1. Interface design
We will implement two interfaces in the system:
GET http://localhost:8888/hello
GET http://localhost:8888/hello/way
The first interface “/hello” will return “Hello World!” String; The second interface, “/hello/way,” returns a JSON string containing user information.
Second, system configuration
We need to add the following dependencies to our application:
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
</dependency>
<dependency>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-servlet</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
Copy the codeAmong them,
Spring-webmvc is designed to use the functionality of Spring MVC
Jetty-servlet is designed to provide built-in servlet containers so that we can run our applications directly without relying on external containers.
Jackson-core and ‘jackson-databind’ provide JSON serialization for our application.
Third, background coding implementation
The domain model
Create a User class that represents User information.
import lombok.AllArgsConstructor;
import lombok.Data;
@Data
@AllArgsConstructor
public class User {
private String username;
private Integer age;
}
Copy the codeThe controller
Create HelloController to handle user requests.
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@RequestMapping("/hello")
public String hello(a) {
return "Hello World!";
}
@RequestMapping("/hello/way")
public User helloWay(a) {
return new User("luopeng".30); }}Copy the codeWhere a method mapped to “/hello” returns “Hello World!” String; Mapping to “/hello/way” returns a JSON string containing user information
Application configuration
In this application, we use Java annotation-based configuration.
AppConfiguration is our main application configuration:
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
@Configuration
@ComponentScan(basePackages = { "com.epom" })
@Import({ MvcConfiguration.class })
public class AppConfiguration {}Copy the codeAppConfiguration scans the files in the com.epom package and automatically registers related beans.
AppConfiguration also introduces MVC configuration class MvcConfiguration:
import java.util.List;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@EnableWebMvc
@Configuration
public class MvcConfiguration implements WebMvcConfigurer {
public void extendMessageConverters(List
> converters)
> {
converters.add(newMappingJackson2HttpMessageConverter()); }}Copy the codeThe MvcConfiguration configuration class enables MVC functionality on the one hand and adds Jackson JSON converters on the other.
Finally, we need to introduce Jetty server:
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;
import com.epom.web.AppConfiguration;
public class JettyServer {
private static final int DEFAULT_PORT = 8888;
private static final String CONTEXT_PATH = "/";
private static final String MAPPING_URL = "/ *";
public void run(a) throws Exception {
Server server = new Server(DEFAULT_PORT);
server.setHandler(servletContextHandler(webApplicationContext()));
server.start();
server.join();
}
private ServletContextHandler servletContextHandler(WebApplicationContext context) {
ServletContextHandler handler = new ServletContextHandler();
handler.setContextPath(CONTEXT_PATH);
handler.addServlet(new ServletHolder(new DispatcherServlet(context)), MAPPING_URL);
handler.addEventListener(new ContextLoaderListener(context));
return handler;
}
private WebApplicationContext webApplicationContext(a) {
AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
context.register(AppConfiguration.class);
returncontext; }}Copy the codeJettyServer will start in the Application class:
public class Application {
public static void main(String[] args) throws Exception {
newJettyServer().run();; }}Copy the codeFour, run,
The 2019-12-18 11:18:35. 637: INFO: : the main: Logging the initialized @ 140 ms to org. Eclipse. Jetty. Util. The StdErrLog 11:18:35. 2019-12-18, 731: the INFO: oejs. Server: main: Jetty - 9.4.22. V20191022; Built: the 2019-10-22 T13: then. 455 z; git: b1e6b55512e008f7fbdf1cbea4ff8a6446d1073b; The JVM 1.8.0 comes with _191 b12-2019-12-18 11:18:35. 762: INFO: oejshC. ROOT: main: Initializing Spring Root WebApplicationContext December 18, 2019 11:18:35 morning org. Springframework. Web. Context. ContextLoader initWebApplicationContext information: Root WebApplicationContext: Initialization started December 18, 2019 11:18:36 morning org. Springframework. Web. Context. ContextLoader initWebApplicationContext information: Root WebApplicationContext initialized in 501 ms 11:18:36 2019-12-18. 263: INFO: oejshC. Root: main: The Initializing Spring DispatcherServlet 'org. Springframework. Web. Servlet. DispatcherServlet - 62043840' December 18, 2019 11:18:36 morning org. Springframework. Web. Servlet. FrameworkServlet initServletBean information: The Initializing the Servlet 'org. Springframework. Web. Servlet. DispatcherServlet - 62043840' December 18, 2019 11:18:36 morning org. Springframework. Web. Servlet. FrameworkServlet initServletBean information: Completed initialization in 5 ms 11:18:36 2019-12-18. 283: INFO: oejsh. ContextHandler: main: Started o.e.j.s.ServletContextHandler@2631f68c{/,null,AVAILABLE} 2019-12-18 11:18:36. 383: INFO: oejs. AbstractConnector: main: Started ServerConnector @ 368239 c8 {HTTP / 1.1, [HTTP / 1.1]} {8888} 0.0.0.0: the 2019-12-18 11:18:36. 383: INFO: oejs. Server: main: Started @888msCopy the codeRespectively in the browser to access the “http://localhost:8888/hello” and “http://localhost:8888/hello/way” address for testing, can see the response of the figure 1 and figure 2.
