add base64Decode and fix PutPolicy Expire

Author: icattlecoder

src/main/java/com/qiniu/api/net/EncodeUtils.java

@@ -36,7 +36,19 @@ public static byte[] urlsafeEncodeBytes(byte[] src) {
 		}
 		return b2;
 	}
-
+	
+	public static byte[] urlsafeBase64Decode(String encoded){
+		byte[] db64 = Base64.decodeBase64(encoded);
+		for(int i=0;i<db64.length;i++){
+			if(db64[i] == '_'){
+				db64[i] = '/';
+			}else if(db64[i] == '-'){
+				db64[i] = '+';
+			}
+		}
+		return db64;
+	}
+	
 	public static String urlsafeEncodeString(byte[] src) {
 		return new String(urlsafeEncodeBytes(src));
 	}

src/main/java/com/qiniu/api/rs/PutPolicy.java

@@ -78,8 +78,10 @@ public String token(Mac mac) throws AuthException, JSONException {
 		if (this.expires == 0) {
 			this.expires = 3600; // 3600s, default.
 		}
+		long orign = this.expires;
 		this.expires = System.currentTimeMillis() / 1000 + expires;
 		byte[] data = this.marshal().getBytes();
+		this.expires = orign;
 		return DigestAuth.signWithData(mac, data);
 	}