Exception in thread "main" java.net.ConnectException: Connection refused: connect

客户端连接异常：

Exception in thread "main" java.net.ConnectException: Connection refused: connect
    at sun.nio.ch.Net.connect0(Native Method)
    at sun.nio.ch.Net.connect(Net.java:454)
    at sun.nio.ch.Net.connect(Net.java:446)
    at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:648)
    at homework.test5.client.main(client.java:16)