怎样实现多线程

案例：下载工具

一、DownLoadJFrame1.java

package util;

import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class DownLoadJFrame1 extends JFrame implements ActionListener{
	// 声明组件
	private JLabel loadJLable;
	private JTextField loadJTextField;
	private JButton lodeJButton;
	
	//随机文件
	private RandomAccessFile accessFile;

	public DownLoadJFrame1() {
     //设置标题
		super("下载工具");
		//设置大小
		this.setSize(400,300);
	   //设置居中
		this.setLocationRelativeTo(null);
		//关闭
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		//设置可见性
		this.setVisible(true);
		
		//设置容器对象
		Container c=this.getContentPane();
		//设置容器面板
		c.setLayout(null);
		//实例化组件
		loadJLable=new JLabel("下载的地址");
		loadJTextField=new JTextField("http://localhost:8080/day31/image/ff.jpg");
		lodeJButton=new JButton("下载");
		//设置组件位置
		loadJLable.setBounds(10,20,80,30);
		loadJTextField.setBounds(90,20,280,30);
		lodeJButton.setBounds(120,100,100,30);
		//添加到面板
		c.add(loadJLable);
		c.add(loadJTextField);
		c.add(lodeJButton);
		
		//添加监听事件
		lodeJButton.addActionListener(this);
		
	}
	public static void main(String[] args) {
		new DownLoadJFrame1();
	}
	@Override
	public void actionPerformed(ActionEvent e) {
	  lodeJButton.setEnabled(false);
	  //获取下载的路径
	  final String path=loadJTextField.getText();
	  try {
		  //根据路径创建URL对象
		URL url=new URL(path);
		//打开连接
		HttpURLConnection httpURLConnection=(HttpURLConnection) url.openConnection();
	    //设置请求方式
		httpURLConnection.setRequestMethod("GET");
		//设置连接的超时时间
		httpURLConnection.setConnectTimeout(5000);
		//设置请求的头信息
		httpURLConnection.setRequestProperty("User-Agent","Mozilla/5.0 (Windows NT 6.2; rv:21.0) Gecko/20100101 Firefox/21.0");
       //获取下载的文件大小
		int size=httpURLConnection.getContentLength();
		//根据下载文件的名称 设置本地保存的文件
		File file=new File("E:"+path.substring(path.lastIndexOf("/")));
		//根据文件创建出对象
		accessFile=new RandomAccessFile(file, "rw");
		//设置大小
		accessFile.setLength(size);
		
		//释放资源
		accessFile.close();
		httpURLConnection.disconnect();
		
		//定义线程的数据量
		int threadNum=3;
		//往里边写数据
		for (int i = 1; i < threadNum; i++) {
			//计算出每个线程下载的平均量（大小）
			int blockSize=size/threadNum;
			//计算机每个线程的开始下载的位置
			final int startSize=(i-1)*blockSize;
			int temp=i*blockSize-1;
			if (i==threadNum) {
				if (temp<size) {
					temp=size;
				}
			}
			//计算出每个线程下载的结束位置
			final int endSize=temp;
			//文件随机读取的对象
			final RandomAccessFile threadFile=new RandomAccessFile(file,"rw");
			//创建线程
			new Thread(){
			public void run() {
				try {
					//根据路径创建URL对象					
					URL url=new URL(path);
					//打开连接
					HttpURLConnection httpURLConnection=(HttpURLConnection) url.openConnection();
					  //设置请求方式
					httpURLConnection.setRequestMethod("GET");
					//设置连接的超时时间
					httpURLConnection.setConnectTimeout(5000);
					//设置请求的头信息
					httpURLConnection.setRequestProperty("User-Agent","Mozilla/5.0 (Windows NT 6.2; rv:21.0) Gecko/20100101 Firefox/21.0");
				    System.out.println(Thread.currentThread().getName()+"从--"+startSize+"---开始下载，到"+endSize+"结束");
				    //设置读取的range的范围
				    httpURLConnection.setRequestProperty("Range","bytes="+startSize+"-"+endSize);
				    //获取输入流对象
				    InputStream is=httpURLConnection.getInputStream();
				    //设置文件开始写入的位置
				    threadFile.seek(startSize);
				    //缓冲区
				    byte  buffer[]=new byte[1024];
				    //读取长度
				    int len=0;
				    while((len=is.read(buffer))!=-1){
				    	//写入
				    	threadFile.write(buffer,0,len);
				    }
				    //释放资源
				    is.close();
				    threadFile.close();
				    httpURLConnection.disconnect();
				    
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			};
			}.start();
		}
		
		//写文件
	  } catch (Exception e1) {
		// TODO Auto-generated catch block
		e1.printStackTrace();
	}
		
	}
}

DownLoadJFrames2.java

package util;

import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JProgressBar;
import javax.swing.JTextField;

public class DownLoadJFrames2 extends JFrame {
	// 声明组件
	private JLabel downlodeJlable;
	private JTextField downlodeJTextField;
	private JButton downlodeJButton;
	
	private JLabel threadNumJable;
	private JTextField threadNumJTextField;
	
	private JProgressBar downlodeJProgressBar;

	public DownLoadJFrames2() {
		super("下载工具");
		// 设置大小
		this.setSize(400, 300);
		// 设置居中显示
		this.setLocationRelativeTo(null);
		// 设置窗体关闭即退出程序
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		// 可见性
		this.setVisible(true);

		// 获取容器对象
		Container c = this.getContentPane();
		// 设置容器面板布局为null
		c.setLayout(null);
		// 实例化组件
		downlodeJlable = new JLabel("下载的地址");
		downlodeJTextField = new JTextField(
				"http://localhost:8080/day31/image/ff.jpg");
		downlodeJButton = new JButton("下载");
		threadNumJable=new JLabel("开启线程数");
		threadNumJTextField=new JTextField("3");
		downlodeJProgressBar=new JProgressBar();
		
		// 设置组件的位置
		downlodeJlable.setBounds(10, 20, 80, 30);
		downlodeJTextField.setBounds(95, 20, 280, 30);
		threadNumJable.setBounds(10,60,80,30);
		threadNumJTextField.setBounds(95,60,280, 30);
		downlodeJProgressBar.setBounds(10,100,360, 10);
		downlodeJButton.setBounds(120, 120, 100, 30);
		
		// 添加到面板中
		c.add(downlodeJButton);
		c.add(downlodeJTextField);
		c.add(downlodeJlable);
		c.add(threadNumJTextField);
		c.add(threadNumJable);
		c.add(downlodeJProgressBar);
		// 添加点击事件
		downlodeJButton.addActionListener(new MyActionListener());

	}

	/**
	 * 内部类
	 * 
	 * @param args
	 */
	class MyActionListener implements ActionListener {
		// 随机文件
		private RandomAccessFile accessFile;

		@Override
		public void actionPerformed(ActionEvent e) {
			downlodeJButton.setEnabled(false);
			// 获取下载的路径
			String path = downlodeJTextField.getText();
			String txThreadNun=threadNumJTextField.getText();
			try {
				// 根据路径创建URL对象
				URL url = new URL(path);
				// 打开连接
				HttpURLConnection httpURLConnection = (HttpURLConnection) url
						.openConnection();
				// 设置请求的方式
				httpURLConnection.setRequestMethod("GET");
				// 设置连接的超时时间
				httpURLConnection.setConnectTimeout(5000);
				// 设置请求的头信息
				httpURLConnection
						.setRequestProperty("User-Agent",
								"Mozilla/5.0 (Windows NT 6.2; rv:21.0) Gecko/20100101 Firefox/21.0");
				//获取状态码
				int startusCode=httpURLConnection.getResponseCode();
				//是否响应成功的判断
				if (startusCode==200) {
				//获取下载的文件大小
				int size=httpURLConnection.getContentLength();
				//根据下载文件的名称 设置本地保存的文件
				File file=new File("E:"+path.substring(path.lastIndexOf("/")));
				//根据文件创建出RandomAccessFile对象
				accessFile=new RandomAccessFile(file,"rw");
                //设置文件大小
				accessFile.setLength(size);
				//设置进度条大小
				downlodeJProgressBar.setMaximum(size);
				downlodeJProgressBar.setValue(0);
				accessFile.close();
				httpURLConnection.disconnect();
				
				//定义线程的数据量
				int threadNum=Integer.parseInt(txThreadNun);
				//往里边写数据
				for (int i = 1; i <=threadNum; i++) {
					//计算出每个线程下载的平均量（大小）
					int blockSize=size/threadNum;
					//计算出每个线程的开始下载的位置
					int startSize=(i-1)*blockSize;
					//计算出每个线程下载的结束位置
                    int endSize=i*blockSize-1;
                    if (i==threadNum) {
						if (endSize<size) {
							endSize=size;
						}
					}
                    //文件随机读取的对象
                    RandomAccessFile threadFile=new RandomAccessFile(file, "rw");
               
					new DownLodeThread(path, startSize, endSize, threadFile, downlodeJProgressBar).start();
                    //写文件
				}
				}
			} catch (Exception e1) {
				// TODO Auto-generated catch block
				e1.printStackTrace();
			}

		}

	}

	public static void main(String[] args) {
		new DownLoadJFrames2();
	}
}

工具包DownLodeThread.java

package util;

import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class DownLodeThread extends Thread {
	// 下载的路径
	private String path;
	// 开始位置
	private int startSize;
	// 结束位置
	private int endSize;
	// 随机读取文件的对象
	private RandomAccessFile threadFile;

	// 实例化
	public DownLodeThread(String path, int startSize, int endSize,
			RandomAccessFile threadFile) {
		super();
		this.path = path;
		this.startSize = startSize;
		this.endSize = endSize;
		this.threadFile = threadFile;
	}

	@Override
	public void run() {
		try {
			// 根据路径创建URL对象
			URL url = new URL(path);
			// 打开连接
			HttpURLConnection httpURLConnection = (HttpURLConnection) url
					.openConnection();

			// 设置请求的方式
			httpURLConnection.setRequestMethod("GET");
			// 设置连接的超时时间
			httpURLConnection.setConnectTimeout(5000);
			// 设置请求的头信息
			httpURLConnection
					.setRequestProperty("User-Agent",
							"Mozilla/5.0 (Windows NT 6.2; rv:21.0) Gecko/20100101 Firefox/21.0");

			System.out.println(Thread.currentThread().getName() + "从--"
					+ startSize + "---开始下载，到" + endSize + "结束");
			// 设置你读取的range的范围
			httpURLConnection.setRequestProperty("Range", "bytes=" + startSize
					+ "-" + endSize);

			// 获取输入流对象
			InputStream is = httpURLConnection.getInputStream();

			// 设置文件开始写入的位置
			threadFile.seek(startSize);
			// 缓冲区
			byte buffer[] = new byte[1024];
			// 读取的长度
			int len = 0;
			// 读取
			while ((len = is.read(buffer)) != -1) {
				// 写入
				threadFile.write(buffer, 0, len);
			}
			// 释放资源
			is.close();
			threadFile.close();
			httpURLConnection.disconnect();

		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

 

二、怎样查询AVI("video/x-msvideo")的类型

用枚举类FileType.java

package util;
/**
 * 枚举
 * @author yanmei
 *
 */

public enum FileType {
	/**
	 * type <mime-mapping> <extension>avi</extension>
	 * <mime-type>video/x-msvideo</mime-type> </mime-mapping>
	 */
	AVI("video/x-msvideo");
	private String value;
	private FileType(String value){
		this.value=value;
		
	}
	public String getValue(){
		return value;
	}
	public static FileType FindByValue(String value){
		FileType fileType=null;
		FileType  types[]=FileType.values();
		for(FileType type:types){
			if (type.getValue().equals(value)) {
				fileType=type;
				break;
			}
		}
		return fileType;
	}
}

 

测试类FileTest.java

package util;

import static org.junit.Assert.*;

import org.junit.Test;

public class FileTest {

	@Test
	public void test() {
		FileType fileType=FileType.FindByValue("video/x-msvideo");
		System.out.println(fileType.name());
	}

}