android通用文件操作
最经用到android的SCCard的文件操作，因此稍作了整理，将它写成一个简单的工具类。其中，可以判断SDCard的是否可用，可用存储空间，文件的创建以及写入数据。经过测试，可以正常使用。代码如下：
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.os.Environment;
import android.os.StatFs;
import android.util.Log;
public class FileUtil {
private static int bufferd = 1024;
private FileUtil() {
}
/*
* <!-- 在SDCard中创建与删除文件权限 --> <uses-permission
* android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/> <!--
* 往SDCard写入数据权限 --> <uses-permission
* android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
*/
// =================get SDCard information===================
public static boolean isSdcardAvailable() {
String status = Environment.getExternalStorageState();
if (status.equals(Environment.MEDIA_MOUNTED)) {
return true;
}
return false;
}
public static long getSDAllSizeKB() {
// get path of sdcard
File path = Environment.getExternalStorageDirectory();
StatFs sf = new StatFs(path.getPath());
// get single block size(Byte)
long blockSize = sf.getBlockSize();
// 获取所有数据块数
long allBlocks = sf.getBlockCount();
// 返回SD卡大小
return (allBlocks * blockSize) / 1024; // KB
}
/**
* free size for normal application
*
* @return
*/
public static long getSDAvalibleSizeKB() {
File path = Environment.getExternalStorageDirectory();
StatFs sf = new StatFs(path.getPath());
long blockSize = sf.getBlockSize();
long avaliableSize = sf.getAvailableBlocks();
return (avaliableSize * blockSize) / 1024;// KB
}
// =====================File Operation==========================
public static boolean isFileExist(String director) {
File file = new File(Environment.getExternalStorageDirectory()
+ File.separator + director);
return file.exists();
}
/**
* create multiple director
*
* @param path
* @return
*/
public static boolean createFile(String director) {
if (isFileExist(director)) {
return true;
} else {
File file = new File(Environment.getExternalStorageDirectory()
+ File.separator + director);
if (!file.mkdirs()) {
return false;
}
return true;
}
}
public static File writeToSDCardFile(String directory, String fileName,
String content, boolean isAppend) {
return writeToSDCardFile(directory, fileName, content, "", isAppend);
}
/**
*
* @param director
* (you don't need to begin with
* Environment.getExternalStorageDirectory()+File.separator)
* @param fileName
* @param content
* @param encoding
* (UTF-8...)
* @param isAppend
* : Context.MODE_APPEND
* @return
*/
public static File writeToSDCardFile(String directory, String fileName,
String content, String encoding, boolean isAppend) {
// mobile SD card path +path
File file = null;
OutputStream os = null;
try {
if (!createFile(directory)) {
return file;
}
file = new File(Environment.getExternalStorageDirectory()
+ File.separator + directory + File.separator + fileName);
os = new FileOutputStream(file, isAppend);
if (encoding.equals("")) {
os.write(content.getBytes());
} else {
os.write(content.getBytes(encoding));
}
os.flush();
} catch (IOException e) {
Log.e("FileUtil", "writeToSDCardFile:" + e.getMessage());
} finally {
try {
if(os != null){
os.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
return file;
}
/**
* write data from inputstream to SDCard
*/
public File writeToSDCardFromInput(String directory, String fileName,
InputStream input) {
File file = null;
OutputStream os = null;
try {
if (createFile(directory)) {
return file;
}
file = new File(Environment.getExternalStorageDirectory()
+ File.separator + directory + fileName);
os = new FileOutputStream(file);
byte[] data = new byte[bufferd];
int length = -1;
while ((length = input.read(data)) != -1) {
os.write(data, 0, length);
}
// clear cache
os.flush();
} catch (Exception e) {
Log.e("FileUtil", "" + e.getMessage());
e.printStackTrace();
} finally {
try {
os.close();
} catch (Exception e) {
e.printStackTrace();
}
}
return file;
}
/**
* this url point to image(jpg)
*
* @param url
* @return image name
*/
public static String getUrlLastString(String url) {
String[] str = url.split("/");
int size = str.length;
return str[size - 1];
}
}
下面对代码进行了测试，使用了AndroidJunitTest，当然另外还需要对SDCard查看操作的权限。
1、对android项目的mainfest.xml进行配置，需要注意targetPacket应当与包名保持一致。
//在mainfest标签下
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<instrumentation
android:name="android.test.InstrumentationTestRunner"
android:targetPackage="com.example.mygeneralutil" >
</instrumentation>
//在mainfest的application标签下
<uses-library android:name="android.test.runner"/>
2、简单的测试代码如下：
import android.test.AndroidTestCase;
import android.util.Log;
public class FileUtilTest extends AndroidTestCase {
public void testIsSdcardAvailable() {
FileUtil.isSdcardAvailable();
Log.e("FileUtil", ""+FileUtil.isSdcardAvailable());
}
public void testGetSDAllSizeKB() {
FileUtil.getSDAllSizeKB();
Log.e("FileUtil", ""+(float)FileUtil.getSDAllSizeKB()/1024/1024);
}
public void testGetSDAvalibleSizeKB() {
FileUtil.getSDAvalibleSizeKB();
Log.e("FileUtil", ""+(float)FileUtil.getSDAvalibleSizeKB()/1024/1024);
}
public void testIsFileExist() {
FileUtil.isFileExist("example");
Log.e("FileUtil", ""+FileUtil.isFileExist("example"));
}
public void testCreateFile() {
Log.e("FileUtil", ""+FileUtil.createFile("forexample"));
}
public void testWriteToSDCardFileStringStringStringBoolean() {
fail("Not yet implemented");
}
public void testWriteToSDCardFileStringStringStringStringBoolean() {
FileUtil.writeToSDCardFile("forexample", "123.txt",
"FileUtil.writeToSDCardFile", "utf-8", true);
}
public void testWriteToSDCardFromInput() {
fail("Not yet implemented");
}
public void testGetUrlLastString() {
fail("Not yet implemented");
}
}