将JVM/JRE设置为自动使用Windows代理

Question

我确实看到了关于为JVM设置代理的问题,但我想问的是如何利用已经配置的代理(在Windows上).

这是我的问题的演示:

1. 转到控制面板 - > Java并设置代理地址.
2. 运行以下简单的applet代码(我正在使用Eclipse IDE):

import java.awt.Graphics;
import javax.swing.JApplet;
import java.util.*;

public class Stacklet extends JApplet {
    private String message;
    public void init(){
        Properties props = System.getProperties();
        message = props.getProperty("http.proxyHost", "NONE");      
        message = (message.length() == 0)? "NONE": message;
    }

    public void paint(Graphics g)
    {
        g.drawString(message, 20, 20);
    }
}

Applet显示"NONE",而不考虑您在Java控制面板中放置的设置.如果Windows代理设置(通常在Internet Explorer中设置)是我可以确定的,但在Java控制面板中执行额外的配置步骤仍然是可接受的解决方案,那将是最好的.

谢谢!

Answer 1

可以使用ProxySelector类检测代理,并通过使用System类的setProperty方法分配环境变量来分配系统代理:

System.setProperty("java.net.useSystemProxies", "true");
System.out.println("detecting proxies");
List l = null;
try {
    l = ProxySelector.getDefault().select(new URI("http://foo/bar"));
} 
catch (URISyntaxException e) {
    e.printStackTrace();
}
if (l != null) {
    for (Iterator iter = l.iterator(); iter.hasNext();) {
        java.net.Proxy proxy = (java.net.Proxy) iter.next();
        System.out.println("proxy type: " + proxy.type());

        InetSocketAddress addr = (InetSocketAddress) proxy.address();

        if (addr == null) {
            System.out.println("No Proxy");
        } else {
            System.out.println("proxy hostname: " + addr.getHostName());
            System.setProperty("http.proxyHost", addr.getHostName());
            System.out.println("proxy port: " + addr.getPort());
            System.setProperty("http.proxyPort", Integer.toString(addr.getPort()));
        }
    }
}

Answer 2

我在这里发现了一个奇怪的行为,试验了建议的代码.

看来,在设置了默认的ProxySelector之后,常规套接字代码(例如创建一个新的Socket)不再起作用了,因为它试图使用socks服务器(不知道为什么会这样做,但对我来说它确实如此) .

所以,如果你,在打电话时

Socket socket = new Socket(host, port);

你收到这样的SocketException:

java.net.SocketException: Malformed reply from SOCKS server
    at java.net.SocksSocketImpl.readSocksReply(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)
    at java.net.Socket.<init>(Unknown Source)

然后尝试将默认的ProxySelector设置为null:

ProxySelector.setDefault(null);

对我来说,这导致了以下小型Java类,我现在用它来简单地检索系统代理设置,而不会影响应用程序的Sockets()的进一步使用,同时正确配置系统以使用代理:

public class ProxyConfig {

  private static String host;
  private static int port;

  public static void init() {
    System.setProperty("java.net.useSystemProxies", "true");
    Proxy proxy = getProxy();
    if (proxy != null) {
      InetSocketAddress addr = (InetSocketAddress) proxy.address();
      host = addr.getHostName();
      port = addr.getPort();

      System.setProperty("java.net.useSystemProxies", "false");
      System.setProperty("http.proxyHost", host);
      System.setProperty("http.proxyPort", ""+port);

    }
    System.setProperty("java.net.useSystemProxies", "false");
  }

  public static String getHost() {
    return host;
  }

  public static int getPort() {
    return port;
  }

  private static Proxy getProxy() {
    List<Proxy> l = null;
    try {
      ProxySelector def = ProxySelector.getDefault();

      l = def.select(new URI("http://foo/bar"));
      ProxySelector.setDefault(null);
    } catch (Exception e) {
      e.printStackTrace();
    }
    if (l != null) {
      for (Iterator<Proxy> iter = l.iterator(); iter.hasNext();) {
        java.net.Proxy proxy = iter.next();
        return proxy;
      }
    }
    return null;
  }
}

Answer 3

这可能有点晚了,但我遇到了同样的问题.我修复它的方法是使用-Djava.net.useSystemProxies = true作为jvm参数.

"请注意,此属性仅在启动时检查一次."

此属性在启动时设置,因此在运行应用程序时不会更改.

我希望这有帮助.

参考:https: //docs.oracle.com/javase/7/docs/api/java/net/doc-files/net-properties.html