Having had to use unsigned bytes for the first time, I also had to learn how Java references these datatypes. I did some research, and found a number of good guides out there but was generally dissatisfied with the approach they took to learn the sub…

写入bytea: File img = new File("/tmp/eclipse.png"); fin = new FileInputStream(img); con = DriverManager.getConnection(url, user, password); pst = con.prepareStatement("INSERT INTO images(data) VALUES(?)"); pst.setBinaryStream(1, fin, (in…

http://darksleep.com/player/JavaAndUnsignedTypes.html —————————————————————————————————————————————————————————————— Java and unsigned int, unsigned short, unsigned byte, unsigned long, etc. (Or rather, the lack thereof) Written by Sean R. Owens, sea…

monic Opcode(in hex) Other bytes Stack[before]→[after] Description aaload 32   arrayref, index → value load onto the stack a reference from an array aastore 53   arrayref, index, value → store into a reference in an array aconst_null 01   → null push…

Chapter 2. The Structure of the Java Virtual Machine 内容列表 2.1. The class File Format (class文件的格式) 2.2. Data Types (数据类型) 2.3. Primitive Types and Values (原始数据类型和值) 2.3.1. Integral Types and Values 2.3.2. Floating-Point Types, Value Sets, and Values 2…

This is a list of the instructions that make up the Java bytecode, an abstract machine language that is ultimately executed by the Java virtual machine. The Java bytecode is generated by language compilers targeting the Java Platform, most notably th…

https://my.oschina.net/renwofei423/blog/17404 1.      PyCodeObject与Pyc文件 通常认为,Python是一种解释性的语言,但是这种说法是不正确的,实际上,Python在执行时,首先会将.py文件中的源代码编译成Python的byte code(字节码),然后再由Python Virtual Machine来执行这些编译好的byte code.这种机制的基本思想跟Java,.NET是一致的.然而,Python Virtual Mac…

String的getBytes()方法是得到一个字串的字节数组,这是众所周知的.但特别要注意的是,本方法将返回该操作系统默认的编码格式的字节数组.如果你在使用这个方法时不考虑到这一点,你会发现在一个平台上运行良好的系统,放到另外一台机器后会产生意想不到的问题.比如下面的程序: class TestCharset {  public static void main(String[] args) {  new TestCharset().execute();  }  private void ex…

IO is a problem difficult to handle in various of systems because it  always becomes a bottleneck in data transfer. in this section, I will introduce some Java classes for two categories of data transfer,  Bytes and Characters, those classes were inc…

转载请注明出处:http://www.cnblogs.com/Joanna-Yan/p/6900536.html Java服务器后台在和Android端App通信时,遇到了两端关于用MD5加密同一包含中文的字符串结果不一致的问题. 具体问题描述: Java服务器后台和Android端AS用了同一个MD5的工具类,且两边项目的默认编码都是UTF-8 ,加密纯英文数字的字符串时,结果一致,对同一包含中文的字符串加密,发现结果不一样,这是为什么呢? 工具类MD5Util代码如下: public cla…