在多个有规律的资源ID获取的时候，可以使用getIdentifier方法来获取，来获取。
用到场景：工具类打成.jar包的时候,有时候会需要引用到res中的资源,这时候不能将资源一起打包,只能通过反射机制动态的获取资源.
public class Resources int getIdentifier (String name, String defType, String defPackage)
Return a resource identifier for the given resource name.
param defType："layout"，"string","drawable","style","color","array"
Parameters
| name | The name of the desired resource. |
|---|---|
| defType | Optional default resource type to find, if "type/" is not included in the name. Can be null to require an explicit type. |
| defPackage | Optional default package to find, if "package:" is not included in the name. Can be null to require an explicit package. |
Returns
- int The associated resource identifier. Returns 0 if no such resource was found. (0 is not a valid resource ID.)
from： http://developer.android.com/reference/android/content/res/Resources.html
public static int getDrawableId(Context paramContext, String paramString) {
return paramContext.getResources().getIdentifier(paramString,
"drawable", paramContext.getPackageName());
}
对于这个方法，官方不推荐:
Note: use of this function is discouraged. It is much more efficient to retrieve resources by identifier than by name.
更好的解决方案，是参照另外一篇博客的使用反射实现的。
http://www.liaohuqiu.net/cn/posts/android-get-resource-id-by-string/
示例代码：
public static int getResId(String variableName, Class<?> c) {
try {
Field idField = c.getDeclaredField(variableName);
return idField.getInt(idField);
} catch (Exception e) {
e.printStackTrace();
return -1;
}
}
使用：
int id = ResourceMan.getResId("icon", R.drawable.class);
这种效率据说比第一种高了4倍。
