Use urlconnection, httpurlconnection, and httpclient to access network resources

The openconnection method of the URL returns a urlconnection, which indicates the communication connection between the application and the URL. The program can send a request to the URL through its instance to read the resources referenced by the URL.

The following is a simple example:

Activity:

Package COM. home. urlconnection; import Java. io. ioexception; import Java. io. inputstream; import java.net. httpurlconnection; import java.net. URL; import java.net. urlconnection; import Java. util. arraylist; import Java. util. list; import Org. apache. HTTP. httpentity; import Org. apache. HTTP. httpresponse; import Org. apache. HTTP. client. clientprotocolexception; import Org. apache. HTTP. client. httpclient; import Org. apache. HTTP. client. entity. urlencodedformentity; import Org. apache. HTTP. client. methods. httppost; import Org. apache. HTTP. impl. client. defaulthttpclient; import Org. apache. HTTP. message. basicnamevaluepair; import Org. apache. HTTP. util. entityutils; import android. app. activity; import android. OS. bundle; import android. view. view; import android. view. view. onclicklistener; import android. webKit. webview; import android. widget. Button; import android. widget. textview; public class mainactivity extends activity implements onclicklistener {private button urlconnectionbtn; private button listener; private textview showtextview; private webview; @ overrideprotected void oncreate (bundle savedinstancestate) {super. oncreate (savedinstancestate); setcontentview (R. layout. activity_main); init ();} Private void Init () {urlconnectionbtn = (button) findviewbyid (R. id. test_url_main_btn_urlconnection); httpurlconnectionbtn = (button) findviewbyid (R. id. test_url_main_btn_httpurlconnection); httpclientbtn = (button) findviewbyid (R. id. test_url_main_btn_httpclient); showtextview = (textview) findviewbyid (R. id. test_url_main_ TV _show); webview = (webview) findviewbyid (R. id. test_url_main_wv); urlconnection BTN. setonclicklistener (this); httpurlconnectionbtn. setonclicklistener (this); httpclientbtn. setonclicklistener (this) ;}@ overridepublic void onclick (view v) {If (V = urlconnectionbtn) {try {// directly use the urlconnection object to connect to URL url = new URL ("http: // 192.168.1.100: 8080/myweb/hello. JSP "); // obtain the urlconnection object urlconnection connection = URL. openconnection (); inputstream is = connection. getinputstream (); byte [] BS = New byte [1024]; int Len = 0; stringbuffer sb = new stringbuffer (); While (LEN = is. Read (BS ))! =-1) {string STR = new string (BS, 0, Len); sb. append (STR);} showtextview. settext (sb. tostring ();} catch (exception e) {e. printstacktrace () ;}}if (V = httpurlconnectionbtn) {// connect to try {URL url = new URL ("http: // 192.168.1.100: 8080/myweb/hello. JSP? Username = ABC "); // get the httpurlconnection object httpurlconnection connection = (httpurlconnection) URL. openconnection (); // set to get connection. setrequestmethod ("get"); If (connection. getresponsecode () = httpurlconnection. http_ OK) {// get the response message string message = connection. getresponsemessage (); showtextview. settext (Message) ;}} catch (exception e) {e. printstacktrace () ;}}if (V = httpclientbtn) {try {// use apachehttp (Important) httpclient client = new defaulthttpclient (); // create an httpget object if get is submitted, otherwise, the httppost object // post is created and submitted in the form of httppost = new httppost ("http: // 192.168.1.100: 8080/myweb/hello. JSP "); // If post is submitted, You can encapsulate the parameters in the set and pass list datalist = new arraylist (); datalist. add (New basicnamevaluepair ("username", "ABC"); datalist. add (New basicnamevaluepair ("PWD", "123"); // urlencodedformentity is used to convert a set to an entity object httppost. sete Ntity (New urlencodedformentity (datalist); // get Method for submission // httpget = new // httpget ("http: // 192.168.1.100: 8080/myweb/Hello. jsp? Username = ABC & Pwd = 321 "); // get the corresponding message httpresponse = client.exe cute (httppost); // get the message content httpentity entity = httpresponse. getentity (); // convert the message object to string content = entityutils. tostring (entity); // display in textview // showtextview. settext (content); // parse the webview of the Webpage Through webview. loaddatawithbaseurl (null, content, "text/html", "UTF-8", null); // parse the URL directly // webview. loadurl (URL);} catch (clientprotocolexception e) {e. printstacktrace ();} catch (ioexception e) {e. printstacktrace ();}}}}

The URL used above is the Web application deployed on the author's local machine. It is not provided here. You can replace it with your own web application.
Layout XML:

<? XML version = "1.0" encoding = "UTF-8"?> <Linearlayout xmlns: Android = "http://schemas.android.com/apk/res/android" Android: layout_width = "match_parent" Android: layout_height = "match_parent" Android: Orientation = "vertical"> <button Android: id = "@ + ID/test_url_main_btn_urlconnection" Android: layout_width = "wrap_content" Android: layout_height = "wrap_content" Android: text = "Connect with urlconnection"/> <button Android: id = "@ + ID/test_url_main_btn_httpurlconnection" Android: layout_width = "wrap_content" Android: layout_height = "wrap_content" Android: text = "Connect with httpurlconnection"/> <button Android: id = "@ + ID/test_url_main_btn_httpclient" Android: layout_width = "wrap_content" Android: layout_height = "wrap_content" Android: text = "Connect with Apache client"/> <textview Android: id = "@ + ID/test_url_main_ TV _show" Android: layout_width = "wrap_content" Android: layout_height = "wrap_content"/> <webview Android: Id = "@ + ID/test_url_main_wv" Android: layout_width = "match_parent" Android: layout_height = "match_parent"/> </linearlayout>

Permission:

 <uses-permission android:name="android.permission.INTERNET" />