php-Novice, questions about PHP manipulating JSON data. Appreciate it!

PHP Data Jsonweb Service

I called an interface through WebService, which returns an XML file. The file content is in this form: (Sorry, personal information is not allowed to disclose). I do not PHP, found on the internet, with file_get_contents ("Interface url") to get the contents of {} on the diagram. Now how can I get to the JSON parameters. For example, I want to get status value to judge? has been studied for a few days, online also looked for a long time. Hope the big God guidance, younger brother Thank you greatly! (c Money can only be this.) T _ T)

Add: I will get the content to a variable, $json =file_get_contents ("Interface url"), and then $str_json=json_decode ($json, true); but it seems that the value in JSON is still not operational.

