JDBC的CRUD操作之PreparedStatement的查询操作

        @Test
	/**
	 * 查询操作
	 */
	public void demo4(){
		Connection conn = null;
		PreparedStatement pstmt = null;
		ResultSet rs = null;
		try{
			// 获得连接:
			conn = JDBCUtils.getConnection();
			// 编写SQL:
			String sql = "select * from user";
			// 预编译SQL:
			pstmt = conn.prepareStatement(sql);
			// 设置参数:
			// 执行SQL:
			rs = pstmt.executeQuery();
			// 遍历结果集:
			while(rs.next()){
				System.out.println(rs.getInt("id")+" "+rs.getString("username")+" "+rs.getString("password")+" "+rs.getString("nickname"));
			}
		}catch(Exception e){
			e.printStackTrace();
		}finally{
			JDBCUtils.release(rs, pstmt, conn);
		}
	}