[大数据]JDBC工具类

JDBC工具类

封装了对数据库进行查询与增删改的方法，采用单例模式。

public class MyDB {
    private static Connection conn;
    private static PreparedStatement ps;
    private static ResultSet rs;
    private static final String url = "jdbc:mysql://localhost:3306/库名?characterEncoding=utf8";
    private static final String username = "root";
    private static final String password = "root";
    private static MyDB myDB;


    private MyDB() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("数据库初始化失败");
        }
    }

    public static MyDB getMyDB() {
        if (myDB == null) {
            myDB = new MyDB();
        }
        return myDB;
    }

    public ResultSet getQuery(String sql, Object... args) {
        try {
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            rs = ps.executeQuery();
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("查询异常");
        }
        return rs;
    }

    public boolean getUpdate(String sql, Object... args) {
        boolean flag = false;
        try {
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < args.length; i++) {
                ps.setObject(i + 1, args[i]);
            }
            flag = ps.executeUpdate() >= 1;
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("增删改异常");
        }
        return flag;
    }

    public void close() {
        try {
            if (rs != null && !rs.isClosed()) {
                rs.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (ps != null && !ps.isClosed()) {
                ps.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        try {
            if (conn != null && !conn.isClosed()) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

简单应用

public class Test {
    static MyDB myDB = MyDB.getMyDB();
    
    private static void method1(String name, String pwd) {
        String sql = "select * from user where name=? and password=?";
        ResultSet rs = null;
        rs = myDB.getQuery(sql, name, pwd);
        try {
            if (rs.next()) {
                System.out.println("登陆成功");
            } else {
                System.out.println("登录失败");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            myDB.close();
        }
    }

    public static void method2(int id) {
        String sql = "delete from user where id = ?";
        if (myDB.getUpdate(sql, id)) {
            System.out.println("增删改成功");
        }
        myDB.close();
    }
}