Programmer Think

catalogue 1, Introduction to canvas 2, Drawing basis 1. Introduction to canvas label 2. canvas Context 4. Case: drawing a table in canvas 5. beginPath status of canvas 6. Draw rectangle rect 7. Draw circular arc 8. Case: draw a pie chart based on a set of data 1, Introduction to canvas Canvas is a new label provided by HTML5 < ca ...

3, Standard object 1. Use the typeof operator to obtain the type of object. Note that the type of NaN is number, and the types of null, array and object {} are object: typeof 123; // 'number' typeof NaN; // 'number' typeof 'str'; // 'string' typeof true; // 'boolean' typeof undefined; // 'undefined' typeof Math.abs; // 'function' typeof null; ...

1, MHA overview MHA (Master HA) is an open source MySQL high availability program. It provides the function of automatic master failover for MySQL master-slave replication architecture. When MHA monitors the failure of the master node, it will promote the slave node with the latest data to become a new master node. During this period, MHA ...

What is it A workflow engine is Activiti I don't care much about the introduction of many other places Do what? What I recorded this time is that only one shell of the workflow engine is used for secondary packaging development The specific process is: 1,Pass on his own Json Structure. Of course, you need to ad ...

Git is a content addressed file system. What do you mean? The core of Git is a simple key value data store. You can insert any type of content into the database and return a key value, which can be retrieved at any time. (1) Directory where Git objects are stored All objects in Git are stored in the local version library Objects in the / ...

It has been ten years since I came to CSDN in 2010 and wrote my first blog in 2013. 590 original articles, 7.86 million times of reading and 190000 followers. Behind these numbers, I paid silently for more than 3000 days and made efforts to write nearly 10 million words. Some people say that everything in the world is met and chance. Yes, beca ...

JS built in object constructor [the external chain image transfer fails, and the source station may have anti-theft chain mechanism. It is recommended to save the image and upload it directly (img-C1Z5e4H4-1620368930653)(C:\Users \ Wang Xiu \ appdata \ roaming \ typora user images \ image-20210408114150517. PNG)] This figure shows the constru ...

This case comes from an SQL optimization of a customer in Xi'an. The optimization itself is not complex, but an interesting problem is found, that is, the index range scanning and back table all use multi block reading. Let's take a look at specific cases.SQL text:UPDATE A_INV_PRINT_DET P SET (P.P_POWER, P.N_POWER, P.V_POWER, P.P_KWH_PRC, P.N_K ...

1, Custom error analyzer First throw an exception in the main method: @SpringBootApplication public class P1Application implements CommandLineRunner { public static void main(String[] args) { final SpringApplication application = new SpringApplication(P1Application.class); application.run(args); } @Autowired ...

C language string I character string 1. It is composed of a group of consecutive characters and is contained with "", and the last character must be '\ 0', which indicates the end of the string, and the ASCII code of '\ 0' is 0 Note: To study a string is to study the characters one by one 2. The memory space occupied by t ...