芥末8.9-优快云博客

原创 linux group user

将一个已有用户, 增加到一个已有用户组中,也就是将用户添加到新用户组中而不必离开原有的其他用户组usermod -a -G vboxsf bitcoin

2017-09-22 21:26:53 303

翻译 Java - Comparator (compare) and Comparable (compareTo)

Using Comparator, we can have n number of comparison logic written for a class.E.g.For a Car ClassWe can have a Comparator class to compare based on car model number. We can also have a Co

2017-02-23 18:25:32 471

原创 How to get the digest hash

How to get the digest hashRemove input script from transaction. We should remove bytes (do not forget about script len)Replace it with the funding script (do not forget about script len)Append S

2016-10-31 11:15:49 358

转载 What goes in to the message of a transaction signature?

I'm trying to create my own transaction from scratch, just to see how it works.I'm currently working backwards, and I'm stuck on the signature of a transaction...Here's my unsigned transaction

2016-10-30 00:05:53 364

转载 How can I extract the SIGHASH flags from the signature?

OP_CHECKSIG extracts a non-stack argument from each signature it evaluates, allowing the signer to decide which parts of the transaction to sign. Since the signature protects those parts of the tran

2016-10-29 23:49:28 371

原创 SIGHASH_NONE, SIGHASH_SINGLE 和SIGHASH_ALL

OP_CHECKSIG: extracts a non-stack argument from each signature it evaluates, allowing the signer to decide which parts of the transaction to sign. Since the signature protects those parts of the trans

2016-10-25 11:31:07 1249

转载 yield

To understand what yield does, you must understand what generators are. And before generators come iterables.IterablesWhen you create a list, you can read its items one by one. Reading i

2016-10-22 17:44:51 248

原创 Linux常用命令

查看运行进程命令ps -ef |grep tomcat安装rpm包命令rpm -e 包名查看rpm包是否已经安装命令rpm -qa | grep mysql卸载rpm包命令rpm -e 包名

2016-10-21 00:33:30 229

原创 OP_PUSHDATA1, OP_PUSHDATA2 和 OP_PUSHDATA4

WordOpcodeHexInputOutputDescriptionOP_PUSHDATA1760x4c(special)dataThe next byte contains the number of bytes to be pushed onto the stack.OP_PUSHDATA2770x4d(specia

2016-10-19 21:46:53 1021

原创 What is SHA-256?

The SHA (Secure Hash Algorithm) is one of a number of cryptographic hash functions. A cryptographic hash is like a signature for a text or a data file. SHA-256 algorithm generates an almost-unique, fi

2016-10-17 22:26:38 316

原创 python repr和str 的区别

The str() function is meant to return representations of values which are fairly human-readable, while repr() is meant to generate representations which can be read by the interpreter (or will force a

2016-10-13 21:27:53 2004

原创 Python slots 作用

在Python中，当我们定义了一个class，创建了一个class的实例后，我们可以给该实例绑定任何属性和方法，当你需要限制可绑定的实例的属性的时候，就可以使用__slots__。如：class Student(object): __slots__ = ('name', 'age') # 限定Student的属性为name, age, 不可以动态添加其他属性

2016-10-13 08:43:26 1524

原创 Python中的init方法与new方法的区别

Python中的__init__方法与__new__方法的区别：__init__ 通常用于初始化一个新实例，控制这个初始化的过程，比如添加一些属性，做一些额外的操作，发生在类实例被创建完以后。它是实例级别的方法。__new__ 通常用于控制生成一个新实例的过程。它是类级别的方法。先与__init__方法执行。

2016-10-08 06:51:31 248

原创马士兵Oracle

Client:图形版sqlplus, 命令行sqlplus, 浏览器, plsql developer超级管理员登录: sqlplus / as sysdba解锁用户: alter user scott account unlock;SQL(Structure Query Language)语言两套标准: SQL1992，SQL1999SQL语言有4类需

2016-09-01 10:51:05 1340 2

原创 Linux 常用命令，如行转列等

#Output the first 3 lineshead -n 3 SRVC_OBLG_DOC_D_20160304_152517.DAT#Output the last 3 linestail -n 3 SRVC_OBLG_DOC_D_20160304_152517.DAT#Output line 3cat fileName | awk 'FNR==3 pr

2016-04-07 12:17:51 1972

原创 Githup 简单使用

Upload the file into repository本地创建文件夹github： cd c:\github\Copy Github Reposity 项目到本地： git clone https://github.com/sdscls/java.git进入项目目录java, 并在java目录下创建一些新文件： cd c:\github\java做一下操作： g

2016-03-17 02:12:51 1566

原创 JDBC知识 - 马士兵视频教程笔记

PreparedStatement：可以灵活指定SQL语句中的变量CallableStatement: Java调用存储过程批处理：st = conn.createStatement(); st.addBatch("insert into dept2 values (21, 'Game1', 'BJ')");st.addBatch("insert into d

2016-03-16 23:54:01 1217

原创 JDBC连接步骤

JDBC: Java Database Connectivity , 连接不同数据库需要不同数据库的类库，但编程的接口是一样的。导入数据库相应的类库创建实例，实例创建后会自动向DrivderManager注册调用DriverManager的getConnection方法，获得Connection实例调用Connection实例的createStatement方法，获得Statement

2016-03-16 23:44:24 366

原创 JDBC-数据库连接字符串

SQLSERVER: Connection conn = DriverManager.getConnection("jdbc:sqlserver://localhost:1433", "sa", "******" );Oracle: Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:o

2016-03-15 23:33:58 359