解决方式一: ( 我用这方式就可以安装了) 

打开在.htaccess 文件裡 最上面开头加上 

php_value max_execution_time 1200 
php_value memory_limit 200M 
php_value post_max_size 200M 
php_value upload_max_filesize 200M 


解决方式二: (这我就不太会请高手解释) 

或者在httpd.conf主机配置里改 

解决方式三: (这个我试过没什麽作用..请高手帮忙解释) 

如出现这种问题则表明，程序运行占用的记忆空间超过了8M,解决方法修改PHP.ini文件将 

memory_limit = 8M ; 
的值改为12M就可以了 

This error message can spring up in a previously functional PHP script when the memory requirements exceed the default 8MB limit. Don’t fret, though, because this is an easy problem to overcome.To change the memory limit for one specific script by including a line such as this at the top of the script: 
ini_set("memory_limit","12M"); 

The 12M sets the limit to 12 megabytes (12582912 bytes). If this doesn’t work, keep increasing the memory limit until your script fits or your server squeals for mercy. 
You can also make this change permanently for all PHP scripts running on the server by adding a line like this to the server’s php.ini file: 
memory_limit = 12M 
Keep in mind that a huge memory limit is a poor substitute for good coding. A poorly written script may inefficiently squander memory which can cause severe problems for frequently executed scripts. However, some applications are run infrequently and require lots of memory like importing and processing a big data file. 
如果是vps云主机，服务器用户推荐大家采用第三种方法。