查看源代码查找获取sd卡剩余容量的代码

• 下载android源码，找到app下的Settings应用源码，导入Settings项目（android项目源码）

• 查找“可用空间”得到

   <string name="memory_available" msgid="418542433817289474">"可用空间"</string>
  

• 查找"memory_available"，得到

  <Preference android:key="memory_sd_avail"
      style="?android:attr/preferenceInformationStyle"
      android:title="@string/memory_available"
      android:summary="00"/>
  

• 查找"memorysdavail"，得到

  //这个字符串就是sd卡剩余容量
  formatSize(availableBlocks * blockSize) + readOnly
  //这两个参数相乘，得到sd卡以字节为单位的剩余容量
  availableBlocks * blockSize
  

• 存储设备会被分为若干个区块，每个区块有固定的大小

• 区块大小 * 区块数量 等于 存储设备的总大小

• 示例代码

  File path = Environment.getExternalStorageDirectory();
      StatFs stat = new StatFs(path.getPath());
      long blockSize;
      long totalBlocks;
      long availableBlocks;
  
      //获取当前系统版本的等级
      if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2){
           blockSize = stat.getBlockSizeLong();
           totalBlocks = stat.getBlockCountLong();
           availableBlocks = stat.getAvailableBlocksLong();
      }
      else{
          blockSize = stat.getBlockSize();
          totalBlocks = stat.getBlockCount();
          availableBlocks = stat.getAvailableBlocks();
      }
  
      TextView tv = (TextView) findViewById(R.id.tv);
      tv.setText(formatSize(availableBlocks * blockSize));
  }
  
  private String formatSize(long size) {
      return Formatter.formatFileSize(this, size);
  }