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AngularJS Example Using a Java RESTful Web Service

Posted Ajay

AngularJS is the current MVV-Whatever JavaScript framework by Google. Among other things, it provides bidirectional data binding.

we choose the following scenario for my ‘Hello-World’ example:

  1. Java backend provides a RESTful web service.
  2. AngularJS consumes the web service.

That’s it.

Project structure

We intentionally put the backend and frontend code in the same project to simplify the example. In a real project you probably want to have seperate projects for front- and backend.

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+---------------------------------------------------+
| demo project                                      |
|                                                   |
| +----------------+              +---------------+ |
| | backend (Java) | < -(REST)- > | frontend (JS) | |
| +----------------+              +---------------+ |
|                                                   |
+---------------------------------------------------+

Since the backend is Java based, we used a Maven default structure (maven-archetype-site-simple):

project structure
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├── _documentation
│   └── readme.txt
├── ngdemo.iml
├── pom.xml
└── src
    └── main
        ├── java
        │   └── ngdemo
        │       ├── domain
        │       │   └── User.java
        │       ├── rest
        │       │   └── UserRestService.java
        │       └── service
        │           └── UserService.java
        └── webapp
            ├── css
            │   └── app.css
            ├── img
            ├── index-async.html
            ├── index.html
            ├── index.jsp
            ├── js
            │   ├── app.js
            │   ├── controllers.js
            │   ├── directives.js
            │   ├── filters.js
            │   └── services.js
            ├── lib
            │   └── angular
            │       ├── angular-cookies.js
            │       ├── angular-cookies.min.js
            │       ├── angular.js
            │       ├── angular-loader.js
            │       ├── angular-loader.min.js
            │       ├── angular.min.js
            │       ├── angular-resource.js
            │       ├── angular-resource.min.js
            │       ├── angular-sanitize.js
            │       ├── angular-sanitize.min.js
            │       └── version.txt
            ├── partials
            │   └── partial1.html
            └── WEB-INF
                └── web.xml

src/main/java is the backend.

src/main/webapp/js is the frontend.

src/main/webapp/ also includes a copy of angular-seed.

RESTful web service (backend)

Jersey is the Java reference implementation for providing REST.

Install the following dependencies in your pom.xml:

pom.xml
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<!-- .. -->
<!-- RESTful web service: Jersey -->
<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-server</artifactId>
    <version>1.17.1</version>
</dependency>
<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-servlet</artifactId>
    <version>1.17.1</version>
</dependency>
<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-json</artifactId>
    <version>1.17.1</version>
</dependency>
<!-- .. -->

Add the following servlet snippet to your web.xml:

web.xml
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<!-- .. -->
<servlet>
    <servlet-name>jersey-serlvet</servlet-name>

    <servlet-class>
        com.sun.jersey.spi.container.servlet.ServletContainer
    </servlet-class>

    <init-param>
        <param-name>com.sun.jersey.config.property.packages</param-name>
        <param-value>ngdemo.rest</param-value>
    </init-param>

    <init-param>
        <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
        <param-value>true</param-value>
    </init-param>

    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>jersey-serlvet</servlet-name>
    <url-pattern>/rest/*</url-pattern>
</servlet-mapping>
<!-- .. -->

Enough configuration for now: Create a simple User object…

User.java
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package ngdemo.domain;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class User {

    private String firstName;
    private String lastName;

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

…and a service class…

UserService.java
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package ngdemo.service;

import ngdemo.domain.User;

public class UserService {

    public User getDefaultUser() {
        User user = new User();
        user.setFirstName("JonFromREST");
        user.setLastName("DoeFromREST");
        return user;
    }
}

…and finally the RESTful Service… (Update 2015-08-07 small fix, thanks Jason):

UserRestService.java
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package ngdemo.rest;

import ngdemo.domain.User;
import ngdemo.service.UserService;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Path("/users")
public class UserRestService {

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public User getDefaultUserInJSON() {
        UserService userService = new UserService();
        return userService.getDefaultUser();
    }
}

Converting the User object to JSON via @Produces(MediaType.APPLICATION_JSON) requires jersey-json in web.xml (POJOMappingFeature).

Consuming web service from AngularJS (frontend)

Don’t forget to add angular-resources.js to your index.html…

Consuming the web service:

services.js
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var services = angular.module('ngdemo.services', ['ngResource']);

services.factory('UserFactory', function ($resource) {
    return $resource('/ngdemo/rest/users', {}, {
        query: {
            method: 'GET',
            params: {},
            isArray: false
        }
    })
});

Usage in controller:

controller.js
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var app = angular.module('ngdemo.controllers', []);

app.controller('MyCtrl1', ['$scope', 'UserFactory', function ($scope, UserFactory) {
    UserFactory.get({}, function (userFactory) {
        $scope.firstname = userFactory.firstName;
    })
}]);

Usage in view:

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<div>
    <p>
        Result from RESTful service is: {{ firstname }}
    </p>
</div>

Output: