android--Classroom Arrangement: Assets directory and external storage of mobile phone

Source: Internet
Author: User

Layout file:

1 <Button2         Android:layout_width= "Match_parent"3 Android:layout_height= "Wrap_content"4 Android:text= "Save asset file to internal storage"5 Android:onclick= "Bt4_onclick"/>6     <ImageView7         Android:layout_width= "Wrap_content"8 Android:layout_height= "Wrap_content"9 Android:id= "@+id/iv_1"Ten android:src= "@drawable/on"/> One     <Button A         Android:layout_width= "Match_parent" - Android:layout_height= "Wrap_content" - Android:text= "Set picture pointing to internal storage" the Android:onclick= "Bt5_onclick"/> -     <Button -         Android:layout_width= "Match_parent" - Android:layout_height= "Wrap_content" + Android:text= "Write to external storage file" - Android:onclick= "Bt6_onclick"/> +     <Button A         Android:layout_width= "Match_parent" at Android:layout_height= "Wrap_content" - Android:text= "Read external storage File" - Android:onclick= "Bt7_onclick"/>

Java class:

1 //Saving asset files to internal storage2      Public voidBt4_onclick (View v)3     {4         Try {5             //manipulating files in the assets directory6             //1. Get Assetsmanager7Assetmanager am =getassets ();8             //2. Manipulate the asset catalog, read-write side-by- side9             //1) Read file to memory InputStreamTenInputStream is = ("Yuantu.png"); One             //2) Write file to directory OutputStream AFileOutputStream fos = openfileoutput ("Test.png", mode_private); -             //Read and write first -             byte[] B =New byte[1024]; the             inti = 0; -              while((i = (b)) >0) -             { -Fos.write (b,0, i); +             } - fos.close (); + is.close (); AToast.maketext (mainactivity. This, "Save file succeeded", Toast.length_short). Show (); at         } -         Catch(Exception e) -         { -Toast.maketext (mainactivity. This, "Error saving file", Toast.length_short). Show (); -         } -  in     } -     //set a picture to point to internal storage to      Public voidBt5_onclick (View v) +     { -         //1. Get the file path theString path = Getfilesdir (). GetAbsolutePath () + "/test.png"; *Toast.maketext (mainactivity. This, "path =" +path, Toast.length_short). Show (); $         //2. Get Bitmap,bitmapfactory.decodefile ("File path") from the image stored internally;Panax NotoginsengBitmap BM =bitmapfactory.decodefile (path); -         //3. Set picture source for picture View the Iv_1.setimagebitmap (BM); +     } A     //write to external storage file the      Public voidBt6_onclick (View v) +     { -         //1. Determine if the SD card is mounted $         if(Environment.getexternalstoragestate (). Equals (environment.media_mounted)) $         { -             //Get text Box contents -String str =Et_1.gettext (). toString (); the             Try { -                 //WriteWuyi                 //1. Constructing the output stream the                 //1) Get file path -                 //get the SD card root directory WuString Path =environment.getexternalstoragedirectory (). GetAbsolutePath (); -  About                 //get the directory that corresponds to the package name $ //String Path = Getexternalfilesdir ("Music"). Getcanonicalpath (); -Toast.maketext (mainactivity. This, "path =" +path, Toast.length_long). Show (); -                 //2) Construction -FileOutputStream fos =NewFileOutputStream (path+ "/test.txt"); APrintStream PS =NewPrintStream (FOS); + ps.print (str); the ps.close (); - fos.close (); $Toast.maketext (mainactivity. This, "Write external file succeeded", Toast.length_short). Show (); the             } the            Catch(Exception e) the            { theToast.maketext (mainactivity. This, "Error storing file", Toast.length_short). Show (); -            } in         } the         Else the         { AboutToast.maketext (mainactivity. This, "SD card is not mounted", Toast.length_short). Show (); the         } the     } the     //read external storage files +      Public voidBt7_onclick (View v) -     { the         //1. Determine if the SD card is mountedBayi         if(Environment.getexternalstoragestate (). Equals (environment.media_mounted)) the         { the             Try { -String Path = Getexternalfilesdir ("Music"). Getcanonicalpath () + "/test.txt"; -FileInputStream FIS =NewFileInputStream (path); the                 byte[] B =New byte[1024]; the                 inti = 0; theString str = ""; the                  while((i = (b)) >0) -                 { thestr + =NewString (b,0, i); the                 } the fis.close ();94Toast.maketext (mainactivity. This, "File content =" +str, toast.length_short). Show (); the             } the            Catch(Exception e) the            {98Toast.maketext (mainactivity. This, "failed to read external file", Toast.length_short). Show (); About            } -         }101         Else102         {103Toast.maketext (mainactivity. This, "SD is not mounted", Toast.length_short). Show ();104         } the}

android--Classroom Arrangement: Assets directory and external storage of mobile phone

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