Bloggers are too lazy to provide a sample program
6, based on UDP Development
(1) Sender:socket-> preparing the packet
Datagramsocket docket = new Datagramsocket ();
Prepare the packet,
InetAddress ia = inetaddress.getbyname (" IP address of each other ");
Datagrampacket DP = new Datagrampacket (Str.getbytes (), full length of bytes , address , port number );
Send Data
Socket.send (DP);
(2) Receiving party:
Datagramsocket socket= New Datagramsocket ( port number );
preparing to receive packets
Byte[] B = new byte[1024];
Datagrampacket DP = new Datagrampacket (b,b.lenth);
Receive Data
Socket.receiver (DP);
to save data from a byte array to a string
string s = new string (Dp.getdata (), 0,dp.getdata (). length);
Add: After you establish this link, you can return data without specifying a port
SocketAddress sa = dp.getsocketaddress ();
byte[] by = Str.getbytes ();
Datagrampacket data = new Datagrampacket (BY,BY.LENGTH,SA);
7. JUnit Add
Right- Click items :"Build path"->configure build path->libararies->add library->junit- >next, down
Pull menu Select JUint4->finish->ok
1.XML declaration statement:<?xml version= "1,0" encoding= "UTF-8"?>
Well-formed XML documents need to meet:
<1> must have an XML declaration
<2> must have and have only one root element
<3> label Case Sensitive
<4> double quotes for attribute values
<5> Label pairs
<6> elements are properly nested
2. DTD Validation:
(1) Function: to limit the format of XML file, ensure the file format is normalized
(2) Realization:
<! DOCTYPE root Tag name [
<! Element tag name (content included in the label)>// between the three are separated by a space
]>
Limit the number of occurrences of a label symbol:
? --0-1 Times
+--1 to multiple times
*--0 to multiple times
(3) Verify attributes:
<! The Attlist property sits in the Tag Property Name property value type [ other ]>
Property type:cdata- biausse text
Other:#REQUIRED-- required
3. External DTD
Introduce syntax:
<! DOCTYPE root element SYSTEM "DTD file " >
Note: The element and attlist tags are used directly in the DTD file
In general, an external DTDis introduced.
File suffix dtd.
Using the DOM to parse the objects used primarily by XML
4. Objects used:Document,NodeList,Node,Element
Document represents The properties of the XML decoupling unit
NodeList represents the label pair collection
Node represents a pair of tags with extreme content
Element represents a label for obtaining a property
(2) Common methods
Document :
Getdocuementelement ():element- get root element
getElementsByTagName (" label "): Gets the specified list of tags
NodeList:
Item (int index): iterates through each node
Element :getattribute (" attribute name "): Returns the value of a property in a tag
Node:
Getnodename ():// Get node name
Gettextcontent ():// Gets the text in the label pair
Note: When you get the property value of a tag, you need to strongly convert the Node object to Element
Before the strong turn, first judge:
If (Node.getnodetype () ==element.element_node) {
Element e = (element) node;
String attribute = E.getattriubute (" attribute name ");
}
UDP development-DTD validation, DOM parsing