Programmer Think

When programming, one function is to save after drawing and then call display.But I often show the last saved picture directly the second time I use it. Later I found that deleting the last saved picture manually will display it correctly, so I used the C#Delete File feature so that I can delete the previous picture before savin ...

install Ubuntu 14.04/16.04 (install using apt get) Refer to Appendix 2 # step 1: install some necessary system tools sudo apt-get update sudo apt-get -y install apt-transport-https ca-certificates curl software-properties-common # step 2: install GPG certificate curl -fsSL http://mirrors.aliyun.com/docker-ce/linux/ubuntu/gpg | sudo apt-key add ...

How to use 1. Introduce rocketmq client   <dependency> <groupId>org.apache.rocketmq</groupId> <artifactId>rocketmq-client</artifactId> <version>4.1.0-incubating</version> </dependency> 2. Write Producer   DefaultMQProducer producer = new DefaultMQProducer("producer_demo"); //Specify the Name ...

Put a picture first:   Explain: 1. For the BeanFactory life cycle of spring, we can customize and implement the functions we need according to the creation of beans Customized usage of container post processor: @Component public class MyInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessorAdapter { /* ...

Multithreading concurrency is mainly multithreading operation resource class, followed by multithreading communication, trilogy, judgment, work, and notification. In order to prevent false wake-up judgment, while must be used. Finally, in order to ensure the order of multithreading execution, Condition matching flag bit can be used to notify t ...

Druid supports SQL [ EXPLAIN PLAN FOR ] [ WITH tableName [ ( column1, column2, ... ) ] AS ( query ) ] SELECT [ ALL | DISTINCT ] { * | exprs } FROM table [ WHERE expr ] [ GROUP BY exprs ] [ HAVING expr ] [ ORDER BY expr [ ASC | DESC ], expr [ ASC | DESC ], ... ] [ LIMIT limit ] [ UNION ALL <another query> ] Duration data type The duration ...

1. Goroutine synchronization [data synchronization] Why goroutine synchronization is needed The concept of gorotine synchronization and several ways of synchronization 1.1 why goroutine synchronization is needed package main import ( "fmt" "sync" ) var A = 10 var wg = sync.WaitGroup{} func Add(){ defer wg.Don ...

@[toc] stay Spring Framework Learning 1 The main topics are some overviews of Spring, Spring factories, Spring attribute injection, and the introduction to IOC, the most important of which is IOC. Let's briefly summarize the IOC in the last article: Then this article mainly talks about another important core in Spring besides IOC: AOP, IOC or ...

Dynamic switching of data sources on the Internet can not meet my current application, and switching back and forth will cause performance problems and crash. And it's not a good way to switch notes on a certain method. So think about it at the top level. Here is my configuration: Initializing multiple spring-mybatis.xml files i ...

Fastjson source address: https://github.com/alibaba/fastjson Fastjson Chinese Wiki: https://github.com/alibaba/fastjson/wiki/Quick-Start-CN     I. introduce dependency 1) FastJson is a toolkit for java background processing json format data 2) FastJson mainly uses the following three classes for parsing json format strings ...