Spring MVC JSON Example

HelloController.java

package com.katkam;

import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.stereotype.Controller;

// import org.springframework.web.servlet.mvc.AbstractController;
// import org.springframework.validation.BindingResult;
// import javax.servlet.http.HttpServletRequest;
// import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.view.RedirectView;

import java.util.Collections;
import java.util.Map;

//For JSON. See:  https://www.mkyong.com/java/jackson-2-convert-java-object-to-from-json/
//Also see:  https://spring.io/guides/tutorials/bookmarks/
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Created by Developer on 12/23/16.
 */
//@RestController
@Controller
public class HelloController {
    @RequestMapping(value = "/hello", method = RequestMethod.GET, produces = "application/json")
    @ResponseBody
    public String hello() throws Exception {
        //return "hello";
        return new ObjectMapper().writeValueAsString("hello");
    }

    @RequestMapping(value = "/hi", method = RequestMethod.GET, produces = "application/json")
    @ResponseBody
    //in the param, set required=true
    public String hi(@RequestParam(value="name", defaultValue="World") String name) {
        return String.format("[\"hi %s\"]", name);
    }
}

pom.xml

<?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>

    <groupId>com.katkam</groupId>
    <artifactId>FusionGate</artifactId>
    <version>1.0-SNAPSHOT</version>

    <packaging>war</packaging>

    <!--
    mvn exec:java -Dexec.mainClass="com.example.Main"
        -Dexec.args="arg0 arg1"
    -->

    <properties>
        <spring.version>4.3.3.RELEASE</spring.version>
        <spring.security.version>4.1.3.RELEASE</spring.security.version>
        <jetty.version>9.4.0.v20161208</jetty.version>
        <jetty.jsp.version>9.2.20.v20161216</jetty.jsp.version>
        <wat.outputdirectory>/Users/nitin/Downloads/tomcat859/webapps/</wat.outputdirectory>
    </properties>

    <dependencies>
        <!-- Spring Framework -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- Spring Security -->
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-web</artifactId>
            <version>${spring.security.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-config</artifactId>
            <version>${spring.security.version}</version>
        </dependency>

        <!-- SLF4J -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.6.1</version>
        </dependency>

        <!-- Servlet, JSP, JSTL -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>2.3.1</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <!-- Jackson for JSON -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.8.5</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.0.0</version>
                <configuration>
                    <outputDirectory>${wat.outputdirectory}</outputDirectory>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

SpringDispatcherConfiguration.java

package com.katkam;

import org.springframework.context.annotation.*;
import org.springframework.web.servlet.config.annotation.*;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.view.*;

/**
 * Created by Developer on 12/23/16.
 */
@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "com.katkam")
public class SpringDispatcherConfiguration {
    @Bean
    public ViewResolver viewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        viewResolver.setViewClass(JstlView.class);
        //viewResolver.setPrefix("/WEB-INF/views/");
        viewResolver.setSuffix(".jsp");
        return viewResolver;
    }
}

SpringWebAppConfiguration.java

package com.katkam;

import javax.servlet.*;
import org.springframework.web.*;
import org.springframework.web.context.support.*;
import org.springframework.web.servlet.DispatcherServlet;

/**
 * Created by Developer on 12/23/16.
 */
public class SpringWebAppConfiguration implements WebApplicationInitializer {
    public void onStartup(ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(SpringDispatcherConfiguration.class);
        ctx.setServletContext(servletContext);

        ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(ctx));

        servlet.setLoadOnStartup(1);
        servlet.addMapping("/");
    }
}

WebSecurityConfig.java

package com.katkam;

import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;

/**
 * Created by Developer on 12/24/16.
 */
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.csrf().disable();
    }
}