目录

ConcurrentHashMap

一、主程序

二、元素类

三、填充任务类

四、执行结果

---

 ConcurrentHashMap

实现ConcurrentMap接口，提供线程安全和保证原子性的全部操作。

• 完全并发读操作
• 高度符合预期的并发插入和删除操作

一、主程序

package xyz.jangle.thread.test.n7_7.concurrenthashmap;import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedDeque;/*** 7.7、线程安全的HashMap(ConcurrentHashMap)* * @author jangle* @email jangle@jangle.xyz* @time 2020年9月15日 下午5:20:15* */
public class M {public static void main(String[] args) {var userHash = new ConcurrentHashMap<String, ConcurrentLinkedDeque<Operation>>();var hashFiller = new HashFiller(userHash);Thread[] threads = new Thread[10];for (int i = 0; i < 10; i++) {threads[i] = new Thread(hashFiller);threads[i].start();}for (int i = 0; i < threads.length; i++) {try {threads[i].join();} catch (InterruptedException e) {e.printStackTrace();}}System.out.println("Size:" + userHash.size());// 用10个并发线程打印map信息userHash.forEach(10, (k, v) -> System.out.println(Thread.currentThread().getName() + ":" + k + ":" + v.size()));// 用10个并发线程打印map信息userHash.forEachEntry(10, entry -> System.out.println(Thread.currentThread().getName() + ":" + entry.getKey() + ":" + entry.getValue().size()));// 用10个并发线程查找元素Operation search = userHash.search(10, (k, v) -> {for (Operation o : v) {if (o.getOperation().endsWith("1")) {return o;}}return null;});System.out.println("查找到结尾为1的元素" + search.getUser() + "," + search.getOperation() + "," + search.getTime());// 查找value列表大于10的user。ConcurrentLinkedDeque<Operation> search2 = userHash.search(10, (k, v) -> {if (v.size() > 10) {return v;}return null;});System.out.println("查找到长度大于10的元素：" + search2.getFirst().getUser() + ",size:" + search2.size());// 计算散列里面的value列表总值Integer totalSize = userHash.reduce(10, (k, v) -> v.size(), (n1,n2) -> n1+n2);System.out.println("散列里value列表总值："+totalSize);}}

二、元素类

package xyz.jangle.thread.test.n7_7.concurrenthashmap;import java.util.Date;/*** 元素类* * @author jangle* @email jangle@jangle.xyz* @time 2020年9月15日 下午5:33:37* */
public class Operation {private String user, operation;private Date time;public String getUser() {return user;}public void setUser(String user) {this.user = user;}public String getOperation() {return operation;}public void setOperation(String operation) {this.operation = operation;}public Date getTime() {return time;}public void setTime(Date time) {this.time = time;}}

三、填充任务类

package xyz.jangle.thread.test.n7_7.concurrenthashmap;import java.util.Date;
import java.util.Random;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedDeque;/*** @author jangle* @email jangle@jangle.xyz* @time 2020年9月15日 下午5:34:57* */
public class HashFiller implements Runnable {private ConcurrentHashMap<String, ConcurrentLinkedDeque<Operation>> userHash;public HashFiller(ConcurrentHashMap<String, ConcurrentLinkedDeque<Operation>> userHash) {this.userHash = userHash;}@Overridepublic void run() {var randomGenerator = new Random();for (int i = 0; i < 100; i++) {var operation = new Operation();String user = "USER" + randomGenerator.nextInt(100);operation.setUser(user);String action = "OP" + randomGenerator.nextInt(10);operation.setOperation(action);operation.setTime(new Date());// 存入map。addOperationToHash(userHash, operation);}}/*** 	将operation进行归类，通过user值进行分类到指定的Queue中。由map管理这些Queue。* * @author jangle* @time 2020年9月15日 下午5:45:17* @param userHash* @param operation*/private void addOperationToHash(ConcurrentHashMap<String, ConcurrentLinkedDeque<Operation>> userHash,Operation operation) {// 这个computeIfAbsent是个并发操作，具有原子性，防止并发时的丢失与冲突ConcurrentLinkedDeque<Operation> opList = userHash.computeIfAbsent(operation.getUser(),user -> new ConcurrentLinkedDeque<>());opList.add(operation);}}

四、执行结果

Size:100
main:USER58:16
main:USER0:9
main:USER59:4
main:USER56:11
main:USER1:9
main:USER57:4
ForkJoinPool.commonPool-worker-3:USER18:12
main:USER2:11
ForkJoinPool.commonPool-worker-9:USER49:11
ForkJoinPool.commonPool-worker-3:USER19:5
ForkJoinPool.commonPool-worker-3:USER16:7
ForkJoinPool.commonPool-worker-15:USER14:21
ForkJoinPool.commonPool-worker-15:USER15:12
ForkJoinPool.commonPool-worker-11:USER89:13
ForkJoinPool.commonPool-worker-7:USER38:13
main:USER54:5
main:USER55:13
main:USER52:8
main:USER53:7
ForkJoinPool.commonPool-worker-7:USER39:12
ForkJoinPool.commonPool-worker-13:USER29:13
ForkJoinPool.commonPool-worker-13:USER27:20
ForkJoinPool.commonPool-worker-11:USER87:18
ForkJoinPool.commonPool-worker-15:USER12:11
ForkJoinPool.commonPool-worker-9:USER47:11
ForkJoinPool.commonPool-worker-5:USER78:15
ForkJoinPool.commonPool-worker-3:USER17:9
ForkJoinPool.commonPool-worker-5:USER79:6
ForkJoinPool.commonPool-worker-9:USER48:5
ForkJoinPool.commonPool-worker-15:USER13:6
ForkJoinPool.commonPool-worker-11:USER88:15
ForkJoinPool.commonPool-worker-13:USER28:4
ForkJoinPool.commonPool-worker-7:USER36:20
main:USER7:6
ForkJoinPool.commonPool-worker-13:USER69:14
ForkJoinPool.commonPool-worker-7:USER37:9
ForkJoinPool.commonPool-worker-11:USER85:12
ForkJoinPool.commonPool-worker-15:USER98:12
ForkJoinPool.commonPool-worker-9:USER45:16
ForkJoinPool.commonPool-worker-5:USER76:11
ForkJoinPool.commonPool-worker-3:USER25:7
ForkJoinPool.commonPool-worker-5:USER77:11
ForkJoinPool.commonPool-worker-9:USER46:9
ForkJoinPool.commonPool-worker-15:USER10:12
ForkJoinPool.commonPool-worker-11:USER86:8
ForkJoinPool.commonPool-worker-7:USER34:5
ForkJoinPool.commonPool-worker-13:USER67:10
main:USER50:3
ForkJoinPool.commonPool-worker-13:USER68:13
ForkJoinPool.commonPool-worker-13:USER65:13
ForkJoinPool.commonPool-worker-7:USER35:4
ForkJoinPool.commonPool-worker-11:USER83:5
ForkJoinPool.commonPool-worker-11:USER84:8
ForkJoinPool.commonPool-worker-11:USER81:14
ForkJoinPool.commonPool-worker-11:USER82:5
ForkJoinPool.commonPool-worker-15:USER99:7
ForkJoinPool.commonPool-worker-9:USER43:9
ForkJoinPool.commonPool-worker-5:USER74:12
ForkJoinPool.commonPool-worker-5:USER75:7
ForkJoinPool.commonPool-worker-3:USER26:4
ForkJoinPool.commonPool-worker-5:USER72:7
ForkJoinPool.commonPool-worker-5:USER73:12
ForkJoinPool.commonPool-worker-5:USER70:13
ForkJoinPool.commonPool-worker-9:USER44:9
ForkJoinPool.commonPool-worker-15:USER11:10
ForkJoinPool.commonPool-worker-15:USER96:13
ForkJoinPool.commonPool-worker-15:USER97:10
ForkJoinPool.commonPool-worker-15:USER94:12
ForkJoinPool.commonPool-worker-11:USER80:11
ForkJoinPool.commonPool-worker-7:USER32:5
ForkJoinPool.commonPool-worker-13:USER66:17
main:USER51:8
ForkJoinPool.commonPool-worker-13:USER63:12
ForkJoinPool.commonPool-worker-7:USER33:8
ForkJoinPool.commonPool-worker-7:USER30:9
ForkJoinPool.commonPool-worker-15:USER95:6
ForkJoinPool.commonPool-worker-9:USER41:5
ForkJoinPool.commonPool-worker-9:USER42:13
ForkJoinPool.commonPool-worker-5:USER71:9
ForkJoinPool.commonPool-worker-3:USER23:10
ForkJoinPool.commonPool-worker-9:USER40:8
ForkJoinPool.commonPool-worker-15:USER92:8
ForkJoinPool.commonPool-worker-7:USER31:13
ForkJoinPool.commonPool-worker-13:USER64:7
main:USER8:8
main:USER9:12
main:USER3:9
main:USER4:11
ForkJoinPool.commonPool-worker-13:USER61:8
ForkJoinPool.commonPool-worker-15:USER93:5
ForkJoinPool.commonPool-worker-15:USER90:10
ForkJoinPool.commonPool-worker-3:USER24:8
ForkJoinPool.commonPool-worker-15:USER91:9
ForkJoinPool.commonPool-worker-13:USER62:10
main:USER5:13
main:USER6:12
ForkJoinPool.commonPool-worker-13:USER60:18
ForkJoinPool.commonPool-worker-3:USER21:8
ForkJoinPool.commonPool-worker-3:USER22:16
ForkJoinPool.commonPool-worker-3:USER20:6
main:USER58:16
ForkJoinPool.commonPool-worker-5:USER89:13
main:USER0:9
ForkJoinPool.commonPool-worker-11:USER29:13
ForkJoinPool.commonPool-worker-9:USER14:21
ForkJoinPool.commonPool-worker-3:USER18:12
ForkJoinPool.commonPool-worker-15:USER38:13
ForkJoinPool.commonPool-worker-13:USER78:15
ForkJoinPool.commonPool-worker-7:USER69:14
ForkJoinPool.commonPool-worker-13:USER79:6
ForkJoinPool.commonPool-worker-15:USER39:12
ForkJoinPool.commonPool-worker-3:USER19:5
ForkJoinPool.commonPool-worker-9:USER15:12
ForkJoinPool.commonPool-worker-9:USER12:11
ForkJoinPool.commonPool-worker-11:USER27:20
main:USER59:4
main:USER56:11
ForkJoinPool.commonPool-worker-5:USER87:18
main:USER1:9
ForkJoinPool.commonPool-worker-11:USER28:4
ForkJoinPool.commonPool-worker-11:USER25:7
ForkJoinPool.commonPool-worker-9:USER13:6
ForkJoinPool.commonPool-worker-3:USER16:7
ForkJoinPool.commonPool-worker-3:USER17:9
ForkJoinPool.commonPool-worker-15:USER36:20
ForkJoinPool.commonPool-worker-13:USER76:11
ForkJoinPool.commonPool-worker-7:USER67:10
ForkJoinPool.commonPool-worker-3:USER49:11
ForkJoinPool.commonPool-worker-3:USER47:11
ForkJoinPool.commonPool-worker-13:USER77:11
ForkJoinPool.commonPool-worker-15:USER37:9
ForkJoinPool.commonPool-worker-9:USER98:12
ForkJoinPool.commonPool-worker-11:USER26:4
main:USER57:4
ForkJoinPool.commonPool-worker-5:USER88:15
main:USER2:11
ForkJoinPool.commonPool-worker-11:USER23:10
ForkJoinPool.commonPool-worker-9:USER10:12
ForkJoinPool.commonPool-worker-15:USER34:5
ForkJoinPool.commonPool-worker-13:USER74:12
ForkJoinPool.commonPool-worker-3:USER48:5
ForkJoinPool.commonPool-worker-7:USER68:13
ForkJoinPool.commonPool-worker-3:USER45:16
ForkJoinPool.commonPool-worker-13:USER75:7
ForkJoinPool.commonPool-worker-15:USER35:4
ForkJoinPool.commonPool-worker-9:USER99:7
ForkJoinPool.commonPool-worker-11:USER24:8
main:USER54:5
ForkJoinPool.commonPool-worker-5:USER85:12
main:USER55:13
ForkJoinPool.commonPool-worker-11:USER21:8
ForkJoinPool.commonPool-worker-9:USER11:10
ForkJoinPool.commonPool-worker-15:USER32:5
ForkJoinPool.commonPool-worker-13:USER72:7
ForkJoinPool.commonPool-worker-3:USER46:9
ForkJoinPool.commonPool-worker-7:USER65:13
ForkJoinPool.commonPool-worker-3:USER43:9
ForkJoinPool.commonPool-worker-13:USER73:12
ForkJoinPool.commonPool-worker-15:USER33:8
ForkJoinPool.commonPool-worker-9:USER96:13
ForkJoinPool.commonPool-worker-11:USER22:16
main:USER52:8
ForkJoinPool.commonPool-worker-5:USER86:8
main:USER53:7
ForkJoinPool.commonPool-worker-11:USER20:6
ForkJoinPool.commonPool-worker-9:USER97:10
ForkJoinPool.commonPool-worker-15:USER30:9
ForkJoinPool.commonPool-worker-13:USER70:13
ForkJoinPool.commonPool-worker-3:USER44:9
ForkJoinPool.commonPool-worker-7:USER66:17
ForkJoinPool.commonPool-worker-3:USER41:5
ForkJoinPool.commonPool-worker-13:USER71:9
ForkJoinPool.commonPool-worker-15:USER31:13
ForkJoinPool.commonPool-worker-9:USER94:12
main:USER7:6
ForkJoinPool.commonPool-worker-5:USER83:5
main:USER50:3
ForkJoinPool.commonPool-worker-9:USER95:6
ForkJoinPool.commonPool-worker-3:USER42:13
ForkJoinPool.commonPool-worker-7:USER63:12
ForkJoinPool.commonPool-worker-3:USER40:8
ForkJoinPool.commonPool-worker-9:USER92:8
main:USER51:8
ForkJoinPool.commonPool-worker-5:USER84:8
main:USER8:8
ForkJoinPool.commonPool-worker-9:USER93:5
ForkJoinPool.commonPool-worker-7:USER64:7
ForkJoinPool.commonPool-worker-9:USER90:10
main:USER9:12
ForkJoinPool.commonPool-worker-5:USER81:14
main:USER3:9
ForkJoinPool.commonPool-worker-9:USER91:9
ForkJoinPool.commonPool-worker-7:USER61:8
main:USER4:11
ForkJoinPool.commonPool-worker-5:USER82:5
main:USER5:13
ForkJoinPool.commonPool-worker-7:USER62:10
main:USER6:12
ForkJoinPool.commonPool-worker-5:USER80:11
ForkJoinPool.commonPool-worker-7:USER60:18
查找到结尾为1的元素USER89,OP1,Tue Sep 15 18:28:53 CST 2020
查找到长度大于10的元素：USER58,size:16
散列里value列表总值：1000