Added watch command

src/main/java/redis/clients/jedis/Client.java

@@ -375,4 +375,8 @@ public class Client extends Connection {
     public void exec() throws JedisException {
 	sendCommand("EXEC");
     }
+
+    public void watch(String key) throws JedisException {
+	sendCommand("WATCH", key);
+    }
 }

src/main/java/redis/clients/jedis/Jedis.java

@@ -486,4 +486,9 @@ public class Jedis {
 	client.disconnect();
     }
 
+    public String watch(String key) throws JedisException {
+	client.watch(key);
+	return client.getStatusCodeReply();
+    }
+
 }

src/test/java/redis/clients/jedis/tests/commands/TransactionCommandsTest.java

@@ -1,5 +1,7 @@
 package redis.clients.jedis.tests.commands;
 
+import java.io.IOException;
+import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -72,4 +74,22 @@ public class TransactionCommandsTest extends Assert {
 	expected.add(2);
 	assertEquals(expected, response);
     }
+
+    @Test
+    public void watch() throws JedisException, UnknownHostException,
+	    IOException {
+	jedis.watch("mykey");
+	String val = jedis.get("mykey");
+	val = "foo";
+	Transaction t = jedis.multi();
+
+	Jedis nj = new Jedis("localhost");
+	nj.connect();
+	nj.set("mykey", "bar");
+	nj.disconnect();
+
+	t.set("mykey", val);
+	List<Object> resp = t.exec();
+	assertEquals(new ArrayList<Object>(), resp);
+    }
 }