多线程 各线程返回值控制

在网上看到很多同事问多线程时，获取子线程的返回值的问题，今天特意看了一下，其实JDK1.6里面已经完全支持了

不但可以控制子线程的返回值，对于子线程的超时时间和终止，取消等都支持

public List<Long> getIdList(ScoreDoc[] scoreDocs, IndexSearcher search)
throws CorruptIndexException, IOException, InterruptedException, ExecutionException {
final int records = 10000;
int len = scoreDocs.length;
List<ScoreDoc[]> scoreDocList = new ArrayList<ScoreDoc[]>(len);
Map<String, FieldSelectorResult> fieldSelections = new HashMap<String, FieldSelectorResult>(
1);
fieldSelections.put("id", FieldSelectorResult.LOAD);
FieldSelector fieldSelector = new MapFieldSelector(fieldSelections);
int threadCount = len / records;
int modCount = len % records;
int srcPos = 0;
if (threadCount > 0 && modCount != 0) {
for (int i = 0; i < threadCount; i++) {
ScoreDoc[] idsArry = new ScoreDoc[records];
System.arraycopy(scoreDocs, srcPos, idsArry, 0, records);
scoreDocList.add(idsArry);
srcPos = srcPos + records;
}
ScoreDoc[] idsArry = new ScoreDoc[modCount];
System.arraycopy(scoreDocs, srcPos, idsArry, 0, modCount);
scoreDocList.add(idsArry);

} else if (threadCount == 0 && modCount != 0) {
ScoreDoc[] idsArry = new ScoreDoc[modCount];
System.arraycopy(scoreDocs, 0, idsArry, 0, modCount);
scoreDocList.add(idsArry);
}

[color=blue][b]Executor executor = Executors.newFixedThreadPool(scoreDocList.size());
List<Long> ids = new ArrayList<Long>(len);
for (int i = 0; i < scoreDocList.size(); i++) {
FutureTask<List<Long>> task = new FutureTask<List<Long>>(new ReadDoc(
scoreDocList.get(i), search, fieldSelector));
executor.execute(task);
ids.addAll(task.get());
}[/b][/color]
return ids;
}

//线程实现类
class ReadDoc implements Callable<List<Long>> {
private ScoreDoc[] scoreDocs;
private IndexSearcher search;
private FieldSelector fieldSelector;

public ReadDoc(ScoreDoc[] scoreDocs, IndexSearcher search, FieldSelector fieldSelector) {
this.scoreDocs = scoreDocs;
this.search = search;
this.fieldSelector = fieldSelector;
}

/*
* (non-Javadoc)
* @see java.util.concurrent.Callable#call()
*/
@Override
public List<Long> call() throws Exception {
List<Long> ids = new ArrayList<Long>();
获取ID集合
for (int i = 0; i < scoreDocs.length; i++) {
Document doc = search.doc(scoreDocs[i].doc, fieldSelector);
ids.add(Long.valueOf(doc.getFieldable("id").stringValue()));
}
return ids;
}
}