After following, you can keep track of his dynamic information in a timely manner
The single responsibility principle requires that the class has only one reason for change, which is implemented by separating order processing, database saving and email notifications into different classes; 2. The opening and closing principle means that the software entity should open up and close the modification, and support the new payment method through interfaces and polymorphisms without modifying the existing code; 3. The Richter replacement principle requires that the subclass can replace the parent class to avoid the problem of behavior inconsistent behavior caused by square inheritance; 4. The interface isolation principle emphasizes that the client should not rely on unwanted interfaces, and split the multifunctional machine interface into independent interfaces of printers, scanners and fax machines; 5. The dependency inversion principle requires that the reliance on abstraction rather than concrete implementation, and the high-level module is decoupled from the low-level module through interfaces, which is convenient for testing and replacement implementation. Applying SOLID principle can improve the ability of Java code
Aug 06, 2025 pm 04:35 PM
continueinsideaswitchstatementnestedwithinalooptargetstheloop,nottheswitch.2.Itskipstheremainingcodeintheloopbodyandproceedstothenextiteration.3.Thisbehaviorcanbypassstatementsaftertheswitch,leadingtounintendedflow.4.Alwaysusebreaktoexitaswitchcaseno
Aug 06, 2025 pm 04:33 PM
Responsive programming is suitable for high concurrency and low latency scenarios in modern Java back-end development. 1. SpringWebFlux implements non-blocking responsive programming based on ProjectReactor, which is suitable for I/O-intensive, large number of concurrent connections or scenarios using responsive databases; 2. Core types Mono and Flux represent asynchronous data streams of 0-1 and 0-N elements respectively, operators such as map, flatMap, onErrorResume, etc. are used to build and process data streams; 3. Thread switching needs to be performed through Schedulers such as boundedElastic or parallel to avoid blocking event loops; 4. Mixed blocking code should be avoided in actual development.
Aug 06, 2025 pm 04:31 PM
$_SESSION and $_COOKIE are the core mechanisms for implementing web application state management in PHP; 1. $_SESSION stores user data through the server and relies on a unique session ID (usually stored in a cookie named PHPSESSID) to maintain user status. It requires calling session_start() to initialize, which has high data security; 2. $_COOKIE stores a small amount of data on the client side, which can be used to persist login status, user preferences or reconnect sessions; 3. Security practices include calling session_regenerate_id(true) after logging in to prevent session fixed attacks, and setting secure cookie parameters (such as secure, h
Aug 06, 2025 pm 04:29 PM
Nevertrust$\_SERVER\['HTTP\_HOST'\]withoutvalidation,asitcanbespoofedtoenableopenredirects;alwayswhitelistalloweddomainsoruseaconfiguredbaseURL.2.Donotrelysolelyon$\_SERVER['REMOTE\_ADDR']forclientIPdetection,asitmayreflectaproxyIP;onlytrust$\_SERVER
Aug 06, 2025 pm 04:27 PM
Alwayscheckarrayboundsusingisset()orarray_key_exists()beforeaccessingelementstopreventundefinedoffseterrors.2.Usearray_key_exists()whendistinguishingbetweenmissingkeysandnullvaluesisnecessary.3.Validateinputarraysearlytoensureexpectedstructure,usingn
Aug 06, 2025 pm 04:25 PM
The core of JavaCollectionsFramework is the three major interfaces: List, Set, and Map. 1. List is an ordered repeatable set. Common implementations include ArrayList (rail access fast) and LinkedList (frequent addition and deletion); 2. Set is an unordered and non-repeatable set, HashSet looks fast, LinkedHashSet maintains the insertion order, TreeSet supports sorting; 3. Map stores key-value pairs, HashMap has high performance and allows null, LinkedHashMap maintains the order of order, TreeSet sorts by key, Hashtable thread-safe but is outdated; when selecting a set, you need to consider whether it needs to be ordered and sorted.
Aug 06, 2025 pm 04:24 PM
/bin and /sbin store basic commands and system management commands; 2./usr stores user programs and related resources; 3./etc is the configuration file directory; 4./var stores variable data such as logs and caches; 5./home and /root are the home directories of ordinary users and root users; 6./tmp and /run are used for temporary files and runtime data; 7./dev, /proc, /sys provides device and system information interfaces; 8./lib and /lib64 contain library files required for system startup; 9./opt and /srv are used for third-party software and service data respectively; FHS improves system management efficiency through standardized directory structure, making the layout of Linux files clear and consistent, making it easy to maintain and
Aug 06, 2025 pm 04:23 PM
JavaFlightRecorder(JFR)andJavaMissionControl(JMC)arebuilt-inJDKtoolsforprofilingJavaapplicationswithminimaloverhead.1.JFRcollectsruntimedatasuchasgarbagecollection,threadcontention,CPUusage,objectallocation,andJVMevents.2.EnableJFRatstartupusing-XX:
Aug 06, 2025 pm 04:14 PM
Set worker_processes to the number of CPU cores or auto, and adjust worker_connections according to the number of concurrent connections to ensure that ulimit-n is higher than the total number of connections; 2. Enable epoll and multi_accept in Linux to improve I/O efficiency; 3. Enable open_file_cache for static content to reduce disk I/O; 4. Configure the buffer size reasonably to avoid memory waste, and optimize proxy_buffer parameters for proxy scenarios; 5. Enable Gzip to compress text type resources, skip small files and compressed content; 6. Enable HTTP/2 to automatically obtain multiplexing performance in SSL scenarios; 7. Use ab or wrk
Aug 06, 2025 pm 04:06 PM
InstallNginxusingtheappropriatepackagemanagerforyourLinuxdistribution,startandenabletheservice,andverifyitisrunning.2.ConfigurethefirewalltoallowHTTPandHTTPStrafficusingufworfirewalld.3.Createabasicsiteconfigurationbysettingupawebdirectory,testpage,a
Aug 06, 2025 pm 04:02 PM
array_splice()istheprecisetoolforremovingspecificelementsfromanarrayinPHP.1.Itmodifiestheoriginalarraybyremovingaspecifiedportionandreturnstheremovedelements.2.Usearray_splice($arr,$offset,$length)toremove$lengthelementsstartingat$offset.3.Removingfr
Aug 06, 2025 pm 03:59 PM
XStatemakesmanagingcomplexUIstateinJavaScriptpracticalbyusingfinitestatemachinesandstatecharts.InsteadofscatteredbooleanslikeisLoadingorisError,itcentralizeslogicintodefinedstatesandtransitions,improvingpredictabilityandreducingbugs.Forexample,aformc
Aug 06, 2025 pm 03:52 PM
Whenyou'reworkingwithgeospatialdatainMySQL,performancecanquicklybecomeabottleneckifthingsaren'tsetupright.Thekeyistostructureyourdata,usetherightindexes,andunderstandhowspatialqueriesbehave.UsetheRightDataTypesMySQL
Aug 06, 2025 pm 03:45 PM
CoreWebVitalscanbeimprovedbyoptimizingLCP,FID,andCLSthroughspecificstrategies:1.ImproveLCPbyoptimizingserverresponsetime,preloadingcriticalresources,compressingimages,eliminatingrender-blockingJavaScriptandCSS,andusingefficientframeworks.2.ReduceFIDb
Aug 06, 2025 pm 03:37 PM
Implementing a simple state machine using PHP switch statement is a practical method for handling finite states and clear transitions. It is suitable for scenarios where the number of states is small, the conversion is predictable and does not require complex logic, such as form processes, order processing or content review; 1. When the number of states is fixed and known, switch can centrally manage state logic; 2. By encapsulating state processing methods, such as handlePostState(), it can isolate state-specific behaviors; 3. Use transitionPost() combined with conditional judgment to ensure that only effective transitions are allowed; 4. It is recommended to use constants to define state values to avoid spelling errors; 5. When states and transitions increase or need persistence and event hooks, you should turn to special libraries such as Finite or Symfo
Aug 06, 2025 pm 03:26 PM
Configuring highly available Linux clusters based on Pacemaker and Corosync must first meet the prerequisites: at least two servers with the same system version, static IP and hostname, password-free SSH between nodes, shared storage (optional) and opening necessary firewall ports; 2. Install corresponding software packages on each node (dnfininstallpacemakerpcs for RHEL/CentOS, etc., Ubuntu uses aptinstallpacemakercorosyncccrmsh), enable the pcsd service and set the same password for Hacluster users; 3. Perform authentication on any node (pcsclusterauthnode1node2) and create sets
Aug 06, 2025 pm 03:22 PM
MySQL 8.0 introduces InvisibleIndexes, allowing temporary hiding of indexes without deleting. 1. Set invisible when creating: Use CREATEINDEX...INVISIBLE; 2. Modify the existing index to invisible: ALTERINDEX...INVISIBLE; 3. Restore visible: ALTERINDEX...VISIBLE. The invisible index is still maintained, but does not participate in the implementation plan generation. It is suitable for testing the effect of new indexes and avoiding the risk of direct online launch. Backup and copy will retain their status, and FORCEINDEX cannot bypass invisibility, and is suitable for performance tuning and indexing strategy adjustment without affecting online services.
Aug 06, 2025 pm 03:20 PM
TomigrateolderapplicationstoMySQL8.0successfully,firstcheckapplicationcompatibility,thencarefullymigrateandconvertdata,updateconfigurationandsecuritysettings,andmonitorperformancepost-migration.1.Checkapplicationcompatibilitybyupdatingdatabasedrivers
Aug 06, 2025 pm 03:07 PM
Usearray_spliceforin-placeinsertionasitmodifiestheoriginalarraydirectly,ismoreefficient,andhassimplersyntax;2.Usearray_mergewitharray_slicewhenpreservingtheoriginalarrayisrequired,asitcreatesanewarraywithoutmutationandsupportsfunctionalprogrammingsty
Aug 06, 2025 pm 03:06 PM
QuarkusisaKubernetes-nativeJavaframeworkthatoptimizescloud-nativedevelopmentbyenablingfaststartup,lowmemoryusage,andseamlesscontainerintegration.1.Itsupportslivecodingwithinstantreloadvia./mvnwquarkus:dev.2.Itusesaunifiedconfigurationmodelthroughappl
Aug 06, 2025 pm 03:01 PM
Thenullcoalescingoperator(??)inPHPsafelyaccessesarraykeyswithouttriggeringnotices.1.Itreturnsthevalueifthekeyexistsandisnotnull;otherwise,itreturnsadefault.2.Itsimplifiesfallbacklogiccomparedtoisset()andternarychecks.3.Itpreservesfalsyvalueslike0,''o
Aug 06, 2025 pm 02:48 PM
Treat$\_SERVERvaluesasuntrustediftheycanbeinfluencedbyuserinput,suchasHTTP\_HOST,REQUEST\_URI,HTTP\_USER\_AGENT,HTTP\_REFERER,andQUERY\_STRING,sincethesecanbemanipulatedbyclients.2.Alwaysescape$\_SERVERdatausinghtmlspecialchars($\_SERVER['value'],ENT
Aug 06, 2025 pm 02:45 PM
Destructuringallowsselectiveextractionofarrayelementsintovariables,improvingreadabilityandreducingcodeverbosity.2.Thefind()methodretrievesthefirstelementmatchingacondition,whilefindIndex()returnsitsindex,bothofferingsaferandmorereadablealternativesto
Aug 06, 2025 pm 02:38 PM
Back up the data and confirm that the system meets the minimum Ubuntu requirements, including running Windows 11 in UEFI mode; 2. Compress at least 50GB of unallocated space from the C disk through the disk management tool; 3. Use Rufus to write Ubuntu ISO to more than 8GB USB disk and set it to GPT and UEFI modes; 4. Turn off fast boot in Windows and temporarily disable SecureBoot; 5. Boot from UEFIUSB, select the "Install Ubuntu parallel with WindowsBootManager" option to complete partitioning and installation; 6. Reboot after installation, if Windows does not display Windows on the GRUB menu, enter Ubuntu to run sudoupdate-
Aug 06, 2025 pm 02:35 PM
The sorting logic in PHP is significantly simplified using the Spaceship Operator(). 1. The operator compares two values and returns -1, 0 or 1, respectively, indicating that the left operand is less than, equal to or greater than the right operand, thereby replacing the lengthy if-else structure; 2. Use $a$b directly in usort, uasort and uksort to achieve ascending sort; 3. Multi-field sorting can be achieved through [$a['field1'],$a['field2']][$b['field1'],$b['field2']]]; 4. Descending sorting only requires exchanging the operand order, such as $b['age']$a['age']; 5. The object attribute sorting is also applicable, such as $a->age$
Aug 06, 2025 pm 02:28 PM
SQL can effectively improve retail sales and inventory efficiency. 1. When analyzing sales trends, count sales and order counts according to time dimensions (such as monthly), identify peaks and troughs, and group them into products or stores to find hot-selling categories; 2. By calculating inventory turnover rate (sales cost/average inventory), identify unsold products (large inventory and no sales in the past three months); 3. Forecast demand based on historical sales volume, and obtain replenishment suggestions based on current inventory; 4. Compare the sales performance and inventory turnover of different stores, discover operational shortcomings and optimize them in a targeted manner. By mastering these methods, you can use SQL to quickly mine the value of retail data.
Aug 06, 2025 pm 02:23 PM
breakexitstheloopimmediatelyafterfindingatarget,idealforstoppingatthefirstmatch.2.continueskipsthecurrentiteration,usefulforfilteringitemsliketemporaryfiles.3.gotojumpstoalabeledstatement,acceptableinrarecaseslikecleanuporerrorhandlingbutshouldbeused
Aug 06, 2025 pm 02:14 PM
UsedirectkeyassignmentforO(1)updates.2.Checkkeyexistenceonlywhennecessarytoavoidoverhead.3.BatchupdatesusingspreadorObject.assignforefficiency.4.PreferMapoverplainobjectsforfrequentupdates.5.Avoidinefficientfull-arrayreprocessingwhendirectupdatessuff
Aug 06, 2025 pm 02:13 PM
The recover function must be called in defer to capture panic; 2. Use recovery in long-running programs such as goroutine or server to prevent the entire program from crashing; 3. Recover should not be abused, only used when it is handled, to avoid replacing normal error handling; 4. Best practices include recording panic information, using debug.Stack() to obtain stack traces and recovering at an appropriate level. Recover is only valid within defer and should be used for debugging with logs. Potential bugs cannot be ignored. In the end, the code should be designed by returning error rather than panic.
Aug 06, 2025 pm 02:08 PM
