What does the exception "java.net.SocketException: Connection reset by peer" mean? How can this be avoided?
It usually happens when the connection was reset by the peer -- that is, when the client unexpectedly closed the socket. This happens when the user clicks "stop", or "reload", or "back", or enters a new URL, or closes his Internet connection, while a resource is still being downloaded (before your server gets to close its socket). This is normal behavior and you shouldn't worry about it.
The server is reporting "connection reset by peer" in the middle of a request. That means one of the following things:
- The browser started a request and the user pressed STOP.
- The browser started an request in one frame and JavaScript on another frame told it to go somewhere else (which has the same effect as a user pressing STOP).
- You have a meta refresh reload someplace that is firing so fast that the previous request hasn't had a chance to complete yet. The five second periodicity makes me pretty suspicious of this.
- You have some network component in between (a router or proxy) that is misbehaving.
- You have some completely separate connection attempts going on that are disobeying the HTTP protocol (such as doing a telnet connection to port 8080 and then disconnecting).
java URLConnection and timeout and non-blocking io
自从JDK1.5以后java.net.URLConnection加入了setConnectTimeout(int timeout)，但是也有办法在JDK1.5以前获得这个功能。
Adding Socket Timeout to java.net.URLConnection
HTTPClient Version 0.3-3
The Jakarta Commons HttpClient
另外，可以通过以下两个语句来设置相应的超时：
System.setProperty("sun.net.client.defaultConnectTimeout", 连接超时毫秒数);
System.setProperty("sun.net.client.defaultReadTimeout", 读数据超时毫秒数);
参见：http://java.sun.com/j2se/1.4.2/docs/guide/net/properties.html
google:set Timeout on URLConnection
Non-blocking IO and blocking queues
Well performing NIO code is a Good Thing. But getting details of how to do it right is difficult. The examples supplied with the JDK are complete noddy. There's a link on Sun's site to an example but that has a race condition. O'Reilly's NIO book cops out on how to use Selector properly. The thing that could make that book useful.
JAVA开发者应该去的20个英文网站
[http://www.javaalmanac.com] - Java开发者年鉴一书的在线版本. 要想快速查到某种Java技巧的用法及示例代码, 这是一个不错的去处.
[http://www.onjava.com] - O'Reilly的Java网站. 每周都有新文章.
[http://java.sun.com] - 官方的Java开发者网站 - 每周都有新文章发表.
[http://www.developer.com/java] - 由Gamelan.com 维护的Java技术文章网站.
[http://www.java.net] - Sun公司维护的一个Java社区网站.
[http://www.builder.com] - Cnet的Builder.com网站 - 所有的技术文章, 以Java为主.
[http://www.ibm.com/developerworks/java] - IBM的Developerworks技术网站; 这是其中的Java技术主页.
[http://www.javaworld.com] - 最早的一个Java站点. 每周更新Java技术文章.
[http://www.devx.com/java] - DevX维护的一个Java技术文章网站.
[http://www.fawcette.com/javapro] - JavaPro在线杂志网站.
[http://www.sys-con.com/java] - Java Developers Journal的在线杂志网站.
[http://www.javadesktop.org] - 位于Java.net的一个Java桌面技术社区网站.
[http://www.theserverside.com] - 这是一个讨论所有Java服务器端技术的网站.
[http://www.jars.com] - 提供Java评论服务. 包括各种framework和应用程序.
[http://www.jguru.com] - 一个非常棒的采用Q&A形式的Java技术资源社区.
[http://www.javaranch.com] - 一个论坛，得到Java问题答案的地方，初学者的好去处。
[http://www.ibiblio.org/javafaq/javafaq.html] - comp.lang.java的FAQ站点 - 收集了来自comp.lang.java新闻组的问题和答案的分类目录.
http://java.sun.com/docs/books/tutorial/] - 来自SUN公司的官方Java指南 - 对于了解几乎所有的java技术特性非常有帮助.
http://www.javablogs.com] - 互联网上最活跃的一个Java Blog网站.
http://java.about.com/] - 来自About.com的Java新闻和技术文章网站.
An Open Source Java SQL Database System-Mckoi SQL
Mckoi SQL Database is an SQL (Structured Query Language) Database management system written for the JavaTM platform. Mckoi SQL Database is optimized to run as a client/server database server for multiple clients, however it can also be embedded in an application as a stand-alone database. It is highly multi-threaded and features an extendable object-oriented engine.
Mckoi SQL Database started as an internal project and has since evolved from its inception in 1998. The main goals of the project are a code base that is simple to maintain and extend, ease of use and administration, robustness, multiple concurrent access, and performance.
[SQLServer 2000 Driver for JDBC]Error establishing socket.
原链接地址
1. Make sure that SQL Server is set to mixed authentication. To do this, open enterprise manager, right click on server/properties; go to security tab and select SQL Server and Windows Authentication. Apparently, the driver from Microsoft cannot handle windows integrated authentication.
2. Keeping the server properties dialog up, go to the general tab and push the network configuration button. Enable TCP/IP (it is disabled by default). If you wish, press properties to change the default port (1433).
3. Add an SQL Server login account (NOT a WINDOWS account (see 1)). You can also use your sa account, but I don't recommend it.
4. Use the login setup in step 3.
Some final notes:
(1) I've seen ads for third party drivers that can use Windows integrated authentication. Try one if you need this feature.
(2) One responder suggested telneting to port 1433 to verify TCP connectivity. The connection is refused on my machine even though I can connect through the driver. And this is how it should be; otherwise there'd be a security risk.
如何在Linux/Unix运行一个守护Java程序
Daemon - Daemon : Java based daemons or services
Introduction
Actualy only the UNIX like platforms are supported. The sources are located in the src/native/unix subdirectory of the project sources. For win32 platfroms the cygwin emulation layer is used. See cygwin for more informations.
In the futur APR may be used to provide more convinient platform support.
http://wrapper.tanukisoftware.org
Configurable tool which allows Java applications to be installed and controlled like native NT or Unix services.Includes fault correction software to automatically restart crashed or frozen JVMs. Critical when app is needed 24x7. Built for flexibility
to run my app:
nohup java -jar JarFile.jar </dev/null >>myLogFile 2>>myErrorFile&