Programmer Group

1, How kotlin throws exceptions Exception handling in Kotlin is similar to that in Java or other languages. A function can end normally or throw an exception when an error occurs. The function caller catches the exception and handles it; If not, the exception is thrown up the call stack again. The basic form of exception handling statements i ...

Learn the second of the notes made by Elasticsearch. catalogue 1, elasticsearch overview. 2, Comparison and selection of Solr and elasticsearch. 1. solr overview. 2. Lucene overview. 3. Applicable scenarios and comparison of Solr and elasticsearch. 4,elasticsearch-head. 3, Kibana overview. 1. kibana overview. 2. kibana is sinicized. ...

After class questions 1-5 1. How many layers are the network communication protocols divided into? What are the problems solved by each layer? >>OSI layer 7 protocol   OSI seven layer network modelfunctionapplication layerDirectly provide services for the user's application processPresentation layerProvides a standard format for net ...

2021SC@SDUSC This article analyzes the direct package and sitemap package of module page web. Note: because the code is short and concise, the analysis of the code is placed in the remarks of the code segment. 1.directive package architecture This folder contains three classes and a static inner class. PageCommentPageDirective.java prov ...

Message Protocol The concept of a message protocol sounds very tall, but what does a message protocol really mean? Message protocol refers to how the data (messages) transmitted by both sides of the communication express their description. For example, HTTP protocol, when a browser opens a web page, it first establishes a connection ...

Introduction to distributed unique IDThe globally unique id of a distributed system is a scenario encountered by all systems. It is often used in search and storage as a unique identification or sorting, such as the globally unique order number and coupon code of a coupon. If two identical order numbers appear, it will undoubtedly be a huge bug ...

1, Introduction RocketMQ is Alibaba's open source distributed messaging middleware. It draws on Kafka's implementation and supports functions such as message subscription and publishing, sequential message, transaction message, timing message, message backtracking, dead letter queue and so on. RocketMQ architecture is mainly divided into four ...

1. Background In this article, I summarized almost all the extension interfaces of Spring & springboot, as well as the usage scenarios of each extension point. And sorted out the sequential call graph of all extensible points from being loaded to the final initialization of a bean in spring. Thus, we can also see how beans are loaded int ...

1, Localstreaminenvironment Localstreaminenvironment is a subclass of streaminexecutionenvironment. It runs programs locally, multithreaded, and in the JVM that instantiates localstreaminenvironment. It generates an embedded Flink cluster in the background and executes programs on the cluster. When instantiating this environment, it uses the de ...

What is Flyweight concept Flyweight Pattern is a structural pattern, which is mainly used to reduce the performance consumption of object creation and destruction, so as to reduce the occupation of memory. Object oriented language can bring some flexibility and expansibility to our development, and it is more in line with people's way of thin ...