Avoid instantiate objects when processing APDU commands

It is preferable to instantiate object only when the applet is instantiated because the garbage collector does not work or is not always available.
cheeriotb · Nov 18, 2018 · 3fb28ed · 3fb28ed
1 parent 15c0156
commit 3fb28ed
Showing 1 changed file with 11 additions and 7 deletions.
diff --git a/src/com/github/cheeriotb/cts/cardlet/OmapiApplet.java b/src/com/github/cheeriotb/cts/cardlet/OmapiApplet.java
@@ -82,7 +82,14 @@ public class OmapiApplet extends Applet {
             (byte) 0x43, (byte) 0x54, (byte) 0x53, (byte) 0x32
     };
 
+    private static AID sAidLongResponse;
+    private static byte[] sResponseBuffer;
+
     private OmapiApplet() {
+        sAidLongResponse = new AID(AID_LONG_RESPONSE, (short) 0, (byte) AID_LONG_RESPONSE.length);
+        sResponseBuffer = new byte[256];
+        Util.arrayFillNonAtomic(sResponseBuffer, (short) 0, (short) sResponseBuffer.length,
+                (byte) 0x00);
     }
 
     public static void install(byte[] bArray, short bOffset, byte bLength) {
@@ -97,9 +104,8 @@ public void process(APDU apdu) throws ISOException {
             switch (buffer[ISO7816.OFFSET_P2] & 0x0C) {
                 // Return FCI template, optional use of FCI tag and length
                 case 0x00:
-                    AID selected = new AID(buffer, ISO7816.OFFSET_CDATA, buffer[ISO7816.OFFSET_LC]);
-                    if (selected.equals(AID_LONG_RESPONSE, (short) 0,
-                            (byte) AID_LONG_RESPONSE.length)) {
+                    if (sAidLongResponse.equals(buffer, ISO7816.OFFSET_CDATA,
+                            buffer[ISO7816.OFFSET_LC])) {
                         response = SELECT_RESPONSE_FCI_LONG;
                     } else {
                         response = SELECT_RESPONSE_FCI_SHORT;
@@ -145,11 +151,9 @@ public void process(APDU apdu) throws ISOException {
                         && apdu.setIncomingAndReceive() != 0x01) {
                     ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
                 }
-                output = new byte[256];
-                Util.arrayFillNonAtomic(output, (short) 0, (short) output.length, (byte) 0x00);
                 apdu.setOutgoing();
-                apdu.setOutgoingLength((short) output.length);
-                apdu.sendBytesLong(output, (short) 0, (short) output.length);
+                apdu.setOutgoingLength((short) sResponseBuffer.length);
+                apdu.sendBytesLong(sResponseBuffer, (short) 0, (short) sResponseBuffer.length);
                 break;
             default:
                 ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);