小编Ste*_*han的帖子

List<String> list = Collections.synchronizedList(new ArrayList<String>());
synchronized (list) {
    list.add("message");
}

块"synchronized(list){}"真的需要吗？

我正在使用Apache HttpClient 4,它工作正常.唯一不起作用的是自定义端口.似乎提取了根目录并忽略了端口.

HttpPost post = new HttpPost("http://myserver.com:50000");
HttpResponse response = httpClient.execute(post);

如果没有定义端口,则http-和https-connections运行良好.方案登记处的定义如下:

final SchemeRegistry sr = new SchemeRegistry();

final Scheme http = new Scheme("http", 80,
      PlainSocketFactory.getSocketFactory());
sr.register(http);

final SSLContext sc = SSLContext.getInstance(SSLSocketFactory.TLS);
  sc.init(null, TRUST_MANAGER, new SecureRandom());
SSLContext.setDefault(sc);

final SSLSocketFactory sf = new SSLSocketFactory(sc,
      SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);

final Scheme https = new Scheme("https", 443, sf);
  sr.register(https);

如何为请求定义自定义端口？

我正在通过Jsch上传SFTP的大文件.在上传过程中,旧文件应该可用,因此我上传到临时文件并将其重命名为新文件.

final String tmpName = dest + "_tmp";
channel.put(source, tmpName);
channel.rename(tmpName, dest);

上传没问题,但重命名失败:

ERROR: Failed to upload files
4: Failure
at com.jcraft.jsch.ChannelSftp.throwStatusError(ChannelSftp.java:2491)
at com.jcraft.jsch.ChannelSftp.rename(ChannelSftp.java:1665)
    ...

我无法弄清楚问题出在哪里.请帮忙

我想设置JPopupMenu打开菜单的按钮的y位置的位置.我的代码在我的第一台显示器上工作正常,但在我的第二台显示器上失败,它有不同的高度.问题是getLocationOnScreen()提供相对于主屏幕的位置,而不是显示组件的实际屏幕.

我的代码:

// screenSize represents the size of the screen where the button is
// currently showing
final Rectangle screenSize = dateButton.getGraphicsConfiguration().getBounds();

final int yScreen = screenSize.height;
int preferredY;

// getLocationOnScreen does always give the relative position to the main screen
if (getLocationOnScreen().y + dateButton.getHeight() + datePopup.getPreferredSize().height > yScreen) {
  preferredY = -datePopup.getPreferredSize().height;
} else {
  preferredY = getPreferredSize().height;
}

datePopup.show(DateSpinner.this, 0, preferredY);

如何在实际监视器上获取组件的位置？