有些时候需要建立子类继承于父类，尤其是java里面很多类是用mybatis generator生成的。通过父类构造子类，好像很麻烦，要逐个字段进行赋值（反正我没有找到其他好办法）。

想到用反射复制的方式来实现。通过研究，做到了。主要是用了fastjson里面的东西。估计已经有其他类库实现了这个功能，可惜我不知道，只能自己搞。

　　

 

1 import java.beans.Statement; 2 import java.lang.reflect.Field; 3 import java.lang.reflect.Method; 4 import java.lang.reflect.Type; 5 import java.util.List; 6  7 import com.alibaba.fastjson.JSON; 8 import com.alibaba.fastjson.util.DeserializeBeanInfo; 9 import com.alibaba.fastjson.util.FieldInfo;10 import com.alibaba.fastjson.util.TypeUtils;11 12 /**13  * Created by fenggqc on 2016/6/29.14  */15 public class Copyer {16 17 18     public static 
      
         void Copy(B bo, S so) throws IllegalAccessException {19 20         try {21             Class bc = bo.getClass();22             if (bo == null || so == null) {23                 return;24             }25 26 27             DeserializeBeanInfo deserializeBeanInfo = DeserializeBeanInfo.computeSetters(so.getClass(), (Type) so.getClass());28             List
       
         getters = TypeUtils.computeGetters(bo.getClass(), null);29 30             List
        
          setters = deserializeBeanInfo.getFieldList();31             Object v;32             FieldInfo getterfield;33             FieldInfo setterfidld;34 35             for (int j = 0; j < getters.size(); j++) {36 37                 getterfield=getters.get(j);38                 for (int i = 0; i < setters.size(); i++) {39                     setterfidld=setters.get(i);40 //                    System.out.println(setterfidld.getName());41 //                    System.out.println(getterfield.getName());42 43                     if (setterfidld.getName().compareTo(getterfield.getName()) == 0) {44                         v = getterfield.getMethod().invoke(bo);45                        setterfidld.getMethod().invoke(so,v);46                         break;47                     }48 49                 }50             }51         } catch (Exception ex) {52             System.out.println(ex.toString());53         }54 55 56     }57 58 59 }
        
       
      

 

1 public class SubClass extends  BaseClass { 2  3     private Date birthday; 4  5  6     public Date getBirthday() { 7         return birthday; 8     } 9 10     public void setBirthday(Date birthday) {11         this.birthday = birthday;12     }13 }14 15 16 public class BaseClass {17 18     private  Integer i;19     private Boolean b;20 21     private  Boolean is;22     private  Boolean isa;23 24     private  String whatname;25 26 27     public Boolean getB() {28         return b;29     }30 31     public void setB(Boolean b) {32         this.b = b;33     }34 35     public Integer getI() {36         return i;37     }38 39     public void setI(Integer i) {40         this.i = i;41     }42 43     public Boolean getIs() {44         return is;45     }46 47     public void setIs(Boolean is) {48         this.is = is;49     }50 51     public Boolean getIsa() {52         return isa;53     }54 55     public void setIsa(Boolean isa) {56         this.isa = isa;57     }58 59     public String getWhatname() {60         return whatname;61     }62 63     public void setWhatname(String whatname) {64         this.whatname = whatname;65     }66 }

 

 

 

测试了一下性能：

1    @Test 2     public void Test() throws InvocationTargetException, IllegalAccessException { 3  4  5         BaseClass baseClass = new BaseClass(); 6         SubClass subClass=new SubClass(); 7  8         baseClass.setB(true); 9         baseClass.setI(1010);10         baseClass.setIs(false);11         baseClass.setWhatname("fgq");12 13 14         Integer i=0;15         List
      
        ii=new ArrayList
       
        ();16         ii.add(1);17         ii.add(10);18         ii.add(100);19         ii.add(1000);20         ii.add(10000);21 22         StopWatch stopWatch=new StopWatch();23 24         stopWatch.reset();;25         stopWatch.start();26         Copyer.Copy(baseClass, subClass);27         stopWatch.stop();28         System.out.println("cache the reflection:"+String.valueOf(stopWatch.getTime()));29 30 31 32 33         for (int j = 0; j < ii.size(); j++) {34             i=0;35             stopWatch.reset();;36             stopWatch.start();37             while ( i
       
      

 

性能结果为：

cache the reflection:120

1 1

10 7

100 53

1000 139

10000 634

感觉还行。呵呵