并发式编程的相关知识--notify和wait、CompletableFuture

1.notify和wait方法的使用

1.1快递到站通知

说明：快递的地点在上海，离快递发货地相聚500km，每次进行改变，快递将会前进100km,当快递前进100km时，需要通知快递当前的位置，当快递到达目的地时，需要通知用户取快递。

1.Express快递初始化方法

package com.nq;

public class Express {
    public final static String DIST_CITY="ShangHai";
    public final static int TOTAIL=500;
    private int km;
    private String site;

    public Express(){

    }

    public Express(int km, String site) {
        this.km = km;
        this.site = site;
    }

    public void change(){
        if(km<TOTAIL){
           km=km+100;
            System.out.println("this Km is "+this.km);
        }

        if(km>=TOTAIL){
           site=DIST_CITY;
            System.out.println("this Express is arrived");
        }
    }

    /**
     * 线程等待公里的变化
     */
    public synchronized void waiKm(){
        while (this.km<=TOTAIL){
          try{
             wait();
              System.out.println("Map thread["+Thread.currentThread().getId()+"] wake ,I will change db");
          }catch (InterruptedException e){
             e.printStackTrace();
          }
        }
    }

    /*线程等待目的地变换*/
    public synchronized void waiSite(){
         while (!this.site.equals(DIST_CITY)){
             try {
                 wait();
                 System.out.println("Notice User thread ["+Thread.currentThread().getId()+" ] wake");
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
         }
        System.out.println("this site is "+this.site+",I will call user");
    }
}

2.TestWN测试方法

package com.nq;

public class TestWN {

    private static Express express=new Express(0,"WUHAN");


    private static class CheckKm extends Thread{
        @Override
        public void run() {
           express.waiKm();
        }
    }

    private static class CheckSite extends Thread{
        @Override
        public void run() {
            express.waiSite();
        }
    }


    public static void main(String[] args) throws InterruptedException {
        for(int i=1;i<2;i++){
            new CheckSite().start();
        }

        for (int i=0;i<2;i++){
           new CheckKm().start();
        }

        Thread.sleep(500);

        for (int i=0;i<5;i++){
           synchronized (express){
               express.change();
               express.notifyAll();
           }
            Thread.sleep(500);
        }
    }
}

1.2数据库连接池方法

1.SqlConnectImpl获取连接池

package com.nq.pool;

import com.nq.tool.SleepTools;

import java.sql.*;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;

/**
 *@Author: Nickel
 *@DATE: 2023/8/19 0:19
 *@Description:
 */
public class SqlConnectImpl implements Connection {

   /**
    *@Author: Nickel
    *@DATE: 2023/8/19 0:18
    *@Description:拿一个数据库链接
    */
    public static final Connection fetchConnection(){
        return new SqlConnectImpl();
    }

    public Statement createStatement() throws SQLException {
        return null;
    }

    public PreparedStatement prepareStatement(String sql) throws SQLException {
        return null;
    }

    public CallableStatement prepareCall(String sql) throws SQLException {
        return null;
    }

    public String nativeSQL(String sql) throws SQLException {
        return null;
    }

    public void setAutoCommit(boolean autoCommit) throws SQLException {

    }

    public boolean getAutoCommit() throws SQLException {
        return false;
    }

    public void commit() throws SQLException {
        SleepTools.ms(70);
    }

    public void rollback() throws SQLException {

    }

    public void close() throws SQLException {

    }

    public boolean isClosed() throws SQLException {
        return false;
    }

    public DatabaseMetaData getMetaData() throws SQLException {
        return null;
    }

    public void setReadOnly(boolean readOnly) throws SQLException {

    }

    public boolean isReadOnly() throws SQLException {
        return false;
    }

    public void setCatalog(String catalog) throws SQLException {

    }

    public String getCatalog() throws SQLException {
        return null;
    }

    public void setTransactionIsolation(int level) throws SQLException {

    }

    public int getTransactionIsolation() throws SQLException {
        return 0;
    }

    public SQLWarning getWarnings() throws SQLException {
        return null;
    }

    public void clearWarnings() throws SQLException {

    }

    public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    public Map<String, Class<?>> getTypeMap() throws SQLException {
        return null;
    }

    public void setTypeMap(Map<String, Class<?>> map) throws SQLException {

    }

    public void setHoldability(int holdability) throws SQLException {

    }

    public int getHoldability() throws SQLException {
        return 0;
    }

    public Savepoint setSavepoint() throws SQLException {
        return null;
    }

    public Savepoint setSavepoint(String name) throws SQLException {
        return null;
    }

    public void rollback(Savepoint savepoint) throws SQLException {

    }

    public void releaseSavepoint(Savepoint savepoint) throws SQLException {

    }

    public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
        return null;
    }

    public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
        return null;
    }

    public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
        return null;
    }

    public Clob createClob() throws SQLException {
        return null;
    }

    public Blob createBlob() throws SQLException {
        return null;
    }

    public NClob createNClob() throws SQLException {
        return null;
    }

    public SQLXML createSQLXML() throws SQLException {
        return null;
    }

    public boolean isValid(int timeout) throws SQLException {
        return false;
    }

    public void setClientInfo(String name, String value) throws SQLClientInfoException {

    }

    public void setClientInfo(Properties properties) throws SQLClientInfoException {

    }

    public String getClientInfo(String name) throws SQLException {
        return null;
    }

    public Properties getClientInfo() throws SQLException {
        return null;
    }

    public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
        return null;
    }

    public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
        return null;
    }

    public void setSchema(String schema) throws SQLException {

    }

    public String getSchema() throws SQLException {
        return null;
    }

    public void abort(Executor executor) throws SQLException {

    }

    public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {

    }

    public int getNetworkTimeout() throws SQLException {
        return 0;
    }

    public <T> T unwrap(Class<T> iface) throws SQLException {
        return null;
    }

    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return false;
    }
}

2.DBPool初始化连接池

package com.nq.pool;

import java.sql.Connection;
import java.util.LinkedList;

public class DBPool {
    /**
     * 容器，存放链接
     */
    private static LinkedList<Connection> pool=new LinkedList<Connection>();

    /**
     * 限制连接池大小为=20
     */
    public DBPool(int initialSize){
       if(initialSize>0){
           for(int i=0;i<initialSize;i++){
               pool.addLast(SqlConnectImpl.fetchConnection());
           }
       }
    }

    /**
     *@Author: Nickel
     *@DATE: 2023/8/19 0:21
     *@Description: 释放链接，通知其他的等待连接的线程
     */
    public void releaseConnection(Connection connection){
      if(connection!=null){
         synchronized (pool){
             pool.addLast(connection);
             //通知其他等待连接的线程
             pool.notifyAll();
         }
      }
    }

    /**
     *@Author: Nickel
     *@DATE: 2023/8/19 0:26
     *@Description: 获取mills内无法获取，将会返回null 1s
     */
    public Connection fetchConnect(long mills) throws InterruptedException {
          synchronized (pool){
              //永不超时
              if(mills<=0){
                   while (pool.isEmpty()){
                        pool.wait();
                   }
                   return pool.removeFirst();
              }else{
                //超时时刻
                long future=System.currentTimeMillis()+mills;
                //等待时长
                long remaining=mills;
                while (pool.isEmpty()&&remaining>0){
                   pool.wait(remaining);
                   /*唤醒一次，重新计算等待时常*/
                   remaining=future-System.currentTimeMillis();
                }
                Connection connection=null;
                if(!pool.isEmpty()){
                    connection=pool.removeFirst();
                }
                return connection;
              }
          }
    }
}

3.测试连接池

package com.nq.pool;

import com.nq.tool.SleepTools;
import javafx.concurrent.Worker;

import java.sql.Connection;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @Auther: Nickel
 * DATE: 2023/8/19 0:45
 * Description:
 * @Version 1.0
 */
public class DBPoolTest {
    static DBPool pool=new DBPool(10);
    //控制器：控制main线程将会等待所有Worker结束才能继续执行
    static CountDownLatch end;

    public static void main(String[] args) {
        //线程数量
        int threadCount=50;
        end=new CountDownLatch(threadCount);
        int count=20;//每个线程的操作次数
        AtomicInteger got=new AtomicInteger();//计数器：统计可以拿到连接的线程
        AtomicInteger notGot=new AtomicInteger();//计数器：统计没有拿到连接的线程
        for(int i=0;i<threadCount;i++){
          Thread thread=new Thread(new Worker(count,got,notGot),"worker"+i);
          thread.start();
        }
    }

    static class Worker implements Runnable{
        int count;
        AtomicInteger got;
        AtomicInteger notGot;

        public Worker(int count, AtomicInteger got, AtomicInteger notGot) {
            this.count = count;
            this.got = got;
            this.notGot = notGot;
        }

        @Override
        public void run() {
          while (count>0){
              try {
                  //从线程池中获取连接，如果1000ms内无法获取到，将会返回null
                  //分别统计连接获取的数量got和未获取的数量notGot
                  Connection connection = pool.fetchConnect(1000);
                  if(connection!=null){
                      SleepTools.ms(2);
                      pool.releaseConnection(connection);
                      got.incrementAndGet();
                  }else{
                      notGot.incrementAndGet();
                      System.out.println(Thread.currentThread().getName() + "等待超时！");
                  }
              } catch (Exception e) {
                  e.printStackTrace();
              }finally {
                  count--;
              }
          }
        }
    }
}

2. CompletableFuture方法的使用

2.1 SupplyAsync和RunAsync的使用

1.SupplyAsync方法使用

package com.nq.future;

import java.util.concurrent.*;

/**
 * @Auther: Nickel
 * DATE: 2023/8/19 23:44
 * Description:
 * @Version 1.0
 *
 * supplyAsync方法的使用
 */
public class SupplyAsync {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService= Executors.newFixedThreadPool(10);

        CompletableFuture<String> task=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            return "Hello";
        },executorService);

        System.out.println(task.get());
    }

    private  static void sleep(int i){
        try {
            TimeUnit.SECONDS.sleep(i);
        } catch (InterruptedException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }
}

2.RunAsync方法使用

package com.nq.future;

import java.util.concurrent.*;

/**
 * @Auther: Nickel
 * DATE: 2023/8/19 23:53
 * Description:
 * @Version 1.0
 */
public class RunAsync {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService= Executors.newFixedThreadPool(10);

        CompletableFuture<Void> task=CompletableFuture.runAsync(()->{
            System.out.println(Thread.currentThread().getName());
        },executorService);

        System.out.println(task.get());
    }

    private  static void sleep(int i){
        try {
            TimeUnit.SECONDS.sleep(i);
        } catch (InterruptedException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }
}

2.2 CompletableFuture中的then*API的使用

1.thenApply、thenApplyAsync、thenAccept

说明：在多线程执行中，任务A执行完成后才能执行任务B

package com.nq.future;

import java.util.concurrent.*;
import java.util.function.Function;
import java.util.function.Supplier;

/**
 * @Auther: Nickel
 * DATE: 2023/8/20 0:03
 * Description:
 * @Version 1.0
 *
 * 任务A执行完成后执行任务B
 */
public class ThenAsync {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService= Executors.newFixedThreadPool(10);

        Supplier<String> taskA=()->{
            System.out.println("1:" + Thread.currentThread().getName());
            return "Hello";
        };

        Function<String,String> taskB=s->{
            System.out.println("2:" + Thread.currentThread().getName());
            return s+" World";
        };

        CompletableFuture<String> future1=CompletableFuture.supplyAsync(taskA,executorService);
        sleep(1);
        future1.thenApply(taskB);

        System.out.println(future1.get());
    }

    private  static void sleep(int i){
        try {
            TimeUnit.SECONDS.sleep(i);
        } catch (InterruptedException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }
}

2.ThenCombine

说明：表示futureA执行完成再执行futureB得到合并的结果

package com.nq.future;

import java.util.concurrent.*;

/**
 * @Auther: Nickel
 * DATE: 2023/8/20 0:32
 * Description:
 * @Version 1.0
 */
public class ThenCombine {

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService= Executors.newFixedThreadPool(10);

        CompletableFuture<String> futureA=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            sleep(3);
            return "Hello";
        },executorService);

        CompletableFuture<String> futureB=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            sleep(3);
            return " World!";
        });

        CompletableFuture<String> result=futureA.thenCombine(futureB,(resultA,resultB)->{
            System.out.println(Thread.currentThread().getName());
            return resultA+resultB;
        });

        System.out.println(result.get());
    }

    private  static void sleep(int i){
        try {
            TimeUnit.SECONDS.sleep(i);
        } catch (InterruptedException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }
}

3.runAfterEither、runAfterBoth

说明：runAfterEither表示其中之一执行完成，返回结果，runAfterBoth表示两者都执行完成后，返回结果，而在方法futureB抛出异常，所以无法执行完成，所以runAfterBoth无法执行。

package com.nq.future;

import java.util.concurrent.*;

/**
 * @Auther: Nickel
 * DATE: 2023/8/20 0:49
 * Description:
 * @Version 1.0
 */
public class RunAfter {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService= Executors.newFixedThreadPool(10);

        CompletableFuture<String> futureA=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            sleep(3);
            return "Hello";
        },executorService);

        CompletableFuture<String> futureB=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            sleep(3);
            throw new NullPointerException();
           // return " World!";
        },executorService);


        System.out.println("-------------");
        futureB.runAfterEither(futureA,()->{
            System.out.println("!!");
        });

        System.out.println("-------------");
        futureB.runAfterBoth(futureA,()->{
            System.out.println("11111");
        });
    }

    private  static void sleep(int i){
        try {
            TimeUnit.SECONDS.sleep(i);
        } catch (InterruptedException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }
}

4.allOf、anyOf

说明：allOf表示futureA和futureB都执行完成才会输出，anyOf表示两者只要其中之一执行完成就会输出

package com.nq.future;

import java.util.concurrent.*;

/**
 * @Auther: Nickel
 * DATE: 2023/8/20 0:49
 * Description:
 * @Version 1.0
 */
public class AllOfAndOf {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService= Executors.newFixedThreadPool(10);

        CompletableFuture<String> futureA=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            sleep(5);
            return "Hello";
        },executorService);

        CompletableFuture<String> futureB=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            return " World!";
        },executorService);


        System.out.println("---------------");
        CompletableFuture.allOf(futureA,futureB).join();
        System.out.println("********");

        System.out.println("---------------");
        CompletableFuture.anyOf(futureA,futureB).join();
        System.out.println("11111111111");

    }

    private  static void sleep(int i){
        try {
            TimeUnit.SECONDS.sleep(i);
        } catch (InterruptedException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }
}

5.getNow

说明：当任务futureA休眠时，拿到的结果是getNow里面的值，当futureA不休眠时，拿到的结果是futureA的值

package com.nq.future;

import java.util.concurrent.*;

/**
 * @Auther: Nickel
 * DATE: 2023/8/20 1:09
 * Description:
 * @Version 1.0
 */
public class Now {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService= Executors.newFixedThreadPool(10);

        CompletableFuture<String> futureA=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            //sleep(5);
            return "Hello";
        },executorService);

        sleep(1);
        System.out.println(futureA.getNow("HaHa"));


    }

    private  static void sleep(int i){
        try {
            TimeUnit.SECONDS.sleep(i);
        } catch (InterruptedException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }
}

6.whenComplete、exceptionally、complete

说明：whenComplete表示有异常执行异常，没有异常，执行正常的逻辑；exceptionally只能执行异常的逻辑；complete表示休眠执行complete中的返回值，不休眠执行complete中的返回值；cancel标记执行线程，不一定真的取消

package com.nq.future;

import java.util.concurrent.*;

/**
 * @Auther: Nickel
 * DATE: 2023/8/20 1:15
 * Description:
 * @Version 1.0
 */
public class ThenComplete {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService= Executors.newFixedThreadPool(10);

        CompletableFuture<String> futureA=CompletableFuture.supplyAsync(()->{
            System.out.println(Thread.currentThread().getName());
            return "Hello";
            //throw new NullPointerException();
        },executorService);

        sleep(1);
         futureA.whenComplete((r,e)->{
            System.out.println(r);
            if(e!=null){
                e.printStackTrace();
            }
        });

        futureA.exceptionally((e)->{
            if(e!=null){
                e.printStackTrace();
            }
            return "失败";
        });

    }

    private  static void sleep(int i){
        try {
            TimeUnit.SECONDS.sleep(i);
        } catch (InterruptedException e) {
            System.out.println(e);
            e.printStackTrace();
        }
    }
}

whenComplete

whenComplete

exceptionally

complete


cancel