<!-- 在SDCard中建立與刪除檔案的許可權 -->  
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />  
    <!-- 往SDCard寫入資料的許可權 -->  
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />  

儲存

 /** 
     * 將物件儲存到本地 
     * @param context 
     * @param
 
 fileName 檔名 
     * @param bean  物件 
     * @return true 儲存成功 
     */  
    public boolean writeObjectIntoLocal(Context context,String fileName,T bean){  
        try {  
            // 通過openFileOutput方法得到一個輸出流，方法引數為建立的檔名（不能有斜槓），操作模式  
            @SuppressWarnings("deprecation")  
            FileOutputStream fos = context.openFileOutput(fileName, Context.MODE_WORLD_READABLE);  
            ObjectOutputStream oos = new
 
 ObjectOutputStream(fos);  
            oos.writeObject(bean);//寫入  
            fos.close();//關閉輸入流  
            oos.close();  
            return true;  
        } catch (FileNotFoundException e) {    
            e.printStackTrace();    
            //Toast.makeText(WebviewTencentActivity.this, "出現異常1",Toast.LENGTH_LONG).show();    
 

            return false;  
        } catch (IOException e) {    
            e.printStackTrace();    
            //Toast.makeText(WebviewTencentActivity.this, "出現異常2",Toast.LENGTH_LONG).show();    
            return false;  
        }   
    }  
    /** 
     * 將物件寫入sd卡 
     * @param fileName 檔名 
     * @param bean  物件 
     * @return true 儲存成功 
     */  
    public boolean writObjectIntoSDcard(String fileName,T bean){  
        if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){    
            File sdCardDir = Environment.getExternalStorageDirectory();//獲取sd卡目錄  
            File sdFile  = new File(sdCardDir, fileName);  
            try {  
                FileOutputStream fos = new FileOutputStream(sdFile);  
                ObjectOutputStream oos = new ObjectOutputStream(fos);  
                oos.writeObject(bean);//寫入  
                fos.close();  
                oos.close();  
                return true;  
            } catch (FileNotFoundException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return false;  
            } catch (IOException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return false;  
            }  
        }  
        else {  
            return false;  
        }  
    }  
    /** 
     * 將集合寫入sd卡 
     * @param fileName 檔名 
     * @param list  集合 
     * @return true 儲存成功 
     */  
    public boolean writeListIntoSDcard(String fileName,List<T> list){  
        if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){    
            File sdCardDir = Environment.getExternalStorageDirectory();//獲取sd卡目錄  
            File sdFile  = new File(sdCardDir, fileName);  
            try {  
                FileOutputStream fos = new FileOutputStream(sdFile);  
                ObjectOutputStream oos = new ObjectOutputStream(fos);  
                oos.writeObject(list);//寫入  
                fos.close();  
                oos.close();  
                return true;  
            } catch (FileNotFoundException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return false;  
            } catch (IOException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return false;  
            }  
        }  
        else {  
            return false;  
        }  
    }  
}  

讀取

  /** 
     * 讀取本地物件 
     * @param context 
     * @param fielName 檔名 
     * @return 
     */  
    @SuppressWarnings("unchecked")  
    public T readObjectFromLocal(Context context,String fielName){  
        T bean;  
        try {  
            FileInputStream fis = context.openFileInput(fielName);//獲得輸入流    
            ObjectInputStream ois = new ObjectInputStream(fis);  
            bean = (T) ois.readObject();  
            fis.close();  
            ois.close();  
            return bean;  
        } catch (StreamCorruptedException e) {    
            //Toast.makeText(ShareTencentActivity.this,"出現異常3",Toast.LENGTH_LONG).show();//彈出Toast訊息    
            e.printStackTrace();    
            return null;  
        } catch (OptionalDataException e) {    
            //Toast.makeText(ShareTencentActivity.this,"出現異常4",Toast.LENGTH_LONG).show();//彈出Toast訊息    
            e.printStackTrace();  
            return null;  
        } catch (FileNotFoundException e) {    
            //Toast.makeText(ShareTencentActivity.this,"出現異常5",Toast.LENGTH_LONG).show();//彈出Toast訊息    
            e.printStackTrace();    
            return null;  
        } catch (IOException e) {    
            e.printStackTrace();    
            return null;  
        } catch (ClassNotFoundException e) {    
            //Toast.makeText(ShareTencentActivity.this,"出現異常6",Toast.LENGTH_LONG).show();//彈出Toast訊息    
            e.printStackTrace();    
            return null;  
        }    
    }  
    /** 
     * 讀取sd卡物件 
     * @param fileName 檔名 
     * @return 
     */  
    @SuppressWarnings("unchecked")  
    public T readObjectFromSdCard(String fileName){  
        if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){  //檢測sd卡是否存在  
            T bean;  
            File sdCardDir = Environment.getExternalStorageDirectory();  
            File sdFile = new File(sdCardDir,fileName);  
            try {  
                FileInputStream fis = new FileInputStream(sdFile);  
                ObjectInputStream ois = new ObjectInputStream(fis);  
                bean = (T) ois.readObject();  
                fis.close();  
                ois.close();  
                return bean;  
            } catch (StreamCorruptedException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return null;  
            } catch (OptionalDataException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return null;  
            } catch (FileNotFoundException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();   
                return null;   
            } catch (IOException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return null;  
            } catch (ClassNotFoundException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return null;  
            }    
        }  
        else {  
            return null;  
        }  
    }  

    /** 
     * 讀取sd卡物件 
     * @param fileName 檔名 
     * @return 
     */  
    @SuppressWarnings("unchecked")  
    public List<T> readListFromSdCard(String fileName){  
        if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){  //檢測sd卡是否存在  
            List<T> list;  
            File sdCardDir = Environment.getExternalStorageDirectory();  
            File sdFile = new File(sdCardDir,fileName);  
            try {  
                FileInputStream fis = new FileInputStream(sdFile);  
                ObjectInputStream ois = new ObjectInputStream(fis);  
                list = (List<T>) ois.readObject();  
                fis.close();  
                ois.close();  
                return list;  
            } catch (StreamCorruptedException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return null;  
            } catch (OptionalDataException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return null;  
            } catch (FileNotFoundException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();   
                return null;   
            } catch (IOException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return null;  
            } catch (ClassNotFoundException e) {    
                // TODO Auto-generated catch block    
                e.printStackTrace();    
                return null;  
            }    
        }  
        else {  
            return null;  
        }  
    }  

}  

補充判斷是否存在

// 判斷檔案是否存在
    public boolean fileIsExists(String strFile) {
        try {
            if (Environment.getExternalStorageState().equals(
                    Environment.MEDIA_MOUNTED)) { // 檢測sd卡是否存在
                File sdCardDir = Environment.getExternalStorageDirectory();// 獲取sd卡目錄
                File sdFile = new File(sdCardDir, strFile);
                if (sdFile.exists()) {
                    return true;
                }
            }
        } catch (Exception e) {
            return false;
        }

        return false;
    }

原文地址