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Java获取gravatar头像链接

Creating the Hash

All URLs on Gravatar are based on the use of the hashed value of an email address. Images and profiles are both accessed via the hash of an email, and it is considered the primary way of identifying an identity within the system. To ensure a consistent and accurate hash, the following steps should be taken to create a hash:

Trim leading and trailing whitespace from an email address
Force all characters to lower-case
md5 hash the final string

As an example, let's say we start with "MyEmailAddress@example.com " (note the trailing space which our hypothetical user entered by mistake). If we md5 encode that string directly, we get the following (in PHP):

echo md5( "MyEmailAddress@example.com " );
// "f9879d71855b5ff21e4963273a886bfc"

If we now run that same email address through the above process, you will see that we get a different result (again in PHP):

$email = trim( "MyEmailAddress@example.com " ); // "MyEmailAddress@example.com"
$email = strtolower( $email ); // "myemailaddress@example.com"
echo md5( $email );
// "0bc83cb571cd1c50ba6f3e8a78ef1346"

This can easily be combined into a single line:

echo md5( strtolower( trim( "MyEmailAddress@example.com " ) ) );

Once you have generated a consistent hash, you can then request either an image or a profile.

Image Requests

If you'd like an easy way of working with Gravatar, then check out Ralf Ebert's jgravatar library, otherwise read on. Things are a little complex in Java. The following class will provide you with a static method that returns the hex format md5 of an input string:

import java.util.*;
import java.io.*;
import java.security.*;
public class MD5Util {
  public static String hex(byte[] array) {
      StringBuffer sb = new StringBuffer();
      for (int i = 0; i < array.length; ++i) {
	  sb.append(Integer.toHexString((array[i]
	      & 0xFF) | 0x100).substring(1,3));        
      }
      return sb.toString();
  }
  public static String md5Hex (String message) {
      try {
	  MessageDigest md = 
	      MessageDigest.getInstance("MD5");
	  return hex (md.digest(message.getBytes("CP1252")));
      } catch (NoSuchAlgorithmException e) {
      } catch (UnsupportedEncodingException e) {
      }
      return null;
  }
}

This class can then be used to return the MD5 hash of an email address (make sure you lower case it first!) like this:

String email = "someone@somewhere.com";
String hash = MD5Util.md5Hex(email);

With the hex string that is returned, you can construct your gravatar URL.

//根据email获取gravatar头像
public static String getGravatar(String email) {
    String emailMd5 = MD5Util.md5Hex(email);
    //设置图片大小32px
    String avatar = "http://www.gravatar.com/avatar/"+emailMd5+"?s=32";
    return avatar;
}

Profile Requests

Base Request

Users may optionally enter a variety of profile information to associate with their Gravatar account. This information is openly-accessible using a similar process to requesting images. A simple profile link looks like this: https://www.gravatar.com/HASH where HASH is the email hash of a user. This request will automatically redirect to their username-based URL, so for example, you might get this: https://www.gravatar.com/205e460b479e2e5b48aec07710c08d50 --> https://en.gravatar.com/beau An important point to note is that profile requests will only resolve for the hash of the primary address on an account. Users may have multiple addresses on a single account, so while a Gravatar image request may return a result, a profile request for the same hash may not.

hCard

Profile pages are fully marked up using hCard, a microformat for programmatically embedding information about people, companies, organizations, and places in HTML and other markup languages. The screenshot below describes some of the main markup involved on a profile page

Email address marked up with class=email (only available via JS/client-side parsing due to spam-protection measures)
IM accounts marked up using class=url (some values only available via JS/client-side parsing due to spam-protection measures)
Phone numbers marked up with class=tel (using type/value subproperties)
Verified accounts marked up with class=url and rel=me
Name marked up with class=fn
Personal Links are marked up with class=url
Image (main Gravatar) is marked up using class=photo