QA Official

Using UDP Protocol to Realize Information Exchange between Two Computers 2019-04-05
About UDP: Encapsulates data and source and destination into data packets without establishing connections;The size of each datagram is limited to 64k;Because there is no connection, it is unreliable protocol.No connection needs to be established, so the speed is high. udp protocol mainly involves two classes: DatagramSocket and DatagramPacket DatagramSocket: used to establish the exit or entry of a data packet. In the construction method, IP is used for the

knn Algorithm Example-Using knn Algorithm to Improve Matching Effect of Dating Websites 2019-04-05
Steps: 1, collect data 2, prepare data 3, analysis of data 4, training algorithm 5, test algorithm 6, using algorithms 1. The data used in this article are date data collected by Helen and can be downloaded from The detailed code is as follows with detailed explanation: #准备数据:从文本文件中解析数据 from numpy import * import operator

winnowing algorithm-extracting document fingerprint features 2019-04-05
The simple explanation of winnowing algorithm is: based on the Hash code of k-gram, the Hash code of partial gram is extracted by minimum rules as the fingerprint of document features, and the position of gram is recorded.The source code and steps are as follows: (1) Mark the document with characters, such as " asdf", and change it to [ (0, " a"), (1, " s"), (2, " d"), (3,

MD5 Information message digest algorithms 2019-04-04
MD5 is Message-Digest Algorithm 5 (Information message digest algorithms 5), which is one of the hashing algorithms widely used by computers.Developed by MD2, MD3 and MD4, it was born in the early 1990s.Used to ensure complete and consistent information transmission.Although it has been cracked, it still has good security and can be used free of charge, so it is still widely used in digital signature, file integrity verification, password encryption

PCA Face Recognition Personal Understanding and Steps 2019-04-04
PCA Face Recognition Personal Understanding and Steps Preface PCA, principal component analysis, is a method of data dimensionality reduction, and is also an ancient and classic face recognition algorithm.Understanding the principle and steps of PCA algorithm is very helpful to our thinking.Although PCA is relatively simple among many face recognition methods, it is not easy to clearly understand the detailed steps and details of PCA face recognition, especially for beginners.

Spring AOP Understanding and Application Scenarios 2019-04-04
AOP related concepts AOP is short for Aspect Oriented Programming, Aspect Oriented Programming.AOP is suitable for applications with crosscutting logic, such as performance monitoring, access control, transaction management, caching, object pool management, and logging.AOP extracts these codes scattered in each business logic into an independent module through horizontal cutting.The key to AOP implementation lies in the AOP proxies automatically created by the AOP framework. AOP proxies can be divided into two categories: static proxies and dynamic proxies, where static proxies refer to the use of commands provided by the AOP framework for compilation, so that AOP proxy classes can be generated at the compilation stage, which is also called compile-time enhancement.

Spring Framework Benefits and IOC Personal Summary 2019-04-04
spring是一个一站式轻量级开源框架,Spring提供了JavaEE各层的解决方案,表现层:Spring MVC,持久层:JdbcTempl

Spring Framework Interview Summary 2019-04-04
1. What is Spring? A: spring's core is a lightweight Container, which implements IoC(Inversion)Of Control) container and non-invasive framework, and provide the implementation of AOP(Aspect-oriented Programming), provide support for Persistence and Transcation;It provides the implementation of MVC Web framework and provides consistent model encapsulation for some common enterprise service API. It is an all-round application framework. In addition, Spring also provides a scheme to integrate with various existing frameworks (Structs, JSF, hibernate, Ibatis, Webwork, etc.

Spring Principle (2) ApplicationContext of IoC Container Initialization Process 2019-04-04
The previous article has already introduced the initialization process of BeanFactory, and this article introduces the initialization of ApplicationContext.There are many implementations of ApplicationContext. here, take the common filesystemxmlApplicationContext as an example to illustrate the initialization process of applicationcontext. start ApplicationContextThe following code initializes an IoC container, filesystemxmlapplicationcext, which can get the configured bean object through getBean. FileSystemXmlApplicationContext ctx = new FileSystemXmlApplicationContext("D:/workspace/demo_spring/src/main/resources/applicationContext.xml"); System.out.println(ctx.getBean("userService")); Let's continue to look at what exactly

Spring's IOC Event Use 2019-04-04
Spring's event mechanism uses Observer pattern Observer pattern defines a one-to-many dependency between objects, so that when an object changes state, all its dependencies will be notified and automatically updated.Themes and observers define a one-to-many relationship.Observers depend on the topic and will be notified whenever the status of the topic changes.Depending on the style of the notification, the observer may be updated with the new value.The power of loose coupling.