Android内存和SD卡的数据存取

内存

向内存存取数据，不需要任何权限

效果图

存

private String fileName = "test.txt";

   public void saveToROM(View view) {
       File file = new File(getFilesDir(), fileName);
       try {
           FileOutputStream fos = new FileOutputStream(file);
           String str = "这是我写入内存的数据";
           fos.write(str.getBytes());
           fos.close();
           Toast.makeText(this, "保存到内存成功", Toast.LENGTH_SHORT).show();
       } catch (Exception e) {
           e.printStackTrace();
           Toast.makeText(this, "保存到内存失败", Toast.LENGTH_SHORT).show();
       }
   }

取

private String fileName = "test.txt";

   public void readFromROM(View view) {
       File file = new File(getFilesDir(), fileName);
       try {
           BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
           String text = br.readLine();
           br.close();
           Toast.makeText(this, "读取:\n" + text, Toast.LENGTH_SHORT).show();
       } catch (Exception e) {
           e.printStackTrace();
       }
   }

保存成功以后，可以在data/data/包名/files下看到文件

SD卡

保存到SD卡和保存到内存基本一样，只不过存储路径不一样，需要SD的存取权限，另外需要注意的是有的设备可能没有SD卡。

权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

存

private String fileName = "test.txt";

public void saveToSD(View view) {
    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
        // sd卡可用
        File file = new File(Environment.getExternalStorageDirectory(), fileName);
        try {
            FileOutputStream fos = new FileOutputStream(file);
            String str = "这是我写入SD卡的数据";
            fos.write(str.getBytes());
            fos.close();
            Toast.makeText(this, "保存到SD卡成功", Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            e.printStackTrace();
            Toast.makeText(this, "保存到SD卡失败", Toast.LENGTH_SHORT).show();
        }
    } else {
        // 当前不可用
        Toast.makeText(this, "SD卡不可用", Toast.LENGTH_SHORT).show();
    }
}

取

private String fileName = "test.txt";

public void readFromSD(View view) {
    if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
        // SD卡可用
        File file = new File(Environment.getExternalStorageDirectory(), fileName);
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
            String text = br.readLine();
            br.close();
            Toast.makeText(this, "读取:\n" + text, Toast.LENGTH_SHORT).show();
        } catch (Exception e) {
            e.printStackTrace();
        }
    } else {
        // SD卡不可用
        Toast.makeText(this, "SD卡不可用", Toast.LENGTH_SHORT).show();
    }
}