Android _ file download, android File Download

Android _ file download, android File Download

Android downloads files from the network

Steps:

1. Use HTTP to download files

-Create an HttpURLConnection object: HttpURLConnection urlConn = (HttpURLConnection) url. openConnection ();

-Get an InputStream object: urlConn. getInputStream ()

-Network access permission: android. permission. INTERNET

2. Write the downloaded file to SDCARD

-Get the directory of the SD card of the current device: Environment. getExternalStrageDirectory ()

-Permission to access the SD card: android. permission. WRITE_EXTERNAL_STORAGE

Code:

Activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <Button        android:id="@+id/btn_txt"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="download lrc" />        <Button        android:id="@+id/btn_mp3"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_below="@id/btn_txt"        android:text="download mp3" /></RelativeLayout>

MainActivity. java

Package com. chay. download; import com. chay. utils. httpDownloader; import android. app. activity; import android. OS. bundle; import android. view. view; import android. view. view. onClickListener; import android. widget. button; public class MainActivity extends Activity {String urlStr_txt = "http: // 192.168.56.1: 8080/mp3/wan. lrc "; String urlStr_mp3 =" http: // 192.168.56.1: 8080/mp3/wan.mp3 "; String path =" mp3/"; String fileName =" wanw."; private Button downloadTxtButton; private Button downloadMp3Button; @ Overrideprotected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); downloadTxtButton = (Button) findViewById (R. id. btn_txt); downloadTxtButton. setOnClickListener (new DownloadTxtListener (); downloadMp3Button = (Button) findViewById (R. id. btn_mp3); downloadMp3Button. setOnClickListener (new DownloadMp3Listener ();} // listener class DownloadTxtListener implements OnClickListener {@ Overridepublic void onClick (View v) {Thread t = new DownloadTxtThread (); t. start (); System. out. println ("txt --->") ;}// download the lyrics file Thread class DownloadTxtThread extends Thread {@ Overridepublic void run () {HttpDownloader httpDownloader = new HttpDownloader (); string lrc = httpDownloader. download (urlStr_txt); System. out. println (lrc) ;}/// listener class DownloadMp3Listener implements OnClickListener {@ Overridepublic void onClick (View v) {Thread h = new DownMp3Thread (); h. start (); System. out. println ("mp3 --->") ;}// download MP3 file Thread class DownMp3Thread extends Thread {@ Overridepublic void run () {HttpDownloader httpDownloader = new HttpDownloader (); int result = httpDownloader. downFile (urlStr_mp3, path, fileName); System. out. println (result );}}}

Tool class:
HttpDownloader. java

Package com. chay. utils; 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; public class HttpDownloader {private URL url URL = null;/*** download an object based on the URL, provided that the content of the object is text, the Return Value of the function is the content in the file * 1. create a URL object * 2. create an HttpURLConnection object through a URL object * 3. obtain InputStram * 4. read data from InputStream * @ param urlStr * @ return */public String download (String urlStr) {StringBuffer sb = new StringBuffer (); String line = null; BufferedReader buffer = null; try {// create a URL object url = new URL (urlStr); // create an Http connection HttpURLConnection urlConn = (HttpURLConnection) url. openConnection (); // read data buffer = new BufferedReader (new InputStreamReader (urlConn. getInputStream () ); While (line = buffer. readLine ())! = Null) {sb. append (line) ;}} catch (Exception e) {e. printStackTrace ();} finally {try {buffer. close ();} catch (Exception e) {e. printStackTrace () ;}} return sb. toString ();}/*** this function returns an integer-1: indicates that the object is downloaded. error 0: indicates that the object is successfully downloaded. 1: indicates that the file already exists */public int downFile (String urlStr, String path, String fileName) {InputStream inputStream = null; try {FileUtils fileUtils = new FileUtils (); if (fileUtils. isFileExist (path + fileName) {return 1;} 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 ;} /*** get the input stream based on the URL ** @ param urlStr * @ return * @ throws MalformedURLException * @ throws IOException */public InputStream getInputStreamFromUrl (String urlStr) throws MalformedURLException, IOException {url = new URL (urlStr); HttpURLConnection urlConn = (HttpURLConnection) url. openConnection (); InputStream inputStream = urlConn. getInputStream (); return inputStream ;}}

FileUtils. java

Package com. chay. utils; 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 () {// obtain the directory of the current external storage device // SDCARDSDPATH = Environment. getExternalStorageDirectory () + "/";}/*** create a file on the SD card ** @ th Rows IOException */public File creatSDFile (String fileName) throws IOException {File file File = new file (SDPATH + fileName); File. createNewFile (); return file;}/*** create a directory on the SD card ** @ param dirName */public File creatSDDir (String dirName) {File dir = new File (SDPATH + dirName); dir. mkdirs (); return dir;}/*** determines whether the folder on the SD card exists */public boolean isFileExist (String fileName) {File file = new File (SDPATH + fileName); Return file. exists ();}/*** write data in an InputStream to the SD card */public File write2SDFromInput (String path, String fileName, InputStream input) {File file = null; outputStream output = null; try {creatSDDir (path); file = creatSDFile (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 e) {e. printStackTrace () ;}} return file ;}}

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