Android SD card read and write operation

 Packagecom.itheima.writesd;ImportJava.io.File;Importjava.io.FileNotFoundException;ImportJava.io.FileOutputStream;Importjava.io.IOException;Importandroid.app.Activity;ImportAndroid.os.Bundle;Importandroid.os.Environment;ImportAndroid.view.View;ImportAndroid.widget.Toast;/*** Write SD card must remember to add permissions*/ Public classMainactivityextendsActivity {@Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);    Setcontentview (R.layout.activity_main); }    /*** Simulate writing a video file to an SD card. */     Public voidClick (View view) {//Check if the status of the SD card is unplugged or is not available        if(Environment.getexternalstoragestate (). Equals (environment.media_mounted)) {File Sdfile /c11>= Environment.getexternalstoragedirectory ();//External storage space            LongSdsize =Sdfile.getfreespace (); if(Sdsize >5* 1024 * 1024) {File file=NewFile (Environment.getexternalstoragedirectory (),//root directory, mnt/sdcard/hlw.3gpSystem.currenttimemillis () + "hlw.3gp");//Empty File                Try{FileOutputStream fos=NewFileOutputStream (file);//file output stream to write files                    byte[] buffer =New byte[1024];//1K, empty data                     for(inti = 0; i < 5*1024; i++) {//empty data file with hlw.3gp of 5 mfos.write (buffer);                } fos.close (); } Catch(Exception e) {e.printstacktrace (); }            }Else{Toast.maketext ( This, "Insufficient SD card space", 0). Show (); }        } Else{Toast.maketext ( This, "SD card is unplugged or not available", 0). Show (); }}} manifest file:<uses-permission android:name= "Android.permission.WRITE_EXTERNAL_STORAGE"/><uses-permission android: Name= "Android.permission.READ_EXTERNAL_STORAGE"/>

Internal Storage directory:

/data/data/Package Name (application name)/files/data/data/Package name (application name)/cache

External storage directory (SD card):

mnt/sdcard/

 PackageCom.itheima.haker;ImportJava.io.BufferedReader;ImportJava.io.File;ImportJava.io.FileInputStream;Importjava.io.FileNotFoundException;Importjava.io.IOException;ImportJava.io.InputStreamReader;Importandroid.app.Activity;ImportAndroid.os.Build;ImportAndroid.os.Bundle;ImportAndroid.view.View;ImportAndroid.widget.Toast; Public classMainactivityextendsActivity {@Overrideprotected voidonCreate (Bundle savedinstancestate) {Super. OnCreate (savedinstancestate);    Setcontentview (R.layout.activity_main); }     Public voidClick (View view) {Try{File File=NewFile ("/data/data/com.itheima.createfile/files/haha.txt");//Internal Storage DirectoryFileInputStream FIS =NewFileInputStream (file);//file input streamBufferedReader br =NewBufferedReader (NewInputStreamReader (FIS));//input stream for wrappingString line = Br.readline ();//read the first lineToast.maketext ( This, line, 0). Show (); } Catch(Exception e) {Toast.maketext ( This, "read failed", 0). Show ();//files in the phone's internal storage space by default is private, other applications are inaccessible, or can be changed to public. E.printstacktrace (); }    }}

Android SD card read and write operation