1、我的第一個多線程程序

方法一： extends Thread

package cn.hanquan.test;public class StartThread extends Thread {@Overridepublic void run() {// 線程入口點for (int i = 0; i < 2000; i++) {System.out.println("偷偷敲代碼");}}public static void main(String[] args) {/** 啟動線程* 1、創建子類對象* 2、調用子類對象的start方法*/StartThread st=new StartThread();st.start();for (int i = 0; i < 2000; i++) {System.out.println("吃飯");}} }

方法二：implements Runnable（推薦）

package cn.hanquan.test;public class StartRun implements Runnable {// 線程入口點@Overridepublic void run() {for (int i = 0; i < 1000; i++)System.out.println("偷偷敲代碼");}public static void main(String[] args) {// 創建實現類對象StartRun sr = new StartRun();// 創建代理類對象Thread t = new Thread(sr);// 啟動t.start();// 三合一：如果一個對象只是用一次，我們可以使用匿名// new Thread(new StartRun()).start();for (int i = 0; i < 1000; i++)System.out.println("我在吃飯");} }

方法三：implements Callable（了解）

功能：多線程下載網頁圖片

package cn.hanquan.test;import java.io.File; import java.io.IOException; import java.net.MalformedURLException; import java.net.URL; import java.util.concurrent.Callable; import java.util.concurrent.ExecutionException; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Future;import org.apache.commons.io.FileUtils;public class TDownloader implements Callable<Boolean> {private String url;private String name;// 構造器public TDownloader(String url, String name) {this.url = url;this.name = name;}// 線程入口點@Overridepublic Boolean call() {WebDownloader.download(url, name);System.out.println("success");return true;}public static void main(String[] args) throws InterruptedException, ExecutionException {TDownloader cd1 = new TDownloader("https://img-blog.csdnimg.cn/20190724224219516.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx,size_16,color_FFFFFF,t_70","1.png");TDownloader cd2 = new TDownloader("https://www.bjsxt.com/wp-content/themes/sxt/statics/images/bjsxt/images/share/project2.png", "2.png");TDownloader cd3 = new TDownloader("https://img-blog.csdnimg.cn/20190722092922681.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx,size_16,color_FFFFFF,t_70","3.png");// 創建執行服務ExecutorService ser = Executors.newFixedThreadPool(3);// 提交執行Future<Boolean> result1 = ser.submit(cd1);Future<Boolean> result2 = ser.submit(cd2);Future<Boolean> result3 = ser.submit(cd3);// 獲取結果boolean r1 = result1.get();boolean r2 = result2.get();boolean r3 = result3.get();// 關閉服務ser.shutdownNow();} }//下載工具 class WebDownloader {public static void download(String url, String name) {try {FileUtils.copyURLToFile(new URL(url), new File(name));} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}} }

運行結果：可以看到，圖片成功被下載

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2、多線程下載圖片

需要使用commons.io

package cn.hanquan.test;import java.io.File; import java.io.IOException; import java.net.MalformedURLException; import java.net.URL;import org.apache.commons.io.FileUtils;public class TDownloader extends Thread {private String url;private String name;// 構造器public TDownloader(String url, String name) {this.url = url;this.name = name;}// 線程入口點@Overridepublic void run() {WebDownloader.download(url, name);System.out.println("success");}public static void main(String[] args) {TDownloader t1 = new TDownloader("https://img-blog.csdnimg.cn/20190724224219516.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx,size_16,color_FFFFFF,t_70","1.png");TDownloader t2 = new TDownloader("https://www.bjsxt.com/wp-content/themes/sxt/statics/images/bjsxt/images/share/project2.png", "2.png");TDownloader t3 = new TDownloader("https://img-blog.csdnimg.cn/20190722092922681.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzQyNDgzMzQx,size_16,color_FFFFFF,t_70","3.png");t1.start();t2.start();t3.start();} }//下載工具 class WebDownloader {public static void download(String url, String name) {try {FileUtils.copyURLToFile(new URL(url), new File(name));} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}} }

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3.使用多線程模擬搶票

出現重復數字的原因是：線程不安全

package cn.hanquan.test;public class StartRun implements Runnable {public static int ticket = 100;// 線程入口點@Overridepublic void run() {while (ticket > 0) {//ticket--;System.out.println(Thread.currentThread().getName() + "->" + ticket--);try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}}}public static void main(String[] args) {// 三合一：如果一個對象只是用一次，我們可以使用匿名new Thread(new StartRun(), "小紅").start();new Thread(new StartRun(), "魔鬼").start();new Thread(new StartRun(), "布谷鳥").start();} }

部分結果

總結

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