Tag:object

  • New features of ES8

    Time:2020-1-27

    ES8 Today, let’s learn some new API of es8. 1. What is the relationship between the use of async / await syntax and promise?2. What is the relationship between object. Values(), object. Keys(), object. Entries()?3、 String padding? What are the syntax and usage scenarios?4. What is object. Getownpropertydescriptors()? What are the usage scenarios of descriptors? […]

  • Data source and connection pool of mybatis principle

    Time:2020-1-27

    In Java engineering projects, we often useMybatisThe principle of the framework is to add, delete, check and modify the data in the databaseJDBCIt makes a layer of encapsulation and optimizes the connection of data sources. Let’s reviewJDBCThe process of operating a database. JDBCOperation database JDBCWhen operating the database, you need to specify the connection type, […]

  • Java dictionary

    Time:2020-1-27

    Java dictionary Data structure overview Map MapIt describes a mapping relationship. A key corresponds to a value. You can add, delete, modify and obtain key / value. Util provides a variety ofMap HashMap: the map implemented by the hash table and the insert / delete search performance are all o (1), and the keys have […]

  • Summary of java knowledge points (3)

    Time:2020-1-27

    abstract class Usage rule Abstract defines abstract classes; Abstract defines abstract methods, which only have declarations and do not need to be implemented; The classes containing abstract methods are abstract classes; Abstract classes can contain ordinary methods or have no abstract methods; Abstract classes cannot be created directly, and reference variables can be defined; Interface […]

  • Design of data authority role of SAP basis debug

    Time:2020-1-27

    Design of data authority role of SAP basis debug   In project practice, due to various reasons, it is necessary to solve some specific problems through debugging, so it involves the definition of debug permission role.   The permission of debug is nothing more than:   1) Database table maintenance permission. SAP object class is […]

  • Socket network programming (3): a quick introduction to socket TCP

    Time:2020-1-26

    Blog Homepage 1. TCP TCP (transmission control protocol) is a transmission control protocol, which is connection oriented, reliable and based on byte stream. TCP communication, like UDP communication, can realize the communication between two computers. Socket objects need to be created at both ends of the communication. The difference is: In UDP, only the sender […]

  • IOS underlying exploration – class extension and associated objects

    Time:2020-1-26

    IOS bottom Exploration Series IOS underlying exploration – alloc & init IOS underlying exploration – calloc and ISA IOS underlying exploration class IOS underlying exploration cache IOS bottom layer exploration method IOS underlying exploration – Message lookup IOS underlying exploration – message forwarding IOS underlying exploration – application loading IOS underlying exploration – class loading […]

  • Java object serialization tool class

    Time:2020-1-26

    Here are the object serialization tool classes I often use in my projects import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.io.Closeable; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * ClassName: SerializationUtils *@ Description: object serialization tool class * @author JornTang *@ date July 22, 2017 */ public class SerializationUtil{ private static Logger log […]

  • JavaScript in-depth interpretation of this from ECMAScript specification

    Time:2020-1-26

    In the sixth part of JavaScript in-depth series, we trace back to the source of this article, and interpret how this is determined when a function is called from the ecmascript5 specification. Preface As mentioned in “JavaScript in depth execution context stack”, when JavaScript code executes a piece of executable code, the corresponding execution context […]

  • From int to integer object, there are still many things in detail

    Time:2020-1-26

    Int is one of the eight primitive types of Java. It’s one of the few things that are not objects in the Java language. Integer is the wrapper class of int. it uses a variable of int type to store data and provides some common operations between integers. The general introduction is just that. Programmers […]

  • Picture real-time preview function

    Time:2020-1-26

    HTML structure part let file = document.querySelector(‘#file’); let preview = document.querySelector(‘#preview’); file.onchange = function(){ //Use FileReader to read local files //Create file read object const fr = new FileReader(); //Get the file selected by the user const one = this.files[0]; //Read file fr.readAsDataURL(one); //When the onload event is triggered after reading the file, preview can […]

  • Djangorestframework, authentication component, permission component, frequency component, URL registrar, responder, paging component

    Time:2020-1-26

    I. certification components 1. Local certification components We know that no matter how we write the route or the corresponding view class, we will go to the dispatch method for distribution, In the source code of the dispatch method in the apiview class we see, there is a self.initial (request, * args, * * kwargs), […]