com.google.appinventor.components.runtime.util

Class FileUtil

java.lang.Object

com.google.appinventor.components.runtime.util.FileUtil

public class FileUtil
extends java.lang.Object

Utilities for reading and writing files to the external storage.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FileUtil.FileException Exception class for reporting back media-related error numbers from ErrorMessages, which the caller can in turn pass to Form.dispatchErrorOccurredEvent if needed.

Method Summary

Methods

Modifier and Type	Method and Description
static void	checkExternalStorageWriteable()
static java.lang.String	copyFile(java.lang.String inputFileName, java.lang.String outputFileName) Copies the contents of one local file to another local file.
static java.lang.String	downloadUrlToFile(java.lang.String url, java.lang.String outputFileName) Downloads the resource with the given URL and writes it as a local file.
static java.io.File	getDownloadFile(java.lang.String extension) Creates a File representing the complete path for a downloaded file, creating the enclosing directories if needed.
static java.io.File	getExternalFile(java.lang.String fileName) Returns the File for fileName in the external storage directory in preparation for writing the file.
static java.lang.String	getFileUrl(java.lang.String localFileName) Returns an URL for the given local file.
static java.io.File	getPictureFile(java.lang.String extension) Creates a File representing the complete path for an image file, creating the enclosing directories if needed.
static java.io.File	getRecordingFile(java.lang.String extension) Creates a File representing the complete path for a recording, creating the enclosing directories if needed.
static byte[]	readFile(java.lang.String inputFileName) Reads the given local file and returns the contents as a byte array.
static java.lang.String	writeFile(byte[] array, java.lang.String outputFileName) Writes the given byte array as a local file.
static java.lang.String	writeStreamToFile(java.io.InputStream in, java.lang.String outputFileName) Writes the contents from the given input stream to the given file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getFileUrl

public static java.lang.String getFileUrl(java.lang.String localFileName)

Returns an URL for the given local file.

readFile

public static byte[] readFile(java.lang.String inputFileName)
                       throws java.io.IOException

Reads the given local file and returns the contents as a byte array.

Parameters:

inputFileName - the name of the file to read from

Returns:

the file's contents as a byte array

Throws:

java.io.IOException

downloadUrlToFile

public static java.lang.String downloadUrlToFile(java.lang.String url,
                                 java.lang.String outputFileName)
                                          throws java.io.IOException

Downloads the resource with the given URL and writes it as a local file.

Parameters:

url - the URL to read from

outputFileName - the name of the file to write to

Returns:

the URL for the local file

Throws:

java.io.IOException

writeFile

public static java.lang.String writeFile(byte[] array,
                         java.lang.String outputFileName)
                                  throws java.io.IOException

Writes the given byte array as a local file.

Parameters:

array - the byte array to read from

outputFileName - the name of the file to write to

Returns:

the URL for the local file

Throws:

java.io.IOException

copyFile

public static java.lang.String copyFile(java.lang.String inputFileName,
                        java.lang.String outputFileName)
                                 throws java.io.IOException

Copies the contents of one local file to another local file.

Parameters:

inputFileName - the name of the file to read to

outputFileName - the name of the file to write to

Returns:

the URL for the local file

Throws:

java.io.IOException

writeStreamToFile

public static java.lang.String writeStreamToFile(java.io.InputStream in,
                                 java.lang.String outputFileName)
                                          throws java.io.IOException

Writes the contents from the given input stream to the given file.

Parameters:

in - the InputStream to read from

outputFileName - the name of the file to write to

Returns:

the URL for the local file

Throws:

java.io.IOException

getPictureFile

public static java.io.File getPictureFile(java.lang.String extension)
                                   throws java.io.IOException,
                                          FileUtil.FileException

Creates a File representing the complete path for an image file, creating the enclosing directories if needed. This does not actually open the file. Any component that calls this must have Manifest.permission.WRITE_EXTERNAL_STORAGE.

Parameters:

extension - file extension, such as "png" or "jpg"

Returns:

the path to the file

Throws:

java.io.IOException - if the enclosing directory cannot be created

FileUtil.FileException - if external storage is not accessible or not writable with the appropriate ErrorMessages error code.

getRecordingFile

public static java.io.File getRecordingFile(java.lang.String extension)
                                     throws java.io.IOException,
                                            FileUtil.FileException

Creates a File representing the complete path for a recording, creating the enclosing directories if needed. This does not actually open the file. Any component that calls this must have Manifest.permission.WRITE_EXTERNAL_STORAGE.

Parameters:

extension - file extension, such as "3gp"

Returns:

the path to the file

Throws:

java.io.IOException - if the enclosing directory cannot be created

FileUtil.FileException - if external storage is not accessible or not writable with the appropriate ErrorMessages error code.

getDownloadFile

public static java.io.File getDownloadFile(java.lang.String extension)
                                    throws java.io.IOException,
                                           FileUtil.FileException

Creates a File representing the complete path for a downloaded file, creating the enclosing directories if needed. This does not actually open the file. Any component that calls this must have Manifest.permission.WRITE_EXTERNAL_STORAGE.

Parameters:

extension - file extension, such as "tmp"

Returns:

the path to the file

Throws:

java.io.IOException - if the enclosing directory cannot be created

FileUtil.FileException - if external storage is not accessible or not writable with the appropriate ErrorMessages error code.

getExternalFile

public static java.io.File getExternalFile(java.lang.String fileName)
                                    throws java.io.IOException,
                                           FileUtil.FileException

Returns the File for fileName in the external storage directory in preparation for writing the file. fileName may contain sub-directories. Ensures that all subdirectories exist and that fileName does not exist (deleting it if necessary).

Parameters:

fileName - The path name of the file relative to the external storage directory

Returns:

the File object for creating fileName in the external storage

Throws:

java.io.IOException - if we are unable to create necessary parent directories or delete an existing file

FileUtil.FileException - if the external storage is not writeable.

checkExternalStorageWriteable

public static void checkExternalStorageWriteable()
                                          throws FileUtil.FileException

Throws:

FileUtil.FileException