Java Network programming
Physical layer.
Data link layer.
Network layer.
Transport layer.
Session layer.
The presentation layer.
Application layer.
The TCP/IP layered interface includes the following functions for the collaboration layer, respectively:
The network interface layer.
Network interconnect layer.
Transport layer.
Application layer.
Socket:
Socket. Sockets. is an abstraction layer.
//Create a client socket to initiate a connection request to the serverSocket socket =NewSocket ("127.0.0.1", 30001); /*Create an input-output stream with an established socket to handle connections to the server side*/ //writing data to the serverBufferedWriter writer =NewBufferedWriter (NewOutputStreamWriter (Socket.getoutputstream ())); Writer.write ("Hello server!!!"); Writer.flush (); //read data from the serverBufferedReader reader =NewBufferedReader (NewInputStreamReader (Socket.getinputstream ())); Char[] ch =New Char[100]; intLen =reader.read (CH); System.out.println ("Information received from the server side:"); System.out.print (NewString (CH, 0, Len)); //Freeing ResourcesReader.close (); Writer.close (); Socket.close ();
Database programming
JDBC is a set of database programming APIs available in Java.
The DriverManager class is used to manage the JDBC-driven service classes.
The connection interface represents a database connection.
The statement interface represents the SQL statement.
The ResultSet interface represents the returned result set.
Connection conn =NULL;//Connection ObjectStatement stmt =NULL;//Statement ObjectResultSet rs =NULL;//Query Result set /*Load Driver*/ Try{class.forname ("Com.mysql.jdbc.Driver"); } Catch(ClassNotFoundException e) {e.printstacktrace (); } /*Create a Connection object*/ //Connection StringString url = "Jdbc:mysql://localhost:3306/java"; //User nameString user = "root"; //PasswordString pwd = "5245"; Try { //Create a connectionconn =drivermanager.getconnection (URL, user, pwd); System.out.println ("Connection succeeded"); } Catch(SQLException e) {e.printstacktrace (); } /*Create a statement object*/ Try{stmt=conn.createstatement (); } Catch(SQLException e) {e.printstacktrace (); } /*send SQL statement execution*/ //Add//String SQL1 =//INSERT into Users (ID,USERNAME,PWD) VALUES (4, ' HXS ', ' 1995 ');//int count = 0;//try {//count = stmt.executeupdate (SQL1);//} catch (SQLException e) {// //e.printstacktrace ();// }/// * Process Execution Results * ///if (count = = 1) {//System.out.println ("add Success");//} else {//System.out.println ("Add failed");// } //EnquiryString sql = "SELECT ID, username, pwd from users"; Try { //get query result setrs =stmt.executequery (SQL); } Catch(SQLException e) {//e.printstacktrace (); } Try { //Loop through the next record while(Rs.next ()) {//get a column value in a rowSYSTEM.OUT.PRINTLN ("id =" + rs.getint ("id") + ", username =" + rs.getstring ("username") + ", pass Word = "+ rs.getstring (" pwd ")); } } Catch(SQLException e) {//e.printstacktrace (); } /*freeing resources: Must-do*/ if(Conn! =NULL) Try{conn.close (); } Catch(SQLException e) {e.printstacktrace (); } finally { if(rs! =NULL) Try{rs.close (); } Catch(SQLException e) {e.printstacktrace (); } finally { if(stmt! =NULL) Try{stmt.close (); } Catch(SQLException e) {e.printstacktrace (); } } } }
XML parsing Technology
XML: Extensible Markup Language.
Form:
Validated processors-check the validity and format specifications of the XML document.
Processor without validation--check the format specification of the XML document.
The XML parser uses two basic APIs:
Document Object Model (DOM): An API based on tree structure.
XML Simple API (SAX): An event-driven API.
<!--Penguin--><penguins> <penguin id= "1" > <name> peas </name> <!--name-- <close>100</close> <!--intimacy values --
<! ELEMENT Pet (dogs,penguins) ><! ELEMENT Dogs (dog*) ><! ELEMENT Dog (name,close,health,breed) ><! Attlist Dog ID CDATA #REQUIRED ><! ELEMENT Penguins (penguin*) ><! ELEMENT Penguin (Name,close,health,gender) ><! attlist Penguin ID CDATA #REQUIRED ><! ELEMENT name (#PCDATA) ><! ELEMENT Close (#PCDATA) ><! ELEMENT Health (#PCDATA) ><! ELEMENT Breed (#PCDATA) ><! ELEMENT gender (#PCDATA) >
Java network programming, database programming, XML parsing technology.