Android Learning notes-File download

Tool Class Fileutils.java

Package com.example.filedownload_01;import java.io.file;import java.io.fileoutputstream;import  java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import  android.os.environment;public class fileutils {private string sdpath;public  String getsdpath ()  {return sdpath;} Public fileutils ()  {//get the current external storage device directory    general is/sdcardsdpath =  Environment.getexternalstoragedirectory ()  +  "/";} /** *  Create file  *  @param  fileName  filename  *  @return   Newly created file on SD card  *   @throws  ioexception */public file createsdfile (string filename)  throws  ioexception {file file = new file (Sdpath + filename); File.createnewfile (); return file;} /** *  creating a directory on an SD card  *  @param  dirName  directory name  *  @return  */public file  createsddir (String diRname)  {file dir = new file (sdpath + dirname);d ir.mkdir (); return dir;} /** *  determine if there are files  *  @param  fileName *  @return on the SD card  */public boolean  isfileexist (String filename)  {file file = new file (SDPATH +  FileName); return file.exists ();} /** *  writes data from a inputstream to the SD card  *  @param  path  paths  *  @param   filename  file name  *  @param  input  input stream  *  @return   writing files to sd card  */public  File write2sdfrominput (string path, string filename, inputstream input)  { File file = null;outputstream output = null;try {createsddir (path); file  = createsdfile (Path + filename); Output = new fileoutputstream (file); byte  buffer[] = new byte[4 * 1024];while  ((input.read (buffer))  != -1)  {output.write (buffer);} Output.flush ();}  catch  (exception e)  {e.printstacktrace ();} Finally{try {output.close ();}  catch  (Exception e2)  {e2.printstacktrace ();}} Return file;}}

httpdownloader.java

Package com.example.filedownload_01;import java.io.bufferedreader;import java.io.file;import  java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import  java.net.httpurlconnection;import java.net.malformedurlexception;import java.net.url;import  Org.apache.http.message.bufferedheader;public class httpdownloader {private url url  = null;public string download (STRING URLSTR)  {StringBuffer sb =  New stringbuffer (); string line = null; Bufferedreader buffer = null;try {url = new url (URLSTR); httpurlconnection urlconnection =  (HttpURLConnection)  url.openconnection (); buffer =  new bufferedreader (New inputstreamreader (Urlconnection.getinputstream ()));while  (line  = buffer.readline ())  != null)  {sb.append (line);}}  catch  (EXCeption e)  {e.printstacktrace ();}  finally {try {buffer.close ();}  catch  (Exception e2)  {e2.printstacktrace ();}} Return sb.tostring ();} /** *  @param  urlStr *             url *  @param  path *              Save Paths  *  @param  fileName *              file name  *  @return   return value-1: Error downloading file, 0 indicates successful download, 1 means file already exists  */public int  DownloadFile (String urlstr, string path, string filename)  {InputStream  Inputstream = null;try {fileutils fileutils = new fileutils ();if  ( Fileutils.isfileexist (path + filename))  {return 1;//  file already exists} else { Inputstream = getinputstreamfromurl (URLSTR); File resultfilE = fileutils.write2sdfrominput (Path, filename,inputstream);if  (resultFile ==  NULL)  {return -1;}}}  catch  (exception e)  {e.printstacktrace (); return -1;}  finally {try {inputstream.close ();}  catch  (exception e)  {e.printstacktrace ();}} return 0;} Public inputstream getinputstreamfromurl (STRING URLSTR)  throws ioexception {url  = new url (URLSTR); httpurlconnection urlconnection =  (HttpURLConnection)  url.openconnection (); InputStream  inputstream = urlconnection.getinputstream (); return inputstream;}}

Mainactivity.java

package com.example.filedownload_01;import android.support.v7.app.actionbaractivity;import  Android. r.integer;import android.os.bundle;import android.os.handler;import android.os.handlerthread; import android.os.looper;import android.os.message;import android.view.menu;import  android.view.menuitem;import android.view.view;import android.view.view.onclicklistener;import  android.widget.button;import android.widget.toast;public class mainactivity extends  actionbaractivity {private button downloadtxtbutton = null;private button  downloadmp3button = null; @Overrideprotected  void oncreate (bundle savedinstancestate)  {super.oncreate (savedinstancestate); Setcontentview (r.layout.activity_main);d ownloadmp3button =   (Button)  findviewbyid (R.id.downloadmp3button);d ownloadtxtbutton =  (button)   Findviewbyid (r.id.downloadtxtbutton);d Ownloadtxtbutton.setonclicklistener (New downloadtextlistener ()); Downloadmp3button.setonclicklistener (New downloadmp3listener ());} class downloadtextlistener implements onclicklistener {@Overridepublic  void  OnClick (VIEW V)  {system.out.println ("Download txt file"); Toast.maketext (mainactivity.this,  "start to download txt",  toast.length_short). Show (); string urlstr =  "HTTP://WWW.51VOA.COM/LRC/201411/SE-HEALTH-SURGICAL-SAFARI-COSMETIC-18NOV14.LRC "; string path =  "umgsai_download/"; string filename =  "TEST.LRC";//generates a Handlerthread object that implements the function of using looper to process Message Queuing          handlerthread handlerthread = new handlerthread ("Handler_ Thread ");         handlerthread.start ();         myhandler myhandler = new myhandler (Handlerthread.getlooper ());     &nbsP;   message msg = myhandler.obtainmessage ();         //msg.obj =  "ABC";  //Simple Data          Bundle bundle = new bundle ();         Bundle.putstring ("Urlstr",  urlstr);         bundle.putstring (" FileName ",  filename);         bundle.putstring (" Path ",  path);         msg.setdata (bundle);         //sends MSG to the target object, which is the handler object that generates the MSG object         msg.sendtotarget ();// Httpdownloader httpdownloader = new httpdownloader ();//string lrc =  Httpdownloader.download ("Http://localhost/menu/log.txt");//system.out.println (LRC);}} class downloadmp3listener implements onclicklistener{@OvErridepublic void onclick (VIEW V)  {//httpdownloader httpdownloader = new  httpdownloader ();//int result = httpdownloader.downloadfile (", " voa/", " Test.mp3 ");//system.out.println (result); Toast.maketext (mainactivity.this,  "Start Download MP3",  toast.length_short). Show (); string urlstr =  "http://127.0.0.1/menu/test.apk"; string path =  "umgsai_download/"; string filename =  "test.apk";//generates a Handlerthread object that implements the function of using looper to process Message Queuing          handlerthread handlerthread = new handlerthread ("Handler_ Thread ");         handlerthread.start ();         myhandler myhandler = new myhandler (Handlerthread.getlooper ());         message msg = myhandler.obtainmessage ();         //msg.obj =  "ABC";  //Simple Data          Bundle bundle = new bundle ();         Bundle.putstring ("Urlstr",  urlstr);         bundle.putstring (" FileName ",  filename);         bundle.putstring (" Path ",  path);         msg.setdata (bundle);         //sends MSG to the target object, which is the handler object that generates the MSG object         msg.sendtotarget ();}} Class myhandler extends handler{public myhandler ()  {}public myhandler (Looper  looper)  {super (Looper);} @Overridepublic  void handlemessage (message msg)  {super.handlemessage (msg); Bundle bundle = msg.getdata (); String urlstr = bundle.getstring ("Urlstr"); string filename = bundle.getstring ("FileName"); String path = bundle.getstring ("path"); Httpdownloader httpdownloader = new httpdownloader ();int result =  Httpdownloader.downloadfile (Urlstr, path, filename); SYSTEM.OUT.PRINTLN (result); Toast.maketext (mainactivity.this,  "~",  toast.length_short). Show ();//string lrc =  Httpdownloader.download (FileName);//system.out.println (LRC);}}}

The task of downloading the file cannot be placed inside the main thread, otherwise it will throw an exception.

There was a problem downloading the MP3 file and it was not resolved.

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Android Learning notes-File download