RT,我是对着视频教程写的代码,但就是会出现nullpoint异常,抓狂;,望各位大虾指教,上代码Dbconfig.properties文件也在package com.MVC.util 下package com.MVC.util;import java.io.FileInputStream;
import java.io.*;
import java.io.IOException;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;import com.mysql.jdbc.Connection;public class ConnectionUtil {
public java.sql.Connection getConnection()
{
String username=null;
String password=null;
String url=null;
String Driver=null;
Properties prop=new Properties();
try {
prop.load(this.getClass().getClassLoader().getResourceAsStream("Dbconfig.properties"));
username=prop.getProperty("username");
password=prop.getProperty("password");
url=prop.getProperty("url");
Driver=prop.getProperty("Driver");
Class.forName(Driver);
return DriverManager.getConnection(url,username,password);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
public static void main(String args[])
{
System.out.println(new ConnectionUtil().getConnection());
}
}
异常信息
Exception in thread "main" java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at com.MVC.util.ConnectionUtil.getConnection(ConnectionUtil.java:22)
at com.MVC.util.ConnectionUtil.main(ConnectionUtil.java:43)
import java.io.*;
import java.io.IOException;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;import com.mysql.jdbc.Connection;public class ConnectionUtil {
public java.sql.Connection getConnection()
{
String username=null;
String password=null;
String url=null;
String Driver=null;
Properties prop=new Properties();
try {
prop.load(this.getClass().getClassLoader().getResourceAsStream("Dbconfig.properties"));
username=prop.getProperty("username");
password=prop.getProperty("password");
url=prop.getProperty("url");
Driver=prop.getProperty("Driver");
Class.forName(Driver);
return DriverManager.getConnection(url,username,password);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
public static void main(String args[])
{
System.out.println(new ConnectionUtil().getConnection());
}
}
异常信息
Exception in thread "main" java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:418)
at java.util.Properties.load0(Properties.java:337)
at java.util.Properties.load(Properties.java:325)
at com.MVC.util.ConnectionUtil.getConnection(ConnectionUtil.java:22)
at com.MVC.util.ConnectionUtil.main(ConnectionUtil.java:43)
解决方案 »
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password=prop.getProperty("password");
url=prop.getProperty("url");
Driver=prop.getProperty("Driver");
你确定这样写对吗?我觉得这样写
String username=request.getParameter("username");
一步:
把配置文件拷贝到src下面;
定义一个FinlInputStream in;
把in打印一下,看是不是为空!
然后prop.load(in);