Programmer Think

openfire send message plug-in (description and source code) Implementation function: Send messages to users directly if they are online, and save them as offline messages when they are not online Send a message to a group. If it is online, it will be sent directly. If it is not online, it will be saved as an offline ...

Introduction Dynamic SQL: dynamic SQL. In this section, we will learn from the official documents of MyBatis. Description The official description is as follows: One of the most powerful features of MyBatis has always been its Dynamic SQL capabilities. If you have any experience with JDBC or any similar framework, you understand how painful it ...

1.ViewStub inheritance relationship public final class ViewStub extends View java.lang.Object ↳ android.view.View ↳ android.view.ViewStub The definition of ViewStub on the official website: a ViewStub is an invisible, zero sized view that can be used to lazily inflate layout resources at runtime. This mea ...

Now third-party logins are very common, such as QQ, Weibo and WeChat. Today we are going to implement how to access QQ to login into our project.To use QQ login, we need to register an account with Tencent Open Platform to get the developer qualification address: http://open.qq ...

KVM Migration Static Migration (Cold Migration)For static migration, you can save a snapshot of the completed client image on the host, shut down or pause the client in the host, copy the client's image file to another host, and start the copied image using the command when the client is started in the source host. Dynamic Migration (Thermal M ...

1 simplified configuration Spring provides a simplified configuration for literals, reference beans, and collections, so if you don't use the special features in the complete configuration, it is recommended to try to use a simplified configuration. 1.1 face value 1.1.1 literal attribute Before simplification: <property name="na ...

Original link: http://www.yiidian.com/mybatis/one-to-one.html 1 What are one-to-one, one-to-many mappings? Take users and orders for example, One-to-one: An order belongs to only one user==>The order is one-to-one with the user One-to-many: A user can have multiple orders==>A user is one-to-many with an order Note: In MyBatis, if you want ...

First, make sure you have PostgreSQL installed. You can refer to my article PostgreSQL literacy tutorial. Create a new JPA project using Eclipse: The Platform selects eclipse link as one of the provider s of JPA. The automatically generated project in Eclipse is shown below: Overwrite the automatically generated xml with the contents of the ...

1. Introduction to ContentProvider The client operation contentResolver and ContentProvider are the same Auxiliary operation class ContentUris of Uri 2.ContentProvider database operation Project class structure 1. Create MetaData 2. Define a subclass of SQLiteOpenHelper class to create and delete me ...

This section introduces the analysis of import tag, which is used to introduce new resource files, such as redis, jdbc and other configuration files for a spring.xml. It is mainly to introduce the idea of recursive loading to the readers, including the idea that the beans tag also uses recursion, but be ...