what is java web container

We mentioned that servlet can understand the Java applet that processes data on the server side, so who is responsible for managing the servlet? At this time we will use the web container. It helps us manage servlets, etc., so that we only need to focus on business logic.

#What is a web container?

Servlet does not have a main method, so how we start a servlet, how to end a servlet, how to find a servlet, etc. are all controlled by another java application. This application we call web container.

Our most common tomcat is such a container. If the web server application gets a request pointing to a servlet, the server hands the servlet not to the servlet itself, but to the container where the servlet is deployed. A container must provide http requests and responses to the servlet, and the container must call the servlet's methods, such as doPost or doGet.

The role of web container

Servlet needs to be managed by the web container, so what are the benefits of adopting this mechanism?

Communication support

Using the methods provided by the container, you can simply realize the dialogue between the servlet and the web server. Otherwise, you have to set up a server to search for band-aids, listen on ports, create new streams, and a series of complex operations. The existence of containers helps us encapsulate this series of complex operations. Allows us to focus on the implementation of business logic in servlets.

Life cycle management

The container is responsible for the entire life cycle of the servlet. How to load classes, instantiate and initialize servlets, call servlet methods, and enable servlet instances to be garbage collected. With containers, we don't have to spend energy thinking about things like resource management and garbage collection.

Multi-threading support

The container will automatically create a new java thread for each servlet request it receives. After the servlet is finished running, the container will automatically end this thread.

Declarative implementation of security

With containers, security can be configured using xml deployment descriptors instead of having to be hardcoded into the servlet.

jsp supports

Container translates jsp into java!

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