.java:137)
at java.lang.Thread.run(Thread.java:534)
java.lang.NullPointerException
at _index__jsp._jspService(_index__jsp.java:53)
at com.caucho.jsp.JavaPage.service(JavaPage.java:75)
at com.caucho.jsp.Page.subservice(Page.java:497)
at com.caucho.server.http.FilterChainPage.doFilter(FilterChainPage.java:
182)
at com.caucho.server.http.Invocation.service(Invocation.java:312)
at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:1
35)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:244
)
at com.caucho.server.http.HttpRequest.handleConnection(HttpRequest.java:
163)
at com.caucho.server.TcpConnection.run(TcpConnection.java:137)
at java.lang.Thread.run(Thread.java:534)
jan4984 2003-06-23
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and,the default "con" is the class's,but not the method's.
kadina 2003-06-23
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怎么有两个Connection和Statement?
rs=st.executeQuery(query);这里的st是null。


package com.syj.data;

import java.sql.*;

public class DataBase {

Connection conn=null;
Statement st=null;
ResultSet rs=null;

public ResultSet getRs(String query){
try{
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver").newInstance();
String url="jdbc:microsoft:sqlserver://172.16.244.206:1433;DatabaseName=syj";

String user="sa";
String password="";
conn= DriverManager.getConnection(url,user,password);
st=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
rs=st.executeQuery(query);
}catch(Exception e){
e.printStackTrace();
}
return rs;
}
}
long_zhi 2003-06-23
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同意楼上说法!
bruni 2003-06-23
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You defined 2 Connection conn = ...

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