最近在写一个项目，需要借助spring的自定义属性编辑器，实现一个分发器的功能，将踩过的坑记录下来，方便下次查阅。

为什么这里提到spring4+呢?
customEditors在spring4.0以下的是Map类型，，key的类型必须是Class类型，而value是一个注入的bean；在spring4.0中，
key和value的类型必须是Class类型，也就是说配置信息中的 customEditors 中的value值不能在是bean，而应该修改成class

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Spring4的自定义属性编辑器实现分发器

1. MatchBean

public interface MatchingBean<T> {
    boolean matching(T factor);
}

2. FactoryList

public interface FactoryList<E extends MatchingBean<K>, K> extends List<E> {
    E getBean(K factor);
}

3. FactoryArrayList

public class FactoryArrayList<E extends MatchingBean<K>, K> extends ArrayList<E> 
implements FactoryList<E, K>, InitializingBean {

    private static final long serialVersionUID = 5705342394882249201L;

    public FactoryArrayList() {
        super();
    }

    public FactoryArrayList(int size) {
        super(size);
    }

    public E getBean(K factor) {
        Iterator<E> itr = iterator();
        while(itr.hasNext()) {
            E beanMatch = itr.next();
            if(beanMatch.matching(factor)) {
                return beanMatch;
            }
        }
        return null;
    }

    public void afterPropertiesSet() throws Exception {
        if (!isEmpty()) {
            Object[] a = toArray();
            OrderComparator.sort(a);
            ListIterator i = listIterator();
            for (int j=0; j<a.length; j++) {
                i.next();
                i.set(a[j]);
            }
        }
    }

}

4. CustomEditorRegistrar

public class CustomEditorRegistrar implements PropertyEditorRegistrar {

    private Map<Class<?>, PropertyEditor> customEditors;

    public void registerCustomEditors(PropertyEditorRegistry registry) {
        if (customEditors != null) {
            Set<Map.Entry<Class<?>, PropertyEditor>> entries = customEditors.entrySet();
            for (Map.Entry<Class<?>, PropertyEditor> entry : entries) {
                registry.registerCustomEditor(entry.getKey(), entry.getValue());
            }
        }
    }

    public void setCustomEditors(Map<Class<?>, PropertyEditor> customEditors) {
        this.customEditors = customEditors;
    }
}

5. 配置文件

<bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
    <property name="customEditors">
        <map>
            <entry key="com.huangcw.utils.bean.FactoryList">
                <ref bean="factoryListEditor"/>
            </entry>
        </map>
    </property>
</bean>

<bean id="factoryListEditor" class="org.springframework.beans.propertyeditors.CustomCollectionEditor">
    <constructor-arg name="collectionType" value="com.huangcw.utils.bean.FactoryArrayList" type="java.lang.Class"></constructor-arg>
</bean>

6. 调用

@Autowired
private FactoryList<IGiftReceiveService,Long> giftReceiveServiceIntegerFactoryList;


ActivityGiftReceviedCondition condition = ActivityGiftReceviedCondition.newBuilder()
            .giftId(Long.parseLong(giftId))
            .num(num)
            .activityId(activityId)).build();
    return Result.getResult(giftService.receiveGift(condition));

SpringBoot版

思路就是 将上面的xml翻译为spring的注解方式即可，其他的matchBean,facotyList都跟上面一样，直接上源码：

1. 自定义属性配置

@Configuration
public class BeanConfig {

    @Bean
    public CustomCollectionEditor customCollectionEditor() {
        CustomCollectionEditor cce =new CustomCollectionEditor(FactoryArrayList.class);
        return cce;
    }

    @Bean
    public CustomEditorRegistrar customEditorRegistrar() {
        CustomEditorRegistrar cec =new CustomEditorRegistrar();
        Map<Class<?>, PropertyEditor> map  = new HashMap();
        map.put(FactoryList.class,customCollectionEditor());
        cec.setCustomEditors(map);
        return cec;
    }

    @Bean
    public CustomEditorConfigurer customEditorConfigurer(){
        CustomEditorConfigurer cec = new CustomEditorConfigurer();
        CustomEditorRegistrar[] propertyEditorRegistrars = new CustomEditorRegistrar[]{
                customEditorRegistrar()
        };
        cec.setPropertyEditorRegistrars(propertyEditorRegistrars);
        return cec;
    }
}

2. 继承MatchingBean的业务接口DispatchService

public interface DispatchService extends MatchingBean<String> {

}

3. 实现DispatchService接口的类，重写matching匹配方法

@Service
public class ADispatchServiceImpl implements DispatchService {


    @Override
    public boolean matching(String factor) {
        return "A".equals(factor);
    }
}

4. 调用方式

@RestController
public class DispatchController {

    @Resource
    private FactoryList<DispatchService,String> factoryDispatchList;

    @RequestMapping("/{a}/cancel/{params}")
    public String dispatch(@PathVariable("a") String airline, @PathVariable("params") String params){

        String result = factoryDispatchList.getBean(a).cancel(params);

        return a+result;
    }

}

这种设计方法，可以简单的实现转发器，我经常在项目里面使用，并且我的同事从前家公司离开之后，也很爱用这种方法,
因为这样写是你的代码很整洁，也符合开闭原则，可扩展性强。