The uri in the project prompts that http://java.sun.com/jsp/jstl/ cannot find the jar package

If the JSP tag library does not exist in eclipse, the problem will be: Can not find the tag library descriptor for “http://java.sun.com/jsp/jstl/core

1. If there is a problem in problem analysis
, we can know that our project is not Import the corresponding jar package, that is:
jstl-1.2.jar
standard-1.1.2.jar
The download address of the corresponding jar package is:
mvn rerepository official website URL: https://mvnrepository.com/
jstl-1.2.jar download The URL is: https://mvnrepository.com/artifact/javax.servlet/jstl/1.2
standard-1.1.2.jar The download URL is: https://mvnrepository.com/artifact/taglibs/standard/1.1.2
2.
The first method of importing jar packages in eclipse is the most direct:
right-click the project to select Build Path, then select Configure Build Path...

first click Java Build Path, select Libraries, and then select Add External JAPs..., import the jar package you downloaded, and refresh it

The second way is ok :

• Delete Web App Libraries in the library of build path configaration.
• At this point, the JAR files in the Webapp/WEB-INF/lib directory in the project can be displayed. Just copy the new jar file directly to lib. Then refresh it!
• Re-add the web app libraries in the library of the build path configaration. That's it!

The third way: directly create a custom library

1. first step:
   
2. second step
   
3. third step
   
4. Step 4
   
   After adding user-defined libraries according to the above steps, you can reuse these defined User Library libraries in the future, saving time for development.