Android读取SD卡内容

以你之姓@ 2022-08-03 15:58 294阅读 0赞

在做开发的时候遇到一个问题就是需要为用户数据做缓存特别是图片文件缓存，下面就来看看SD卡的读写操作：

**Android读取手机SD卡内容：**

①所需权限：

<uses-permission android:name="android.permission.MOUNT\_UNMOUNT\_FILESYSTEMS" />  
  
<uses-permission android:name="android.permission.WRITE\_EXTERNAL\_STORAGE" />

②判断是否挂载：

if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
    			Log.i("test", "有SD卡::"+Environment.getExternalStorageDirectory());
    		}else {
    			Log.i("test", "没有SD卡");
    		}

③保存文件：

String fileName = "xxxxx";
    String dir = "xxx";
    File dirFile = new File(dir);
    if (!dirFile.exists()) {
    	dirFile.mkdirs();
    }
    File file = new File(dir + "/" +fileName);
    try {
    	file.createNewFile();
    	OutputStream outputStream = new FileOutputStream(file);
    	//写文件
    	outputStream.flush();
    	outputStream.close();
    } catch (IOException e) {
    	e.printStackTrace();
    }

④读文件示例：

File file = new File(path);
    if(file.exists()){
    	Bitmap bitmap = BitmapFactory.decodeFile(path);
    	if(bitmap == null){
    		file.delete();
    		return null;
    	}else {
    		return bitmap;
    	}
    }

⑤获取SD卡总容量：

public long getSDAllSize(){  
     //取得SD卡文件路径  
     File path = Environment.getExternalStorageDirectory();   
     StatFs sf = new StatFs(path.getPath());   
     //获取单个数据块的大小(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; //单位Byte  
     //return (allBlocks * blockSize)/1024; //单位KB  
     return (allBlocks * blockSize)/1024/1024; //单位MB  
    }

⑥获取SD卡剩余容量：

public long getSDFreeSize(){  
     //取得SD卡文件路径  
     File path = Environment.getExternalStorageDirectory();   
     StatFs sf = new StatFs(path.getPath());   
     //获取单个数据块的大小(Byte)  
     long blockSize = sf.getBlockSize();   
     //空闲的数据块的数量  
     long freeBlocks = sf.getAvailableBlocks();  
     //返回SD卡空闲大小  
     //return freeBlocks * blockSize;  //单位Byte  
     //return (freeBlocks * blockSize)/1024;   //单位KB  
     return (freeBlocks * blockSize)/1024 /1024; //单位MB  
    }