【OA】（急）Java HTTP Post Get 的OA请教怎么做

Description
Publish a service on the web with two endpoints:
1. /messages takes a message (a string) as a POST and returns the SHA256 hash digest of
that message (in hexadecimal format)
2. /messages/<hash> is a GET request that returns the original message. A request to a
non-existent<hash> should return a 404 error.

Example
Let’s say you publish to http://mywebsite.com/ (you don’t need a custom domain for this
project, any IP address we can access will do):

$ curl -X POST -H "Content-Type: application/json" -d '{"message": "foo"}' http://mywebsite.com/messages
{
"digest": "2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae"
}

You can calculate that your result is correct on the command line:
$ echo -n "foo" | shasum -a 256
2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae -

You can now query your service for the original message:
$ curl
http://mywebsite.com/messages/2c ... fa0f98a5e886266e7ae
{
"message": "foo"
}
$ curl -i
http://mywebsite.com/messages/aa ... aaaaaaaaaaaaaaaaaaa
HTTP/1.0 404 NOT FOUND Content-Type: application/json Content-Length: 36
Server: Werkzeug/0.11.5 Python/3.5.1 Date: Wed, 31 Aug 2016 14:21:11 GMT
{
"err_msg": "Message not found"
}
(your specifics may vary, all that matters is that you get a 404)





作出python了
但是java做不出来（只作出一部分）
请教高手能不能帮一把

1. private static String sha256(String base) {
   
2.             try{
   
3.                 MessageDigest digest = MessageDigest.getInstance("SHA-256");
   
4.                 byte[] hash = digest.digest(base.getBytes("UTF-8"));
   
5.                 StringBuffer hexString = new StringBuffer();
   
6. 
   
7.                 for (int i = 0; i < hash.length; i++) {
   
8.                     String hex = Integer.toHexString(0xff & hash[i]);
   
9.                     if(hex.length() == 1) hexString.append('0');
   
10.                     hexString.append(hex);
    
11.                 }
    
12. 
    
13.                 return hexString.toString();
    
14.             } catch(Exception ex){
    
15.                throw new RuntimeException(ex);
    
16.             }
    
17.         }

复制代码