• Java dictionary


    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 […]

  • Spring 5 Reference Guide: AspectJ annotations


    What is AspectJ annotation To use AOP in spring, there are two ways, one is annotation, the other is XML configuration. This article mainly explains how to open spring AOP through annotation. @AspectJ is a style of declaring aspects to annotate Java classes with annotations. @The AspectJ style was introduced by the AspectJ project as […]

  • Druiddatasource and mybatis conspire, resulting in OOM


    First sufferDruidDataSourceA surprise attack Incident One ordinary working day, I finished the business code of the product requirements as usual, and suddenly received the alarm message from the monitoring platform. I thought it was some business bugs that caused the error report. When I read the error report discovery log, I wrotejava.lang.OutOfMemoryError: Java heap space。 […]

  • Using Ajax to climb today’s top street to take pictures of the United States and the United States


    In this section, we take today’s headlines as an example to try to analyze Ajax requests to grab web data. The goal to capture this time is to take beautiful pictures of today’s headlines. After the capture, download each group of pictures into folders and save them locally. Xiaobian has created a two thousand person […]

  • Kafka Study Notes


    Kafka Study Notes Kafka was named after a writer named Franz Kafka. Kafka is an open source message engine system. It is also a distributed flow processing platform. Kafka supports both point-to-point model and publish / subscribe model. Why use kakfa? Four words: cut peak and fill valley! Kafka terminology Record: message, referring to Kafka […]

  • 1. Generic


    I. generic Generics are encapsulation, simplifying repetitive work 1. Generic methods public static void Show(T tParameter) {   Console.WriteLine(“This is {0}, parameter = {1}, type = {2}”, typeof(CommonMethod).Name, tParameter.GetType(), tParameter); } 2. generic class public class GenericClass{} 3. Generic interface public interface GenericInterface{} 4. Generic delegation public delegate void Do(); 5. Generic constraints Public static void […]

  • Creating SQL statements dynamically for Oracle and MySQL


    MYSQL: @Query(value = “select * from project_demand where project_id=?1 and if(?2!=”,demand_id in (select demand_id from demand_user where user_id=?2),1=1)”,nativeQuery = true) If (? 2! = ‘, demand_id in (select demand_ Oracle: DECODE(VALUE,IF1,THEN1,IF2,THEN2,IF2,THEN2,..,ELSE) Indicates that if the value is equal to IF1, the result of the decode function returns then1,… Or else if it is not equal […]

  • How to write a practical bind?


    Preface This is the fifth part of the source code analysis of anderscore.js. If you are interested in this series, please click Under core analysis / watch, you can see the dynamic update at any time. Things to be done from JSthisAt first, do you often feel that you can’t control and know it? For […]

  • Python error message is: sudo: apt get: command not found


    1. Problem description The error message is: sudo: apt get: command not found 2. Causes and Solutions Use Yum install XXX under CentOS Differences between Yum and apt getGenerally speaking, famous Linux systems are basically divided into two categories:1. RedHat series: RedHat, CentOS, Fedora, etc2. Debian series: Debian, Ubuntu, etcRedHat collection1. The common installation package […]

  • C ා parameters passed in when the desktop program starts


    using System;using System.Collections.Generic;using System.Linq;using System.Windows.Forms; namespace WindowsFormsApplication8{ static class Program { /// ///The main entry point for the application. /// [STAThread] public static void Main(string[] args)//Add parameter and receive value. When the program is started by dragging a file, the first value of the parameter array is the path of the file { if (args.Count()>0) […]

  • [20191213] invalid bind_award prompt under toad 12.txt


    [20191213] invalid bind_award prompt under toad 12.txt –//Link to http://blog.itpub.net/267265/viewspace-2130781/ test, and find the test error at that time. Check again if you have time 1. environment:[email protected]> @ ver1PORT_STRING                    VERSION        BANNER—————————— ————– ——————————————————————————–x86_64/Linux 2.4.xx       Oracle Database 11g Enterprise Edition Release – 64bit Production create table t as select rownum id ,lpad(‘x’,100,’x’) name ,lpad(‘1’,1) […]