category : 计算机那些事

Java: JDK居然有个叫整型池的东西

其实下面这些个assert语句都可以通过junit测试。 12345678@Testpublic void integerValueOfTest() { Assert.assertTrue(Integer.valueOf(-128) == Integer.valueOf(-128)); Assert.assertFalse(Integer.valueOf(128) == Integer.valueOf(128)); Assert.assertTrue(Integer.valueOf(127) == Integer.valueOf(127)); Assert.assertTrue(Integer.valueOf(1) == Integer.valueOf(1)); Assert.assertFalse(Integer.valueOf(1000) == Integer.valueOf(1000));}


之前博客一直以纯静态的方式托管在GitHub Page里面(是基于Hexo的),遗憾的是 百度蜘蛛频繁乱爬,导致GitHub对它采取了屏蔽。(参考:解决 Github Pages 禁止百度爬虫的方法与可行性分析)另外这篇文章末尾给出了一个解决该问题的可行方法,但是我个人没有试。 GitHub Page虽然支持自定义域名,但是对https支持的不好(这是一个次要的理由)。



Java Mail中文乱码


Nginx: 简单负载均衡

工作之前的时候,做任何web项目,我都会选择用PHP,简洁,快速,有时候很赞同PHP是世界上最好的语言,但是有些时候还是不如Java来的利索。可惜的是Java“不支持”热部署(至少在生产环境下不建议热部署), 导致每次部署都会有一段服务下线的时间(更糟糕的是用户的session也会随之丢失,最最糟糕的时候,每次部署,有时候还不得不重启一下Tomcat)。

Jackson: deserialize nested object

I am implementing a RESTful server inside my company. The workflow is very straight-forward: request and response. However, nothing is easy, the RESTful service is based on an existed project, which handles database operations, and the entities inside that project is pretty complex(a lot of interfaces and abstract classes).

Fix: Tomcat7 restart too slow in Ubuntu 14.04

I have two servers in DigitalOcean, and both of them are Ubutun with tomcat 7. Recently, I found that if I want to restart tomcat, it will cost me more than 5 minutes(No errors during this). And the worest is(almots half an hour): 1INFO: Server startup in 1497026 ms

Java: Test a file is image or not

There are many ways to check whether a file is image. For example, check the file extension(jpg, png, gif …). But this is not so safe, in a web environment, user may rename XXX.exe, to XXX.jpg, then s/he can succeed to upload it. In this case, it can induce security problem.

Note: why SVN is so slow to connect to server

It happens from one month ago after I changed my windows domain password(Damn windows forced me to do that). Then every time when I want to commit to server, I need to input my password(SVN won’t save it for me), what’s more, SVN always needs more than 3 minutes to connect with server at background.

Hello World to XSLT

DefinitionXSL stands for EXtensible Stylesheet Language, and is a style sheet language for XML documents. (XSL = Style Sheets for XML) XSLT stands for XSL Transformations. In this tutorial you will learn how to use XSLT to transform XML documents into other formats, like XHTML. You can try a online demo here: