这建立在我的previous question上。java线程从静态内部类访问外部类
我的ftp服务器有10个文件,比如test1.txt,test2.txt等等。我希望能够同时下载多个文件(最多3个)。我打电话downloadFilesByPattern(....)
如果我不使用downloadFile()同步,那么只有一些文件不是全部下载。如果我使用同步,那么所有的文件都会下载,但我不认为它们并行发生。问题是因为实例变量被传递给所有线程,并且该实例上的方法被所有线程调用。
public class FTPClientService implements IClient {
private String username;
private String password;
private String port;
private String host;
private String path;
FTPClient client = new FTPClient();
private static class DownloadTask implements Runnable {
private String name;
private String toPath;
private IClient client;
public DownloadTask(String name, String toPath, IClient client) {
this.name = name;
this.toPath = toPath;
this.client = client;
}
@Override
public void run() {
System.out.println("download = " + name);
client.downloadFile(name, toPath);
}
}
public void downloadFilesByPattern(String fileNamePattern, final String outputFilePath) {
if(!changeDirectory()){
return;
}
try {
//get a list of file names that match the pattern
String[] names = client.listNames();
ExecutorService pool = Executors.newFixedThreadPool(3);
for (String name : names) {
//check if the filename matches the pattern
Pattern pattern = Pattern.compile(fileNamePattern);
Matcher matcher = pattern.matcher(name);
if(matcher.find()){
System.out.println("Match found = " + name);
pool.submit(new DownloadTask(name, outputFilePath, this));
}else{
System.out.println("No match = " + name);
}
}
pool.shutdown();
try {
pool.awaitTermination(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
} catch (InterruptedException ex) {
}
} catch (IOException ex) {
}
}
public synchronized void downloadFile(String fileName, String outputFilePath) {
FileOutputStream fos = null;
try {
fos = new FileOutputStream(outputFilePath+"/"+fileName);
if(this.isFilePresent(fileName)){
//look for fileName in the path and write it to
client.retrieveFile(fileName, fos);
System.out.println("Downloading file " + fileName + " ...");
}else{
System.out.println("Could not find file " + fileName);
}
} catch (IOException ex) {
} finally {
try {
fos.close();
} catch (IOException ex) {
}
}
}
}
谢谢你将改变名称 – user373201