谢谢beyondii(十万个为什么), 连上了,但出现了错误,请帮我看看!!java.lang.NullPointerException at hero.heroDBConnect1.<init>(heroDBConnect1.java:42) at _setup__jsp._jspService(/setup.jsp:19) 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:135) at com.caucho.server.http.RunnerRequest.handleRequest(RunnerRequest.java:342) at com.caucho.server.http.RunnerRequest.handleConnection(RunnerRequest.java:272) at com.caucho.server.TcpConnection.run(TcpConnection.java:137) at java.lang.Thread.run(Thread.java:536)我的部分程序如下: package hero; import java.sql.*; public class heroDBConnect1 { private Connection conn = null; private Statement stmt = null; private PreparedStatement prepstmt = null; public int PageSize=10;
连上了,但出现了错误,请帮我看看!!java.lang.NullPointerException
at hero.heroDBConnect1.<init>(heroDBConnect1.java:42)
at _setup__jsp._jspService(/setup.jsp:19)
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:135)
at com.caucho.server.http.RunnerRequest.handleRequest(RunnerRequest.java:342)
at com.caucho.server.http.RunnerRequest.handleConnection(RunnerRequest.java:272)
at com.caucho.server.TcpConnection.run(TcpConnection.java:137)
at java.lang.Thread.run(Thread.java:536)我的部分程序如下:
package hero;
import java.sql.*;
public class heroDBConnect1 {
private Connection conn = null;
private Statement stmt = null;
private PreparedStatement prepstmt = null;
public int PageSize=10;
private void init()
{
try
{
Class.forName("org.gjt.mm.mysql.Driver");
}
catch(java.lang.ClassNotFoundException e)
{
System.out.println("erro");
}
try
{
if (conn!=null)
conn.close(); conn=DriverManager.getConnection("jdbc:mysql://218.7.4.180/herodata?user=hero&password=dhero&useUnicode=true&characterEncoding =8859_1");
//conn=DriverManager.getConnection(sConnStr);
}
catch(SQLException ex)
{
System.err.println("dfss");
}
}
public heroDBConnect1() throws Exception {
init();
stmt = conn.createStatement();
}
出了问题。
但是在本地,把218.7.4.180,改成127.0.0.1,就没问题
218.7.4.180就是你的本机ip?我记得mysql有一个ip限制访问,必须在他的服务器上配置那些ip是可以安全访问服务器的
他们是专门提供mysql的
只运行init(),不会出错。
加上 stmt = conn.createStatement();
就不行了
这个空间是我申请的,不是本地服务器!
编译成功!看来是真的是connection没有成功,那该怎么办呢?
我这里也联不上,是啥意思