抛出NullPointerException异常

更新时间：2019-01-31 15:43:32 209次访问

package JDBC;

import java.io.IOException;

import java.io.InputStream;

import java.sql.Connection;

import java.sql.Driver;

import java.sql.SQLException;

import java.util.Properties;

public class TestJDBC {

public Connection getConnection()  {

String driverClass = null;

String jdbcUrl = null;

String user = null;

String password = null;

InputStream in = getClass().getClassLoader().getResourceAsStream("jdbc.properties");

Properties properties = new Properties();

try {

properties.load(in);

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

driverClass = properties.getProperty("driver");

jdbcUrl = properties.getProperty("jdbcUrl");

user = properties.getProperty("user");

password = properties.getProperty("password");

Driver driver=null;

try {

driver = (Driver) Class.forName(driverClass).newInstance();

} catch (InstantiationException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (IllegalAccessException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

Properties info = new Properties();

info.put("user", user);

info.put("password", password);

Connection connection=null;

try {

connection = driver.connect(jdbcUrl, info);

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return connection;

}

public static void main(String[] args) {

TestJDBC t = new TestJDBC();

Connection c = t.getConnection();

System.out.println(c);

}

}

抛出Exception in thread "main" java.lang.NullPointerException异常

这个程序(估计你是参考别人的)需要配置文件的,配置文件名为

jdbc.properties

要在与class同一目录,里面要存放driver/jdbcUrl等信息,且要真实有效的(与你的系统有关)

网上的程序不是拿来就能用的,你先必须看懂才可以