一开始我用的是sqlServer2000和java程序做连接,总是连不上,部分代码如下:package myprograme;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
import java.io.*;
public class LoginHandle extends HttpServlet
{
String jdbcDriver="com.microsoft.jdbc.sqlserver.SQLServerDriver";
String jdbcUrl="jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=LoginDatabase";
Connection con;
Statement sta;
ResultSet res;
public void init()
{
try
{
Class.forName(jdbcDriver);
}
catch(ClassNotFoundException cnfe)
{
cnfe.printStackTrace();
}
try
{
con=DriverManager.getConnection(jdbcUrl,"sa","123");//是不是这上有问题?????
}
catch(SQLException sqle)
{
sqle.printStackTrace();
}
}
public void doPost(HttpServletRequest req,HttpServletResponse resp)
{
resp.setContentType("text/html");
tomcat 抛出空指针异常,提示Connection 对象con没有实例化,(没有取到值)我以为是数据库的问题,
我现在用的是mysql,和servlet连接。一连测试好几天了,数据库也总是连接不上,
部分代码如下:
package rh;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.sql.*;
import bean.User;
//import java.
public class RegisterHandle extends HttpServlet
{
private String jdbcDriver="org.git.mm.mysql.Driver";
private String jdbcUrl="jdbc:mysql://localhost:3306/userinfo";
private Statement sta;
private Connection con;
private ResultSet res;
public void init()
{
try
{
Class.forName(jdbcDriver);
}
catch(ClassNotFoundException cnfe)
{
cnfe.printStackTrace();
}
try
{
con=DriverManager.getConnection(jdbcUrl,"root","123");
}
catch(SQLException sqle)
{
sqle.printStackTrace();
}
}
tomcat 还是抛出空指针异常,con没有实例化,
请问各位大哥,是不是驱动程序的jar包,我放错地方了,应该放在哪儿?
classpath 环境变量呢?
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;
import java.io.*;
public class LoginHandle extends HttpServlet
{
String jdbcDriver="com.microsoft.jdbc.sqlserver.SQLServerDriver";
String jdbcUrl="jdbc:microsoft:sqlserver://127.0.0.1:1433;DatabaseName=LoginDatabase";
Connection con;
Statement sta;
ResultSet res;
public void init()
{
try
{
Class.forName(jdbcDriver);
}
catch(ClassNotFoundException cnfe)
{
cnfe.printStackTrace();
}
try
{
con=DriverManager.getConnection(jdbcUrl,"sa","123");//是不是这上有问题?????
}
catch(SQLException sqle)
{
sqle.printStackTrace();
}
}
public void doPost(HttpServletRequest req,HttpServletResponse resp)
{
resp.setContentType("text/html");
tomcat 抛出空指针异常,提示Connection 对象con没有实例化,(没有取到值)我以为是数据库的问题,
我现在用的是mysql,和servlet连接。一连测试好几天了,数据库也总是连接不上,
部分代码如下:
package rh;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.sql.*;
import bean.User;
//import java.
public class RegisterHandle extends HttpServlet
{
private String jdbcDriver="org.git.mm.mysql.Driver";
private String jdbcUrl="jdbc:mysql://localhost:3306/userinfo";
private Statement sta;
private Connection con;
private ResultSet res;
public void init()
{
try
{
Class.forName(jdbcDriver);
}
catch(ClassNotFoundException cnfe)
{
cnfe.printStackTrace();
}
try
{
con=DriverManager.getConnection(jdbcUrl,"root","123");
}
catch(SQLException sqle)
{
sqle.printStackTrace();
}
}
tomcat 还是抛出空指针异常,con没有实例化,
请问各位大哥,是不是驱动程序的jar包,我放错地方了,应该放在哪儿?
classpath 环境变量呢?
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/WEB-INF/lib/下就可以了
首先你目前用的是什么IDE?在IDE中你的程序是否提示有错误呢?有错的话,就是你配置有错误
如果是web项目将jar放到WEB-INF/lib下
加上三个sqlserver的驱动包。。到
/WEB-INF/lib/
eclipse的报错信息如下:
Usage: javaw [-options] class [args...]
(to execute a class)
or javaw [-options] -jar jarfile [args...]
(to execute a jar file)where options include:
-client to select the "client" VM
-server to select the "server" VM
-hotspot is a synonym for the "client" VM [deprecated]
The default VM is client.
-cp <class search path of directories and zip/jar files>
-classpath <class search path of directories and zip/jar files>
A ; separated list of directories, JAR archives,
and ZIP archives to search for class files.
-D<name>=<value>
set a system property
-verbose[:class|gc|jni]
enable verbose output
-version print product version and exit
-version:<value>
require the specified version to run
-showversion print product version and continue
-jre-restrict-search | -jre-no-restrict-search
include/exclude user private JREs in the version search
-? -help print this help message
-X print help on non-standard options
-ea[:<packagename>...|:<classname>]
-enableassertions[:<packagename>...|:<classname>]
enable assertions
-da[:<packagename>...|:<classname>]
-disableassertions[:<packagename>...|:<classname>]
disable assertions
-esa | -enablesystemassertions
enable system assertions
-dsa | -disablesystemassertions
disable system assertions
-agentlib:<libname>[=<options>]
load native agent library <libname>, e.g. -agentlib:hprof
see also, -agentlib:jdwp=help and -agentlib:hprof=help
-agentpath:<pathname>[=<options>]
load native agent library by full pathname
-javaagent:<jarpath>[=<options>]
load Java programming language agent, see java.lang.instrument
-splash:<imagepath>
show splash screen with specified image
common/lib;和WEBINFO/lib目录下都有驱动程序的jar包。
用dos 控制台编译没有问题, tomcat运行时提示有空指针异常:
Connection 对象con没有实例化
我现在开始有点怀疑JDK,有问题
JDK的那个目录下,你去看看,好像要什么三个文件,以前整过打包出来的三个文件。。SQL的好像
现在好像有sp4了
我不记得 sqlserver的 URL是不是这样写了还有,你用 eclipse 写个测试用例,看看能不能连上数据库,首先判断下是哪里出了问题吧
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import entity.ChannelInfo;
public class Conn {
String cSql="sun.jdbc.odbc.JdbcOdbcDriver"; Connection con;
Statement stm;
ResultSet rs; public Conn() {
try {
Class.forName(cSql);
} catch (ClassNotFoundException ex) {
ex.printStackTrace();
} }
public boolean open(){
String sql="jdbc:odbc:accp";
try {
con = DriverManager.getConnection(sql);
stm=con.createStatement();
if(stm!=null)
{
return true;
}
} catch (SQLException ex) {
ex.printStackTrace();
} return false; } public boolean judgeUser(String userName,String passWord){
boolean judge=this.open();
if(userName!=null&&passWord!=null&&judge)
{
try {
rs = stm.executeQuery("select * from userInfo where userName='"+userName+"' and passWord='"+passWord+"'");
if(rs.next())
{
return true;
} } catch (SQLException ex) {
ex.printStackTrace();
}
}
return false; }public ArrayList getChannelList(){
ArrayList arrayList=new ArrayList();
open();
try {
rs = stm.executeQuery("select * from channelInfo");
while(rs.next())
{
ChannelInfo channle=new ChannelInfo();
channle.setChannelId(rs.getString(1));
channle.setChannelName(rs.getString(2));
channle.setUserId(rs.getString(3));
arrayList.add(channle);
}
} catch (SQLException ex) {
ex.printStackTrace();
}
return arrayList; }
}