Android data storage-Network Storage

1. obtain data from the Internet:

1. Using the httpurlconnection object, we can obtain webpage data from the network.

URL url = new URL ("http://www.sohu.com ");

Httpurlconnection conn = (httpurlconnection) URL. openconnection ();

Conn. setconnecttimeout (5*1000); // sets the connection timeout.

Conn. setrequestmethod ("get"); // initiate a request in get Mode

If (conn. getresponsecode ()! = 200)

Throw new runtimeexception ("request URL failed ");

Inputstreamis = conn. getinputstream (); // gets the input stream returned by the network.

String result =
Readdata (is, "GBK ");

Conn. Disconnect ();

// The first parameter is the input stream, and the second parameter is character set encoding.

Public static string readdata (inputstream insream, string charsetname) throws exception {

Bytearrayoutputstream outstream = new bytearrayoutputstream ();

Byte [] buffer = new byte [1024];

Int Len = 0;

While (LEN = insream. Read (buffer ))! =-1 ){

Outstream. Write (buffer, 0, Len );

}

Byte [] DATA = outstream. tobytearray ();

Outstream. Close ();

Insream. Close ();

Return newstring (data, charsetname );

2. Using the httpurlconnection object, we can obtain file data from the network.

URL url = new URL ("http://photocdn.sohu.com/20100125/Img269812337.jpg ");

Httpurlconnection conn = (httpurlconnection) URL. openconnection ();

Conn. setconnecttimeout (5*1000 );

Conn. setrequestmethod ("get ");

If (conn. getresponsecode ()! = 200)

Throw new runtimeexception ("request URL failed ");

Inputstreamis = conn. getinputstream ();

Readasfile (is, "img269812337.jpg ");

Public static void readasfile (inputstream insream, file) throws exception {

Fileoutputstream outstream = new fileoutputstream (File );

Byte [] buffer = new byte [1024];

Int Len = 0;

While (LEN = insream. Read (buffer ))! =-1 ){

Outstream. Write (buffer, 0, Len );

}

Outstream. Close ();

Insream. Close ();

}

2. Send request parameters to the Internet

1. Using the httpurlconnection object, we can send request parameters to the network.

String requesturl = "http: // localhost: 8080/itcast/contanctmanage. Do ";

Map <string, string> requestparams = new hashmap <string, string> ();

Requestparams. Put ("Age", "12 ");

Requestparams. Put ("name", "China ");

Stringbuilder Params = new stringbuilder ();

For (Map. Entry <string, string> entry: requestparams. entryset ()){

Params. append (entry. getkey ());

Params. append ("= ");

Params. append (urlencoder. encode (entry. getvalue (), "UTF-8 "));

Params. append ("&");

}

If (Params. Length ()> 0)

Params. deletecharat (Params. Length ()-1 );

Byte [] DATA = Params. tostring (). getbytes ();

URL realurl = new URL (requesturl );

Httpurlconnection conn = (httpurlconnection) realurl. openconnection ();

Conn. setdooutput (true); // The output must be allowed when a POST request is sent.

Conn. setusecaches (false); // No cache is used.

Conn. setrequestmethod ("Post ");

Conn. setrequestproperty ("connection", "keep-alive"); // maintain a persistent connection

Conn. setrequestproperty ("charset", "UTF-8 ");

Conn. setrequestproperty ("Content-Length", String. valueof (data. Length ));

Conn. setrequestproperty ("Content-Type", "application/X-WWW-form-urlencoded ");

Dataoutputstream outstream = new dataoutputstream (conn. getoutputstream ());

Outstream. Write (data );

Outstream. Flush ();

If (conn. getresponsecode () = 200) {// if the return code is 200, the data returned by the server is obtained.

String result =
Readasstring (conn. getinputstream (), "UTF-8"); // This method is the read method of the custom stream

Outstream. Close ();

System. Out. println (result );

}

2. Send XML data to the Internet

Using the httpurlconnection object, we can send XML data to the network.

Stringbuilder xml = new stringbuilder ();

XML. append ("<? XML version = \ "1.0 \" encoding = \ "UTF-8 \"?> ");

XML. append ("<m1v = 10000> ");

XML. append ("<UI = 1 d = \" n73 \ "> China </u> ");

XML. append ("</M1> ");

Byte [] xmlbyte = xml. tostring (). getbytes ("UTF-8 ");

URL url = new URL ("http: // localhost: 8080/itcast/contanctmanage. do? Method = readxml ");

Httpurlconnection conn = (httpurlconnection) URL. openconnection ();

Conn. setconnecttimeout (5*1000 );

Conn. setdooutput (true); // allow output

Conn. setusecaches (false); // No cache is used.

Conn. setrequestmethod ("Post ");

Conn. setrequestproperty ("connection", "keep-alive"); // maintain a persistent connection

Conn. setrequestproperty ("charset", "UTF-8 ");

Conn. setrequestproperty ("Content-Length", String. valueof (xmlbyte. Length ));

Conn. setrequestproperty ("Content-Type", "text/XML; charset = UTF-8 ");

Dataoutputstream outstream = new dataoutputstream (conn. getoutputstream ());

Outstream. Write (xmlbyte); // send XML data

Outstream. Flush ();

If (conn. getresponsecode ()! = 200)

Throw new runtimeexception ("request URL failed ");

Inputstreamis = conn. getinputstream (); // get the returned data

String result = readasstring (is, "UTF-8"); // Method for custom stream reading

Outstream. Close ();