参考：http://www.cnblogs.com/spring3mvc/archive/2010/11/23/2414741.html
自己写代码经常是顺着逻辑写下去，写完后run一下，ok就玩完事了。直到遇到一个又一个的问题的时候才回头过来重新修改。这就是没有测试的悲剧。因此，在今后的代码中一定要尝试着去写测试，去做测试。
发现Apache Server下有个工具ab可以进行并发请求，正好有个需求想要知道并发下的访问情况。
1.下载
访问：http://httpd.apache.org/download.cgi
然后点击：
然后跳到一个页面说只提供源码，自己编译，云彩。不过也提供了推荐第三方编译，选择第一个：
然后是选择镜像和版本，不要选择德国的：
2.安装
我这是买椟还珠的游戏，不想去了解Apache的功能，只想要ab。所以直接解压，然后在bin目录找到ab就可以了：
3.测试
输入ab就可以看到帮助文档
D:\Java\httpd-2.4.23-x64-vc14\Apache24\bin>ab ab: wrong number of arguments Usage: ab [options] [http://]hostname[:port]/path Options are: -n requests Number of requests to perform -c concurrency Number of multiple requests to make at a time -t timelimit Seconds to max. to spend on benchmarking This implies -n 50000 -s timeout Seconds to max. wait for each response Default is 30 seconds -b windowsize Size of TCP send/receive buffer, in bytes -B address Address to bind to when making outgoing connections -p postfile File containing data to POST. Remember also to set -T -u putfile File containing data to PUT. Remember also to set -T -T content-type Content-type header to use for POST/PUT data, eg. 'application/x-www-form-urlencoded' Default is 'text/plain' -v verbosity How much troubleshooting info to print -w Print out results in HTML tables -i Use HEAD instead of GET -x attributes String to insert as table attributes -y attributes String to insert as tr attributes -z attributes String to insert as td or th attributes -C attribute Add cookie, eg. 'Apache=1234'. (repeatable) -H attribute Add Arbitrary header line, eg. 'Accept-Encoding: gzip' Inserted after all normal header lines. (repeatable) -A attribute Add Basic WWW Authentication, the attributes are a colon separated username and password. -P attribute Add Basic Proxy Authentication, the attributes are a colon separated username and password. -X proxy:port Proxyserver and port number to use -V Print version number and exit -k Use HTTP KeepAlive feature -d Do not show percentiles served table. -S Do not show confidence estimators and warnings. -q Do not show progress when doing more than 150 requests -l Accept variable document length (use this for dynamic pages) -g filename Output collected data to gnuplot format file. -e filename Output CSV file with percentages served -r Don't exit on socket receive errors. -m method Method name -h Display usage information (this message) D:\Java\httpd-2.4.23-x64-vc14\Apache24\bin>
举例：
D:\Java\httpd-2.4.23-x64-vc14\Apache24\bin>ab -n 20 -c 10 localhost:8080/user/all
-n表示一共请求20次
-c表示并发量为10次。
也就是说，会进行两个并发，每次10个。
唯有不断学习方能改变！ -- Ryan Miao
