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This article introduces what are the knowledge points of Servlet and Jsp, the content is very detailed, interested friends can refer to, hope to be helpful to you.

EL expression

Function: for more convenient communication between Servlet and Jsp

It turns out that this is how the data is obtained:

Now the EL expression looks like this:

${str} ${user.addr.town} ${map.a}

One by one, it's really convenient to drink too much.

Pre-use preparation of JSTL:Jsp standard tag library

Function: it is too annoying to write java code in jsp. It is much more convenient to write this java code in jstl.

Guide packages jstl.jar and standard.jar are required before use

Tag library needs to be introduced in jsp files.

Out tags, set tags and remove tags

The function of the out tag is to output

The purpose of the set tag is to store key-value pairs

The function of the remove tag is to delete the key-value pair

The out tag is used as follows:

The set tag is used as follows:

The use of the remove tag is as follows:

If tags and choose tags

The function of if tag is the function of if in java.

The function of choose tag is the function of if ·else in java.

The if tag is used as follows:

This is the if judgment in jstl.

The choose tag is used as follows:

This is the choose tag of jstl.

He he

Foreach tag

It's just a cycle.

There are two uses: constant loop and dynamic loop. For example, you can see what's going on.

Constant loop usage: starting point is 1, end point is 5, step size is 1

This is the cycle of jstl-- ${vs.index}

Dynamic loop usage (important): very similar to the way for loops traverse the list in java

${str}

What are the knowledge points about Servlet and Jsp? so much for sharing here. I hope the above content can be helpful to you and learn more knowledge. If you think the article is good, you can share it for more people to see.

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