我想使用ExecutorService来运行一系列相同的Runnable / Callable任务。我一直在寻找一个教程或一个例子，但没有涉及实际设置现有Runnable / Callable对象的值，然后使用submit（）将该对象发送回ExecutorService。
基本上，这就是我想要做的事情：
InetAddress.getByName(host)来获取每台主机上的数据。 所以，现在，有10,000（+）台服务器，它需要永远。所以，我的想法是使用ExecutorService来管理线程池。我似乎无法弄清楚的是如何检测一个线程何时完成，以便我可以获取数据。然后我需要获取列表中的下一个服务器，将其放入Task中，然后将（）提交回ExecutorService。
那就是说，到目前为止我所读到的内容似乎指向以下内容：ExecutorService，submit（），Callable，Future。
所以，作为伪造的过程：
因此，这方面的教程或示例会很棒...尤其是将新值放入WorkerTask（）的示例。此外，我对这个提议的解决方案有任何想法吗？这是坏的，好的，或者如果有另一种方式，我是开放的。
02/09/2014 - 编辑并添加
嗨，所以以下是第一次切入。但回答提出的一些问题：
- 我已经解决了将新数据放入Worker并重新提交到ExecutorService的问题...请参阅代码段。
- 我也解决了“获取内容”的问题......我只是将Future（）结果转换为Worker类...请参阅代码片段。
- 最后，虽然我可以将每个服务器分配给Worker（）和Future（），但我担心当前10,000会增长并且内存将成为问题。
那就是说，这是第一次尝试，而且效果很好。运行速度更快，只使用getNumbnerThreads（）Worker和Future对象：
public List<ServerBean> lookupHostIps ( List<ServerBean> theServerList ) {
//ServerBean serverDto = null;
ServerBean ipDto = null;
List<ServerBean> theResults = new ArrayList<ServerBean>();
List<HostLookupWorker> theWorkers = new ArrayList<HostLookupWorker>( getNumberThreads() );
List<Future<HostLookupWorker>> theFutures = new ArrayList<Future<HostLookupWorker>>( getNumberThreads() );
ExecutorService executor = Executors.newFixedThreadPool ( getNumberThreads() );
// WORKERS : Create the workers...prime them with a server
// bean...
//
for (int j = 0; j < getNumberThreads(); j++) {
//for (int j = 0; j < theServerList.size(); j++) {
theWorkers.add ( new HostLookupWorker( theServerList.get(j) ) );
Future<HostLookupWorker> theFuture = executor.submit ( theWorkers.get ( j ) );
theFutures.add ( j, theFuture );
}
int lloopItems = getNumberThreads(); /* loops thru all servers */
//int lloopThreads = 0; /* loops thru threads */
int lidxThread = 0; /* what thread is ready */
//int lidxFuture = 0; /* what future is ready */
boolean lblnNext = false; /* is a thread done/ready */
int lidxWorkers = 0; /* tracks the futures */
while ( lloopItems < theServerList.size() ) {
// READY : Is one of the threads ready for more work?
if ( lblnNext ) {
// VALUE : Grab the thread by index and set the next
// server value.
theWorkers.get ( lidxThread ).setBean ( theServerList.get(lloopItems) );
getLog().debug ( "Thread [" + lidxThread + "] Assigned Host ["+theServerList.get(lloopItems).getServerName ()+"] " );
// FUTURE : Package a new Future<HostLookupWorker>
// and submit it to the thread pool.
Future<HostLookupWorker> theFuture = executor.submit ( theWorkers.get ( lidxThread ) );
theFutures.add ( lidxThread, theFuture );
lblnNext = false; /* reset to allow for another thread */
lloopItems++; /* increment the main loop counter */
}
while ( !(lblnNext) ) {
try {
if ( theFutures.get(lidxWorkers).get() != null ) {
// GET THE STUFF : Grab the results from the Future...
HostLookupWorker ltheItem = theFutures.get(lidxWorkers).get();
if ( ltheItem.getValue () != null ) {
if (!ltheItem.getValue ().contains("Cannot find host")){
ipDto = new ServerBean ();
ipDto.setServerId ( ltheItem.getBean ().getServerId() );
ipDto.setServerName ( ltheItem.getBean ().getServerName() );
ipDto.setIpAddress ( ltheItem.getValue () );
theResults.add(ipDto);
}
lidxThread = lidxWorkers; /* this thread is ready for more work */
lblnNext = true; /* flag the upper condition to assign new work */
getLog().debug ( "Thread [" + lidxThread + "] Host ["+ltheItem.getHost ()+"] has IP ["+ltheItem.getValue()+"]" );
}
}
else {
getLog().debug ( "Thread [" + lidxThread + "] NULL" );
}
lidxWorkers++; /* next worker/future */
if ( lidxWorkers >= getNumberThreads() ) {
lidxWorkers = 0;
}
}
catch(ExecutionException e){
getLog().error ( e );
}
catch(InterruptedException e){
getLog().error ( e );
}
}
}
executor.shutdown ();
return theResults;
}
这是Worker / Thread类：
import java.net.*;
import java.util.concurrent.Callable;
import com.lmig.cdbatch.dto.ServerBean;
public class HostLookupWorker implements Callable {
private InetAddress node = null;
private String value = null;
private boolean busy = false;
private ServerBean bean = null;
public HostLookupWorker () {
this.busy = false;
}
// public HostLookupWorker ( String theHost ) {
// this.busy = false;
// this.host = theHost;
// }
public HostLookupWorker ( ServerBean theItem ) {
this.busy = false;
this.bean = theItem;
//this.host = theItem.getServerName ().trim ();
}
public String lookup ( String host ) {
if ( host != null ) {
// get the bytes of the IP address
try {
this.node = InetAddress.getByName ( host );
}
catch ( UnknownHostException ex ) {
this.value = "Not Found [" + getHost() + "]";
return "Not Found [" + host + "]";
}
if ( isHostname(host) ) {
getBean().setIpAddress ( node.getHostAddress() );
return node.getHostAddress();
}
else { // this is an IP address
//return node.getHostName();
return host;
}
}
return host;
} // end lookup
public boolean isHostname(String host) {
// Is this an IPv6 address?
if (host.indexOf(':') != -1)
return false;
char[] ca = host.toCharArray();
// if we see a character that is neither a digit nor a period
// then host is probably a hostname
for (int i = 0; i < ca.length; i++) {
if (!Character.isDigit(ca[i])) {
if (ca[i] != '.')
return true;
}
}
// Everything was either a digit or a period
// so host looks like an IPv4 address in dotted quad format
return false;
} // end isHostName
// public void run() {
// value = lookup ( getHost() );
//
// }
public Object call() throws Exception {
Thread.sleep ( 10000 );
this.busy = true;
this.value = lookup ( getHost() );
this.busy = false;
return this;
}
public String getHost() {
return getBean().getServerName ().trim ();
}
public void setHost(String host) {
getBean().setServerName ( host.trim () );
}
public InetAddress getNode() {
return node;
}
public void setNode(InetAddress node) {
this.node = node;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
public boolean isBusy() {
return busy;
}
public void setBusy(boolean busy) {
this.busy = busy;
}
public ServerBean getBean() {
return bean;
}
public void setBean(ServerBean bean) {
this.bean = bean;
}
}
所以，总结一下：
- 这个过程确实有效，并且工作得很快
- 我需要修改一下代码，因为有getNumberThreads（） - 当更大的while（）循环结束时，1期货未经处理...
所以，我现在正在努力的是如何检测线程何时完成...我已经看到了多个示例，一个测试Future（）！= null，其他测试Future（）== null 。那么哪一个是对的？
答案 0 :(得分：0)
我认为在这种情况下最好的方法是为每个服务器创建一个任务，因为它们将由pull中的线程执行，然后使用tge future对象来检索任务返回的服务器信息。