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The transformation operator we learned before cannot access the timestamp information and watermark information of the event. This is extremely important in some application scenarios. For example, map conversion operators such as MapFunction cannot access the timestamp or the event time of the current event. Based on this, the DataStream API ...

This article is excerpted from the Flyweight Pattern of "design patterns should be learned in this way"1 story backgroundBecause a programmer changed a method parameter in the production environment and changed the int type to Integer type, because money was involved, the company suffered heavy losses and the programmer was dismissed. ...

1, String (1) Representation of string java.lang.String represents an immutable character sequence. String is used to represent a sequence composed of characters. It is the most commonly used reference data type. Another string is an array of character (Char) types. (2) String creation • standards: Declare before use • creation ...

Reproduced in https://www.jianshu.com/p/d83623eb56dc 1, System functional requirements Add contact: add a new contact to the address book. The information includes (name, gender, age, contact number, home address) and records up to 1000 people Show contacts: displays all contact information in the address book Find contact: delete the specified ...

Background: in C + +, dynamic memory is usually managed through a pair of operators new, which allocate space for an object in dynamic memory and return the pointer of the object. You can choose to initialize the object; delete, accept the pointer of a dynamic object, destroy the object and free the memory associated with it. It is easy to have ...

One is to realize cross domain access 1. If the API you want to develop is called by the front-end project (such as Vue), the first step must be to realize cross domain access. The implementation of cross domain access in Koa2 framework is slightly different from that in Express. You need to install Koa2 CORS middleware to realize cross do ...

re.match() find one from scratch re.search() found one** re.findall() find all **Returns a list. If there is no, it is an empty list re.findall('\d','chuan1zhi2')   The result is['1','2'] re.sub() replace re.sub('\d','_','chuan1zhi2')   The result is['chuan_zhi_'] Re.compile** Returns a model p with the same method as re, but with dif ...

Original text: Introduction and principle of CGLIB (through inherited dynamic proxy)   1, What is CGLIB? CGLIB is a powerful and high-performance code generation package. It provides a proxy for classes that do not implement interfaces, and provides a good supplement to the dynamic proxy of JDK. You can usually use Java's dynamic proxy to cr ...

Core concepts and models of network programming 1. Question How to program network? 2. The essence of network programming Using the interface function provided by the operating system, the application has the ability to send and receive network data. The network interface is a function provided by the operating system at the code level ...

What is SPI technology The full name of SPI is Service Provider Interface, which means Service Provider Interface. If we don't write framework code or develop plug-ins, we may not be so familiar with SPI mechanism, but if we read such as Dubbo and JDBC database Driver package, Spring and the recently popular Spring Boot related starter compo ...