原始JDBC连接

package jdbc;

import org.junit.jupiter.api.Test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class JDBCUtils {
public static Connection connection;
private static String url="jdbc:mysql://localhost:3306/aaa?useUnicode=true&characterEncoding=utf-8";
private static String username="root";
private static String password="root";

static{
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(url,username,password);

} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}

public static Connection getConnection(){
return connection;
}

@Test
public void test(){
Connection connection = JDBCUtils.getConnection();
System.out.println(connection);
}
}

解耦JDBC连接

package jdbc;

import org.junit.jupiter.api.Test;

import java.io

FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class JDBCUtils2 {
private static Connection connection;
private static String url;
private static String username;
private static String password;

static {
try {
//动态加载驱动
Class.forName("com.mysql.jdbc.Driver");
//加载配置文件
Properties properties = new Properties();
properties.load(new FileInputStream("src/main/java/db.properties"));
url = properties.getProperty("url");
username = properties.getProperty("username");
password = properties.getProperty("password");

connection = DriverManager.getConnection(url,username,password);

} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}

public static Connection getConnection(){
return connection;
}

@Test
public void test(){
Connection connection = JDBCUtils2.getConnection();
System.out.println(connection);
}
}