标签: 文件系统数据内存手机
2014-06-02 16:08 1626人阅读 收藏 举报
在程序中,有很多保存和获取数据的方法,本篇文章,主要介绍使用文件系统对程序中的数据进行保存和读取的操作
我直接写了一个帮助类,进行文件的写入和读取操作
-
-
-
-
-
-
- public class FileHelper {
-
- private static final String TAG = "FileHelper";
- private Context mContext;
-
- FileHelper(Context _mContext) {
- mContext = _mContext;
- }
-
-
- public void save(String fileName, String content) {
-
- FileOutputStream fileOutputStream = null;
- try {
- fileOutputStream = mContext.openFileOutput(fileName,
- Context.MODE_PRIVATE);
- fileOutputStream.write(content.getBytes());
-
- } catch (FileNotFoundException e) {
- e.printStackTrace();
- } catch (IOException e) {
- e.printStackTrace();
- } finally {
- try {
-
- if (fileOutputStream != null) {
- fileOutputStream.close();
- }
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- }
-
-
- public void read(String fileName) {
- FileInputStream fileInputStream = null;
- try {
- fileInputStream = mContext.openFileInput(fileName);
- int len = 0;
- byte[] buffer = new byte[1024];
- ByteArrayOutputStream byteArrayInputStream = new ByteArrayOutputStream();
- while ((len = fileInputStream.read(buffer)) != -1) {
- byteArrayInputStream.write(buffer, 0, len);
- }
- String string = new String(byteArrayInputStream.toByteArray());
- Log.d(TAG, string);
- } catch (FileNotFoundException e) {
- e.printStackTrace();
- } catch (IOException e) {
- e.printStackTrace();
- } finally {
- if (fileInputStream != null) {
- try {
- fileInputStream.close();
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- }
-
- }
- }
注意:使用写入操作的时候,写入的内容会将上次写入的内容进行覆盖
写入的文件保存在/data/data/package name/files目录下,使用DDMS可以进行查看
如下图所示:
使用DDMS将文件导出,即可查看内容
上面这些是将数据写入到我们的手机自带的存储空间里,如果想写入我们的SDCard,那么应该怎么做呢?
下面的写入到SDCard的操作
-
- public boolean saveToSDCard(String fileName, String content) {
-
-
- if (!Environment.getExternalStorageState().equals(
- Environment.MEDIA_MOUNTED)) {
- return false;
- }
-
- FileOutputStream fileOutputStream = null;
- File file = new File(Environment.getExternalStorageDirectory(),
- fileName);
- try {
- fileOutputStream = new FileOutputStream(file);
- fileOutputStream.write(content.getBytes());
- return true;
- } catch (FileNotFoundException e) {
- e.printStackTrace();
- } catch (IOException e) {
- e.printStackTrace();
- } finally {
- try {
-
- if (fileOutputStream != null) {
- fileOutputStream.close();
- }
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- return false;
- }
下面是读取位于SDCard根目录下文件的操作方法
-
- public String readFromSD(String fileName) {
- FileInputStream fileInputStream = null;
- File file = new File(Environment.getExternalStorageDirectory(),
- fileName);
- try {
- fileInputStream = new FileInputStream(file);
- int len = 0;
- byte[] buffer = new byte[1024];
- ByteArrayOutputStream byteArrayInputStream = new ByteArrayOutputStream();
- while ((len = fileInputStream.read(buffer)) != -1) {
- byteArrayInputStream.write(buffer, 0, len);
- }
- String string = new String(byteArrayInputStream.toByteArray());
- return string;
- } catch (FileNotFoundException e) {
- e.printStackTrace();
- } catch (IOException e) {
- e.printStackTrace();
- } finally {
- if (fileInputStream != null) {
- try {
- fileInputStream.close();
- } catch (IOException e) {
- e.printStackTrace();
- }
- }
- }
-
- return null;
- }