05: Spring 4 MVC RESTful Web Service Beginner Tutorial step by step

Posted on June 24, 2017 by

Install RESTClient from WizTools.org

Step 1: RESTClient is required to test the RESful web services. Go to

http://download.wiztools.org/rest-client/archive/index.html

Download the latest version of “restclient-ui-3.2.2-jar-with-dependencies.jar” file. Copy it to “c:\tools” and run it by Double-Clicking if you are running on windows. If outside windows you can run it as shown below.

c:\tools>java -jar restclient-ui-3.2.2-jar-with-dependencies.jar

1 2	c:\tools>java -jar restclient-ui-3.2.2-jar-with-dependencies.jar

RESTClient from WizTools to test RESTful web services

pom.xml with XML & JSON data binding

Step 2: The pom.xml with “jackson-databind“, which will be used to convert the response data into JSON string, and “jackson-dataformat-xml“, which will be used to convert the response data to XML.

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mytutorial</groupId>
    <artifactId>simpleWeb</artifactId>
    <packaging>war</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>simpleWeb Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>compile</scope>
        </dependency>

        <!-- Spring MVC -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.3.9.RELEASE</version>
        </dependency>

        <!-- JSON data binding -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.8.9</version>
        </dependency>
        <!-- XML data binding -->
        <dependency>
            <groupId>com.fasterxml.jackson.dataformat</groupId>
            <artifactId>jackson-dataformat-xml</artifactId>
            <version>2.8.9</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>simpleWeb</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.1.0</version>
                <configuration>
                    <failOnMissingWebXml>false</failOnMissingWebXml>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

<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/maven-v4_0_0.xsd">

<groupId>com.mytutorial</groupId>

<artifactId>simpleWeb</artifactId>

<version>1.0-SNAPSHOT</version>

<name>simpleWeb Maven Webapp</name>

<url>http://maven.apache.org</url>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

</dependency>

<groupId>javax.servlet</groupId>

<artifactId>javax.servlet-api</artifactId>

<scope>compile</scope>

</dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-webmvc</artifactId>

<version>4.3.9.RELEASE</version>

</dependency>

<groupId>com.fasterxml.jackson.core</groupId>

<artifactId>jackson-databind</artifactId>

</dependency>

<groupId>com.fasterxml.jackson.dataformat</groupId>

<artifactId>jackson-dataformat-xml</artifactId>

</dependency>

</dependencies>

<build>

<finalName>simpleWeb</finalName>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-war-plugin</artifactId>

<failOnMissingWebXml>false</failOnMissingWebXml>

</configuration>

</plugin>

</plugins>

</build>

</project>

Define the model class Account.java

Step 3: Define the Account.java with 3 fields & getters/setters in the package “com.mytutorial.model”.

package com.mytutorial.model;

import java.io.Serializable;
import java.math.BigDecimal;

public class Account implements Serializable {

    private static final long serialVersionUID = 1L;

    private String id;
    private String name;
    private BigDecimal balance;

    public Account(String id, String name, BigDecimal balance) {
        this.id = id;
        this.name = name;
        this.balance = balance;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public BigDecimal getBalance() {
        return balance;
    }

    public void setBalance(BigDecimal balance) {
        this.balance = balance;
    }

    @Override
    public String toString() {
        return "Account [id=" + id + ", name=" + name + ", balance=" + balance + "]";
    }

}

package com.mytutorial.model;

import java.io.Serializable;

import java.math.BigDecimal;

public class Account implements Serializable {

private static final long serialVersionUID = 1L;

private String id;

private String name;

private BigDecimal balance;

public Account(String id, String name, BigDecimal balance) {

this.id = id;

this.name = name;

this.balance = balance;

}

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public BigDecimal getBalance() {

return balance;

}

public void setBalance(BigDecimal balance) {

this.balance = balance;

}

@Override

public String toString() {

return "Account [id=" + id + ", name=" + name + ", balance=" + balance + "]";

}

Define the controller class AccountController.java

Step 3: Define the AccountController.java with 3 fields & getters/setters in the package “com.mytutorial.controller”.

package com.mytutorial.controller;

import java.math.BigDecimal;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.mytutorial.model.Account;

@RestController
@RequestMapping("/v1/forecasting")
public class AccountController {

    @RequestMapping(value = "/accounts", method = RequestMethod.GET)
    public Account[] getAccounts() {
        Account[] accounts = new Account[] { new Account("123", "John R", BigDecimal.valueOf(235.00)),
                new Account("345", "Peter J", BigDecimal.valueOf(2505.60)) };

        return accounts;
    }

}

package com.mytutorial.controller;

import java.math.BigDecimal;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

import com.mytutorial.model.Account;

@RestController

@RequestMapping("/v1/forecasting")

public class AccountController {

@RequestMapping(value = "/accounts", method = RequestMethod.GET)

public Account[] getAccounts() {

Account[] accounts = new Account[] { new Account("123", "John R", BigDecimal.valueOf(235.00)),

new Account("345", "Peter J", BigDecimal.valueOf(2505.60)) };

return accounts;

}

Spring Java Configs for wiring up

Step 4: Spring Java configs in the package “com.mytutorial.config”

package com.mytutorial.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "com.mytutorial.controller")
public class SimpleWebConfiguration {
    
}

package com.mytutorial.config;

import org.springframework.context.annotation.ComponentScan;

import org.springframework.context.annotation.Configuration;

import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Configuration

@EnableWebMvc

@ComponentScan(basePackages = "com.mytutorial.controller")

public class SimpleWebConfiguration {

}

Bootstrap the Spring dispatcher Servlet with the mapping URI of “/entry/*” & the above “SimpleWebConfiguration” for the controllers

package com.mytutorial.config;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class SimpleWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SimpleWebConfiguration.class};
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return null;
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/entry/*" };
    }

}

package com.mytutorial.config;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class SimpleWebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

@Override

protected Class<?>[] getRootConfigClasses() {

return new Class[]{SimpleWebConfiguration.class};

}

@Override

protected Class<?>[] getServletConfigClasses() {

return null;

}

@Override

protected String[] getServletMappings() {

return new String[] { "/entry/*" };

}

Build simpleWeb.war & deploy to Tomcat

Step 5: Copy the “simpleWeb.war” to Tomcat’s “webapps” folder and start the Tomcat server.

c:\tools\apache-tomcat-9.0.0.M21-windows-x64\apache-tomcat-9.0.0.M21\bin>startup.bat

1 2	c:\tools\apache-tomcat-9.0.0.M21-windows-x64\apache-tomcat-9.0.0.M21\bin>startup.bat

Start the RESTClient from WizTools.org

Step 6: Double-Clicking “c:\tools\restclient-ui-3.2.2-jar-with-dependencies.jar” on windows or

c:\tools>java -jar restclient-ui-3.2.2-jar-with-dependencies.jar

1 2	c:\tools>java -jar restclient-ui-3.2.2-jar-with-dependencies.jar

XML Data

http://localhost:8080/simpleWeb/entry/v1/forecasting/account

<Accounts>
   <item>
      <id>123</id>
	  <name>John R</name>
	  <balance>235.0</balance>
   </item>
   <item>
      <id>345</id>
	  <name>Peter J</name>
	  <balance>2505.6</balance>
   </item>
</Accounts>

<item>

</item>

<item>

<name>Peter J</name>

</item>

</Accounts>

JSON Data

http://localhost:8080/simpleWeb/entry/v1/forecasting/accounts.json

You need to add “.json” suffix to the URL to get JSON data.

[
  {"id":"123","name":"John R","balance":235.0},
  {"id":"345","name":"Peter J","balance":2505.6}
]

[

{"id":"123","name":"John R","balance":235.0},

{"id":"345","name":"Peter J","balance":2505.6}

]

Further discussions

Q. What if you want the URL “http://localhost:8080/simpleWeb/entry/v1/forecasting/accounts” to return JSON data instead of XML.
A. If you want it to return JSON data: “produces={MediaType.APPLICATION_JSON_VALUE}”:

package com.mytutorial.controller;

import java.math.BigDecimal;

import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.mytutorial.model.Account;

@RestController
@RequestMapping("/v1/forecasting")
public class AccountController {

    @RequestMapping(value = "/accounts", method = RequestMethod.GET, produces={MediaType.APPLICATION_JSON_VALUE})
    public Account[] getAccounts() {
        Account[] accounts = new Account[] { new Account("123", "John R", BigDecimal.valueOf(235.00)),
                new Account("345", "Peter J", BigDecimal.valueOf(2505.60)) };

        return accounts;
    }
}

package com.mytutorial.controller;

import java.math.BigDecimal;

import org.springframework.http.MediaType;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

import com.mytutorial.model.Account;

@RestController

@RequestMapping("/v1/forecasting")

public class AccountController {

@RequestMapping(value = "/accounts", method = RequestMethod.GET, produces={MediaType.APPLICATION_JSON_VALUE})

public Account[] getAccounts() {

Account[] accounts = new Account[] { new Account("123", "John R", BigDecimal.valueOf(235.00)),

new Account("345", "Peter J", BigDecimal.valueOf(2505.60)) };

return accounts;

}

If you want it to return XML data: produces={MediaType.APPLICATION_XML_VALUE}

Note that @RestController is used instead of “@Controller“. If you were to use “@Controller“, you need to use the annotation @ResponseBody as in “public @ResponseBody Account[] getAccounts()” as shown below:

package com.mytutorial.controller;

import java.math.BigDecimal;

import org.springframework.http.MediaType;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import com.mytutorial.model.Account;

@Controller
@RequestMapping("/v1/forecasting")
public class AccountController {

    @RequestMapping(value = "/accounts", method = RequestMethod.GET, produces={MediaType.APPLICATION_XML_VALUE})
    public @ResponseBody Account[] getAccounts() {
        Account[] accounts = new Account[] { new Account("123", "John R", BigDecimal.valueOf(235.00)),
                new Account("345", "Peter J", BigDecimal.valueOf(2505.60)) };

        return accounts;
    }
}

package com.mytutorial.controller;

import java.math.BigDecimal;

import org.springframework.http.MediaType;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.ResponseBody;

import com.mytutorial.model.Account;

@Controller

@RequestMapping("/v1/forecasting")

public class AccountController {

@RequestMapping(value = "/accounts", method = RequestMethod.GET, produces={MediaType.APPLICATION_XML_VALUE})

public @ResponseBody Account[] getAccounts() {

Account[] accounts = new Account[] { new Account("123", "John R", BigDecimal.valueOf(235.00)),

new Account("345", "Peter J", BigDecimal.valueOf(2505.60)) };

return accounts;

}

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05: Spring 4 MVC RESTful Web Service Beginner Tutorial step by step

Install RESTClient from WizTools.org

pom.xml with XML & JSON data binding

Define the model class Account.java

Define the controller class AccountController.java

Spring Java Configs for wiring up

Build simpleWeb.war & deploy to Tomcat

Start the RESTClient from WizTools.org

XML Data

JSON Data

Further discussions

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