計算表示填充的屬性數量的Java對象的百分比

Question

考慮一個POJO具有n個屬性。如何獲得表示POJO的填充屬性（分配值/非空值）數量的百分比值？
POJO是MySql數據庫中的一個實體，我使用Java，Hibernate和Spring。

Answer 1

嘿，你可以這樣做：

public class CountReflection { 

    public static void main(final String[] args) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException { 

     PoJo p = new PoJo(); 
     p.setA("a"); 

     Field[] fields = p.getClass().getDeclaredFields(); 

     int amountOfFields = 0; 
     int amountOfFieldsNotNull = 0; 

     for (Field field : fields) { 
      amountOfFields++; 
      Field declaredField = p.getClass().getDeclaredField(field.getName()); 
      declaredField.setAccessible(true); 
      Object value = declaredField.get(p); 
      if (value != null) { 
       amountOfFieldsNotNull++; 
      } 
     } 
     System.out.println("amountOfFields " + amountOfFields); 
     System.out.println("amountOfFieldsNotNull " + amountOfFieldsNotNull); 
     float percent = (amountOfFieldsNotNull * 100.0f)/amountOfFields; 
     System.out.println("percent of not null " + percent); 
    } 

} 

隨着POJO：

public class PoJo { 

    private String a; 
    private String b; 
    private String c; 
    private String d; 
    private String e; 

    public String getA() { 
     return a; 
    } 

    public void setA(final String a) { 
     this.a = a; 
    } 

    public String getB() { 
     return b; 
    } 

    public void setB(final String b) { 
     this.b = b; 
    } 

    public String getC() { 
     return c; 
    } 

    public void setC(final String c) { 
     this.c = c; 
    } 

    public String getD() { 
     return d; 
    } 

    public void setD(final String d) { 
     this.d = d; 
    } 

    public String getE() { 
     return e; 
    } 

    public void setE(final String e) { 
     this.e = e; 
    } 

}