Spring

Building Java Projects with Maven

Guide from spring.io for mvn learning. Write a pom.xml for packaging configuration.

#build package
mvn compile

#package project
mvn package

#Maven also maintains a repository of dependencies on your local machine (usually in a .m2/repository directory in your home directory) for quick access to project dependencies. 
#If you’d like to install your project’s JAR file to that local repository, then you should invoke the install goal:
mvn install 

#unit test
mvn test 

Building a RESTful Web Service

Write a RESTful Web Service with Spring RequestMapping annotation.

package hello;

import java.util.concurrent.atomic.AtomicLong;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class GreetingController {

    private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @RequestMapping("/greeting")
    public Greeting greeting(@RequestParam(value="name", defaultValue="World") String name) {
        return new Greeting(counter.incrementAndGet(),
                            String.format(template, name));
    }
}

The @RequestMapping annotation ensures that HTTP requests to /greeting are mapped to the greeting() method.

The above example does not specify GET vs. PUT, POST, and so forth, because @RequestMapping maps all HTTP operations by default. Use @RequestMapping(method=GET) to narrow this mapping.

@RequestParam binds the value of the query string parameter name into the name parameter of the greeting() method. This query string parameter is explicitly marked as optional (required=true by default): if it is absent in the request, the defaultValue of “World” is used.

The implementation of the method body creates and returns a new Greeting object with id and content attributes based on the next value from the counter, and formats the given name by using the greeting template.