ThreadPool

1.代码示例

package threadPool;import java.io.*;import java.util.*;import java.util.concurrent.*;/** * @version 1.02 2015-06-21 * @author Cay Horstmann */public class ThreadPoolTest{   public static void main(String[] args) throws Exception   {      try (Scanner in = new Scanner(System.in))      {         System.out.print("Enter base directory (e.g. /usr/local/jdk5.0/src): ");         String directory = in.nextLine();         System.out.print("Enter keyword (e.g. volatile): ");         String keyword = in.nextLine();            ExecutorService pool = Executors.newCachedThreadPool();            MatchCounter counter = new MatchCounter(new File(directory), keyword, pool);         Future<Integer> result = pool.submit(counter);            try         {            System.out.println(result.get() + " matching files.");         }         catch (ExecutionException e)         {            e.printStackTrace();         }         catch (InterruptedException e)         {         }         pool.shutdown();            int largestPoolSize = ((ThreadPoolExecutor) pool).getLargestPoolSize();         System.out.println("largest pool size=" + largestPoolSize);      }   }}/** * This task counts the files in a directory and its subdirectories that contain a given keyword. */class MatchCounter implements Callable<Integer>{   private File directory;   private String keyword;   private ExecutorService pool;   private int count;   /**    * Constructs a MatchCounter.    * @param directory the directory in which to start the search    * @param keyword the keyword to look for    * @param pool the thread pool for submitting subtasks    */   public MatchCounter(File directory, String keyword, ExecutorService pool)   {      this.directory = directory;      this.keyword = keyword;      this.pool = pool;   }   public Integer call()   {      count = 0;      try      {         File[] files = directory.listFiles();         List<Future<Integer>> results = new ArrayList<>();         for (File file : files)            if (file.isDirectory())            {               MatchCounter counter = new MatchCounter(file, keyword, pool);               Future<Integer> result = pool.submit(counter);               results.add(result);            }            else            {               if (search(file)) count++;            }         for (Future<Integer> result : results)            try            {               count += result.get();            }            catch (ExecutionException e)            {               e.printStackTrace();            }      }      catch (InterruptedException e)      {      }      return count;   }   /**    * Searches a file for a given keyword.    * @param file the file to search    * @return true if the keyword is contained in the file    */   public boolean search(File file)   {      try      {         try (Scanner in = new Scanner(file, "UTF-8"))         {            boolean found = false;            while (!found && in.hasNextLine())            {               String line = in.nextLine();               if (line.contains(keyword)) found = true;            }                     return found;         }      }      catch (IOException e)      {         return false;      }   }}