#Java

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May 27, 2020Programming
Key-Exchange Logic for Encrypting Interface Data in Front-End/Back-End Separated Projects (Addendum: MITM Man-in-the-Middle Attack)
Earlier I wrote "Key-Exchange Logic for Encrypting Interface Data in Front-End/Back-End Separated Projects (RSA, AES)", explaining the encryption/decryption strategy when front and back ends exchange data. As my understanding and grasp of network programming grew, two months later I had to write another addendum to patch my previous article, because improper use still can't achieve absolute security. The previous article didn't mention the man-in-the-middle attack, so I'm adding it here.
ProgrammingDevelopmentJavaCodeSecurity
May 26, 2020Programming
Why You Can't Use double/float for Transactions and Financial Currency in Java — Use BigDecimal
Why can't you use double/float for transactions and financial currency in Java? In daily use, floating-point calculations with double/float often produce unexpected results, because binary can't precisely represent most decimal fractions. Today we'll discuss how to do decimal calculations correctly in Java.
ProgrammingDevelopmentJavaCode
April 15, 2020Programming
Resolving the SLF4J Warning "Class path contains multiple SLF4J bindings" — logback and log4j Package Conflict
The SLF4J warning "Class path contains multiple SLF4J bindings" appears in the run log, for example after referencing sdk.renfei.net in SpringBoot. Actually this is a Jar package conflict; you just need to exclude the conflicting Jar package.
ProgrammingDevelopmentJavaCode
April 9, 2020Programming
Use the editor-fold Tag to Fold Your Code and Optimize Its Structure
In real work we often write very long class files, and code readability keeps getting worse. Think about scrolling up and down through hundreds or even over a thousand lines to find the piece of code you want — isn't there a more elegant way? Of course there is. Today I'm introducing the editor-fold tag to optimize your code structure.
ProgrammingDevelopmentJavaCodeIDEA
March 25, 2020Programming
Key-Exchange Logic for Encrypting Interface Data in Front-End/Back-End Separated Projects (RSA, AES)
In front-end/back-end separated projects, sensitive info such as passwords and amounts often needs to be transmitted. Signature/verification algorithms only guarantee data isn't tampered with, but can't keep data confidential. If the user's password is transmitted in plaintext, it can be intercepted by nodes in the network. Although most network operators don't intercept transmitted content, you can't rule out whether the WiFi the user connects to is a phishing network, so sensitive info needs encryption when transmitted. This article discusses how to securely let the client and server exchange keys.
ProgrammingDevelopmentJavaCodeSecurity
March 11, 2020Programming
Encrypt Passwords Properly to Prevent Database Drains and Protect User Login Security
In daily development, passwords are generally just simply MD5'd, and some systems even store users' plaintext passwords directly. If a hacker drains the database and downloads the entire thing, they can log into any account and do dangerous, even irreparable, things. So encrypt passwords properly to protect user account security.
ProgrammingDevelopmentJavaCodeSecurity
March 10, 2020Programming
Tutorial: Actively Pushing Web Pages to Google Search with the Google Indexing API
Google, the world's number one search engine, has long supported webmasters proactively pushing pages, but not through a visual interface for ordinary users — it is done via a programming API. Many webmasters are not professional developers, and because Google requires verifying site ownership, I cannot simply build a visual interface where webmasters enter their own keys. So I wrapped Google's API in a secondary layer to lower the difficulty of using it.
ProgrammingDevelopmentJavaCodeWebsiteOpen Source
March 7, 2020Programming
Can't Tell Object, Generic <T>, and Wildcard <?> Apart in Java? Here's the Clarification
Students who like to study may notice that in other people's code, sometimes Object is returned, and sometimes a <T> generic is used. Code using <T> generics may also contain symbols like <?>. From vague memories of school years ago, you might roughly understand that Object is the parent of all types and can represent any type, and that generics don't restrict the type and can also represent all types — at which point you get confused. Today I'll make their differences clear.
ProgrammingDevelopmentJavaCode
March 5, 2020Programming
GoF's 23 Design Patterns Explained and Demonstrated: (1) Singleton Pattern — Lazy Singleton and Eager Singleton
The Singleton pattern is defined as a pattern where a class has only one instance and the class can create that instance by itself. It is mainly used to solve the frequent creation and destruction of objects, while ensuring logical correctness — for example, only one Task Manager can be opened in Windows, avoiding the waste of memory resources from opening multiple Task Manager windows, or errors such as inconsistent content shown in different windows.
ProgrammingDevelopmentJavaCode
March 4, 2020Programming
GoF's 23 Design Patterns Explained and Demonstrated: Overview
The term "design pattern" did not originally appear in software design, but in architecture. In 1977, the renowned American architect and director of the Center for Environmental Structure at UC Berkeley, Christopher Alexander, described common architectural design problems in his book A Pattern Language: Towns, Buildings, Construction and proposed 253 basic patterns for designing towns, neighborhoods, houses, gardens, and rooms. In 1987, Kent Beck and Ward Cunningham first applied Christopher Alexander's pattern ideas to the generation of graphical user interfaces in Smalltalk, but it did not draw the attention of the software community.
ProgrammingDevelopmentJavaCode