做jar，jar代码获取资源不能直接引用 R.xx.name,

有两种方法：

1.通过方法: int android.content.res.Resources.getIdentifier(String name,String defType,String defPackage)

2.通过反射

第一种方法比较常见，主要看第二种方法：

public class ResoureExchange {

private static final String TAG = ResoureExchange.class.getName();

private static ResoureExchange self;

private Context mContext;

private static Class> CDrawable = null;

private static Class> CLayout = null;

private static Class> CId = null;

private static Class> CAnim = null;

private static Class> CStyle = null;

private static Class> CString = null;

private static Class> CArray = null;

public static ResoureExchange getInstance(Context context){

if(self == null){

self = new ResoureExchange(context);

}

return self;

}

private ResoureExchange(Context context){

this.mContext = context.getApplicationContext();

try{

CDrawable = Class.forName(this.mContext.getPackageName() + ".R$drawable");

CLayout = Class.forName(this.mContext.getPackageName() + ".R$layout");

CId = Class.forName(this.mContext.getPackageName() + ".R$id");

CAnim = Class.forName(this.mContext.getPackageName() + ".R$anim");

CStyle = Class.forName(this.mContext.getPackageName() + ".R$style");

CString = Class.forName(this.mContext.getPackageName() + ".R$string");

CArray = Class.forName(this.mContext.getPackageName() + ".R$array");

}catch(ClassNotFoundException e){

Log.i(TAG,e.getMessage());

}

}

public int getDrawableId(String resName){

return getResId(CDrawable,resName);

}

public int getLayoutId(String resName){

return getResId(CLayout,resName);

}

public int getIdId(String resName){

return getResId(CId,resName);

}

public int getAnimId(String resName){

return getResId(CAnim,resName);

}

public int getStyleId(String resName){

return getResId(CStyle,resName);

}

public int getStringId(String resName){

return getResId(CString,resName);

}

public int getArrayId(String resName){

return getResId(CArray,resName);

}

private int getResId(Class> resClass,String resName){

if(resClass == null){

Log.i(TAG,"getRes(null," + resName + ")");

throw new IllegalArgumentException("ResClass is not initialized. Please make sure you have added neccessary resources. Also make sure you have " + this.mContext.getPackageName() + ".R$* configured in obfuscation. field=" + resName);

}

try {

Field field = resClass.getField(resName);

return field.getInt(resName);

} catch (Exception e) {

Log.i(TAG, "getRes(" + resClass.getName() + ", " + resName + ")");

Log.i(TAG, "Error getting resource. Make sure you have copied all resources (res/) from SDK to your project. ");

Log.i(TAG, e.getMessage());

}

return -1;

}

}

直接看代码，一目了然。[来源于反编译友盟统计jar]

原文作者：