Jakarta Expression Language API and Java Library Integration: The key to achieving efficient development
Title: Jakarta Expression Language API and Java Library Integration: The key to achieving efficient development
Summary: Jakarta Exposition Language (referred to as EL) is a dynamic expression language, which can improve development efficiency with the Java class library integration.This article focuses on the basic concepts and usage methods of Jakarta El API, and shows how to integrate it with the Java class library to achieve the key to efficient development.
I. Introduction
With the continuous development of enterprise Java applications, developers need to process and operate data more efficiently.Jakarta El API provides a simple and powerful dynamic expression language, which can be integrated with the Java class library to achieve more efficient development.This article will focus on the basic concepts and usage methods of Jakarta El API, as well as how to integrate it with the Java library.
Introduction to Jakarta El API
1. Jakarta El API Overview
Jakarta Expression Language (referred to as EL) is a language for dynamic computing expressions that can handle and operate data flexibly.It can be used to access, modify and calculate attributes and methods in various Java objects (such as JavaBean, MAP, and arrays).Jakarta El API defines a set of interfaces and classes to analyze and calculate EL expressions.
2. Jakarta El API basic usage
The basic usage of Jakarta El API is divided into two steps: resolution expression and computing expression.
-Base expression: Use EL parser to analyze EL expressions into an EL expression object.The parser can be obtained by calling the static method of `javax.el.expressionFactory`` newInstance () `.
-Acut the expression: Calculate the value of the expression using the EL expression object.You can calculate the value of the expression by calling the expression of the expression `GetValue (Context, ExpectedType). The` Context` represents the context environment when calculating, and `ExpectedType` represents the return type of expectations.
Third, Jakarta El API and Java -class library integration
1. Import in the Jakarta El API Library
First, the Jakarta El API library needs to be imported into the Java project.It can be implemented by adding the following dependencies in the construction configuration file (such as pom.xml) to achieve::
<dependency>
<groupId>javax.el</groupId>
<artifactId>javax.el-api</artifactId>
<version>3.0.1-b05</version>
</dependency>
2. Create and configure the context environment
When integrated Jakarta El API with Java libraries, you need to create and configure a context environment for use when calculating expressions.You can use the `javax.el.beanelresolverve class to create and configure the context environment.This class provides a way to pack the JavaBean object into an EL object.
3. Calculate expression using Jakarta El API
After completing the above configuration, you can use the Jakarta El API to calculate the expression.Through the context environment (that is, `javax.elcontext` objects) and EL expression objects, the result of the expression can be calculated by calling the` GetValue (Context, ExpectedType) `method.
Fourth, sample code
The following is an example code that shows how to use the Jakarta El API and Java class libraries to calculate the value of the expression:
import javax.el.*;
public class Main {
public static void main(String[] args) {
// Create an EL parser
ExpressionFactory factory = ExpressionFactory.newInstance();
// Create EL expression
String expressionString = "${user.name}";
ELExpression expression = (ELExpression) factory.createExpression(expressionString);
// Create the context environment
ELContext context = new BeanELResolver(user);
// Calculate the value of the expression
String result = (String) expression.getValue(context, String.class);
// Output results
System.out.println ("Result:" + Result);
}
}
In the above code, we first created an EL parser and then created an EL expression object through the parser.Next, we created a context environment and packaged user objects as EL objects.Finally, we use the context environment and EL expression object to calculate the value of the expression and output the results.
5. Summary
This article introduces the basic concepts and usage methods of Jakarta Expression Language (EL) API, and shows how to integrate it with the Java library to achieve efficient development.By using the Jakarta El API, developers can process and operate data more efficiently to improve development efficiency.It is hoped that this article will help readers understand how to use Jakarta El API and Java -class libraries.