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Relational structured storage has some disadvantages, because it needs to define all columns and their corresponding types in advance. However, in the process of business development, it may be necessary to expand the description function of a single column. At this time, if the JSON data type can be used well, the boundary between the storage ...

1, What is circular dependency Two or more objects refer to each other, i.e A rely on B，B rely on C，C Again dependent A For example: @service public class A { private B b; @Autowired public void setB(B b) { this.b= b; } } @service public class B { private A a; @Autowired public vo ...

Select structureHello, welcome back. I'm Peng Peng! HAKUNA MATATA!!!On the basis of data and operation, there is a new demand: process control. Generally, the code execution process will not be executed in the end. Many times, the appropriate direction will be selected according to the changes of data, and even the running results of the progra ...

Teach you how to import the third-party library of Go language 1, Get using go get The go command go get allows us to quickly and easily download or update the go language pack and its dependent files from the network, compile and install them. First enter go --help in command line mode to view the following information. Go is a tool for ma ...

iterator Returns an iterator that points to the first element of the container std::map<Key,T,Compare,Allocator>::begin, std::map<Key,T,Compare,Allocator>::cbegin iterator begin(); (C++11 front) iterator begin() noexcept; (C++11 rise) const_iterator begin( ...

📖 Content of this article: 23 design patterns -- structural model (I) adapter pattern bridge pattern combination pattern 📆 Last updated: December 26, 2021 23 kinds of design patterns this column makes you learn how to beat me - constructive pattern - factory pattern abstract factory pattern singleton pattern builder pattern prototype patter ...

1, Encapsulation 1.private keyword Overview: private is a modifier that can be used to modify members (member variables, member methods) Features: members modified by private can only be accessed in this class. If private modified member variables need to be used by other classes, corresponding operations are provided The "get va ...

Latest update: 2021.12. 24 Environment: CLion2021.3; 64-bit macOS Big Sur 14. Documents 14.1 What is a file 1. From the point of view of file function, it can be divided into program files and data files: (1) Program files: source file (.c), target file (.obj), executable program (under windows.exe) (2) Data file: The contents of the file ...

1. The essence of IOC Map container: the essence of IOC container is a map ApplicationContext context: holds a reference to BeanFactory Bean factory factory: responsible for obtaining beans from containers BeanDefinitionReader parser: responsible for parsing all configuration files Definition meta information configuration: xml, yml, ann ...

Hello everyone, let me share Java In process control Switch Multiple selection structure Look at my previous blog, you will know that the previous if judgment deals with interval problems, The Switch multi selection structure we are going to talk about today deals with the same amount of problems This is the Switch syntax: Write an exa ...