在静态方法中不能调用非静态变量，但getclass()可以换个形式来调用

数据库连接的工具类

package com.tools;

import java.io.IOException;
import java.io.InputStream;
import java.sql.SQLException;
import java.util.Properties;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Driver;
import com.mysql.jdbc.ResultSet;
import com.mysql.jdbc.Statement;

public class Tools {

public static Connection getconnetion() throws ClassNotFoundException{

String dri=null;
String jdbcurl=null;
String userString=null;
String passwordString=null;

Connection connection=null;
InputStream inputStream=Tools.class.getClassLoader().getResourceAsStream("jdbc.properties");
System.out.println(inputStream);
Properties properties=new Properties();
try {
properties.load(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
dri=properties.getProperty("driver");
jdbcurl=properties.getProperty("jdbcurl");
userString=properties.getProperty("user");
passwordString=properties.getProperty("password");

Properties info=new Properties();
info.put("user", userString);
info.put("password", passwordString);

try {
Driver driver=(Driver) Class.forName(dri).newInstance();
try {
connection=(Connection) driver.connect(jdbcurl, info);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {

e.printStackTrace();
}

return connection;

}
public static void realese(ResultSet resultSet,Connection connection,Statement statement){
if(resultSet!=null){
try {
resultSet.close();
System.out.println("ok1");
} catch (Exception e) {
e.printStackTrace();
}
}
if(statement!=null){
try {
statement.close();
System.out.println("ok2");
} catch (Exception e) {
e.printStackTrace();
}
}
if(connection!=null){
try {
connection.close();
System.out.println("ok3");
} catch (Exception e) {
e.printStackTrace();
}
}

}
public static void updatele(String sql){
try {
Statement statement=(Statement)getconnetion().createStatement();
statement.executeUpdate(sql);
} catch (ClassNotFoundException | SQLException e) {

e.printStackTrace();
}
}
}