Apache does not have write permission on html folder

I installed apache, MySQL, PHP in CentOS 7. All work well, except apache cannot write file in html folder. I found this problem when I used file_put_contents. I tried

1. Change owner of /var/www to apache:apache, not work
2. Added Order allow,deny Allow from all to <Directory "/var/www/html"> in httpd.conf, restart httpd service, not work
3. chmod -R 0777 /var/www/html, not work

What is wrong with my server? Please help me!

UPDATE1: result of ls -al /var/www/html

total 40
drwxrwxrwx.  5 apache apache 4096 Sep 23 10:19 .
drwxr-x---.  4 apache apache   31 Sep 18 01:50 ..
drwxrwxrwx. 15 apache apache 4096 Sep 23 08:43 folder1
drwxrwxrwx+ 10 apache apache 4096 Sep 23 10:19 folder2
-rwxrwxrwx.  1 apache apache 1574 Sep  5 08:55 favicon.ico
-rwxrwxrwx.  1 apache apache  603 Sep 22 05:05 .htaccess
-rwxrwxrwx.  1 apache apache 9841 Sep  8 08:34 index.php
drwxrwxrwx.  8 apache apache 4096 Sep 23 08:44 folder3

UPDATE 2: apache error_log (I changed all IP address) – Edited, change to new error_log, after stop httpd, backup error_log, start httpd

[Thu Sep 24 07:06:47.540295 2015] [core:notice] [pid 14439] SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0
[Thu Sep 24 07:06:47.541787 2015] [suexec:notice] [pid 14439] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Thu Sep 24 07:06:47.569389 2015] [so:warn] [pid 14439] AH01574: module rewrite_module is already loaded, skipping
[Thu Sep 24 07:06:47.572287 2015] [auth_digest:notice] [pid 14439] AH01757: generating secret for digest authentication ...
[Thu Sep 24 07:06:47.573315 2015] [lbmethod_heartbeat:notice] [pid 14439] AH02282: No slotmem from mod_heartmonitor
[Thu Sep 24 07:06:47.600913 2015] [mpm_prefork:notice] [pid 14439] AH00163: Apache/2.4.6 (CentOS) PHP/5.4.16 configured -- resuming normal operations
[Thu Sep 24 07:06:47.600943 2015] [core:notice] [pid 14439] AH00094: Command line: '/usr/sbin/httpd -D FOREGROUND'

Answer

Thank all guy! I fixed my problem with this guide:

http://blog.lysender.com/2015/07/centos-7-selinux-php-apache-cannot-writeaccess-file-no-matter-what/

I hope it will be helpful.