处理java异常(handling java exception)

 这个问题与java异常有关，为什么有些情况下，即使异常被捕获并且没有exit（）语句，程序也会退出，但是当抛出异常时？ 我的代码看起来像这样 
 
    void bindProxySocket(DefaultHttpClientConnection proxyConnection, String hostName, HttpParams params)
{
    if (!proxyConnection.isOpen()) 
    {

        Socket socket = null;
        try {
            socket = new Socket(hostName, 80);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try
        {
            proxyConnection.bind(socket, params);
        }
        catch(IOException e)
        {
            System.err.println ("couldn't bind socket");
            e.printStackTrace();
        }
    }
}
 
 接着 
 
 我将这种方法称为： 
 
bindProxySocket(proxyConn, hostName, params1);
 
 但是，程序退出了，尽管我想通过执行其他操作来处理异常，是否可以这样，因为我没有在try catch子句中包含方法调用？ 如果我再次捕获异常，即使它已经在方法中，会发生什么？ 以及如果我想只在发生异常时清除finally子句中的资源，否则我该怎么办？否则，我想继续执行该程序？ 我猜在这种情况下，我必须包括整段代码，直到我可以用try语句清理资源，或者我可以在句柄异常声明中执行它吗？ 其中一些问题是针对这个具体案例的，但我想对我所有的问题都做出全面的回答以备将来参考。 谢谢 
 
 编辑： 
 
java.net.UnknownHostException: www.dsewew324f.com
    at java.net.PlainSocketImpl.connect(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)
    at homework3.Proxy.bindProxySocket(Proxy.java:666)
    at homework3.Proxy$3.handle(Proxy.java:220)
    at org.apache.http.protocol.HttpService.doService(HttpService.java:293)
    at org.apache.http.protocol.HttpService.handleRequest(HttpService.java:212)
    at homework3.Proxy.start(Proxy.java:472)
    at homework3.Proxy.main(Proxy.java:1282)
Exception in thread "main" java.lang.IllegalArgumentException: Socket may not be null
    at org.apache.http.impl.DefaultHttpClientConnection.bind(DefaultHttpClientConnection.java:80)
    at homework3.Proxy.bindProxySocket(Proxy.java:674)

This questions is related to java exceptions, why are there some cases that when an exception is thrown the program exits even though the exception was caught and there was no exit() statement? my code looks something like this
 
    void bindProxySocket(DefaultHttpClientConnection proxyConnection, String hostName, HttpParams params)
{
    if (!proxyConnection.isOpen()) 
    {

        Socket socket = null;
        try {
            socket = new Socket(hostName, 80);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try
        {
            proxyConnection.bind(socket, params);
        }
        catch(IOException e)
        {
            System.err.println ("couldn't bind socket");
            e.printStackTrace();
        }
    }
}
 
and then
 
I call this method like this:
 
bindProxySocket(proxyConn, hostName, params1);
 
but, the program exits, although I want to handle the exception by doing something else, can it be because I didn't enclose the method call within a try catch clause? what happens if I catch the exception again even though it's already in the method? and what should I do if i want to clean resources in the finally clause only if an exception occurs and otherwise I want to continue with the program? I am guessing in this case I have to include the whole piece of code until I can clean the resources with in a try statement or can I do it in the handle exception statement? some of these questions are on this specific case, but I would like to get a thorough answer to all my questions for future reference. thanks
 
edit:
 
java.net.UnknownHostException: www.dsewew324f.com
    at java.net.PlainSocketImpl.connect(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)
    at homework3.Proxy.bindProxySocket(Proxy.java:666)
    at homework3.Proxy$3.handle(Proxy.java:220)
    at org.apache.http.protocol.HttpService.doService(HttpService.java:293)
    at org.apache.http.protocol.HttpService.handleRequest(HttpService.java:212)
    at homework3.Proxy.start(Proxy.java:472)
    at homework3.Proxy.main(Proxy.java:1282)
Exception in thread "main" java.lang.IllegalArgumentException: Socket may not be null
    at org.apache.http.impl.DefaultHttpClientConnection.bind(DefaultHttpClientConnection.java:80)
    at homework3.Proxy.bindProxySocket(Proxy.java:674)

原文：https://stackoverflow.com/questions/2700705