java mongodb orm implementation-ORM based on mongodb-driver
Introduction: MongoDB is a very promising database, and MongoDB officially locates itself as a generic database, which is somewhat like MySQL. Although its popularity is far from the level of MySQL, there is one possible inappropriate comparison. Like MySQL N years ago, MongoDB will become stronger and more popular over time.
Due to the comple ...
Posted by shlomikalfa on Sun, 28 Nov 2021 16:00:56 -0800
[Java Foundation] 21 File
file
File Stream
Files operate as streams in programs
flow
The path through which data travels between data sources (files) and programs (memory)
Input stream: Path of data from data source (file) to program (memory)Output stream: Path of data from program (memory) to data source (file)
Common file operations
Create file object related ...
Posted by Barnacles on Sun, 28 Nov 2021 15:09:55 -0800
JUC high concurrency programming II
5. Collection thread safety
Thread unsafe demo for collection
ArrayListpackage com.codetip.codejuc.juc.conllections;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
public class ThreadArrayList {
public static void main(String[] args) {
List<String> list = new ArrayList<>();
for ...
Posted by Nolan on Sun, 28 Nov 2021 14:43:19 -0800
File upload, download and three-tier architecture
File upload, download and three-tier architecture
1. File upload
method requires post submission, and get limits the size of the data.
enctype needs to use multipart/form-data or it will directly error (binary data is required).
A fifile control is required.
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
...
Posted by stereofrog on Sun, 28 Nov 2021 13:17:17 -0800
Learning Java concurrency tools -- CountDownLatch and CyclicBarrier
preface
Continue to briefly summarize the tool classes for concurrent process control in Java. This article summarizes CountDownLatch and CyclicBarrier
CountDownLatch
Latch means door latch in Chinese. CountDown means CountDown. Count down to 0 and the door latch is opened. You can see the usage scenario of this tool from the name. For e ...
Posted by webAmeteur on Sun, 28 Nov 2021 13:16:17 -0800
★★ | MySQL | how to filter out duplicate data for mass insertion?
There are six tables in the online library with duplicate data, two of which are relatively large, one 960000 + and one 300000 +. Because the same problem has been handled before, we directly brought the last Python de duplication script. The script is very simple, that is, connect to the database, find out the dupli ...
Posted by durahman on Sun, 28 Nov 2021 13:09:09 -0800
Daily class 1 - handwritten ArrayList iterator
summary
Continue with the previous chapter: Daily class - handwritten ArrayList - Generic , this article will talk about the implementation details of the iterator of ArrayList. Due to space constraints, this article first implements the one-way iterative method iterator(), and the two-way iterative listIterator() ...
Posted by I WanT To Code PHP on Sun, 28 Nov 2021 12:52:16 -0800
20 Processes and Threads
Process concept
A process is a running program, such as QQ, that starts a process and the operating system allocates memory for that process. When we use Thunder, a process is started, and the operating system will allocate new memory space for Thunder.A process is either an execution of a program or a running program. Is a dynamic process: th ...
Posted by noise on Sun, 28 Nov 2021 12:46:43 -0800
Java foundation lambda expression
1. Concept
lambda expressions are a new feature added in Java 8.More generally, a lambda expression is like an anonymous method: it provides a list of formal parameters and the body of the statement represented by these parameters.The evaluation of lambda expressions produces Functional interface Examples of. The evaluation of the expression w ...
Posted by jami3 on Sun, 28 Nov 2021 12:31:11 -0800
Primary and foreign key constraints, creation and deletion of parent-child tables in MySQL
summary
This article mainly uses the Navicat for MySQL tool to analyze the common constraints of the SQL language through programming and code testing: primary key constraints And foreign key constraints.
Each table in the business needs to have one and only one primary key.
There can be multiple foreign keys in a table, but ...
Posted by rgilchrist on Sun, 28 Nov 2021 11:11:26 -0800