Category:Java

  • Some thoughts and understandings of high availability

    Time:2020-1-19

    The source of this article is public number: originality zero. In the current Internet era, under the impact of high concurrency, we must also ensure thatService high availability, if the service is not highly available, it means: The system doesn’t provide services 7 * 24 hours a day, so the user experience is particularly poor. […]

  • Detailed explanation of hash table knowledge points in Java data structure and algorithm

    Time:2020-1-19

    The structure of the tree is almost the same. Now we say that a data structure is called hash table. What is the use of hash table? We know that the time complexity of tree operation is usually o (logn). Is there a faster data structure? Of course, it is a hash table; 1. Introduction […]

  • File upload of spring MVC

    Time:2020-1-18

    SummaryFile upload is a common function in Java Web projects. If the purpose of file upload is not achieved, the following steps are required:1. The method property of the form must be set to post.2. The enctype attribute of the form must be set to multipart / form data (the browser will use binary flow […]

  • An example of the conversion between XML and JSON in Java

    Time:2020-1-18

    The example of this article describes how to implement the conversion between XML and JSON in Java. To share with you for your reference, as follows: Narrator: Recently, the conversion between XML and JSON has been confused. Here’s a demo for future use. Topic: The project format is: Jar packages are checked out one by […]

  • In depth analysis of spring 5 source code — use of AOP and AOP custom label

    Time:2020-1-17

    We know that there are some disadvantages in OO programming. When we need to introduce the same common behavior for multiple objects without inheritance relationship, such as log, security detection, etc., we only need to introduce the common behavior in each object, so a lot of repetitive code will be generated in the program, so […]

  • How to save a picture after receiving it in Java background

    Time:2020-1-17

    Java is an object-oriented programming language. It not only absorbs the advantages of C + + language, but also discards the concepts of multi inheritance and pointer which are difficult to understand in C + +. Therefore, Java language has two characteristics: powerful function and easy to use. As a representative of the static object-oriented […]

  • `Differences between ‘abstract class’ and’ interface ‘in Java

    Time:2020-1-16

    abstract class JavaAllowed inabstractThe modifier declares the method. At this time, only the method is defined but not implemented(abstractThe decorated method has no body, only a signature and a semicolonBelow isabstractMethods and theabstractClass related rules: As long as there is one in the classabstractMethod, the class itself automatically becomesabstract, and must be declared asabstract classOtherwise, […]

  • Understand java checked and unchecked exceptions through examples

    Time:2020-1-16

    Java exceptions are divided into two types: checked and unchecked. The other is called exception and error. In short, checked can be recovered during execution, while unchecked exception is an unhandled error. Checked exception: Indicates invalid, not predictable in the program. For example, invalid user input, file does not exist, network or database link error. […]

  • Essentials of java knowledge (2)

    Time:2020-1-15

    I. set 1. Iterable v.s. IteratorBoth are interfaces, and the inherited interface in collection is Iterable.Iteratable expresses that the collection has the ability of iterative access, while iterator represents the implementation, which can be from small to large or from large to small. https://zhuanlan.zhihu.com/p/52366312 2. Comparable v.s. Comparator https://www.cnblogs.com/skywang12345/p/3324788.html 3. set https://www.cnblogs.com/LittleHann/p/3690187.html Collection needs multi-purpose […]

  • An example of how to integrate spring task with mall to implement timed tasks

    Time:2020-1-15

    abstract This paper focuses on the process of integrating spring task with mall, taking batch modification of overtime orders as an example. Spring task is a lightweight timed task tool independently developed by spring, which is simpler and more convenient than quartz, and can be used without introducing other dependencies. Cron expression is a string, […]

  • Auto download Zar configuration management

    Time:2020-1-14

    Maven Download:Https://maven.apache.org/ download on the official website: binary zip archive apache-maven-3.6.2-bin.zip Installation free decompression   Conf / settings.xml configuration under mavenLocal warehouse: D:/repoConfigure image central warehouse: Alibaba cloud central warehouse mirrorId repositoryId local_maven https://maven.aliyun.com/repository/public//Alibaba cloud Zar package download address Configure environment variables:Configure: Maven? Home in the system variableConfigure to: D: \ wordsoft \ apache-maven-3.6.0 (Maven […]

  • Deep understanding of Java HashMap’s dead cycle

    Time:2020-1-14

    Preface In the Taobao intranet, I saw a colleague posted that a CPU was 100% online broken, and this happened many times. The reason is that the Java language uses HashMap to create a race condition in the concurrent situation, which leads to a dead cycle. I also experienced this 4 or 5 years ago. […]