CompletableFuture--給future調用增加回調或聚合操作

CompletableFuture--增大內存節省時間。整合多個future調用，來減少時間

例如：第一個future 返回時1s，第二個返回時2s，第三個返回是3s   CompletableFuture 可以聚合這個三個future,為每個future增加回調，使在3s內處理完這三個future.

1.定義urserInfo

package com.zhou.test.completableFuturetest;

/**
 * Copyright (C), 2015-2020, XXX有限公司
 * FileName: UserInfo
 * Author:   Administrator
 * Date:     2020/2/28 13:39
 * Description:
 */
public class UserInfo {
    private Integer id;
    private String name;
    private Integer jobId;
    private String jobDes;
    private Integer carId;
    private String carDes;
    private Integer homeId;
    private String homeDes;

    public Integer getId() {
        return id;
    }

    public UserInfo setId(Integer id) {
        this.id = id;
        return this;
    }

    public String getName() {
        return name;
    }

    public UserInfo setName(String name) {
        this.name = name;
        return this;
    }

    public Integer getJobId() {
        return jobId;
    }

    public UserInfo setJobId(Integer jobId) {
        this.jobId = jobId;
        return this;
    }

    public String getJobDes() {
        return jobDes;
    }

    public UserInfo setJobDes(String jobDes) {
        this.jobDes = jobDes;
        return this;
    }

    public Integer getCarId() {
        return carId;
    }

    public UserInfo setCarId(Integer carId) {
        this.carId = carId;
        return this;
    }

    public String getCarDes() {
        return carDes;
    }

    public UserInfo setCarDes(String carDes) {
        this.carDes = carDes;
        return this;
    }

    public Integer getHomeId() {
        return homeId;
    }

    public UserInfo setHomeId(Integer homeId) {
        this.homeId = homeId;
        return this;
    }

    public String getHomeDes() {
        return homeDes;
    }

    public UserInfo setHomeDes(String homeDes) {
        this.homeDes = homeDes;
        return this;
    }
}

2.定義

package com.zhou.test.completableFuturetest;

import java.util.concurrent.TimeUnit;

/**
 * Copyright (C), 2015-2020, XXX有限公司
 * FileName: QueryUtils
 * Author:   Administrator
 * Date:     2020/2/28 13:40
 * Description:
 */
public class QueryUtils {
    public String queryCar(Integer carId) {
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "car_desc";
    }

    public String queryJob(Integer jobId) {
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "job_desc";
    }

    public String queryHome(Integer homeId) {
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return "home_desc";
    }
}

3.定義

package com.zhou.test.completableFuturetest;
import java.util.function.Supplier;
/**
 * Copyright (C), 2015-2020, XXX有限公司
 * FileName: QuerySuppiler
 * Author:   Administrator
 * Date:     2020/2/28 13:42
 * Description:
 */
public class QuerySuppiler implements Supplier<String> {
    private Integer id;
    private String type;
    private QueryUtils queryUtils;

    public QuerySuppiler(Integer id, String type, QueryUtils queryUtils) {
        this.id = id;
        this.type = type;
        this.queryUtils = queryUtils;
    }

    @Override
    public String get() {
        if ("home".equals(type)) {
            return queryUtils.queryHome(id);
        } else if ("job".equals(type)) {
            return queryUtils.queryJob(id);
        } else if ("car".equals(type)) {
            return queryUtils.queryCar(id);
        }
        return null;
    }
}

4.定義

package com.zhou.test.completableFuturetest;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.function.Consumer;
import java.util.function.Supplier;
import java.util.stream.Collectors;

/**
 * @author idea * @data 2020/2/22
 */
public class QueryUserService {
    private Supplier<QueryUtils> queryUtilsSupplier = QueryUtils::new;

    public UserInfo converUserInfo(UserInfo userInfo) {
        long begin = System.currentTimeMillis();
        QuerySuppiler querySuppiler1 = new QuerySuppiler(userInfo.getCarId(), "car", queryUtilsSupplier.get());
        CompletableFuture<String> getCarDesc = CompletableFuture.supplyAsync(querySuppiler1);
        getCarDesc.thenAccept(new Consumer<String>() {  //--1
            @Override
            public void accept(String carDesc) {
                userInfo.setCarDes(carDesc);
            }
        });
        QuerySuppiler querySuppiler2 = new QuerySuppiler(userInfo.getHomeId(), "home", queryUtilsSupplier.get());
        CompletableFuture<String> getHomeDesc = CompletableFuture.supplyAsync(querySuppiler2);
        getHomeDesc.thenAccept(new Consumer<String>() {  //--2

            @Override
            public void accept(String homeDesc) {
                userInfo.setHomeDes(homeDesc);
            }
        });
        QuerySuppiler querySuppiler3 = new QuerySuppiler(userInfo.getJobId(), "job", queryUtilsSupplier.get());
        CompletableFuture<String> getJobDesc = CompletableFuture.supplyAsync(querySuppiler3);
        getJobDesc.thenAccept(new Consumer<String>() {  //--3

            @Override
            public void accept(String jobDesc) {
                userInfo.setJobDes(jobDesc);
            }
        });
        CompletableFuture<Void> getUserInfo = CompletableFuture.allOf(getCarDesc, getHomeDesc, getJobDesc);
        getUserInfo.thenAccept(new Consumer<Void>() {
            @Override
            public void accept(Void result) {
                long end = System.currentTimeMillis();
                System.out.println("全部完成查詢耗時="+(end - begin));
            }
        });
        getUserInfo.join();
        //--4
        return userInfo;
    }

    public static void main(String[] args) {
        long begin = System.currentTimeMillis();        //多線程環境需要注意線程安全問題
        List<UserInfo> userInfoList = Collections.synchronizedList(new ArrayList<>());
        for (int i = 0; i <= 20; i++) {
            UserInfo userInfo = new UserInfo();
            userInfo.setId(i);
            userInfo.setName("username" + i);
            userInfo.setCarId(i);
            userInfo.setJobId(i);
            userInfo.setHomeId(i);
            userInfoList.add(userInfo);
        }        //stream 查詢一個用戶花費3s  並行計算后一個用戶1秒左右 查詢21個用戶花費21秒        //parallelStream 速度更慢
        userInfoList.stream().map(userInfo -> {
            QueryUserService queryUserService = new QueryUserService();
            userInfo = queryUserService.converUserInfo(userInfo);
            return userInfo;
        }).collect(Collectors.toList());
        System.out.println("=============");
        long end = System.currentTimeMillis();
        System.out.println(end - begin);
    }
}