需求描述
统计语数英及格的人数
- 数据库设计
select * from grade;
| grade_id | student_id | grade_course | grade_num |
|---|---|---|---|
| 1 | 1 | 语文 | 1 |
| 2 | 1 | 数学 | 85 |
| 3 | 1 | 英语 | 83 |
| 4 | 2 | 语文 | 16 |
| 5 | 2 | 数学 | 21 |
| 6 | 2 | 英语 | 14 |
| 7 | 3 | 语文 | 59 |
| 8 | 3 | 数学 | 52 |
| 9 | 3 | 英语 | 9 |
| 10 | 4 | 语文 | 36 |
| 11 | 4 | 数学 | 46 |
| 12 | 4 | 英语 | 26 |
代码处理
controller
- 传统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还需要解析成对应的对象才能返回给前端
@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层
-- 传统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());
/* 打印结果
*英语Thread[RxCachedThreadScheduler-3,5,main]
*语文Thread[RxCachedThreadScheduler-2,5,main]
*数学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层
<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>
实现效果
-
传统curd方案
image.png -
RxJava方案
image.png
代码分析
- 数据持久层处理方式不变
- 逻辑service层如果通过多次查询合并返回给前端的情况下适用Flowable来进行并发提高响应速度。
- controller层对返回的Flowable/abservable要做层解析然后返回给前端
