异步代码的重构实例2——VswmPmsCouponController。这是重构之后的代码

VswmPmsCouponController_Refactored.java

package com.vip.phoenix.vswm.pms.controller;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.vip.penguin.coupon.param.BindParams;
import com.vip.penguin.dto.BaseDto;
import com.vip.penguin.pms.param.CouponParam;
import com.vip.penguin.pms.pojo.Coupon;
import com.vip.penguin.pms.service.PMSCouponService;
import com.vip.phoenixfwk.play.support.HttpContext;
import com.vip.phoenixfwk.play.web.UserBaseController;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import play.data.Form;
import play.libs.F.Function;
import play.libs.F.Promise;
import play.mvc.Result;

import java.util.List;

/**
 * Created by jacob.wu on 2015/9/25.
 */
@Component
public class VswmPmsCouponController extends UserBaseController {
    @Autowired
    PMSCouponService pmsCouponService;

    /**
     * 绑定优惠券
     */
    public Promise<Result> bind() {
        BindParams params = Form.form(BindParams.class).bindFromRequest().get();
        final int uid = (int) HttpContext.getUserId();
        params.setUserId(uid);

        //绑定优惠券
        Promise<BaseDto> couponPromise = pmsCouponService.bind(params);

        //从用户的优惠券列表中获取绑定的优惠券，作为返回结果
        Promise<BaseDto<Coupon>> resultCouponPromise = augmentCouponBaseDtoPromise(couponPromise, uid);

        //返回结果
        return resultCouponPromise.map(new Function<BaseDto<?>, Result>() {
            @Override
            public Result apply(BaseDto<?> baseDto) throws Throwable {
                ObjectMapper mapper = new ObjectMapper();
                String jsonString = mapper.writeValueAsString(baseDto);
                return ok(jsonString);
            }
        });
    }

    /**
     * 对于绑定优惠券返回的结果（一个包含coupon的BaseDto对象），先查出用户所有的优惠券列表，然后在列表中找到对应的coupon，用列表中的coupon替代优惠券返回的coupon。
     * 之所以要这样做，因为绑定优惠券返回的结果coupon包含的字段不全，不包含前端所需要的"满多少减多少"等信息。
     */
    private Promise<BaseDto<Coupon>> augmentCouponBaseDtoPromise(Promise<BaseDto> couponPromise, final int uid) {
        Promise<BaseDto<Coupon>> resultPromise = couponPromise.flatMap(new Function<BaseDto, Promise<BaseDto<Coupon>>>() {
            @Override
            public Promise<BaseDto<Coupon>> apply(final BaseDto boundCouponBaseDto) throws Throwable {
                Coupon coupon = (Coupon)boundCouponBaseDto.getData();
                Promise<BaseDto<Coupon>> resultPromise = Promise.pure((BaseDto<Coupon>) boundCouponBaseDto);
                if (coupon != null) {
                    final String sn = coupon.getCoupon_sn();
                    if (sn != null) {
                        Promise<Coupon> couponInListPromise = getCouponFromUserCouponList(uid, sn);

                        //在列表中找出这次绑定的优惠券，获取详细信息。
                        resultPromise = couponInListPromise.map(new Function<Coupon, BaseDto<Coupon>>() {
                            @Override
                            public BaseDto<Coupon> apply(Coupon listBaseDto) throws Throwable {
                                Coupon coupon = listBaseDto;

                                if (coupon != null) { //在列表中找到这次绑定的优惠券
                                    //设置到返回结果
                                    boundCouponBaseDto.setData(coupon);
                                }
                                return (BaseDto<Coupon>)boundCouponBaseDto;
                            }
                        });
                    }
                }
                //如果没有在列表中找到这次绑定的券，则直接返回绑定得到的结果
                return resultPromise;
            }
        });
        return resultPromise;
    }

    /**
     * 得到用户所有的优惠券列表，然后根据输入的sn在列表中找到对应的优惠券
     */
    private Promise<Coupon> getCouponFromUserCouponList(final long uid, final String sn) {
        CouponParam param = new CouponParam();
        param.setUserId(uid);
        param.setSize(10000);
        param.setOffset(0);
        //得到用户所有的优惠券的列表
        Promise<BaseDto> couponListPromise = pmsCouponService.getList(param);
        return couponListPromise.map(new Function<BaseDto, Coupon>() {
            @Override
            public Coupon apply(BaseDto listBaseDto) throws Throwable {
                List<Coupon> couponList = (List<Coupon>)listBaseDto.getData();

                //在列表中找到sn对应的优惠券
                Coupon target = VswmPmsCouponController.findCouponBySn(couponList, sn);
                return target;
            }
        });
    }

    /**
     * 遍历列表，找到具有指定sn的优惠券
     */
    private static Coupon findCouponBySn(List<Coupon> couponList, String sn) {
        if (couponList == null || sn == null) {
            return null;
        }
        Coupon target = null;
        for (Coupon couponInList : couponList) {
            if (sn.equals(couponInList.getCoupon_sn())) {
                target = couponInList;
                break;
            }
        }
        return target;
    }
}