React中设置setState?

Question

我想在React中调用ajax设置ＤＡＴＡ，可是setState时报错？为什么报错信息如下？我该如何修改？
代码打包之类的是好的？可以打印出ＴＥＳＴ

index.bundle.js?__VERSION:91 Uncaught TypeError: Cannot read property 'setState' of null

at success (http://localhost:8000/js/index.bundle.js?__VERSION:91:26)

at ajaxSuccess (http://localhost:8000/js/index.bundle.js?__VERSION:1906:31)

at XMLHttpRequest.xhr.onreadystatechange (http://localhost:8000/js/index.bundle.js?__VERSION:2107:99)