How to integrate the Contract4J5 framework in the Java class library

Integrate the Contract4J5 framework in the Java class library, you need to follow the following steps: Step 1: Download and install Contract4J5 framework You can download the latest version of the framework from the official website of Contract4j5 (https://contract4j5.github.io/).After downloading, unzip it into your development environment. Step 2: Create the java project Use your favorite integrated development environment (IDE) to create a new Java project.Make sure you have configured the Java development environment and related class libraries. Step 3: Import the framework class library Find the `Contract4j5-X.X.JAR` file (please replace the version number of the frame) from the Contract4J5 framework directory, and import it into your Java project. Step 4: Add aspectj support The Contract4J5 framework is implemented based on Aspectj, so you need to ensure that your development environment has been configured with ASPECTJ support.Usually, you can implement it by adding the Maven dependency item of Aspectj or enable the aspectj plugin in the IDE. Step 5: Create a contract4j5 annotation class In your Java project, create a new class and add a note of the Contract4j5.Note is used to define contracts and Join Points.For example, you can create a class called "SAMPLECONTRACT" and use the @Contract annotation to mark this class: import org.contract4j5.contract.Contract; import org.contract4j5.contract.Invar; import org.contract4j5.contract.Post; import org.contract4j5.contract.Pre; @Contract public class SampleContract { @Invar private boolean isPositive(int number) { return number >= 0; } @Pre("arg < 100") @Post("result > 0") public int calculate(int arg) { return arg * 2; } } In the above example, the `@controlcontract` is marked with the`@controlcontract` annotation, indicating that this is a component category.Then we define an infusion method of `iSpositive` to ensure that the parameters that are introduced are positive numbers.Next, we define a `Calculating method, and use@pre` and@post` to define the front conditions and rear conditions. Step 6: Enable aspectj weaving In the configuration file of your Java project, ASPECTJ weaving is enabled so that the Contract4J5 framework can be woven into the contract to check the logic at runtime.The specific configuration method varies from the development environment.For example, in the Spring Boot project, you can add the following configuration in the `Application.properties` file: spring.aop.auto=true Step 7: Run and test the contract Compile and run your Java project.When calling the `Calculate` method, the Contract4J5 framework will automatically check whether the front conditions and rear conditions of the contract will automatically check whether.If the conditions are not met, the corresponding abnormalities will be thrown. Through these steps, you successfully integrate the Contract4J5 framework in the Java class library, using contract annotations to define and check the front conditions and rear conditions.According to your project needs, you can use more Contract4J5 features, such as Assertions, Annitation Metadata, and more complicated contract expression.