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[TOC] I. fsimage and edit files 1. Basic concepts txid: namenode gives a unique id for each operation event (add, delete, and change operation), which is called txid. Generally, txid is automatically increased from 0. For each additional operation, txid is automatically increased by 1. fsimage: It is a mirror file of the metadata of namenode i ...

1 set the syntax format of html file xsd file Write xsd file according to the properties of POJO. for example <?xml version="1.0" encoding="UTF-8" ?> <schema xmlns="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.zhangyh.com/schema/user" elementFormDefault="qualified"> <element name="user"> ...

I. nature of icons Font awesome icon is a font, and its technical term is Icon Font. In essence, it is a character encoded with PUA (Private Unicode Area) code point Unicode. Therefore, the icons of font awesome icon and Bootstrap are the same as those of Wingdings font, and the difference is nothing but encoding. II. Drawing pictures After ...

IOC container IOC containers, sometimes called dependency injection (DI). Through the dependencies defined by the object itself, these dependencies are injected into the bean when it is created. This process is contrary to our normal design. We usually have a new object in the object, which is our program control management object. In spring, w ...

Author: Han Tianfeng's original address: Click to view What is the consortium? The first published explanation of the coroutine appeared later, in 1963. The concept of the coroutine is longer than that of the c language. The term coroutine is coined by Melvin Conway in 1958, after which it is applied to construction of an assembly program. The ...

demand Adaptive size text: Design sketch: In project development, developers lay out some pages with text according to a set of sizes provided by UI personnel. Often less consideration will be given to some data limits, resulting in the problem of screen adaptation. For example: Text (or numeric) length is variable, such as experience value, nu ...

Today, let's talk about the use of broadcasting. Broadcasting is also used to disseminate messages within app. There are both senders and receivers of broadcasting. See the code specifically to illustrate the use of broadcasting. 1. Broadcasting Write a page to send broadcasts, and see the comment ...

The script is well written. Get off work early! In addition to writing program code, programmer's daily work inevitably needs to deal with related testing and verification work. For example, access to a Web site has been impassable, you need to determine whether the address is accessible, what the server returns, and then determine what the pro ...

Project introduction Creation time: October 4, 2019 16:30:09 Functions: Android remote service production and test run, AIDL service. Introduction to development environment: Android API = 29, Android 10, and Android Studio Make complaints More than N articles were searched online, either for a long time or for different operations of IDE de ...

Principle: Base64 is one of the most common encoding methods for transmitting 8Bit bytecode on the network. Base64 is a way to represent binary data based on 64 printable characters. About the coding rule: Change 3 characters into 4 characters. (2) Add a newline character for every 76 characters. (In ...