出现了一个500的错误,空指针错误!~~~高分求救
开发工具my eclipse
下面是我的连接数据库的DBbean
package guojian;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class dbbean {
private static final String DRIVER_CLASS="com.microsoft.sqlserver.jdbc.SQLServerDriver";
private static final String DRIVER_URL="jdbc:sqlserver://localhost:1433;databaseName=addressBooka";
private static final String DATABASE_USER="sa";
private static final String DATABASE_PASSWORD="sa";
public static Connection getConnection(){
Connection dbConnection=null;
try {
Class.forName(DRIVER_CLASS);
dbConnection=DriverManager.getConnection(DRIVER_URL
,DATABASE_USER,DATABASE_PASSWORD);
}catch(ClassNotFoundException sqlex){
System.out.println("建立连接的时候出现了错误"+sqlex.getMessage());
} catch(SQLException sqlex){
System.out.println("加载驱动的时候出现了错误!"+sqlex.getMessage());
} finally {
}
return dbConnection;
}
public static void closeConnection(Connection dbConnection){
try {
if(dbConnection!=null&&(!dbConnection.isClosed())){
dbConnection.close();
}
}catch(SQLException sqlEx){
System.out.println(sqlEx.getMessage());
}
}
}
下面是我的添加语句
package guojian;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import guojian.dbbean;
public class insertinfo {
private Connection conn=null;
private Statement st=null;
private ResultSet rs=null;
public boolean insert(userbean uid)
{
dbbean dbc=new dbbean();
try{
conn=dbc.getConnection();
st=conn.createStatement();
String sql="insert into user values('"+uid.getUserid()+"','"+uid.getPassword()+"')";
int rs=st.executeUpdate(sql);
if(rs==1)
{
return true;
}else
{
return false;
}
}catch(SQLException ex)
{
System.out.println("查询的时候出现了错误"+ex.getMessage());
}return false;
}
}
下面是我的servlet
package guojian;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class insertservlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
userbean us=new userbean();
us.setUserid(request.getParameter("userid"));
us.setPassword(request.getParameter("password"));
insertinfo ub=new insertinfo();
if(ub.insert(us))
{
request.getRequestDispatcher("/cussees.jsp").forward(request,response);
}else
{
request.getRequestDispatcher("/lose.jsp").forward(request,response);
}
out.flush();
out.close();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
doGet(request,response);
out.flush();
out.close();
}
}
-------------------------------------------------
错误
建立连接的时候出现了错误com.microsoft.sqlserver.jdbc.SQLServerDriver
2008-4-27 9:40:48 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet insertservlet threw exception
java.lang.NullPointerException
at guojian.insertinfo.insert(insertinfo.java:21)
at guojian.insertservlet.doGet(insertservlet.java:23)
at guojian.insertservlet.doPost(insertservlet.java:41)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:216)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:634)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:445)
at java.lang.Thread.run(Thread.java:595)