Android 获取有规律资源Id解决方案

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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。