json = '["a", "B", "C"]'
puts "Unsafe #{unsafe_json
(json).inspect}" 
#输出Unsafe 
["a", "B", "C"] 

json = 'puts "Danger 
Will Robinson"' 
puts "Unsafe #{unsafe_json
(json).inspect}" 

module SafeJSON  
require 'monitor'  
def SafeJSON.build_safe_json  
ret = nil  
waiter = ''  
waiter.extend(MonitorMixin)  
wait_cond = waiter.new_cond  
Thread.start do  
$SAFE = 4  
ret = Proc.new {|json|  
eval(json.gsub(/(["'])/s*:/s*
(['"0-9tfn/[{])/){"#{$1}=>#{$2}"}) }  
waiter.synchronize do wait_cond.signal  
end  
end 
waiter.synchronize do wait_
cond.wait_while { ret.nil? } end  
return ret  
end  
@@parser = SafeJSON.build_safe_json  
# Safely parse the JSON input  
def SafeJSON.parse(input)  
@@parser.call(input)  
rescue SecurityError  
return nil  
end 
end 

peoples=SafeJSON.parse('
{"peoples":[{"name":"site120","
email":"site120@163.com","sex":"男"},
{"name":"site120_2","email":"site1
20@163.com_2","sex":"男_2"}]}') 
puts peoples["peoples"][1]["name"]
 #输出site120_2 

gem install json_pure

 require "open-uri"
 require 'json'

 def index
  uri = '*****'
  response = nil
  begin
   open(uri) do |http|
    response = http.read
   end
   @json = JSON::parse(response)
  rescue => text
   # 异常处理
   logger.error("GetMailListserror=" + text)
   flash.now[:error] = '获取邮件列表失败。'
  end
 end