Question

我正在尝试使用Java连接mysql。我正在使用db.properties文件来获取连接详细信息。

我是一个使用db.properties文件的新人。我的代码有什么问题??

如下所示

#mysql DB properties
#DB_DRIVER_CLASS=com.mysql.jdbc.Driver
#DB_URL=jdbc:mysql://localhost:8080/ci_intro
#DB_USERNAME=root
#DB_PASSWORD=

我的Java类文件是

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

public class JDBCExample {

public static void main(String[] argv) throws IOException,
        ClassNotFoundException, SQLException {

    System.out
            .println("-------- MySQL JDBC Connection Testing ------------");

    Properties props = new Properties();
    FileInputStream in = new FileInputStream("db.properties");
    props.load(in);
    in.close();

    String driver = props.getProperty("DB_DRIVER_CLASS");
    if (driver != null) {
        Class.forName(driver);
    }

    String url = props.getProperty("DB_URL");
    String username = props.getProperty("DB_USERNAME");
    String password = props.getProperty("DB_PASSWORD");

    Connection con = DriverManager.getConnection(url, username, password);

    if (con != null) {
        System.out.println("You made it, take control your database now!");
    } else {
        System.out.println("Failed to make connection!");
    }
}
}

我收到以下错误

-------- MySQL JDBC Connection Testing ------------
Exception in thread "main" java.sql.SQLException: The url cannot be null
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.avn.notificationengine.JDBCExample.main(JDBCExample.java:33)

Answer 1

删除#文件中的“*.properties”。 “#”之后的所有内容都是评论。您的*.properties应为：

#mysql DB properties
DB_DRIVER_CLASS=com.mysql.jdbc.Driver
DB_URL=jdbc:mysql://localhost:8080/ci_intro
DB_USERNAME=root
DB_PASSWORD=

JDBC连接中的空URL

1 个答案: