java 多线程处理一个list的集合

 

原文：http://blog.csdn.net/jenny8080/article/details/52100312

 

将一组数据平均分成n组
/**
 * 将一组数据平均分成n组
 *
 * @param source 要分组的数据源
 * @param n      平均分成n组
 * @param <T>
 * @return
 */
public static <T> List<List<T>> averageAssign(List<T> source, int n) {
    List<List<T>> result = new ArrayList<List<T>>();
    int remainder = source.size() % n;  //(先计算出余数)
    int number = source.size() / n;  //然后是商
    int offset = 0;//偏移量
    for (int i = 0; i < n; i++) {
        List<T> value = null;
        if (remainder > 0) {
            value = source.subList(i * number + offset, (i + 1) * number + offset + 1);
            remainder--;
            offset++;
        } else {
            value = source.subList(i * number + offset, (i + 1) * number + offset);
        }
        result.add(value);
    }
    return result;
}

 

 

 

 

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import com.ziyun.cms.util.CalcFoldMD5Util;
import com.ziyun.cms.util.MD5Util;

public class App {

    public static void main(String[] args) {
        try {
            long start = System.currentTimeMillis();
            
            String folderPath= "D:\\test\\ABC";
 
            List<File> list = CalcFoldMD5Util.getFileList(new File(folderPath));

            Map map = averageAssign(list, 0, folderPath);
            
            long end = System.currentTimeMillis();
            System.out.println((end - start)/1000 + "秒");
            
            map.forEach((key, value) -> {
                System.out.println(key + ":" + value);
            });
            
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
 
    
    /**
     * 将一组数据平均分成n组
     *
     * @param source 要分组的数据源
     * @param n      平均分成n组
     * @param <T>
     * @return
     * @throws ExecutionException 
     * @throws InterruptedException 
     */
    public static Map averageAssign(List<File> source, final int nThreads, String path) throws InterruptedException, ExecutionException  {
        if (source == null || source.isEmpty()) {
            return null;
        }
        ExecutorService executorService = Executors.newFixedThreadPool(nThreads);
        List<Future<Map>> futures = new ArrayList<Future<Map>>(nThreads);
        String path1 = path.replaceAll("\\\\", "/");
        
        Map map = new HashMap(1000);
        
        int remainder = source.size() % nThreads;  //(先计算出余数)
        int number = source.size() / nThreads;  //然后是商
        int offset = 0;//偏移量
        for (int i = 0; i < nThreads; i++) {
            List<File> value = null;
            if (remainder > 0) {
                value = source.subList(i * number + offset, (i + 1) * number + offset + 1);
                remainder--;
                offset++;
            } else {
                value = source.subList(i * number + offset, (i + 1) * number + offset);
            }
            
            final List<File> subList = value;
            Callable<Map> task = new Callable<Map>() {
                public Map call() throws Exception {
                    Map<String, String> map = new HashMap<String, String>(300);
                    for (File file : subList) {
                        //文件夹不比较md5值
                        if (file.isFile()) {
                            String key = file.getAbsolutePath().replaceAll("\\\\", "/").replace(path1, "");
                            String md5 = MD5Util.calcMD5(file);
                            map.put(key, md5);
                        }
                    }
                    return map;
                    
                }
            };
            futures.add(executorService.submit(task));
        }
        for (Future<Map> future : futures) {
            map.putAll(future.get());
        }
        executorService.shutdown();

         // 等待子线程结束，再继续执行下面的代码
        executorService.awaitTermination(180, TimeUnit.SECONDS);

return map;
    }
}