提取，並通過反射

Question

我想設定一些枚舉的默認值，我使用下面的方法設置的枚舉值：

private void checkEnum(Field field, String setMethod) { 
    // TODO Auto-generated method stub 
    try { 
     String className = Character.toUpperCase(field.getName().charAt(0)) + 
     field.getName().substring(1); 
     Class<?> cls = Class.forName("com.citigroup.get.zcc.intf." + className); 
     Object[] enumArray = cls.getEnumConstants(); 

     //set to the last Enum which is unknown 
     invoke(setMethod, enumArray[enumArray.length - 1]); 
    } catch(Exception e) { 
     System.out.println(e.toString()); 
    } 
}  

的問題實際上是設置枚舉。我已經提取了枚舉類型，但是然後調用MethodInvoker。傳入Enum對象證明是一個問題。所有枚舉都具有以下內容作爲枚舉數組的最後一個元素。

private Object invoke(String methodName, Object newValue) { 
    Object value = null; 
    try { 
     methodInvoker.setTargetMethod(methodName); 

     if (newValue != null) { 
      methodInvoker.setArguments(new Object[]{newValue}); 
     } else { 
      methodInvoker.setArguments(new Object[]{});    
      } 
     methodInvoker.prepare(); 
     value = methodInvoker.invoke(); 
    } catch (ClassNotFoundException e) { 
     throw new IllegalStateException("Method invocation failed. " + e.getMessage(),e); 
    } catch (NoSuchMethodException e) { 
     throw new IllegalStateException("Method invocation failed. " + e.getMessage(),e); 
    } catch (java.lang.reflect.InvocationTargetException e) { 
     throw new IllegalStateException("Method invocation failed. " + e.getMessage(),e); 
    } catch (IllegalAccessException e) { 
     throw new IllegalStateException("Method invocation failed. " + e.getMessage(),e); 
    } 

    return value; 
} 

所以我迷路了，爲什麼

invoke(setMethod, enumArray[enumArray.length -1]); 

是不是我的設置枚舉

：

EnumName.UNKNOWN 

然而，這不被通過，它看起來像invoke方法設置

Answer 1

我試圖讓你的代碼運行。該methodInvoker.prepare（）調用被扔： java.lang.IllegalArgumentException異常：無論是「targetClass」或「targetObject」需要

所以我在課堂上缺少的參數，並將該代碼的工作，如果我理解你的用例。 您似乎設置了一個靜態字段，其名稱必須是com.citigroup.get.zcc.intf中Enum類的名稱，並且字段名稱中的第一個字符已降低。

這是我修改後的代碼：

public void checkEnum(Field field, String setMethod, Class clazz) { 
     try { 
     String className = Character.toUpperCase(field.getName().charAt(0)) + 
      field.getName().substring(1); 
     Class<?> cls = Class.forName("com.citigroup.get.zcc.intf." + className); 
     Object[] enumArray = cls.getEnumConstants(); 

     //set to the last Enum which is unknown 
     invoke(setMethod, enumArray[enumArray.length - 1], clazz); 
     } catch (Exception e) { 
     System.out.println(e.toString()); 
     } 
    } 
    private Object invoke(String methodName, Object newValue, Class clazz) { 
     Object value = null; 
     try { 
     MethodInvoker methodInvoker = new MethodInvoker(); // this was missing 
     methodInvoker.setTargetMethod(methodName); 
     methodInvoker.setTargetClass(clazz); // This was missing 

     if (newValue != null) { 
      methodInvoker.setArguments(new Object[]{newValue}); 
     } else { 
      methodInvoker.setArguments(new Object[]{}); 
     } 
     methodInvoker.prepare(); 
     value = methodInvoker.invoke(); 
     } catch (ClassNotFoundException e) { 
     throw new IllegalStateException("Method invocation failed. " + e.getMessage(), e); 
     } catch (NoSuchMethodException e) { 
     throw new IllegalStateException("Method invocation failed. " + e.getMessage(), e); 
     } catch (java.lang.reflect.InvocationTargetException e) { 
     throw new IllegalStateException("Method invocation failed. " + e.getMessage(), e); 
     } catch (IllegalAccessException e) { 
     throw new IllegalStateException("Method invocation failed. " + e.getMessage(), e); 
     } 

     return value; 
    } 
    } 

我的測試代碼相似（顯示爲一個枚舉類礦井，MethodNameHelper先前已發佈到StackExchange）：

public class StackExchangeTestCase { 
    protected static final Logger log = Logger.getLogger(StackExchangeTestCase.class); 
    public static Show show; 
    public static void setShow(Show newShow) { 
    show = newShow; 
    } 

    @Test 
    public void testJunk() throws Exception { 

    Method me = (new Util.MethodNameHelper(){}).getMethod(); 
    Class<?> aClass = me.getDeclaringClass(); 
    Field att1 = aClass.getField("show"); 
    show = null; 

    methodNameHelper.checkEnum(att1, "setShow", aClass); 

    System.out.println(show); // worked 
    } 
}