Java反射中getDeclaredField和getField的區別

getDeclaredField是可以獲取一個類的所有字段. 
getField只能獲取類的public 字段. 

public Field getDeclaredField(String name)  
       throws NoSuchFieldException, SecurityException {  
       checkMemberAccess(Member.DECLARED, ClassLoader.getCallerClassLoader());  
       Field field = searchFields(privateGetDeclaredFields(false), name);  
       if (field == null) {  
           throw new NoSuchFieldException(name);  
       }  
       return field;  
   }  
  
  
rivate Field getField0(String name) throws NoSuchFieldException {  
       Field res = null;  
       // Search declared public fields  
       if ((res = searchFields(privateGetDeclaredFields(true), name)) != null) {  
           return res;
    }  

　　

getField其實調用的是getField0. 
他們最后都調用了searchFields. 
不過getDeclaredField傳入的是privateGetDeclaredFields(false), 
getField傳入的是privateGetDeclaredFields(true);

private Field[] privateGetDeclaredFields(boolean publicOnly) {  
       checkInitted();  
       Field[] res = null;  
       if (useCaches) {  
           clearCachesOnClassRedefinition();  
           if (publicOnly) {  
               if (declaredPublicFields != null) {  
                   res = (Field[]) declaredPublicFields.get();  
               }  
           } else {  
               if (declaredFields != null) {  
                   res = (Field[]) declaredFields.get();  
               }  
           } 

　　

 

可以看到傳入條件為true的時候使用的是declaredPublicFields,意思是public字段 
為false的時候使用的是declaredFields.

 當然declaredFields和declaredPublicFields最終的來源是:

private native Field[] getDeclaredFields0(boolean publicOnly);