JDBC 連線 MySQL 完整教學與範例程式碼

Java 連接 MySQL 資料庫：環境建置與程式實作

前置準備

1. 確認已安裝 Java 環境（JDK/JRE）與 MySQL 資料庫
2. 下載 MySQL Connector/J JDBC 驅動程式（mysql-connector-java-3.1.14-bin.jar）
3. 將 JAR 檔放入 JRE/lib/ext 目錄（如 C:\Program Files\Java\jre6\lib\ext）

資料庫連線工具類別 DBConfigure

import java.sql.*;

public class DBConfigure {
    private Statement stmt = null;
    private ResultSet rs = null;
    private Connection conn = null;
    private String sql;
    private String strurl;

    public DBConfigure() {}

    public void openConn() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String user = "root";
            String passwd = "123456";
            String dbName = "jobsearch";
            conn = DriverManager.getConnection(
                "jdbc:mysql://localhost/" + dbName + "?user=" + user + "&password=" + passwd);
        } catch (Exception e) {
            System.out.println("OpenConnection: " + e.getMessage());
        }
    }

    public ResultSet executeQuery(String sql) {
        try {
            stmt = conn.createStatement();
            rs = stmt.executeQuery(sql);
        } catch (SQLException e) {
            System.err.println("executeQuery: " + e.getMessage());
        }
        return rs;
    }

    public void executeUpdate(String sql) {
        try {
            stmt = conn.createStatement();
            stmt.executeUpdate(sql);
        } catch (SQLException e) {
            System.out.println("executeUpdate: " + e.getMessage());
        }
    }

    public void closeStmt() {
        try { if (stmt != null) stmt.close(); }
        catch (SQLException e) { System.err.println("closeStmt: " + e.getMessage()); }
    }

    public void closeConn() {
        try { if (conn != null) conn.close(); }
        catch (SQLException e) { System.err.println("closeConn: " + e.getMessage()); }
    }
}

測試程式

import java.sql.*;

public class Test {
    public static void main(String[] args) {
        try {
            DBConfigure db = new DBConfigure();
            ResultSet rs = null;
            db.openConn();

            String sql = "SELECT * FROM page";
            rs = db.executeQuery(sql);
            while (rs.next()) {
                System.out.println(rs.getString("content"));
            }
            db.closeStmt();
            db.closeConn();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

常用匯入類別

• java.sql.Connection
• java.sql.DriverManager
• java.sql.ResultSet
• java.sql.SQLException
• java.sql.Statement

提示： 新版專案建議使用 Maven/Gradle 管理依賴，驅動類別名稱已更新為 com.mysql.cj.jdbc.Driver（Connector/J 8.0+），連線字串建議加上 useSSL=false&serverTimezone=UTC 等參數。