需求描述

統(tǒng)計(jì)語數(shù)英及格的人數(shù)

• 數(shù)據(jù)庫設(shè)計(jì)
  select * from grade;

代碼處理

controller

• 傳統(tǒng)curd方案

   @GetMapping("/passedCount")
    public Map<String, Long> passedCount(){
        return gradeRxService.studnetPassedCount();
    }

• RxJava方案

    // controller
    @GetMapping(value = "/passedCountObservable")
    public Flowable passedCountObservable(){
        return gradeRxService.passedCountObservable();
    }
// 返回的Flowable還需要解析成對(duì)應(yīng)的對(duì)象才能返回給前端
@Configuration
@ComponentScan(basePackages = { "com.muyf.alibaba.curd.*" })
public class WebConfig extends WebMvcConfigurerAdapter {
    @Override
    public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
        returnValueHandlers.add(new ObservableReturnValueHandler());
        returnValueHandlers.add(new FlowableReturnValueHandler());
    }
}
public class FlowableReturnValueHandler implements AsyncHandlerMethodReturnValueHandler {
    @Override
    public boolean isAsyncReturnValue(Object returnValue, MethodParameter returnType) {
        return returnValue != null && supportsReturnType(returnType);
    }

    @Override
    public boolean supportsReturnType(MethodParameter returnType) {
        return Observable.class.isAssignableFrom(returnType.getParameterType());
    }

    @Override
    public void handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer,
                                  NativeWebRequest webRequest) throws Exception {

        if (returnValue == null || !Flowable.class.isInstance(returnValue))  {
            mavContainer.setRequestHandled(true);
            return;
        }

        final Flowable<?> flowable = Flowable.class.cast(returnValue);
        WebAsyncUtils.getAsyncManager(webRequest)
                .startDeferredResultProcessing(new FlowableAdapter<>(flowable), mavContainer);
    }

    private static class FlowableAdapter<T> extends DeferredResult<T> {
        public FlowableAdapter(Flowable<T> flowable) {
            flowable.subscribe(this::setResult, this::setErrorResult);
        }
    }
}

service層

-- 傳統(tǒng)curd方案

   @Override
    public Map<String, Long> studnetPassedCount() {
        Map<String,Long> result = new ConcurrentHashMap<>();
        for (String courseName : CourseEnum.courseArray) {
            List<Grade> grades = gradeMapper.selectStudentCountGreatThanGradeNumInCourse(courseName, Long.valueOf(60));
            result.put(courseName,Long.valueOf(grades.size()));
        }
        return result;
    }

• RxJava方案

    @Override
    public Flowable<GradePassDTO> passedCountObservable() {
        return Flowable.fromArray(CourseEnum.courseArray.toArray()).parallel().runOn(Schedulers.io()).map(course -> {
            System.out.println(course.toString()+Thread.currentThread());
            /* 打印結(jié)果
            *英語Thread[RxCachedThreadScheduler-3,5,main]
            *語文Thread[RxCachedThreadScheduler-2,5,main]
            *數(shù)學(xué)Thread[RxCachedThreadScheduler-4,5,main]
            */
            List<Grade> grades = gradeMapper.selectStudentCountGreatThanGradeNumInCourse(course.toString(), Long.valueOf(60));
            GradePassDTO dto = new GradePassDTO(course.toString(),Long.valueOf(grades.size()));
            return dto;
        }).sequential();
    }

Mapper層

<select id="selectStudentCountGreatThanGradeNumInCourse" resultType="com.muyf.alibaba.curd.domain.grade.Grade">
        select <include refid="Base_Column_List"/> from grade where grade_course = #{courseName} and grade_num > #{gradeNum};
</select>

實(shí)現(xiàn)效果

• 傳統(tǒng)curd方案

  
  
  image.png

• RxJava方案

  
  
  image.png

代碼分析

• 數(shù)據(jù)持久層處理方式不變
• 邏輯service層如果通過多次查詢合并返回給前端的情況下適用Flowable來進(jìn)行并發(fā)提高響應(yīng)速度。
• controller層對(duì)返回的Flowable/abservable要做層解析然后返回給前端