Android file IO

[Context method: The data folder of this application]

Public FileInputStreamOpenFileInput(String name)
Throws FileNotFoundException

Public FileOutputStreamOpenFileOutput(String name, int mode)
Throws FileNotFoundException

Package org. crazyit. io; import java. io. fileInputStream; import java. io. fileOutputStream; import java. io. printStream; import android. app. activity; import android. OS. bundle; import android. view. view; import android. view. view. onClickListener; import android. widget. button; import android. widget. editText; public class FileTest extends Activity {final String FILE_NAME = "crazyit. bin "; @ Overridepublic void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. main); System. out. println (new StringBuilder (""). append ("B "). append ("c "). toString (); // obtain two buttons: Button read = (Button) findViewById (R. id. read); Button write = (Button) findViewById (R. id. write); // get the final EditText edit1 = (EditText) findViewById (R. id. edit1); final EditText edit2 = (EditText) findViewById (R. id. edit2); // bind the event listener write for the write button. setOnClickListener (new OnClickListener () {@ Overridepublic void onClick (View source) {// write the content in edit1 into the file write (edit1.getText (). toString (); edit1.setText ("") ;}}); read. setOnClickListener (new OnClickListener () {@ Overridepublic void onClick (View v) {// read the content of the specified file and display edit2.setText (read ());}});} private String read () {try {// open the file input stream FileInputStream FD = openFileInput (FILE_NAME); byte [] buff = new byte [1024]; int hasRead = 0; stringBuilder sb = new StringBuilder (""); // read the file content while (hasRead = Fi. read (buff)> 0) {sb. append (new String (buff, 0, hasRead);} // close the input stream of the file. close (); return sb. toString ();} catch (Exception e) {e. printStackTrace ();} return null;} private void write (String content) {try {// open the file output stream FileOutputStream fos = openFileOutput (FILE_NAME, MODE_APPEND) in append mode ); // package FileOutputStream into PrintStreamPrintStream ps = new PrintStream (fos); // output file content ps. println (content); // close the file output stream ps. close ();} catch (Exception e) {e. printStackTrace ();}}}

Data Files of applications are stored in/data/by default/ /Files directory.

[Read and write files on the SD card]

Private String read () {try {// if the mobile phone is inserted with an SD card, and the application has the permission to access the SD if (Environment. getExternalStorageState (). equals (Environment. MEDIA_MOUNTED) {// obtain the storage directory File sdCardDir = Environment corresponding to the SD card. getExternalStorageDirectory (); // obtain the input stream FileInputStream (new FileInputStream (sdCardDir. getCanonicalPath () + FILE_NAME); // wrap the specified input stream into BufferedReaderBufferedReader br = new BufferedReader (new InputStreamReader (FCM); Str IngBuilder sb = new StringBuilder (""); String line = null; // read the file content cyclically while (line = br. readLine ())! = Null) {sb. append (line);} // closes the resource br. close (); return sb. toString () ;}} catch (Exception e) {e. printStackTrace ();} return null;} private void write (String content) {try {// if the SD card is inserted into the mobile phone and the application has the permission to access SD if (Environment. getExternalStorageState (). equals (Environment. MEDIA_MOUNTED) {// obtain the directory File sdCardDir = Environment of the SD card. getExternalStorageDirectory (); File targetFile = new File (sdCardDir. getCanonicalPath () + FILE_NAME); // create the RandomAccessFile object RandomAccessFile raf = new RandomAccessFile (targetFile, "rw") with the specified file; // move the file record pointer to the last raf. seek (targetFile. length (); // output file content raf. write (content. getBytes (); // disable RandomAccessFileraf. close () ;}} catch (Exception e) {e. printStackTrace ();}}