QA Official

In-depth understanding of Spring's two major features (IOC and AOP)

https://qaofficial.com/post/2019/04/04/113651-in-depth-understanding-of-springamp#x27s-two-major-features-ioc-and-aop.html 2019-04-04
As we all know, the core features of Spring are IOC and AOP, IOC(Inversion of Control), or "Inversion of Control";AOP(Aspect-OrientedProgramming), or "Aspect Oriented Programming".The reference book Spring In Action shares my personal understanding of these two features. IOC:IOC, another term is DI(Dependency Injection), which means dependency injection.It is not a technical realization, but a design idea.In any program project with practical development significance, we will use many classes to describe their unique functions and complete specific business logic through the mutual cooperation between classes.

KNN Algorithm Actual Combat-Handwritten Number Recognition

https://qaofficial.com/post/2019/04/04/68912-knn-algorithm-actual-combat-handwritten-number-recognition.html 2019-04-04
KNN Algorithm Brief Introduction For a brief introduction of KNN algorithm, please refer to: K- Nearest Neighbor Algorithm (KNN) Handwritten Number Recognition kNN algorithm is mainly applied to text classification and similar recommendation. This paper will describe an example of classification. What is handwriting recognition?Please refer to Wikipedia Introduction: Handwriting Recognition Data Download: Handwritten Recognition Data Data Description: Each handwritten digit has been processed into 32 * 32 binary text in advance, and the storage format is txt file.

Personal Summary of Dimension Reduction PCA Principle

https://qaofficial.com/post/2019/04/04/68771-personal-summary-of-dimension-reduction-pca-principle.html 2019-04-04
Overview PCA is a classical dimensionality reduction method. The basic PCA is a linear dimensionality reduction method and is essentially a linear coordinate transformation. There are two kinds of classical PCA objective optimization interpretation ideas: one is to maximize variance in a single dimension, and the other is to minimize the distance from the sample point to the hyperplane by using the idea of least square linear regression.

Principal Component Analysis (PCA)-MATLAB Program and Detailed Explanation of Functions

https://qaofficial.com/post/2019/04/04/68797-principal-component-analysis-pca-matlab-program-and-detailed-explanation-of-functions.html 2019-04-04
Reference Source: http://www.cnblogs.com/Hand-Head/articles/5156435.html http://www.matlabsky.com/thread-11751-1-1.html matlab Help Documents Program Source Code Download Link: http://download.csdn.net/detail/ckzhb/9903051 contains three M files: drtool_pca: function encapsulation.Box drawings are not included.Pca _ test: example of MATLAB-PCA () function princmp _ test: example of MATLAB-princmp () function example shows: It uses 9 indicators to measure the quality of life in 329 cities in the United States: climate, housing, health, crime rate, transportation, education, art, entertainment and economy. For

Several Common Encryption Methods and Codes

https://qaofficial.com/post/2019/04/04/68879-several-common-encryption-methods-and-codes.html 2019-04-04
import java.io.UnsupportedEncodingException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.Scanner; import org.apache.commons.codec.binary.Hex;/** * 常見的几种加密方式 */public class Encrypt { public static void main(String[] args) { Scanner sc = new Scanner(System.in); String next = sc.next(); //123 String md5str = string2MD5(next); //202CB962AC59075B964B07152D234B70 String sha1str = string2Sha1(next); //40bd001563085fc35165329ea1ff5c5ecbdbbeef String sha256str = String2SHA256(next); //a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3 String sha256Javastr = String2SHA256StrJava(next); //a665a45920422f9d417e4867efdc4fb8a04a1f3fff1fa07e998e86f7f7a27ae3 System.out.println("next"); System.out.println("md5str:"+md5str); System.out.println("sha1str:"+sha1str); System.out.println("sha256str:"+sha256str); System

Simple Text Emotion Analysis in python

https://qaofficial.com/post/2019/04/04/68827-simple-text-emotion-analysis-in-python.html 2019-04-04
Brief Introduction to Emotional Analysis; Emotional analysis is to analyze whether a sentence is subjective or objective, and whether it expresses positive or negative emotions.Principles such as the following sentence: " The picture of this mobile phone is excellent and its operation is relatively smooth.But taking pictures is really terrible!The system is not good either. "(1) emotional words to analyze a sentence is positive or negative, the simplest and most

Simple Understanding of MD5 Information message digest algorithms

https://qaofficial.com/post/2019/04/04/68882-simple-understanding-of-md5-information-message-digest-algorithms.html 2019-04-04
最近在做一个微项目的时候用到了MD5信息摘要算法,所以就简单的了解了一下,我把我的了解写下来,用作以后的学习。1. Simple Understanding of MD5 MD5的全称是Me

Some Concepts of Entropy and Consistency of Maximum Likelihood and Cross Entropy

https://qaofficial.com/post/2019/04/04/68874-some-concepts-of-entropy-and-consistency-of-maximum-likelihood-and-cross-entropy.html 2019-04-04
Information Quantity of Random Events In order to describe the information content of a random event, self-information is defined. Self-information indicates the degree of uncertainty. There is no information when an event is certain to occur.The smaller the probability of an event, the greater the amount of information. The uncertainty brought by the unknown is the target to be described by the self-information. Self-information: i (x) = log _ i \ frac { 1 } { p (x) } notice: the amount of self-information here does not represent the size of the role of information.

Spring-Several Scenarios of IOC Container Bean Instantiation

https://qaofficial.com/post/2019/04/04/113450-spring-several-scenarios-of-ioc-container-bean-instantiation.html 2019-04-04
Several Scenarios of Bean Instantiation 1. instantiation of Beandefinitionregistrypostprocessor: extension of standard BeanFactoryPostProcessor. BeanFactoryPostProcessor is used to further define the registered BeanDefinition. IoC container is essentially bean management.Therefore, BeanActionTypostProcessor itself is also a Bean. To further define BeanActionTypostProcessor's BeanDefinition, register through BeanDefinitionRegistryPostProcessor. BeanDefinitionRegistryPostProcessor and its subclasses are the most instantiated Beans of Ioc container.They implement class call refresh () method call invokebeanfactorypostprocessors (beanfactory) in configurableapplicationcontext (applicationcontext subinterface);Method is instantiated when

Tell me about the concepts of AOP and IOC in spring and how they are applied in Spring

https://qaofficial.com/post/2019/04/04/110533-tell-me-about-the-concepts-of-aop-and-ioc-in-spring-and-how-they-are-applied-in-spring.html 2019-04-04
Today the landlord continues to share a classic Java quiz: Tell me about the concepts of AOP and IOC in spring and how they are applied in Spring. AOP: Aspect Oriented Programming IOC: Dependence Inversion or Inversion of Control For the specific meaning of AOP and IOC in spring, the landlord has consulted relevant materials online and now shares them with you:   1. IOC(Inverse of Control): Inversion of Control, also known as dependency inversion.