Javaがmysqlにデータを挿入するときに文字化けするコードの解決策

static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
    static final String DB_URL = "jdbc:mysql://localhost:3306/dbname?characterEncoding=UTF-8";

package com.music.test;

import java.sql.*;

public class DBMySQL {
    // JDBC 驱动名及数据库 URL
    static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
    static final String DB_URL = "jdbc:mysql://localhost:3306/dbname?characterEncoding=UTF-8";

    // 数据库的用户名与密码，需要根据自己的设置
    static final String USER = "***";
    static final String PASS = "***";
    private Connection conn = null;

    public DBMySQL() {
        try {
            // 注册 JDBC 驱动
            Class.forName("com.mysql.jdbc.Driver");
            // 打开链接
            System.out.println("连接数据库...");
            conn = DriverManager.getConnection(DB_URL, USER, PASS);
        } catch (SQLException se) {
            // 处理 JDBC 错误
            se.printStackTrace();
        } catch (Exception e) {
            // 处理 Class.forName 错误
            e.printStackTrace();
        }
    }

    public int insert(Album album) {
        int i = 0;
        String sql = "insert into album (album_name,singer,album_url) values(?,?,?)";
        try {

            PreparedStatement preStmt = conn.prepareStatement(sql);
            preStmt.setString(1, album.getAlbum_name());
            preStmt.setString(2, album.getSinger());// 或者：preStmt.setInt(1,值);
            preStmt.setString(3, album.getAlbum_url());// 或者：preStmt.setInt(1,值);

            i = preStmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }

        return i;// 返回影响的行数，1为执行成功
    }
}