需求：如何將一個類轉換成一個Map，同時針對類中的屬性有要求，Date型別 需要變成String，YYYY －MM-DD HH:mm:ss 物件需要變成json。如何寫一個通用的工具

下面是具體的實現方式

public interface ValueMapper {

    String value(Object object);
}
public class JsonValueMapper implements ValueMapper {
    @Override
    public String value(Object object) {
        return JSON.toJSONString(object);
    }

}
public class DefaultValueMapper implements ValueMapper{
    @Override
    public String value(Object o) {
        if ( null == o){
            return null;
        }
        if (o instanceof Date){
            Date date = (Date)o;
            return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date);
        }else if (o instanceof Money){
            Money money = (Money)o;
            return money.toString();
        } else {
            return o.toString();
        }
    }

}
public class LocalSimpleCache {
    
    private Map<String,Object> cache = new ConcurrentHashMap<String, Object>();
    
    public void put(String key, Object value) {
        cache.put(key, value);
    }

    public Object get(String key) {
        return cache.get(key);
    }

}
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface FacadeValue {

    String key() default "";
    
    Class<? extends ValueMapper> mapper() default DefaultValueMapper.class;
    
    boolean discardNull() default true;
}

public class FacadeValueAnnotation {
    
    
    private Map<Field,FacadeValue> fieldToFacadeValue;

    public Map<Field, FacadeValue> getFieldToFacadeValue() {
        return fieldToFacadeValue;
    }

    public void setFieldToFacadeValue(Map<Field, FacadeValue> fieldToFacadeValue) {
        this.fieldToFacadeValue = fieldToFacadeValue;
    }
}
public class FacadeMapper {

    private  static LocalSimpleCache localSimpleCache=new LocalSimpleCache();
    
    
    public static Map<String,String> toMap(Object o){
        FacadeValueAnnotation facadeValueAnnotation=getFacadeValueAnnotation(o.getClass());
        Map<String,String> mapResult = Maps.newHashMap();
        facadeValueAnnotation.getFieldToFacadeValue().forEach((k,v)->{
            Object object=ReflectionUtils.getField(k, o);
            if(object==null){
                if(!v.discardNull()){
                    mapResult.put(v.key(), "");
                }
            }else{
                mapResult.put(v.key(), getValueMapper(v.mapper()).value(object));
            }
        });
        return mapResult;
    }
    
    /**
     * 獲取值轉換的map
     *
     * @param mapperClass
     * @return
     */
    private static ValueMapper getValueMapper(Class<? extends ValueMapper> mapperClass) {
        // 先判斷快取中是否有,如果有直接返回
        ValueMapper mapper = (ValueMapper) localSimpleCache
                .get(mapperClass.getName());
        if (mapper != null) {
            return mapper;
        } else {
            try {
                mapper = mapperClass.newInstance();
                localSimpleCache.put(mapperClass.getName(), mapper);
                return mapper;
            } catch (Exception e) {
                return null;
            }
        }
    }
private static FacadeValueAnnotation getFacadeValueAnnotation(Class clazz){
        FacadeValueAnnotation facadeValueAnnotation=(FacadeValueAnnotation)localSimpleCache.get(clazz.getName());
        if(facadeValueAnnotation==null){
            facadeValueAnnotation=hardParse(clazz);
            localSimpleCache.put(clazz.getName(), facadeValueAnnotation);
        }
        return facadeValueAnnotation;
    }

    /**
     * 
     * @param clazz
     * @return
     */
    private static FacadeValueAnnotation hardParse(Class clazz) {
        List<Field> fields = FieldUtils
                .getFieldsListWithAnnotation(clazz,FacadeValue.class);
        if(!CollectionUtils.isEmpty(fields)){
            Map<Field, FacadeValue> result = Maps.newHashMap();
            for(Field field:fields){
                field.setAccessible(true);
                result.put(field, field.getAnnotationsByType(FacadeValue.class)[0]);
            }
            FacadeValueAnnotation facadeValueAnnotation=new FacadeValueAnnotation();
            facadeValueAnnotation.setFieldToFacadeValue(result);
            return  facadeValueAnnotation;
        }
        return null;
    }
    
    
}
 

public class Person {

    @FacadeValue(key="person_name")
    private String name;
    
    @FacadeValue(key="person_birthday",mapper=DefaultValueMapper.class)
    private Date birthday;
    
    @FacadeValue(key="person_age",mapper=DefaultValueMapper.class)
    private String age;
    
    @FacadeValue(key="person_address",mapper=JsonValueMapper.class)
    private Address address;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }  
}

public class Address {

    @FacadeValue(key="address_street")
    private String street;
    
    @FacadeValue(key="address_doorNo")
    private String doorNo;

    public String getStreet() {
        return street;
    }
    public void setStreet(String street) {
        this.street = street;
    }

    public String getDoorNo() {
        return doorNo;
    }
    public void setDoorNo(String doorNo) {
        this.doorNo = doorNo;
    }
       
}
public class Test {

    /**
     * 
     * @param args
     */
    public static void main(String[] args) {

        Person person=new Person();
        Address address=new Address();
        address.setDoorNo("111");
        address.setStreet("中央大到");
        person.setAddress(address);
        person.setAge("12");
        person.setBirthday(new Date());
        person.setName("ysgsk");
       
        System.out.println(FacadeMapper.toMap(person));
        
    }

}