finishi Broker.java 1.0

Signed-off-by: jsxhhyf <jsxhhyf@gmail.com>
finish Server.java 1.0
tiny modified Broker.java
change Flightinfo class to FlightEntity class

Signed-off-by: jsxhhyf <jsxhhyf@gmail.com>
update the algorithm of broker and server
modify 
Broker.Handler
Server.SocketHandler

Signed-off-by: jsxhhyf <jsxhhyf@gmail.com>
add a test client class Main.java

Signed-off-by: jsxhhyf <jsxhhyf@gmail.com>
add a class to test Broker
modify Main to test queryFlightByLocaAndDate

Signed-off-by: jsxhhyf <jsxhhyf@gmail.com>
fix some bugs

Signed-off-by: jsxhhyf <jsxhhyf@gmail.com>
test query to three database simultaneously

Signed-off-by: jsxhhyf <jsxhhyf@gmail.com>