Jdbc小结_4

1.test preparedStatement类

@Test
	public void testPreparedStatement() {
		Connection connection = null;
		PreparedStatement preparedStatement = null;

		try {
			connection = JDBCTools.getConnection();
			String sql = "INSERT INTO customers (name, email, birth) "
					+ "VALUES(?,?,?)";

			preparedStatement = connection.prepareStatement(sql);
			preparedStatement.setString(1, "ATGUIGU");
			preparedStatement.setString(2, "[email protected]");
			preparedStatement.setDate(3,
					new Date(new java.util.Date().getTime()));

			preparedStatement.executeUpdate();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCTools.releaseDB(null, preparedStatement, connection);
		}
	}

2.补充JdbcTools 类通用方法update(String sql,object ...args);

	public static void update(String sql, Object ... args){
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		
		try {
			connection = JDBCTools.getConnection();
			preparedStatement = connection.prepareStatement(sql);
			
			for(int i = 0; i < args.length; i++){
				preparedStatement.setObject(i + 1, args[i]);
			}
			
			preparedStatement.executeUpdate();
			
		} catch (Exception e) {
			e.printStackTrace();
		} finally{
			JDBCTools.releaseDB(null, preparedStatement, connection);
		}
	}

3.Sql注入攻击

sql注入是利用某些系统没有对用户输入的数据进行充分的检查而是用户再输入数据中注入非法的sql语句或命令，从而利用系统的sql引擎完成恶意的行为的做法

对于java而言，防止ｓｑｌ注入的做法　用ＰｒｅｐａｒｅｄＳｔａｔｅｍｅｎｔ代替Ｓｔａｔｅｍｅｎｔ

/**
	 * SQL 注入.
	 */
	@Test
	public void testSQLInjection() {
		String username = "a' OR PASSWORD = ";
		String password = " OR '1'='1";

		String sql = "SELECT * FROM users WHERE username = '" + username
				+ "' AND " + "password = '" + password + "'";

		System.out.println(sql);

		Connection connection = null;
		Statement statement = null;
		ResultSet resultSet = null;

		try {
			connection = JDBCTools.getConnection();
			statement = connection.createStatement();
			resultSet = statement.executeQuery(sql);

			if (resultSet.next()) {
				System.out.println("登录成功!");
			} else {
				System.out.println("用户名和密码不匹配或用户名不存在. ");
			}

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCTools.releaseDB(resultSet, statement, connection);
		}
	}

Sql=select * from users where user ='x' orpassword='x'and +password ='x' or '1'='1'