JDK7并行计算框架介绍二 Fork/Join开发实例

开发环境：

JDK7.0 + Eclipse3.6 + JUnit4

完整代码：

代码文件一：SortTask.java

package forktest; import java.util.*; import java.util.concurrent.RecursiveAction; import java.util.concurrent.ForkJoinPool; import java.util.concurrent.ForkJoinTask; import junit.*; public class SortTask extends RecursiveAction {     final long[] array;     final int hi;     final int lo;     private int THRESHOLD = 30;     //构造函数     public SortTask(long[] array)     {         this.array = array;         this.lo = 0;         this.hi = array.length - 1;             }     //构造函数     public SortTask(long[] array,int lo,int hi)     {         this.array = array;         this.lo = lo;         this.hi = hi;             }     //implement RecusiveTask must     protected void compute() {         if(hi - lo < THRESHOLD) {             sequentiallySort(array,lo,hi);                      }         else         {               int pivot = partition(array,lo,hi);             System.out.println("\npivot = " + pivot + ", low = " + lo + ", high = " + hi);             System.out.println("array" + Arrays.toString(array));             //注意此处接口有变化，老版本是coInvake，已不支持该接口             invokeAll(new SortTask(array,lo,pivot-1),new SortTask(array,pivot+1,hi));           }     }     //任务分割     private int partition(long[] array,int lo,int hi){         long x = array[hi];         int i = lo - 1;         for (int j = lo; j < hi; j++) {             if (array[j] <= x) {                  i++;                  swap(array, i, j);             }         }         swap(array, i + 1, hi);         return i+1;     }     //执行排序     private void sequentiallySort(long[] array,int lo,int hi){         Arrays.sort(array,lo,hi+1);     }     //数值交换     private void swap(long[] array,int i,int j){         if(i !=j)         {             long tmp = array[i];             array[i] = array[j];             array[j] = tmp;                     }     } }

代码文件二：TestForkJoinSimple.java

package forktest; import junit.*; import org.junit.Before; import org.junit.Test; import static org.junit.Assert.*; import java.util.*; import java.util.concurrent.TimeUnit; import java.util.concurrent.RecursiveAction; import java.util.concurrent.ForkJoinPool; import java.util.concurrent.ForkJoinTask; import forktest.SortTask; public class TestForkJoinSimple {     private static final int NARRAY = 16; //For demo only     long[] array = new long[NARRAY];     Random rand = new Random();     @Before     public void setUp() {         for (int i = 0; i < array.length; i++) {             array[i] = rand.nextLong()%100; //For demo only         }     }     @Test     public void testSort() throws Exception {         ForkJoinTask sort = new SortTask(array);         ForkJoinPool fjpool = new ForkJoinPool();         fjpool.submit(sort);         fjpool.shutdown();         fjpool.awaitTermination(30, TimeUnit.SECONDS);         assertTrue(checkSorted(array));     }     boolean checkSorted(long[] a) {         for (int i = 0; i < a.length - 1; i++) {             if (a[i] > (a[i + 1])) {                 return false;             }         }         return true;     } }

运行结果：

pivot = 5, low = 0, high = 15 array[-88, -97, -25, -33, -25, 10, 62, 91, 43, 85, 35, 26, 57, 78, 66, 79] pivot = 4, low = 0, high = 4 array[-88, -97, -25, -33, -25, 10, 62, 91, 43, 85, 35, 26, 57, 78, 66, 79] pivot = 2, low = 0, high = 3 array[-88, -97, -33, -25, -25, 10, 62, 91, 43, 85, 35, 26, 57, 78, 66, 79] pivot = 0, low = 0, high = 1 array[-97, -88, -33, -25, -25, 10, 62, 91, 43, 85, 35, 26, 57, 78, 66, 79] pivot = 1, low = 1, high = 1 array[-97, -88, -33, -25, -25, 10, 62, 91, 43, 85, 35, 26, 57, 78, 66, 79] pivot = 3, low = 3, high = 3 array[-97, -88, -33, -25, -25, 10, 62, 91, 43, 85, 35, 26, 57, 78, 66, 79] pivot = 13, low = 6, high = 15 array[-97, -88, -33, -25, -25, 10, 62, 43, 35, 26, 57, 78, 66, 79, 91, 85] pivot = 11, low = 6, high = 12 array[-97, -88, -33, -25, -25, 10, 62, 43, 35, 26, 57, 66, 78, 79, 91, 85] pivot = 9, low = 6, high = 10 array[-97, -88, -33, -25, -25, 10, 43, 35, 26, 57, 62, 66, 78, 79, 91, 85] pivot = 6, low = 6, high = 8 array[-97, -88, -33, -25, -25, 10, 26, 35, 43, 57, 62, 66, 78, 79, 91, 85] pivot = 8, low = 7, high = 8 array[-97, -88, -33, -25, -25, 10, 26, 35, 43, 57, 62, 66, 78, 79, 91, 85] pivot = 7, low = 7, high = 7 array[-97, -88, -33, -25, -25, 10, 26, 35, 43, 57, 62, 66, 78, 79, 91, 85] pivot = 10, low = 10, high = 10 array[-97, -88, -33, -25, -25, 10, 26, 35, 43, 57, 62, 66, 78, 79, 91, 85] pivot = 12, low = 12, high = 12 array[-97, -88, -33, -25, -25, 10, 26, 35, 43, 57, 62, 66, 78, 79, 91, 85] pivot = 14, low = 14, high = 15 array[-97, -88, -33, -25, -25, 10, 26, 35, 43, 57, 62, 66, 78, 79, 85, 91] pivot = 15, low = 15, high = 15 array[-97, -88, -33, -25, -25, 10, 26, 35, 43, 57, 62, 66, 78, 79, 85, 91]

注意事项：

JDK版本必须是7.0及以上版本，否则不支持；JUnit必须是4.0及以上版本，否则不支持。