我用tomcat运行jsp,出现HTTP STATUS 505 错误,我想知道505错误代表什么?还有这是什么原因造成的?错误详情如下: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: java.lang.NullPointerException
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:532)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:426)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root cause java.lang.NullPointerException
electric.dbs.Newsdb.selectsql(Newsdb.java:34)
org.apache.jsp.index_jsp._jspService(index_jsp.java:74)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:384)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.10 logs.
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:532)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:426)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
root cause java.lang.NullPointerException
electric.dbs.Newsdb.selectsql(Newsdb.java:34)
org.apache.jsp.index_jsp._jspService(index_jsp.java:74)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:384)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
note The full stack trace of the root cause is available in the Apache Tomcat/6.0.10 logs.
空指针
electric.dbs.Newsdb.selectsql(Newsdb.java:34)
这是你的类??看34行是什么,
electric.dbs.Newsdb.selectsql(Newsdb.java:34)从这儿可以看出Newsdb.java类第34行出现空指针异常
package electric.dbs;
import electric.dbs.Dbnews;
import electric.dbs.news;
import java.util.Collection;
import java.util.ArrayList;//5
import java.sql.SQLException;
import java.sql.ResultSetMetaData;
import java.sql.ResultSet;
import java.util.Iterator;
import java.sql.*;//10
import javax.servlet.http.*;
import electric.electricUtils.*;
/**
* <p>Title: </p>
* <p>Description: </p>//15
* <p>Copyright: Copyright (c) 2005</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*///20
public class Newsdb {
public Newsdb() {
}
public int selectsql(int st)
{ //25
String countSql="SELECT COUNT(*) FROM NEWS WHERE STATUS<>1";
Connection co=null;
ResultSet r = null;
PreparedStatement pstm = null;
int size=0; //30
int sizepa=0;
try {
co = DbConnectionManager.getConnection();
pstm = co.prepareStatement(countSql); //34
r = pstm.executeQuery();
while (r.next()) {
size = r.getInt(1);
sizepa=(int)size/st;
if(size%st>0)
{
debug一下,看看是不是co是null,
返回了NULL