20165219 2017-2018-2 "Java Programming" Week 9 Learning Summary
Textbook Knowledge Summary
URL class
The URL class is an important class in the java.net package. Applications that use URLs to create objects are called client programs. A URL object usually contains the most basic three parts of information: protocol, address and resource.
Construction method:
public URL(String protocol,String host,String file) throws MalformedURLException InetAddress
public URL (String spec) throws MalformedURLException
InetAddress class
UDP datagram, broadcast datagram
socket
The combination of source IP address and destination IP address and source port number and destination port number is called a socket
The server establishes a ServerSocket object, the ServerSocket object is responsible for waiting for the client request to establish a socket connection, and the client establishes a Socket object to send a socket connection request to the server.
Java remote call
Summary of wrong questions
1 Which of the following statements is correct?
A. The JVM considers this application to have a total of two threads.
B . JVM认为这个应用程序只有一个主线程 。
C. The JVM considers this application to have only one thread.
D. The program has compilation errors and cannot be run.
2 Which of the following statements about daemon threads is correct?
A . thread.setDaemon(true)必须在thread.start()之前设置，否则会报IllegalThreadStateException异常。
B . 如果用户线程已经全部退出运行，只剩下守护线程存在，那么虚拟机也就退出了。
C . 将线程转换为守护线程可以通过调用Thread对象的setDaemon(true)方法来实现。
D . 守护线程应该永远不去访问固有资源，如文件、数据库，因为它会在任何时候甚至在一个操作的中间发生中断。
code hosting
