java多线程自学实现方式

╰+攻爆jí腚メ 2023-07-10 14:18 5阅读 0赞

实现多线程编程的方式主要有有两种，一种是继承 Thread 类，另一种是实现 Runnable 接口。使用继承 Thread 类创建线程，最大的局限就是不能多继承，所以为了支持多继承，完全可以实现 Runnable 接口的方式。需要说明的是，这两种方式在工作时的性质都是一样的，没有本质的区别。  
**1.继承Thread类**，需要重写run方法，然后调用start（）方法，三步走

import java.io.File;
    import java.io.IOException;
    import java.net.MalformedURLException;
    import java.net.URL;
    
    import org.apache.commons.io.FileUtils;
    
    public class Thread01 extends Thread { 
    	private URL url;
    	private File name;
    	public void run() { 
    		try { 
    			webserver();
    		} catch (IOException e) { 
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		System.out.println(name+"is already");
    	}
    	public void webserver() throws IOException { 
    		FileUtils.copyURLToFile(url, name);
    	}
    	public Thread01(URL url,File name) { 
    		this.url=url;
    		this.name=name;
    	}
    	public static void main(String[] args) throws MalformedURLException { 
    		//创建子类对象
    		Thread01 td1=new Thread01(new URL("https://image.baidu.com/search/detail?ct=503316480&z=0&ipn=d&word=%E5%9B%BE%E7%89%87&step_word=&hs=0&pn=1&spn=0&di=181720&pi=0&rn=1&tn=baiduimagedetail&is=0%2C0&istype=0&ie=utf-8&oe=utf-8&in=&cl=2&lm=-1&st=undefined&cs=3173584241%2C3533290860&os=1133571898%2C402444249&simid=3493630544%2C246115770&adpicid=0&lpn=0&ln=1410&fr=&fmq=1583203139520_R&fm=&ic=undefined&s=undefined&hd=undefined&latest=undefined&copyright=undefined&se=&sme=&tab=0&width=undefined&height=undefined&face=undefined&ist=&jit=&cg=&bdtype=0&oriquery=&objurl=http%3A%2F%2Fa0.att.hudong.com%2F78%2F52%2F01200000123847134434529793168.jpg&fromurl=ippr_z2C%24qAzdH3FAzdH3Fp7rtwg_z%26e3Bkwthj_z%26e3Bv54AzdH3Ftrw1AzdH3Fwa_0b_cd_a8daaaaa8dnb908n99n9cdl0ln8mb_3r2_z%26e3Bip4s&gsm=1&rpstart=0&rpnum=0&islist=&querylist=&force=undefined"),new File("tiger.png"));
    		Thread01 td2=new Thread01(new URL("https://image.baidu.com/search/detail?ct=503316480&z=0&ipn=d&word=%E5%9B%BE%E7%89%87&step_word=&hs=0&pn=3&spn=0&di=8030&pi=0&rn=1&tn=baiduimagedetail&is=0%2C0&istype=0&ie=utf-8&oe=utf-8&in=&cl=2&lm=-1&st=undefined&cs=1906469856%2C4113625838&os=1062705421%2C520912533&simid=3285371631%2C209838447&adpicid=0&lpn=0&ln=1410&fr=&fmq=1583203139520_R&fm=&ic=undefined&s=undefined&hd=undefined&latest=undefined&copyright=undefined&se=&sme=&tab=0&width=undefined&height=undefined&face=undefined&ist=&jit=&cg=&bdtype=0&oriquery=&objurl=http%3A%2F%2Fa2.att.hudong.com%2F36%2F48%2F19300001357258133412489354717.jpg&fromurl=ippr_z2C%24qAzdH3FAzdH3Fp7rtwg_z%26e3Bkwthj_z%26e3Bv54AzdH3Ftrw1AzdH3Fwd_nm_9b_8lnaaaa8nc0dcb8nn98d9blnc9080_3r2_z%26e3Bip4s&gsm=3&rpstart=0&rpnum=0&islist=&querylist=&force=undefined"), new File("strawberry.png"));
    		td1.start();
    		td2.start();
    	}
    	
    }

**2.实现runnable 接口**，重写run方法，使用start（）方法调用，由于runnable接口中**只有一个抽象方法run（）**，所以需要创建代理类Thread才能调用start（）方法（方便共享资源，避免单继承的弊端）

package cn.xl.thread;
    
    import java.io.File;
    import java.io.IOException;
    import java.net.MalformedURLException;
    import java.net.URL;
    
    import org.apache.commons.io.FileUtils;
    
    public class RunImplement implements Runnable { 
    	public static void main(String[] args) throws MalformedURLException { 
    		//创建实现类对象
    		RunImplement sr1=new RunImplement(new URL("https://image.baidu.com/search/detail?ct=503316480&z=0&ipn=d&word=%E5%9B%BE%E7%89%87&step_word=&hs=0&pn=1&spn=0&di=181720&pi=0&rn=1&tn=baiduimagedetail&is=0%2C0&istype=0&ie=utf-8&oe=utf-8&in=&cl=2&lm=-1&st=undefined&cs=3173584241%2C3533290860&os=1133571898%2C402444249&simid=3493630544%2C246115770&adpicid=0&lpn=0&ln=1410&fr=&fmq=1583203139520_R&fm=&ic=undefined&s=undefined&hd=undefined&latest=undefined&copyright=undefined&se=&sme=&tab=0&width=undefined&height=undefined&face=undefined&ist=&jit=&cg=&bdtype=0&oriquery=&objurl=http%3A%2F%2Fa0.att.hudong.com%2F78%2F52%2F01200000123847134434529793168.jpg&fromurl=ippr_z2C%24qAzdH3FAzdH3Fp7rtwg_z%26e3Bkwthj_z%26e3Bv54AzdH3Ftrw1AzdH3Fwa_0b_cd_a8daaaaa8dnb908n99n9cdl0ln8mb_3r2_z%26e3Bip4s&gsm=1&rpstart=0&rpnum=0&islist=&querylist=&force=undefined"),new File("tiger.png"));
    		RunImplement sr2=new RunImplement(new URL("https://image.baidu.com/search/detail?ct=503316480&z=0&ipn=d&word=%E5%9B%BE%E7%89%87&step_word=&hs=0&pn=3&spn=0&di=8030&pi=0&rn=1&tn=baiduimagedetail&is=0%2C0&istype=0&ie=utf-8&oe=utf-8&in=&cl=2&lm=-1&st=undefined&cs=1906469856%2C4113625838&os=1062705421%2C520912533&simid=3285371631%2C209838447&adpicid=0&lpn=0&ln=1410&fr=&fmq=1583203139520_R&fm=&ic=undefined&s=undefined&hd=undefined&latest=undefined&copyright=undefined&se=&sme=&tab=0&width=undefined&height=undefined&face=undefined&ist=&jit=&cg=&bdtype=0&oriquery=&objurl=http%3A%2F%2Fa2.att.hudong.com%2F36%2F48%2F19300001357258133412489354717.jpg&fromurl=ippr_z2C%24qAzdH3FAzdH3Fp7rtwg_z%26e3Bkwthj_z%26e3Bv54AzdH3Ftrw1AzdH3Fwd_nm_9b_8lnaaaa8nc0dcb8nn98d9blnc9080_3r2_z%26e3Bip4s&gsm=3&rpstart=0&rpnum=0&islist=&querylist=&force=undefined"), new File("strawberry.png"));
    		//创建代理类对象
    		Thread t1=new Thread(sr1);
    		Thread t2=new Thread(sr2);
    		t1.start();
    		t2.start();
    
    		
    	}
    
    	private URL url;
    	private File name;
    	public void run() { 
    		for(int i=0;i<1000;i++) { 
    		System.out.println(name);
    	}
    		
    		
    	}
    	public void webserver() throws IOException { 
    		FileUtils.copyURLToFile(url, name);
    	}
    	public RunImplement(URL url,File name) { 
    		this.url=url;
    		this.name=name;
    	}
    }

**3.runnable共享资源**，一个资源多个线程共享，其中Thread.currentThread()指的是当前线程的引用

public class Web12306 implements Runnable{ 
    	private int ticketNums=99;
    	@Override
    	public void run() { 
    		while(true) { 
    			if(ticketNums<0)
    				break;
    			System.out.println(Thread.currentThread().getName()+"-->"+ticketNums--);
    		}
    	}
    	public static void main(String[] args) { 
    		Web12306 web=new Web12306();
    		new Thread(web, "码农").start();
    		new Thread(web, "码畜").start();
    		new Thread(web, "蚂蝗").start();
    	}
    }

**4.实现Callable（初学者了解）**，首先要实现callable接口，创建Callable方法，run（）方法改为call（）方法，并且可以返回异常  
一、创建目标对象  
二、创建执行服务  
三、提交执行  
四、获取结果  
五、关闭服务  
**5.代理**  
静态代理由程序员创建或由特定工具自动生成源代码，再对其编译。在程序运行前，代理类的.class文件就已经存在了。动态代理类：在程序运行时，运用反射机制动态创建而成。