判断资源存在与否如判断一个drawable的图片存在及通过id加载图片

其实这个问题在我的以前的琐碎里已经记录过了

现在拿出来 免得到时候需要的人在找

int i=  getResources().getIdentifier("icon", "drawable", getPackageName()) ;
      if(i>0)
      {Log.i("aa","aa");}
      else
      {Log.i("vbv","aa");}

 

或者

 int resID = getResources().getIdentifier("org.loveandroid.androidtest:drawable/gallery_photo_1",null,null);

 

int resID = getResources ( ). getIdentifier ( "org.anddev.android.testproject:drawable/bug", null, null );
// or
int resID = getResources ( ). getIdentifier ( "bug", "drawable", "org.anddev.android.testproject" );

第一个参数其实

full_package:type/filename_without_ending是这种格式 然后其他的可以为null

int idFlag = getResources().getIdentifier(   
      getPackageName() + ":drawable/flag",    
      null, null);   
// 或是   
int idFlag = getResources().getIdentifier(   
      "flag", "drawable", getPackageName());  

 

var Drawable[] dw = new Drawable[10];   
  
for (int i = 1; i <= 10; i++) {   
  int id = getResources().getIdentifier(   
                    "flag" + i,    
                    "drawable", getPackageName());   
  dw[i-1] = getResources().getDrawable(id);   
}

 用反射发 可以得到 所有的资源

private void    
  _DumpAllResourceIDs(Class<?> classType)    
    throws IllegalArgumentException {   
  Field[] fIDs = classType.getFields();   
           
  try {   
    for (int i = 0; i < fIDs.length; i++) {   
      Field fld = fIDs[i];   
      int nID = fld.getInt(null);   
      Log.d("dbg",   
        classType.getSimpleName() + " " +    
        i + ": " +    
        fld.getName() + "=" +   
        nID);   
    }   
  } catch (Exception e) {   
    throw new IllegalArgumentException();   
  }   
}  

 

import java.lang.reflect.Field;   
...   
  _DumpAllResourceIDs(R.layout.class);   
  _DumpAllResourceIDs(R.drawable.class);  

 结果

R$layout 0: main=2130903040  
R$layout 1: small_spinner_dropdown_item=2130903041  
R$drawable 0: icon=2130837504