Linux/Mac: 
1,yum -y install httpd-tools
     View information: ab-V
2,http://httpd.apache.org/download.cgi#apache24

Windows: http://www.apachehaus.com/cgi-bin/download.plx
 Unzip after downloading and append PATH environment variables such as "; E:\software\Apache24\bin"

#We can simulate 100 concurrent users and send 100 requests to a page#
ab -n 100 -c 100 -p E:\param.txt -T application/json http://xx.com

Common parameters
 -n Number of requests
 -c concurrency number
 -p parameter text path
 -T Request Parameter Type

More parameters
 -n Number of requests executed in the test session.By default, only one request is executed.
-c Number of requests generated at one time.The default is one at a time.
-t The maximum number of seconds the test takes.Its internal implicit value is -n 50000, which limits testing on the server to a fixed total time.By default, there is no time limit.
-p contains files that require POST data.
-P Provides BASIC authentication trust to a transit agent.User names and passwords are separated by one: and sent in base64 encoding.This string is sent regardless of whether the server needs it (that is, if a 401 certification requirement code is sent).
Content-type header information used by -T POST data.
The -v setting shows how detailed the information is - 4 or more values show header information, 3 or more values show response codes (404,200, etc.), and 2 or more values show warnings and other information.
-V Displays the version number and exits.
-w Outputs the results in an HTML table format.By default, it is a table of two column widths on a white background.
-i Execute HEAD requests, not GET s.
-x Sets the string of the <table>property.
-X uses a proxy server for requests.
-y Sets the string of the <tr>property.
-z sets the string for the <td>property.
-C appends a Cookie: line to the request.Typically, this is a parameter pair of name=value, which can be repeated.
-H appends additional header information to the request.Typically, this parameter is a valid header information line that contains colon-separated pairs of fields and values (for example, "Accept-Encoding:zip/zop;8bit").
-A Provides BASIC authentication trust to the server.User names and passwords are separated by one: and sent in base64 encoding.This string is sent regardless of whether the server needs it (that is, if a 401 certification requirement code is sent).
-h Displays how to use it.
-d does not display the message "percentage served within XX [ms] table" (support for previous versions).
-e produces a comma-separated (CSV) file that contains the corresponding percentage of time (in subtle units) needed to process requests for each corresponding percentage (from 1% to 100%).This format is more useful than the'gnuplot'format because it is already'binary'.
-g Writes all test results to a'gnuplot'or TSV (Tab delimited) file.This file can be easily imported into Gnuplot,IDL,Mathematica,Igor or even Excel.The title of the first behavior.
-i Execute HEAD requests, not GET s.
-k enables the HTTP KeepAlive function, which executes multiple requests in an HTTP session.KeepAlive is not enabled by default.
-q If the number of requests processed is greater than 150, ab outputs a progress count at stderr for every 10% or 100 requests processed.This-q tag suppresses this information.