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Spring Cloud and Spring Boot

This note is to summarize the techno, from an older springframework (2003) dev.

Spring Boot

To get started with Spring Boot see this REST service app guide. Use Spring initialzr tool to get the maven project starting code. The starter guide use Spring Web.

When creating app to be deployed as container think to add Actuator to get health, metrics, sessions, ...

To build: ./mvnw clean package. To run the main executable: java -jar target/demo-0.0.1-SNAPSHOT.jar

@SpringBootApplication is a convenience annotation that adds: @Configuration, @EnableAutoConfiguration (Tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings), @ComponentScan. (look for other components, configurations, and services in package, letting it find the controllers.

REST resources are @RESTController and the methods are annoted with @GetMapping, @PostMapping... To use test driven development add the dependency

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

And then test classes like:

import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@SpringBootTest
@AutoConfigureMockMvc
public class GreetingControllerTests {

    @Autowired
    private MockMvc mockMvc;

    @Test
    public void noParamGreetingShouldReturnDefaultMessage() throws Exception {

        this.mockMvc.perform(get("/greeting")).andDo(print()).andExpect(status().isOk())
                .andExpect(jsonPath("$.content").value("Hello, World!"));
    }
}

One of the most complete app is KC container service

To Remember

  • Spring boot app is a main with @SpringBootApplication annotation to let the injection and bean management working
  • Bean is the IoC component of your application managed by Spring. A function can become a bean using @Bean.
  • @Configuration indicates that a class declares one or more @Bean methods and may be processed by the Spring container to generate bean definitions.

Some how to

  • Define the app-root for url: add properties: server.servlet.context-path: orderms
  • Get the VScode to recognize org.springframework package: use Update Project on the pom.xml

  • Copy a java bean properties into another one: use BeanUtils from spring: The bean needs to have getters and setters

    public static Order from(OrderDTO dto){

    Order mappedOrder = new Order();
    BeanUtils.copyProperties(dto, mappedOrder);
    return mappedOrder;
}

Add swagger UI

  • Add springfox dependency
  • Add swagger configuration via Docket bean

Spring Cloud

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