I am going to make a Spring MVC web application in which the application is separated vertically. Each module is going to encapsulate the functionalities related to the same feature.

Let consider an imaginary simple example:

1. feature-1: User can add/remove/edit Cartesian coordinate (x,y).
2. feature-2: Show the coordinates in a plane chart.

So the vertical separation that I considered here is one module for feature-1 and another module for feature-2.

1. Module 1: includes the entities, persistence and views for add/remove/edit
2. Module 2: includes the service to read coordination from persistence and a view for the chart.

I also considered another module that is just index page and a controller that loads that index page in which it is just a container for the other modules to load their view there. This index page will have a navigation bar for add coordinate and show chart. These navigation should hand over the control to another controller which is in another module.

I build this project structure:

─── project
    │
    ├── add-coordinate
    │    ├── src
    │    │   └── main
    │    │       ├── java
    │    │       │   └── com.example.coordinate.add
    │    │       │       ├── controller
    │    │       │       │   └── CoordinateController.java
    │    │       │       ├── persistence
    │    │       │       │   └── CoordinateRepository.java
    │    │       │       └── entity
    │    │       │           └── coordinate.java
    │    │       └── resources
    │    │           └── static
    │    │               ├── css
    │    │               │   └── style.css
    │    │               └── templates
    │    │                   └── coordinate.html
    │    └── pom.xml
    │
    ├── show-coordinate
    │    ├── src
    │    │   └── main
    │    │       ├── java
    │    │       │   └── com.example.coordinate.show
    │    │       │       ├── controller
    │    │       │       │   └── ShowCoordinateController.java
    │    │       │       └── service
    │    │       │           └── CoordinateService.java
    │    │       └── resources
    │    │           └── static
    │    │               ├── css
    │    │               │   └── style.css
    │    │               └── templates
    │    │                   └── showCoordinate.html
    │    └── pom.xml
    │
    ├── index-coordinate
    │    ├── src
    │    │   └── main
    │    │       ├── java
    │    │       │   └── com.example.coordinate.index
    │    │       │       ├── controller
    │    │       │       │   └── IndexController.java
    │    │       │       └── IndexApplication.java
    │    │       └── resources
    │    │           └── static
    │    │               ├── css
    │    │               │   └── style.css
    │    │               └── templates
    │    │                   └── index.html
    │    └── pom.xml
    │
    └── pom.xml

This is the parent pom.xml (unrelated parts are omitted):

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <groupId>com.example</groupId>
    <artifactId>coordinate</artifactId>
    <version>${revison}</version>
    <packaging>pom</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.5</version>
    </parent>

    <properties>
        ...
        <!--    Project Version -->
        <build.type>SNAPSHOT</build.type>
        <variance.version>1.0.0</variance.version>
        <revison>${variance.version}-${build.type}</revison>
    </properties>

    <modules>
        <module>index-coordinate</module>
        <module>add-coordinate</module>
        <module>show-coordinate</module>
    </modules>

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

And this is add-coordinate pom:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <artifactId>add-coordinate</artifactId>

    <parent>
        <groupId>com.example</groupId>
        <artifactId>coordinate</artifactId>
        <version>${revison}</version>
    </parent>

    <properties>
        <start-class>com.example.coordinate.index.IndexApplication</start-class>
    </properties>

    <dependencies>
        <dependency>-->
            <groupId>com.example</groupId>
            <artifactId>coordinate-index</artifactId>
            <version>${revison}</version>
        </dependency>
        <!--other dependecies like Spring Boot, Sprong MVC, DB, ...-->
        ...
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Here is the controller for add-coordinate:

@Controller
public class CoordinateController {

    @RequestMapping("/coordinate")
    public String addCoordinatePage() {
        return "coordinate";
    }
}

Now, index page is loaded properly, but the problem is that when the nav bar for add coordinate is clicked and the request is sent to http://localhost:8080/coordinate, the page cannot be resolved. Which means the controller has not been started with my application. Does anyone know how I can resolve this problem?

CodePudding user response：

The problem solved by adding the following annotation to IndexApplication

@SpringBootApplication
@ComponentScan(basePackages = {"com.example.coordinate.*"})
@EnableJpaRepositories(basePackages = {"com.example.coordinate.*"})
@EntityScan(basePackages = {"com.example.coordinate.*"})
public class IndexApplication {

    public static void main(String args[]) {
        SpringApplication.run(Application.class);
    }
}

And added the