本文要為大家介紹如何使用synchronized實作Lock程式碼，以下是實戰案例，需要的朋友可以參考借鏡。
方式一：
public synchronized void a(){
//TODO
}方式二：
public void b(){
synchronized(this){
//TODO
}
}從這兩種方式來你看，鎖都是加在｛｝之間的，我們再來看看Lock是如何做的呢:
public void c() {
lock.lock();
try {
// TODO
} finally {
lock.unlock();
}
}這種方式的鎖是加在lock( )和unlock()之間的，所以要實作一個lock功能，就要想怎麼實作這樣兩個方法，lock()和unlock()方法，先定義一個框架如下：
public void lock(){
}
public void unlock(){
}
然後要想怎麼用synchronized去實作這兩個方法。
現在其實只是稍微清楚了一點思路，但是還不知道怎麼去填充這兩個方法，這是後再來分析一下Lock的加鎖有什麼特點，再來看看這段程式碼：
public void c() {
lock.lock();
//When current thread get the lock, other thread has to wait
try {
//current thread get in the lock, other thread can not get in
// TODO
}
finally {
lock.unlock();
//current thread release the lock
}
}
這段程式碼我只是加了一點註釋，別的什麼都沒有做，是不是幫忙理解這段程式碼，看看出現頻率最高的字是什麼，是currentthread，那我們去填充lock()和unlock()方法的時候是不是注意到要抓住currentthread這個關鍵字就可以找到解決方案呢？答案是肯定的。
接著分析，使用synchronized的時候該如何讓執行緒等待呢？是用wait()方法。怎麼讓執行緒喚醒呢，是用notify()方法。那麼就要在lock()方法中使用wait()方法，在unlock()方法中使用notify()方法。那我們在使用wait()和notify()的時候是有一個條件的，想想我們應該用什麼作為條件呢？
我們應該使用當前鎖是否被佔用作為判斷條件，如果鎖被佔用，currentthread等待，想想我們在使用synchronized的時候是不是一直使用的這個條件，答案也是肯定的。
再來分析什麼時候釋放鎖，使用什麼作為條件，想想如果線程A拿到了鎖，線程B能釋放嗎？當然不能，如果B能釋放就違反了原則，當然不能。肯定是A線程的鎖只能A來釋放。所以判斷條件就是判斷持有鎖的執行緒是不是currentthread，如果是的話，可以釋放，不是的話當然不能。
現在來看看完整的程式碼：
package test.lock;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
public class NaiveLock {
private static final long NONE = -1;
private long owner = NONE;
private Boolean isLooked() {
return owner != NONE;
}
public synchronized void lock() {
long currentThreadId = Thread.currentThread().getId();
if (owner == currentThreadId) {
throw new IllegalStateException("Lock has been acquired by current thread");
}
while (this.isLooked()) {
System.out.println(String.format("thread %s is waitting lock", currentThreadId));
try {
wait();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
owner = currentThreadId;
System.out.println(String.format("Lock is acquired by thread %s", owner));
}
public synchronized void unlock() {
if (!this.isLooked() || owner != Thread.currentThread().getId()) {
throw new IllegalStateException("Only Lock owner can unlock the lock");
}
System.out.println(String.format("thread %s is unlocking", owner));
System.out.println();
owner = NONE;
notify();
}
public static void main(String[] args) {
final NaiveLock lock = new NaiveLock();
ExecutorService executor = Executors.newFixedThreadPool(20, new ThreadFactory() {
private ThreadGroup group = new ThreadGroup("test thread group");
{
group.setDaemon(true);
}
@Override
public Thread newThread(Runnable r) {
return new Thread(group, r);
}
}
);
for (int i = 0; i < 20; i++) {
executor.submit(new Runnable() {
@Override
public void run() {
lock.lock();
System.out.println(String.format("thread %s is running...", Thread.currentThread().getId()));
try {
Thread.sleep(new Random().nextint(1000));
}
catch (InterruptedException e) {
e.printStackTrace();
}
lock.unlock();
}
}
);
}
}
}
#執行一下看看結果：
Lock is acquired by thread 8 thread 8 is running... thread 27 is waitting lock thread 26 is waitting lock thread 25 is waitting lock thread 24 is waitting lock thread 23 is waitting lock thread 22 is waitting lock thread 21 is waitting lock thread 20 is waitting lock thread 19 is waitting lock thread 18 is waitting lock thread 17 is waitting lock thread 16 is waitting lock thread 15 is waitting lock thread 14 is waitting lock thread 13 is waitting lock thread 12 is waitting lock thread 11 is waitting lock thread 10 is waitting lock thread 9 is waitting lock thread 8 is unlocking Lock is acquired by thread 27 thread 27 is running... thread 27 is unlocking Lock is acquired by thread 26 thread 26 is running... thread 26 is unlocking Lock is acquired by thread 25 thread 25 is running... thread 25 is unlocking Lock is acquired by thread 24 thread 24 is running... thread 24 is unlocking Lock is acquired by thread 23 thread 23 is running... thread 23 is unlocking Lock is acquired by thread 22 thread 22 is running... thread 22 is unlocking Lock is acquired by thread 21 thread 21 is running... thread 21 is unlocking Lock is acquired by thread 20 thread 20 is running... thread 20 is unlocking Lock is acquired by thread 19 thread 19 is running... thread 19 is unlocking Lock is acquired by thread 18 thread 18 is running... thread 18 is unlocking Lock is acquired by thread 17 thread 17 is running... thread 17 is unlocking Lock is acquired by thread 16 thread 16 is running... thread 16 is unlocking Lock is acquired by thread 15 thread 15 is running... thread 15 is unlocking Lock is acquired by thread 14 thread 14 is running... thread 14 is unlocking Lock is acquired by thread 13 thread 13 is running... thread 13 is unlocking Lock is acquired by thread 12 thread 12 is running... thread 12 is unlocking Lock is acquired by thread 11 thread 11 is running... thread 11 is unlocking Lock is acquired by thread 10 thread 10 is running... thread 10 is unlocking Lock is acquired by thread 9 thread 9 is running... thread 9 is unlocking
如果把for循環改成30次，再看一下結果：
Lock is acquired by thread 8 thread 8 is running... thread 27 is waitting lock thread 26 is waitting lock thread 25 is waitting lock thread 24 is waitting lock thread 23 is waitting lock thread 22 is waitting lock thread 21 is waitting lock thread 20 is waitting lock thread 19 is waitting lock thread 18 is waitting lock thread 17 is waitting lock thread 16 is waitting lock thread 15 is waitting lock thread 14 is waitting lock thread 13 is waitting lock thread 12 is waitting lock thread 11 is waitting lock thread 10 is waitting lock thread 9 is waitting lock thread 8 is unlocking Lock is acquired by thread 27 thread 27 is running... thread 8 is waitting lock thread 27 is unlocking Lock is acquired by thread 27 thread 27 is running... thread 26 is waitting lock thread 27 is unlocking Lock is acquired by thread 27 thread 27 is running... thread 25 is waitting lock thread 27 is unlocking Lock is acquired by thread 24 thread 24 is running... thread 27 is waitting lock thread 24 is unlocking Lock is acquired by thread 23 thread 23 is running... thread 24 is waitting lock thread 23 is unlocking Lock is acquired by thread 22 thread 22 is running... thread 23 is waitting lock thread 22 is unlocking Lock is acquired by thread 22 thread 22 is running... thread 21 is waitting lock thread 22 is unlocking Lock is acquired by thread 22 thread 22 is running... thread 20 is waitting lock thread 22 is unlocking Lock is acquired by thread 22 thread 22 is running... thread 19 is waitting lock thread 22 is unlocking Lock is acquired by thread 22 thread 22 is running... thread 18 is waitting lock thread 22 is unlocking Lock is acquired by thread 17 thread 17 is running... thread 17 is unlocking Lock is acquired by thread 16 thread 16 is running... thread 16 is unlocking Lock is acquired by thread 15 thread 15 is running... thread 15 is unlocking Lock is acquired by thread 14 thread 14 is running... thread 14 is unlocking Lock is acquired by thread 13 thread 13 is running... thread 13 is unlocking Lock is acquired by thread 12 thread 12 is running... thread 12 is unlocking Lock is acquired by thread 11 thread 11 is running... thread 11 is unlocking Lock is acquired by thread 10 thread 10 is running... thread 10 is unlocking Lock is acquired by thread 9 thread 9 is running... thread 9 is unlocking Lock is acquired by thread 8 thread 8 is running... thread 8 is unlocking Lock is acquired by thread 26 thread 26 is running... thread 26 is unlocking Lock is acquired by thread 25 thread 25 is running... thread 25 is unlocking Lock is acquired by thread 27 thread 27 is running... thread 27 is unlocking Lock is acquired by thread 24 thread 24 is running... thread 24 is unlocking Lock is acquired by thread 23 thread 23 is running... thread 23 is unlocking Lock is acquired by thread 21 thread 21 is running... thread 21 is unlocking Lock is acquired by thread 20 thread 20 is running... thread 20 is unlocking Lock is acquired by thread 19 thread 19 is running... thread 19 is unlocking Lock is acquired by thread 18 thread 18 is running... thread 18 is unlocking
相信看了這些案例你已經掌握了方法，更多精彩請關注php中文網其它相關文章！
相關讀取：
php如何實作堆疊資料結構以及括號匹配演算法的程式碼範例詳解
php中最簡單的字串匹配演算法，php匹配演算法_PHP教程
以上是使用synchronized實作一個Lock程式碼詳解的詳細內容。更多資訊請關注PHP中文網其他相關文章！
優化PHP代碼：減少內存使用和執行時間May 10, 2025 am 12:04 AMTooptimizePHPcodeforreducedmemoryusageandexecutiontime,followthesesteps:1)Usereferencesinsteadofcopyinglargedatastructurestoreducememoryconsumption.2)LeveragePHP'sbuilt-infunctionslikearray_mapforfasterexecution.3)Implementcachingmechanisms,suchasAPC
PHP電子郵件：分步發送指南May 09, 2025 am 12:14 AMphpisusedforsendendemailsduetoitsignegrationwithservermailservicesand andexternalsmtpproviders，自動化intifications andMarketingCampaigns.1）設置設置yourphpenvenvironnvironnvironmentwithaweberswithawebserverserververandphp，確保themailfunctionisenabled.2）useabasicscruct
如何通過PHP發送電子郵件：示例和代碼May 09, 2025 am 12:13 AM發送電子郵件的最佳方法是使用PHPMailer庫。 1)使用mail()函數簡單但不可靠，可能導致郵件進入垃圾郵件或無法送達。 2)PHPMailer提供更好的控制和可靠性，支持HTML郵件、附件和SMTP認證。 3)確保正確配置SMTP設置並使用加密（如STARTTLS或SSL/TLS）以增強安全性。 4)對於大量郵件，考慮使用郵件隊列系統來優化性能。
高級PHP電子郵件：自定義標題和功能May 09, 2025 am 12:13 AMCustomHeadersheadersandAdvancedFeaturesInphpeMailenHanceFunctionalityAndreliability.1）CustomHeadersheadersheadersaddmetadatatatatataatafortrackingandCategorization.2）htmlemailsallowformattingandttinganditive.3）attachmentscanmentscanmentscanbesmentscanbestmentscanbesentscanbesentingslibrarieslibrarieslibrariesliblarikelikephpmailer.4）smtppapapairatienticationaltication enterticationallimpr
使用PHP和SMTP發送電子郵件的指南May 09, 2025 am 12:06 AM使用PHP和SMTP發送郵件可以通過PHPMailer庫實現。 1)安裝並配置PHPMailer，2)設置SMTP服務器細節，3)定義郵件內容，4)發送郵件並處理錯誤。使用此方法可以確保郵件的可靠性和安全性。
使用PHP發送電子郵件的最佳方法是什麼？May 08, 2025 am 12:21 AMThebestapproachforsendingemailsinPHPisusingthePHPMailerlibraryduetoitsreliability,featurerichness,andeaseofuse.PHPMailersupportsSMTP,providesdetailederrorhandling,allowssendingHTMLandplaintextemails,supportsattachments,andenhancessecurity.Foroptimalu
PHP中依賴注入的最佳實踐May 08, 2025 am 12:21 AM使用依賴注入(DI)的原因是它促進了代碼的松耦合、可測試性和可維護性。 1)使用構造函數注入依賴，2)避免使用服務定位器，3)利用依賴注入容器管理依賴，4)通過注入依賴提高測試性，5)避免過度注入依賴，6)考慮DI對性能的影響。
PHP性能調整技巧和技巧May 08, 2025 am 12:20 AMphpperformancetuningiscialbecapeitenhancesspeedandeffice，whatevitalforwebapplications.1）cachingwithapcureduccureducesdatabaseloadprovesrovessetimes.2）優化
熱AI工具
Undresser.AI Undress
人工智慧驅動的應用程序，用於創建逼真的裸體照片
AI Clothes Remover
用於從照片中去除衣服的線上人工智慧工具。
Undress AI Tool
免費脫衣圖片
Clothoff.io
AI脫衣器
Video Face Swap
使用我們完全免費的人工智慧換臉工具，輕鬆在任何影片中換臉！
熱門文章
熱工具
VSCode Windows 64位元 下載
微軟推出的免費、功能強大的一款IDE編輯器
Dreamweaver Mac版
視覺化網頁開發工具
mPDF
mPDF是一個PHP庫，可以從UTF-8編碼的HTML產生PDF檔案。原作者Ian Back編寫mPDF以從他的網站上「即時」輸出PDF文件，並處理不同的語言。與原始腳本如HTML2FPDF相比，它的速度較慢，並且在使用Unicode字體時產生的檔案較大，但支援CSS樣式等，並進行了大量增強。支援幾乎所有語言，包括RTL（阿拉伯語和希伯來語）和CJK（中日韓）。支援嵌套的區塊級元素（如P、DIV），
禪工作室 13.0.1
強大的PHP整合開發環境
Dreamweaver CS6
視覺化網頁開發工具
