android--Asynchronous Task Asynctask

Example: Using an asynchronous task to download from the network

package com.example.xiaocool.anysctaskdemo;import android.app.progressdialog;import  android.content.context;import android.os.asynctask;import android.os.bundle;import  android.support.v7.app.actionbaractivity;import android.view.view;import android.widget.button; import android.widget.textview;import java.io.bufferedreader;import java.io.inputstreamreader; Import java.net.malformedurlexception;import java.net.uri;import java.net.urlconnection;public  class MainActivity extends ActionBarActivity {    private  textview show;    private button download;     @Override     protected void oncreate (bundle savedinstancestate)  {         super.oncreate (savedinstancestate);         setcontentview (r.layout.activity_Main);        show =  (TextView)  this.findviewbyid ( R.id.show_down);        download =  (Button)   This.findviewbyid (R.id.button);         download.setonclicklistener (new  view.onclicklistener ()  {            @ Override            public void onclick ( VIEW&NBSP;V)  {                 downtask task = new downtask (mainactivity.this);                 try {                     /**                      *  starts to perform time-consuming tasks                       */                      task.execute (New uri ("http://news.baidu.com/"));                 } catch  (exception e)  {                      E.printstacktrace ();                 }            }         });    }    /**     *  params   Start Task executionThe type of input parameter      * Progress  the progress of the background task completion is worth the type,     *  result    after the background execution task finishes   returns the type of the result      *  if you do not need to specify a type  Void      * <p/>     *  overridden methods have system calls       */    class downtask extends asynctask<uri, integer,  String> {        ProgressDialog progressDialog;         //defines the number of read rows that are recorded          int hasread = 0;        context mcontext;         public downtask (Context context)  {             mContext = context;         }        /**         *  The task that the background thread is about to complete, which can call Publishprogress (progress value) to update the execution progress of the task           *         *  @param  params          *  @return          */          @Override          Protected string doinbackground (Uri... params)  {             stringbuilder sb = new stringbuilder ();             try {                 urlconnection conn = params[0].tourl (). OpenConnection ();   &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;//Open conn Connection corresponding input stream, packaged into Bufferreader   Objects                  Bufferedreader br = new bufferedreader (                         new  InputStreamReader (Conn.getinputstream (),  "Utf-8")                  );                 String line = null;                 while  ((Line = br.readline ())  !=  null)  {                     sb.appEnd (line +  "\ n");                     hasRead++;                     //Update task Execution Progress                      publishprogress ( Hasread);                 }                 return  Sb.tostring ();            } catch  ( Exception e)  {                 e.printstacktrace ();             }             return null;        }         /**         *  Called Publishprogress (Progress value) in the Doinbackground method, the method is triggered after the progress of the task is updated           *         *  @param  values          */         @Override          protected void onprogressupdate (Integer... values)  {            show.settext ("read" +values[0]);             progressdialog.setprogress (Values[0]);         }        /**          *  This method will be called when executing the background time-consuming program, which is used to complete some initialization preparations, such as displaying a progress bar on the interface           */         @Override          protected void onpreexecute ()  {             progressdialog = new progressdialog (Mcontext);             progressdialog.settitle ("The task is executing! ");             progressdialog.setmessage (" The task is executing, Later!! ");             //Cancel button not available              progressdialog.setcancelable (False);             progressdialog.setmax (202);             progressdialOg.setprogressstyle (progressdialog.style_horizontal);             progressdialog.setindeterminate (False);             progressdialog.show ();        }         /**         *  When the Doinbackground method is complete, the system automatically calls the method   and passes the return value of Doinbackground () to the method           *         *  @param  s          */         @Override          protected void onpostexecute (string s)  {             //back to html  page content              show. SetText (s);             progressdialog.dismiss ();         }    }}

android--Asynchronous Task Asynctask