四、单位转换类 DensityUtils.java
public class DensityUtils
{
private DensityUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}
/**
* dp转px
*
* @param context
* @param val
* @return
*/
public static int dppx(Context context, float dpVal)
{
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
dpVal, context.getResources().getDisplayMetrics());
}
/**
* sp转px
*
* @param context
* @param val
* @return
*/
public static int sppx(Context context, float spVal)
{
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
spVal, context.getResources().getDisplayMetrics());
}
/**
* px转dp
*
* @param context
* @param pxVal
* @return
*/
public static float pxdp(Context context, float pxVal)
{
final float scale = context.getResources().getDisplayMetrics().density;
return (pxVal / scale);
}
/**
* px转sp
*
* @param fontScale
* @param pxVal
* @return
*/
public static float pxsp(Context context, float pxVal)
{
return (pxVal / context.getResources().getDisplayMetrics().scaledDensity);
}
}
TypedValue：
Container for a dynamically typed data value. Primarily used with Resources for holding resource values.
applyDimension(int unit, float value, DisplayMetrics metrics)：
Converts an unpacked complex data value holding a dimension to its final floating point value.
五、SD卡相关辅助类 SDCardUtils.java
public class SDCardUtils
{
private SDCardUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}
/**
* 判断SDCard是否可用
*
* @return
*/
public static boolean isSDCardEnable()
{
return Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED);
}
/**
* 获取SD卡路径
*
* @return
*/
public static String getSDCardPath()
{
return Environment.getExternalStorageDirectory().getAbsolutePath()
+ File.separator;
}
/**
* 获取SD卡的剩余容量 单位byte
*
* @return
*/
public static long getSDCardAllSize()
{
if (isSDCardEnable())
{
StatFs stat = new StatFs(getSDCardPath());
// 获取空闲的数据块的数量
long availableBlocks = (long) stat.getAvailableBlocks() - ;
// 获取单个数据块的大小（byte）
long freeBlocks = stat.getAvailableBlocks();
return freeBlocks * availableBlocks;
}
return ;
}
/**
* 获取指定路径所在空间的剩余可用容量字节数，单位byte
*
* @param filePath
* @return 容量字节 SDCard可用空间，内部存储可用空间
*/
public static long getFreeBytes(String filePath)
{
// 如果是sd卡的下的路径，则获取sd卡可用容量
if (filePath.startsWith(getSDCardPath()))
{
filePath = getSDCardPath();
} else
{// 如果是内部存储的路径，则获取内存存储的可用容量
filePath = Environment.getDataDirectory().getAbsolutePath();
}
StatFs stat = new StatFs(filePath);
long availableBlocks = (long) stat.getAvailableBlocks() - ;
return stat.getBlockSize() * availableBlocks;
}
/**
* 获取系统存储路径
*
* @return
*/
public static String getRootDirectoryPath()
{
return Environment.getRootDirectory().getAbsolutePath();
}
}
