【狂神說Java】繼承thread類
阿新 • • 發佈:2021-09-14
執行緒建立
- Thread:繼承Thread類(重點)
- Runnable:實現Runnable介面(重點)
- Callable:實現Callable介面(瞭解)
繼承Thread類
- 自定義執行緒類繼承 Thread類
- 重寫run()方法,編寫執行緒執行體
- 建立執行緒物件,呼叫start()方法啟動執行緒
// 重寫run()方法, alt+insert快捷鍵 public class StartThread1 extends Thread{ // 執行緒入口點 @Override public void run() { // 執行緒體 for (int i = 0; i < 20; i++) { System.out.println("多執行緒"); } } } // 呼叫start()方法啟動執行緒 public class MainThread { public static void main(String[] args) { // 建立執行緒物件 StartThread1 th1 = new StartThread1(); th1.start(); // start 啟用後和底下程式碼交替執行 for (int i = 0; i < 2000; i++) { System.out.println("main方法"); } } }
- 下載圖片
執行緒開啟不一定立即執行,需要看CPU的排程
import org.apache.commons.io.FileUtils; import java.io.File; import java.io.IOException; import java.net.URL; public class PicThread extends Thread { private String url = ""; // 網路圖片地址 private String name = ""; // 儲存路徑 // 構造器,初始化地址 public PicThread(String url,String name){ this.url = url; this.name = name; } @Override public void run() { WebDownloader webDownloader = new WebDownloader(); webDownloader.downloader(url, name); System.out.println("路徑"+name); } // 啟動執行緒 public static void main(String[] args) { String url = "https://img0.bdstatic.com/static/searchdetail/img/logo-2X_2dd9a28.png"; String name = "C:\\Users\\Jie7\\IdeaProjects\\Test\\src\\baidulogo"; // 多執行緒,啟動,無序 PicThread picThread1 = new PicThread(url, name +"1.png"); PicThread picThread2 = new PicThread(url, name +"2.png"); PicThread picThread3 = new PicThread(url, name +"3.png"); picThread1.start(); picThread2.start(); picThread3.start(); } } class WebDownloader { // 遠端下載 // 遠端路徑,儲存地址+名字 public void downloader(String url, String name) { try { FileUtils.copyURLToFile(new URL(url), new File(name)); } catch (IOException e) { e.printStackTrace(); System.out.println("檔案下載失敗"); } } }