android代码中动态获取资源ID

package com.example.resid;

import android.content.Context;
import android.content.res.Resources;

public class ResourcesId {
private static final String TAG = "ResourcesId";
private static Context mContext;
private static Resources mResources;
private static String mPackageName;

private ResourcesId() {}

private static class ResourcesIdHolder {
private static ResourcesId instance = new ResourcesId();
}
private static void setContext(Context context) {
if (context != null) {
mContext = context.getApplicationContext();
mResources = mContext.getResources();
mPackageName = mContext.getPackageName();
}
}

public static ResourcesId getInstance(Context context) {
ResourcesIdHolder.instance.setContext(context);
return ResourcesIdHolder.instance;
}

public int getResourcesId(String defType, String name) {
if (mResources != null) {
return mResources.getIdentifier(name, defType, mPackageName);
}
return 0;
}

public static int getResourcesId(Context context, String defType, String name) {
return ResourcesId.getInstance(context).getResourcesId(defType, name);
}
}