打發(fā)22點(diǎn)~24點(diǎn)

Java中Stream和parallelStream，前者是單管，后者是多管，運(yùn)行時(shí)間上做一個(gè)小對(duì)比，直接上代碼：

/**
 * 
 * @author zhangy6
 * <p>對(duì)比Stream、parallelStream</p>
 * @date 2017-07-25
 */
public class StreamTest {
    public static void main(String[] args) {
        String path = "pku_training.utf8";
        try {
            List<String> list = IOUtil.readFile2List(path, "utf-8");
            
            long start = System.currentTimeMillis();
            list.stream().
            filter(e -> StringUtils.isNotBlank(e)).
            map(e -> getIdiom(e)).
            collect(Collectors.toList());
            System.out.println("stream : " + (System.currentTimeMillis() - start) + "ms");
            
            start = System.currentTimeMillis();
            list.parallelStream().
            filter(e -> StringUtils.isNotBlank(e)).
            map(e -> getIdiom(e)).
            collect(Collectors.toList());
            System.out.println("parallelStream : " + (System.currentTimeMillis() - start) + "ms");
            
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
    
    private static List<String> getIdiom(String string) {
        String[] array = string.split("\\s+");
        List<String> list = Arrays.asList(array);
        
        return list.stream().filter(e -> e.length() == 4).collect(Collectors.toList());
    }
}

代碼是讀取一個(gè)分詞訓(xùn)練語(yǔ)料，大小7.37MB，然后找出其中四個(gè)字的單詞/成語(yǔ)，對(duì)比一下Stream和ParallelStream運(yùn)行時(shí)間（筆記本win10），結(jié)果如下：

stream : 317ms
parallelStream : 90ms

多管就是比單管強(qiáng)很多，線程都不用了。