因为工作需要，需要获取应用的apk传递给新浪微博或者微信去申请授权 所以需要程序内获取签名上传服务器
做法如下：
public static String getAPPSecretString(Activity activity){
String backString="";
try {
PackageInfo mPackageInfo=activity.getPackageManager().getPackageInfo(GlobalConfig.APP_PACKAGE_NAME, 64);
Signature xx[]=mPackageInfo.signatures;
byte[] arrayOfByte= mPackageInfo.signatures[0].toByteArray();
backString= digest(arrayOfByte);
} catch (NameNotFoundException e1) {
e1.printStackTrace();
}
return backString;
}
private static final char hexDigits[] = { '0', '1', '2', '3', '4', '5',
'6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
public static final String digest(String message) {
try {
byte[] strTemp = message.getBytes();
MessageDigest mdTemp = MessageDigest.getInstance("MD5");
mdTemp.update(strTemp);
byte[] md = mdTemp.digest();
int j = md.length;
char str[] = new char[j * 2];
int k = 0;
for (int i = 0; i < j; i++) {
byte byte0 = md[i];
str[k++] = hexDigits[byte0 >>> 4 & 0xf];
str[k++] = hexDigits[byte0 & 0xf];
}
return new String(str);
} catch (Exception e) {
return null;
}
}
public static final String digest(byte[] strTemp) {
try {
// byte[] strTemp = message.getBytes();
MessageDigest mdTemp = MessageDigest.getInstance("MD5");
mdTemp.update(strTemp);
byte[] md = mdTemp.digest();
int j = md.length;
char str[] = new char[j * 2];
int k = 0;
for (int i = 0; i < j; i++) {
byte byte0 = md[i];
str[k++] = hexDigits[byte0 >>> 4 & 0xf];
str[k++] = hexDigits[byte0 & 0xf];
}
return new String(str);
} catch (Exception e) {
return null;
}
}