Struts2（驗證登陸用戶 DB:mysql）

1. 首先要下載Connector/J地址：http://www.mysql.com/downloads/connector/j/

這是MySQL官方提供的連接方式：

解壓後得到jar庫文件，需要在工程中導入該庫文件

2. 先寫一個class來連接數據庫

public class dbconnector {
    public static final String url = "jdbc:mysql://127.0.0.1/test";
    public static final String name = "com.mysql.jdbc.Driver";
    public static final String user = "root";
    public static final String password = "";

    public Connection conn = null;
    public PreparedStatement pst = null;

    public dbconnector(String sql) {
        try {
            Class.forName(name);// 指定連接類型
            conn = DriverManager.getConnection(url, user, password);// 獲取連接
            pst = conn.prepareStatement(sql);// 準備執行語句
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void close() {
        try {
            this.conn.close();
            this.pst.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

}

3. 在Dao類中執行

public String select(User user) {
        Map<String, String> usersMap = new HashMap<String, String>();
        String sql = null;
        dbconnector db1 = null;
        ResultSet ret = null;

        try {
            sql = "select * from user";//SQL語句
            db1 = new dbconnector(sql);
            ret = db1.pst.executeQuery();//執行語句，得到結果集
            while (ret.next()) {
                String uid = ret.getString(1);
                String uname = ret.getString(2);
                String upassword = ret.getString(3);
                usersMap.put(uname,upassword);
            }//顯示數據

            ret.close();
            db1.close();//關閉連接

            // 傳入的用戶的用戶名與密碼
            String userName = user.getUsername();
            String password = user.getPassword();

            if (usersMap.containsKey(userName)
                    && usersMap.get(userName).equals(password)) {
                return "1";
            } else {
                return "0";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

4. 可以在執行類裏寫一個main函數來測試

public static void main(String[] args) {
        UserDaoJDBC udj = new UserDaoJDBC();
        User u = new User();
        u.setUsername("tester01");
        u.setPassword("tester");
        System.out.println(udj.select(u));
    }