本文主要介紹如何寫數據到sd卡,這裏主要到的技術是Environment中的方法.java
1.android
2.實現代碼:緩存
/datasave/src/com/amos/datasave/savePasswordService.java ide
//寫數據到sdcard public void savePasswordToSDCard(String name, String password) { // android 2.1 /sdcard/xx.txt // android 2.2 /mnt/sdcard/xx.txt // self_define /excard/xx.txt // File externalStorageDirectory = Environment.getExternalStorageDirectory(); // String path = externalStorageDirectory.getPath(); // System.out.println("path:" + path); // 要存儲的內容 String content = name + ":" + password; Log.d(tag, "檢驗sdcard是否可用?"); //判斷sdcard是否存在? if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){ Log.d(tag, "sdcard不可用!"); Toast.makeText(context, "沒有找到SDCard!", Toast.LENGTH_LONG); return ; }; try { // File file = new File("/sdcard/qqpassword.txt"); // File file = new File(path + "/qqpassword2.txt"); File file = new File(Environment.getExternalStorageDirectory(), "/qqpassword2.txt"); FileOutputStream fos = new FileOutputStream(file); fos.write(content.getBytes()); fos.flush(); fos.close(); } catch (Exception e) { e.printStackTrace(); } }
在android2.1及之前版本中,其sdcard目錄在根目錄,2.2,2.3之後其sdcard目錄就變成了/mnt/sdcard了,以及一些廠商自定義的android系統,可能也會把sdcard的名稱改的各不相同.這裏若是仍是用絕對路徑,那麼程序的兼容性將會大大下降.這裏主要用到了Enviroment類.this
android.os.Environmentspa
其主要方法有:code
package com.amos.datasave; import java.io.File; import java.io.FileOutputStream; import android.annotation.SuppressLint; import android.content.Context; import android.os.Environment; import android.util.Log; import android.widget.Toast; @SuppressLint("WorldWriteableFiles") public class savePasswordService { private Context context; private String tag = "savePasswordService"; public savePasswordService(Context context) { this.context = context; } public void savePasswordToFile(String name, String password) { // 這裏設置文件的權限 String content = name + ":" + password; Log.d(tag, "設置文件的讀寫權限"); try { FileOutputStream fileOutput = context.openFileOutput("LoginTestConfig.txt", Context.MODE_WORLD_READABLE | Context.MODE_WORLD_WRITEABLE); fileOutput.write(content.getBytes()); fileOutput.flush(); fileOutput.close(); } catch (Exception e) { Log.d(tag, "設置文件的讀寫權限失敗!"); e.printStackTrace(); } } //寫數據到sdcard public void savePasswordToSDCard(String name, String password) { // android 2.1 /sdcard/xx.txt // android 2.2 /mnt/sdcard/xx.txt // self_define /excard/xx.txt // File externalStorageDirectory = Environment.getExternalStorageDirectory(); // String path = externalStorageDirectory.getPath(); // System.out.println("path:" + path); // 要存儲的內容 String content = name + ":" + password; Log.d(tag, "檢驗sdcard是否可用?"); //判斷sdcard是否存在? if(!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){ Log.d(tag, "sdcard不可用!"); Toast.makeText(context, "沒有找到SDCard!", Toast.LENGTH_LONG); return ; }; try { // File file = new File("/sdcard/qqpassword.txt"); // File file = new File(path + "/qqpassword2.txt"); File file = new File(Environment.getExternalStorageDirectory(), "/qqpassword2.txt"); FileOutputStream fos = new FileOutputStream(file); fos.write(content.getBytes()); fos.flush(); fos.close(); } catch (Exception e) { e.printStackTrace(); } } }
如何獲取sdcard的大小?blog
StatFs statFs = new StatFs(Environment.getExternalStorageDirectory().getPath()); long blockSize = statFs.getBlockSize(); long blockCount = statFs.getBlockCount(); long sdCardSize = blockSize*blockCount; Log.d(tag,""+sdCardSize );
這裏使用的是Environment中的方法獲取到sdcard的路徑,而後將其路徑經過StatFs類,該類主要獲取指定文件路徑下的文件信息(filesystem info).rem
獲取其塊大小,塊數量.get