mysql - 我无法使用 Intellij 连接到 Maven 中的 mysql 服务器

Question

我遇到问题，当我尝试连接数据库时出现错误:

[MySQL] Can't connect to the mysql server: Could not create connection to database server. Attempted reconnect 3 times. Giving up.

我能够连接到 Intelij 中的“数据库”选项卡，所以数据库可能没有任何问题，或者它是一个错误，但我无法修复它。我将衷心感谢您的帮助。我预先感谢您。

这是我的代码:

package Code;

import Database.MySQLManager;

public class ModuleSearcher {

public static void main(String[] args) {

    MySQLManager mySQLManager = new 
MySQLManager("localhost","username","password","login",3306);
    mySQLManager.connect();


}

}

另一个:

package Database;

import java.sql.*;

public class MySQLManager {

private String hostname, username, password, database;
private int port;

private Connection con;

public MySQLManager( String hostname, String username, String password, 
String database, int port ) {
    this.hostname = hostname;
    this.username = username;
    this.password = password;
    this.database = database;
    this.port = port;
}

//<editor-fold desc="Connect">
public void connect( ) {
    try {
        this.con = DriverManager.getConnection( "jdbc:mysql://" + hostname + 
":" + port + "/" + database +
                "?autoReconnect=" + true, username, password );

        if ( !con.isClosed( ) && con != null ) {
            System.out.println( "[MySQL] Sucessfully connected." );
        }

    } catch ( SQLException err ) {
        System.err.println( "[MySQL] Can't connect to the mysql server: " + 
err.getMessage( ) );
    }
}
//</editor-fold>

//<editor-fold desc="Close">
public void close( ) {
    try {
        if ( !con.isClosed( ) && con != null ) {
            con.close( );
            if ( con.isClosed( ) ) {
                System.out.println( "[MySQL] Connection successfully 
closed." );
            } else {
                System.err.println( "[MySQL] Can't close the mysql 
connection" );
            }
        }
    } catch ( SQLException err ) {
        System.err.println( "[MySQL] Can't close the mysql connection: " + 
err.getMessage( ) );
    }
}
//</editor-fold>

//<editor-fold desc="Update">
public void update( String query ) {
    try {
        PreparedStatement ps = con.prepareStatement( query );
        ps.executeUpdate( );
    } catch ( SQLException err ) {
        System.err.println( "[MySQL] Update error: " + err.getMessage( ) );
    }
}
//</editor-fold>

//<editor-fold desc="Query">
public ResultSet query( String query ) {
    ResultSet rs = null;
    try {
        PreparedStatement ps = con.prepareStatement( query );
        rs = ps.executeQuery( );
    } catch ( SQLException err ) {
        System.err.println( "[MySQL] Query error: " + err.getMessage( ) );
    }
    return rs;
}
//</editor-fold>

//<editor-fold desc="Getter + Setter">
public String getHostname( ) {
    return hostname;
}

public String getUsername( ) {
    return username;
}

public String getPassword( ) {
    return password;
}

public String getDatabase( ) {
    return database;
}

public int getPort( ) {
    return port;
}

public Connection getCon( ) {
    return con;
}
//</editor-fold>

}

pom:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>ModuleSearcher</groupId>
<artifactId>ModuleSearcher</artifactId>
<version>1.0-SNAPSHOT</version>

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.9-rc</version>
    </dependency>
</dependencies>

</project>

Answer 1

这与 Intellij 无关。看起来您的服务器没有在本地主机端口 3306 上运行。请检查您的服务器是否正在运行。

如果服务器是 5.x，也尝试使用 5.1.6 连接器。