1线程管理
在这一节中，我们将学习如何创建和运行一个线程。在Java语言中，我们有两种方式创建一个线程：
1. 扩展Thread类，覆盖run()方法
2. 构建一个实现Runnable接口的类，定义自己run()方法，然后，实用则个类的实例对象作为Thread构造方法的参数来创建Thread对象。
创建一个线程对象，它不会创建一个新的执行线程。也就是说，调用一个实现了Runnable接口的类的run()方法，它不会创建一个新的执行线程。仅仅是调用start()方法时，一个新的线程才会被创建。
Thread类保存了一些能够帮助我们标示一个线程的属性信息。
1. ID: 每个线程独一无二的标识符。
2. Name: 存储线程的名称。
3. Priority: 线程对象的优先级属性，其值范围是0到10.除非有特殊要求，一般不推荐修改线程的优先级属性。
4. Status: 这个属性表示线程当前的状态，在Java中，有六种状态：new、runnable
Blocked、time waiting和terminated。
创建一个简单的线程程序。
public class Worker implements Runnable{
private intnumber;
/**
* Constructor of the class
* @param number : The number
*/
public Worker(intnumber) {
this.number=number;
}
/**
* Method that do the calculations
*/
@Override
public voidrun() {
for (int i=1; i<=10; i++){
System.out.printf("%s: %d * %d = %d\n",Thread.currentThread().getName(),number,i,i*number);
}
}
/**
* @param args
*/
public staticvoidmain(String[] args) {
//create 10 thread, chart one
long t1 = System.currentTimeMillis();
for(int i = 0 ; i < 10; i++){
Worker worker = new Worker(i);
Thread thread = new Thread(worker);
thread.start();
}
System.out.println("-----------------------"+(System.currentTimeMillis() - t1));
}
}
在看另一个搜索文件的功能，扫描指定文件目录下的文件。完整代码如下：
import java.io.File;
import java.util.concurrent.TimeUnit;
public class FileSearchRunnable implements Runnable {
/**
* Initial path for the search
*/
private StringinitPath;
/**
* Name of the file we are searching for
*/
private StringfileName;
/**
* Constructor of the class
*
* @param initPath
* : Initial path for the search
* @param fileName
* : Name of the file we are searching for
*/
public FileSearchRunnable(String initPath, String fileName) {
this.initPath = initPath;
this.fileName = fileName;
}
/**
* Main method of the class
*/
@Override
public voidrun() {
File file = new File(initPath);
if (file.isDirectory()) {
try {
directoryProcess(file);
} catch (InterruptedException e) {
System.out.printf("%s: The search has been interrupted",Thread.currentThread().getName());
cleanResources();
}
}
}
/**
* Method for cleaning the resources. In thiscase, is empty
*/
private voidcleanResources() {
}
/**
* Method that process a directory
*
* @param file
* : Directory to process
* @throws InterruptedException
* : If the thread is interrupted
*/
private voiddirectoryProcess(File file) throws InterruptedException {
// Get the content of the directory
File list[] = file.listFiles();
if (list !=null) {
for (int i = 0; i < list.length; i++) {
if (list[i].isDirectory()) {
// If is a directory, process it
directoryProcess(list[i]);
} else {
// If is a file, process it
fileProcess(list[i]);
}
}
}
// Check the interruption
if (Thread.interrupted()) {
throw new InterruptedException();
}
}
/**
* Method that process a File
*
* @param file
* : File to process
* @throws InterruptedException
* : If the thread is interrupted
*/
private voidfileProcess(File file) throws InterruptedException {
System.out.println("current file : "+file.getAbsolutePath());
// Check the name
if (file.getName().equals(fileName)) {
System.out.printf("%s : %s\n",Thread.currentThread().getName(),file.getAbsolutePath());
System.exit(0);
}
// Check the interruption
if (Thread.interrupted()) {
throw new InterruptedException();
}
}
/**
* @param args
*/
public staticvoidmain(String[] args) {
FileSearchRunnable searcher=new FileSearchRunnable("C:\\","USERPRIKEY.HS");
Thread thread=new Thread(searcher);
// Starts the Thread
thread.start();
// Wait for ten seconds
try {
TimeUnit.SECONDS.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}