JAVA 63rd-about Client Server & amp; URL Class & amp; URLConnection

JAVA 63rd-about Client Server & amp; URL Class & amp; URLConnection

Common clients and servers

Client:

Browser: IE: pop-up window, Cheetah: pop-up window, multiple tags, competitive effect

Server:

Server: TomCat: 1. process the request 2. Respond

To make TomCat work for us, the related classes written in java must implement interface Serverlet.

The powerful aspect of a browser is its parsing capability. It can be parsed in many formats.

Server and client principles

Custom Server:

Public static void main (String [] args) throws IOException {ServerSocket ss = new ServerSocket (9090); // Tomcat is 8080 Socket socket = ss. accept (); InputStream in = socket. getInputStream (); System. out. println ("ip:" + socket. getInetAddress (). getHostAddress (); byte [] buf = new byte [1024]; int len = in. read (buf); String text = new String (buf, 0, len); System. out. println (text); PrintWriter out = new PrintWriter (socket. getOutputStream (), true); out. println ("hello"); socket. close (); ss. close ();}

Use the existing client IE to find out what requests the client sends to the server?

Request Line: Request Method/1.html request resource path: http Protocol version

Request Message Header: property name: Property Value

Request body

Simulate a browser to obtain information

Public static void main (String [] args) throws IOException {Socket s = new Socket ("192.168.1.1", 8080); // get it from tomcat, browser information PrintWriter out = new PrintWriter (s. getOutputStream (), true); out. println ("GET/HTTP /..... "); out. println (".... "); out. println (".... "); out. println (".... "); out. println (".... "); out. println (".... "); InputStream in = s. getInputStream (); byte [] buf = new byte [1024]; int len = in. read (buf); String line = new String (buf, 0, len); System. out. println (line); // obtain the locally written html code s. close ();}

Response:

Response line: http Protocol version response status code Description

Response Message attributes. Property name: Property Value

Response body:-> above html source code

PS: the browser is too hard to write, so many vendors are applying the original IE Kernel

Class URL

ClassURLRepresents a unified resource identifier, which is a pointer to the Internet "resource. A resource can be a simple file or directory, or a reference to a more complex object, such as a query of a database or search engine.

Every URL is a URI, but not every URI is a URL.

Public static void URL_Demo () throws MalformedURLException {String strurl = "http: // 127.0.0.1: 8080/myhtml/1.html? Name = wang "; // http://www.baidu.com/baidu? Word = java, search for javaURL url = new URL (strurl) in the Baidu address bar; System. out. println ("Protocol:" + url. getProtocol (); // obtain the host protocol System. out. println ("Host:" + url. getHost (); // obtain the host name System. out. println ("Port:" + url. getPort (); // obtain the port System. out. println ("File:" + url. getFile (); // obtain the file System. out. println ("Path:" + url. getPath (); // obtain the path part of the System. out. println ("Query:" + url. getQuery (); // obtain the query part}

Protocol: http
Host: 127.0.0.1
Port: 8080
File:/myhtml/1.html? Name = wang
Path:/myhtml/1.html
Query: name = wang

Public static void URL_Demo () throws IOException {String strurl = "http: // 127.0.0.1: 8080/myhtml/1.html? Name = wang "; URL url = new URL (strurl); InputStream in = url. openStream (); // open the connection to this URL and return an InputStream used to read from this connection. /** Principle: * openConnection () * returns a URLConnection object, which indicates the connection to the remote object referenced by the URL. * URLConnection conn = url. openConnection (); * System. out. println (connection); * The underlying layer encapsulates the http resolution method for URLs. This object is a java built-in object that can parse specific protocols + * 1 in the socket * URLConnection class. string str = conn. getHeaderField ("Contend-Type"); * System. out. println (str); // responds to a message of the text type * then you can determine the type of the text based on the response result. Based on the specified parser, parse data * actually uses Socket and Protocol * 2. inputStream in = conn.getinputstream()); to get the response body of 1.html ** so the url. the principle of openStream () is: * URLConnection conn = url. openConnection (); * InputStream in = conn. getInputStream (); */byte [] buf = new byte [1024]; int len = in. read (buf); String str = new String (buf, 0, len); System. out. println (str); // get the response body of 1.html. The url help is parsed into the html source code in. close ();}

Common Network Architecture
1. C/S: client/server (client, server)

Early stage:

Both VC ++ and VB are C/S.

Features:

The software of this structure, both the client and the server, must be written, and the development cost is high and the maintenance is troublesome.

Benefits:

The client can share part of the operation locally. 360 anti-virus: the 3D effects of the game are all calculated locally.

2. B/S: browsEr/server (browser, server)

Features:

The software of this structure is only developed on the server, and the client is directly replaced by a browser

Relatively low development costs and simpler Maintenance

Disadvantage: all operations are performed on the server.