Java 2

Week 6

Movie Project DAO

Course Objectives

Students will demonstrate an understanding multitier software design
Students will understand the use of standard collections and generics in the Java programming language
Students will understand elementary Thread programming in Java
Students will create software that performs standard data operations with Java and a relational database
Students will use streams to communicate with sockets and files
Students will apply elementary XML functionality in Java
Students will understand the importance of using standard Object Oriented Programming (OOP) design tools such as the Unified Modeling Language (UML)
Students will demonstrate a preference for messages and Exceptions for communicating between components
Students will systematize Test Driven Development

Data Sources

Create a new Java Maven project called Movies. Use the "edu.kirkwood" package.
I want to create a program that allows us to get Movie data from a variety of resources: XML, JSON, MySQL, and MongoDB.
To efficiently switch between different data sources, you should use the Data Access Object (DAO) pattern.
The core idea is to define a common interface that dictates what data operations can be performed (e.g., "get all movies"), and then create separate classes that implement this interface for each specific data source.
The main application will only interact with the interface, not the concrete classes, making it easy to swap the data source with minimal code changes.

Movie class

Create a "edu.kirkwood.model" package.
Create a class called "Movie". Add the following code.

package edu.kirkwood.model;

import java.util.Objects;

// A simple Plain Old Java Object (POJO)
public class Movie implements Comparable<Movie> {
    private String id;
    private String title;
    private int releaseYear;

    public Movie() {
    }

    public Movie(String id, String title, int releaseYear) {
        this.id = id;
        this.title = title;
        this.releaseYear = releaseYear;
    }

    public String getId() {
        return id;
    }

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

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public int getReleaseYear() {
        return releaseYear;
    }

    public void setReleaseYear(int releaseYear) {
        this.releaseYear = releaseYear;
    }

    @Override
    public String toString() {
        return "Movie{" +
                "id='" + id + '\'' +
                ", title='" + title + '\'' +
                ", releaseYear=" + releaseYear +
                '}';
    }

    /**
     * Compares two Movie objects by their release year (0-9), then title (A-Z)
     * @param o The other Movie being compared
     * @return an integer, in order if less than or equal to 0, not in order if greater than 0
     */
    @Override
    public int compareTo(Movie o) {
        int result = Integer.compare(this.releaseYear, o.getReleaseYear());
        if(result == 0) {
            result = this.title.compareTo(o.title);
        }
        return result;
    }

    @Override
    public boolean equals(Object o) {
        if (o == null || getClass() != o.getClass()) return false;
        Movie movie = (Movie) o;
        return releaseYear == movie.releaseYear && Objects.equals(title, movie.title);
    }

    @Override
    public int hashCode() {
        return Objects.hash(title, releaseYear);
    }
}

Movie XML data

The OMDb API allows access to movie data in XML format using a GET request like this.
API stands for "Application Programming Interface"
https://www.omdbapi.com/?s=Batman&page=1&type=movie&apikey=359a6530&r=xml
The value returned looks like this:
- Note the totalResults and response attributes of the root tag.
- Note the result tags.

<root totalResults="503" response="True">
  <result title="Batman Begins" year="2005" imdbID="tt0372784" type="movie" poster="https://m.media-amazon.com/images/M/MV5BODIyMDdhNTgtNDlmOC00MjUxLWE2NDItODA5MTdkNzY3ZTdhXkEyXkFqcGc@._V1_SX300.jpg"/>
  <result title="The Batman" year="2022" imdbID="tt1877830" type="movie" poster="https://m.media-amazon.com/images/M/MV5BMmU5NGJlMzAtMGNmOC00YjJjLTgyMzUtNjAyYmE4Njg5YWMyXkEyXkFqcGc@._V1_SX300.jpg"/>
  <result title="Batman v Superman: Dawn of Justice" year="2016" imdbID="tt2975590" type="movie" poster="https://m.media-amazon.com/images/M/MV5BZTJkYjdmYjYtOGMyNC00ZGU1LThkY2ItYTc1OTVlMmE2YWY1XkEyXkFqcGc@._V1_SX300.jpg"/>
  <result title="Batman v Superman: Dawn of Justice" year="2016" imdbID="tt2975590" type="movie" poster="https://m.media-amazon.com/images/M/MV5BZTJkYjdmYjYtOGMyNC00ZGU1LThkY2ItYTc1OTVlMmE2YWY1XkEyXkFqcGc@._V1_SX300.jpg"/>
  <result title="Batman" year="1989" imdbID="tt0096895" type="movie" poster="https://m.media-amazon.com/images/M/MV5BYzZmZWViM2EtNzhlMi00NzBlLWE0MWEtZDFjMjk3YjIyNTBhXkEyXkFqcGc@._V1_SX300.jpg"/>
  <result title="Batman Returns" year="1992" imdbID="tt0103776" type="movie" poster="https://m.media-amazon.com/images/M/MV5BZTliMDVkYTktZDdlMS00NTAwLWJhNzYtMWIwMDZjN2ViMGFiXkEyXkFqcGc@._V1_SX300.jpg"/>
  <result title="Batman & Robin" year="1997" imdbID="tt0118688" type="movie" poster="https://m.media-amazon.com/images/M/MV5BYzU3ZjE3M2UtM2E4Ni00MDI5LTkyZGUtOTFkMGIyYjNjZGU3XkEyXkFqcGc@._V1_SX300.jpg"/>
  <result title="Batman Forever" year="1995" imdbID="tt0112462" type="movie" poster="https://m.media-amazon.com/images/M/MV5BMTUyNjJhZWItMTZkNS00NDc4LTllNjUtYTg3NjczMzA5ZTViXkEyXkFqcGc@._V1_SX300.jpg"/>
  <result title="The Lego Batman Movie" year="2017" imdbID="tt4116284" type="movie" poster="https://m.media-amazon.com/images/M/MV5BMTcyNTEyOTY0M15BMl5BanBnXkFtZTgwOTAyNzU3MDI@._V1_SX300.jpg"/>
  <result title="Batman v Superman: Dawn of Justice (Ultimate Edition)" year="2016" imdbID="tt18689424" type="movie" poster="https://m.media-amazon.com/images/M/MV5BOTRlNWQwM2ItNjkyZC00MGI3LThkYjktZmE5N2FlMzcyNTIyXkEyXkFqcGdeQXVyMTEyNzgwMDUw._V1_SX300.jpg"/>
</root>

XML dependencies

Add the necessary libraries to your pom.xml for making HTTP requests and parsing XML.
Use most current versions
Reload the Maven file.

<dependencies>
    <dependency>
        <groupId>jakarta.xml.bind</groupId>
        <artifactId>jakarta.xml.bind-api</artifactId>
        <version>4.0.4</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jaxb</groupId>
        <artifactId>jaxb-runtime</artifactId>
        <version>4.0.6</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.dataformat</groupId>
        <artifactId>jackson-dataformat-xml</artifactId>
        <version>2.20.0</version>
    </dependency>
</dependencies>

XML Model Classes

Create an "xml" package inside the "model" package.
Create a class called "MovieSearchResult".
The structure of the XML requires two classes: one for the root element and another for the repeating <result> elements.
- This class handles the result elements.
- These are annotated for either JAXB or Jackson.

package edu.kirkwood.model.xml;

import jakarta.xml.bind.annotation.*; // For JAXB
// import com.fasterxml.jackson.data.format.xml.annotation.*; // For Jackson

@XmlAccessorType(XmlAccessType.FIELD) // Tells JAXB to use fields directly
public class MovieSearchResult {

    @XmlAttribute(name = "title")
    private String title;

    @XmlAttribute(name = "year")
    private String year;

    @XmlAttribute(name = "imdbID")
    private String imdbID;

    @XmlAttribute(name = "type")
    private String type;

    @XmlAttribute(name = "poster")
    private String poster;

    public String getTitle() {
        return title;
    }

    public String getYear() {
        return year;
    }

    public String getImdbID() {
        return imdbID;
    }

    public String getType() {
        return type;
    }

    public String getPoster() {
        return poster;
    }

    @Override
    public String toString() {
        return "MovieSearchResult{" +
                "title='" + title + '\'' +
                ", year='" + year + '\'' +
                ", imdbID='" + imdbID + '\'' +
                ", type='" + type + '\'' +
                ", poster='" + poster + '\'' +
                '}';
    }
}

XML Model Classes

Create a class called "OmdbMovieResponse".
The structure of the XML requires two classes: one for the root element and another for the repeating <result> elements.
- This class handles the root element.
- These are annotated for either JAXB or Jackson.

package edu.kirkwood.model.xml;

import jakarta.xml.bind.annotation.*; // For JAXB
// import com.fasterxml.jackson.data.format.xml.annotation.*; // For Jackson

import java.util.List;

@XmlRootElement(name = "root")
@XmlAccessorType(XmlAccessType.FIELD) // Tells JAXB to use fields directly
public class OmdbMovieResponse {

    @XmlElement(name = "result")
    private List<MovieSearchResult> searchResults;

    @XmlAttribute(name = "totalResults")
    private int totalResults;

    @XmlAttribute(name = "response")
    private String response;

    public List<MovieSearchResult> getSearchResults() {
        return searchResults;
    }

    public int getTotalResults() {
        return totalResults;
    }

    public String getResponse() {
        return response;
    }
}

MovieDAO interface

Create a "edu.kirkwood.dao" package.
Create an interface called "MovieDAO". Add the following code.

package edu.kirkwood.dao;

import edu.kirkwood.model.Movie;
import java.util.List;
import java.util.Optional;

/**
 * The data access interface for movies.
 * This contract defines the operations for any data source.
 */
public interface MovieDAO {

    /**
     * Finds a single movie by its unique ID.
     * @param id The ID of the movie to find.
     * @return The movie if found, otherwise empty.
     */
    Movie findById(String id);

    /**
     * Retrieves all movies from the data source that match the title.
     * @param title
     * @return A list of all movies.
     */
    List<Movie> search(String title);
}

MovieDAOXml class

Next, create a separate class for each data source that implements your MovieDAO interface.
Create a package called "impl" inside "dao" for implementation. Create a class called MovieDAOXml.

package edu.kirkwood.dao.impl;

import edu.kirkwood.dao.MovieDAO;
import edu.kirkwood.model.Movie;
import java.util.List;
import java.util.Optional;

public class XmlMovieDAO implements MovieDAO {
    private final String url;

    public XmlMovieDAO(String url) {
        this.url = url;
    }

    /**
     * Logic to parse the XML file and return the movie matching the ID.
     * @param id The ID of the movie to find.
     * @return The movie if found, otherwise empty.
     */
    @Override
    public Movie findById(String id) {
        System.out.println("Fetching movie " + id + " from XML...");
        return null;
    }

    /**
     * Logic to parse the entire XML file and return a list of all movies.
     * @param title
     * @return A list of all movies.
     */
    @Override
    public List<Movie> search(String title) {
        System.out.println("Searching for " + title + " from XML...");
        return List.of();
    }
}

MovieDAO interface

Update the "MovieDAO" interface from the previous class with the following code.

package edu.kirkwood.dao;

import edu.kirkwood.model.xml.MovieSearchResult;

import java.util.List;

/**
 * The data access interface for movies.
 * This contract defines the operations for any data source.
 */
public interface MovieDAO<T> {
    
    /**
     * Retrieves all movies from the data source that match the title.
     * @param title
     * @return A list of all movies.
     */
    List<MovieSearchResult> search(String title);
}

XmlMovieDAO class

Next, create a separate class for each data source that implements your MovieDAO interface.
Create a package called "impl" inside "dao" for implementation. Create a class called MovieDAOXml.

package edu.kirkwood.dao.impl;

import edu.kirkwood.dao.MovieDAO;

import edu.kirkwood.model.xml.MovieSearchResult;
import edu.kirkwood.model.xml.OmdbMovieResponse;

import jakarta.xml.bind.JAXBContext; // JAXB
import jakarta.xml.bind.Unmarshaller; // JAXB

import java.io.StringReader;
import java.net.URI;
import java.net.URLEncoder;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.List;

public class XmlMovieDAO implements MovieDAO {
    private String apiURL = null;

    public XmlMovieDAO(String apiURL) {
        this.apiURL = apiURL;
    }
}

XmlMovieDAO class

Add a search method.

package edu.kirkwood.dao.impl;

import edu.kirkwood.dao.MovieDAO;

import edu.kirkwood.model.xml.MovieSearchResult;
import edu.kirkwood.model.xml.OmdbMovieResponse;

import jakarta.xml.bind.JAXBContext; // JAXB
import jakarta.xml.bind.Unmarshaller; // JAXB

import java.io.StringReader;
import java.net.URI;
import java.net.URLEncoder;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.List;

public class XmlMovieDAO implements MovieDAO {
    private String apiURL = null;

    public XmlMovieDAO(String apiURL) {
        this.apiURL = apiURL;
    }
    
    /**
     * Finds movies by a search term.
     * @param searchTerm The movie title to search
     * @return List<MovieSearchResult> the list of movies
     */
    public List<MovieSearchResult> search(String searchTerm) {
        if(apiURL == null) {
            throw new IllegalArgumentException("XML API URL is not configured in application.properties");
        }
        // URL-encode the search term to handle spaces and special characters
        String encodedSearchTerm = URLEncoder.encode(searchTerm, StandardCharsets.UTF_8);
        apiURL = String.format("%s&s=%s&page=1", apiURL, encodedSearchTerm);

        try {
            HttpRequest request = HttpRequest.newBuilder()
                    .uri(URI.create(apiURL))
                    .build();
            HttpClient httpClient = HttpClient.newHttpClient();
            HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());

            return Collections.emptyList();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return Collections.emptyList();
    }
}

XmlMovieDAO class

Add a parseXml method.

package edu.kirkwood.dao.impl;

import edu.kirkwood.dao.MovieDAO;

import edu.kirkwood.model.xml.MovieSearchResult;
import edu.kirkwood.model.xml.OmdbMovieResponse;

import jakarta.xml.bind.JAXBContext; // JAXB
import jakarta.xml.bind.Unmarshaller; // JAXB

import java.io.StringReader;
import java.net.URI;
import java.net.URLEncoder;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.charset.StandardCharsets;
import java.util.Collections;
import java.util.List;

public class XmlMovieDAO implements MovieDAO {
    private String apiURL = null;

    public XmlMovieDAO(String apiURL) {
        this.apiURL = apiURL;
    }
    
    /**
     * Finds movies by a search term.
     * @param searchTerm The movie title to search
     * @return List<MovieSearchResult> the list of movies
     */
    public List<MovieSearchResult> search(String searchTerm) {
        if(apiURL == null) {
            throw new IllegalArgumentException("XML API URL is not configured in application.properties");
        }
        // URL-encode the search term to handle spaces and special characters
        String encodedSearchTerm = URLEncoder.encode(searchTerm, StandardCharsets.UTF_8);
        apiURL = String.format("%s&s=%s&page=1", apiURL, encodedSearchTerm);

        try {
            HttpRequest request = HttpRequest.newBuilder()
                    .uri(URI.create(apiURL))
                    .build();
            HttpClient httpClient = HttpClient.newHttpClient();
            HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());

            return parseXml(response.body());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return Collections.emptyList();
    }
    
    /**
     * Logic to parse the entire XML file and return a list of all movies.
     * @param xml The raw XML data
     * @return List<MovieSearchResult> the list of movies
     */
    private List<MovieSearchResult> parseXml(String xml) throws Exception {
        JAXBContext context = JAXBContext.newInstance(OmdbMovieResponse.class);
        Unmarshaller unmarshaller = context.createUnmarshaller();
        StringReader reader = new StringReader(xml);
        OmdbMovieResponse movieResponse = (OmdbMovieResponse) unmarshaller.unmarshal(reader);
        return movieResponse.getSearchResults() != null ? movieResponse.getSearchResults() : Collections.emptyList();
    }
}

Application Properties

Create a properties file in your resources folder (src/main/resources/application.properties)
Set the desired data source. (XML, JSON, MYSQL, MONGODB), the API key, and parser preference (JAXB, JACKSON)
- My API key is 359a6530 in case you don't want to sign up for a key.

datasource.type=XML
xml.apiURL=https://www.omdbapi.com/?r=xml&type=movie&apikey=<your-api-key>

The Factory

To efficiently switch data sources, you can use a Factory pattern.
Now, create a class called "MovieDAOFactory" in the "dao" package to read the application.properties file.
This class reads a configuration setting and provides the correct DAO implementation.
This line creates a single static Properties object named props.
- Is is similar to a Python dictionary or Java map, designed to hold key-value pairs from the .properties file.

package edu.kirkwood.dao;

import edu.kirkwood.dao.impl.*;

import java.io.InputStream;
import java.util.Properties;

public class MovieDAOFactory {

    private static final Properties props = new Properties();

}

The Factory

A static { ... } block is a code block that only runs only once, the very first time the class is loaded.
This example finds the application.properties file and initializes the static props variable.
InputStream is AutoCloseable, so it can be written in a try-with-resources block.
The getClassLoader() method returns the class loader. The ClassLoader has a method called getResourceAsStream().

package edu.kirkwood.dao;

import edu.kirkwood.dao.impl.*;

import java.io.InputStream;
import java.util.Properties;

public class MovieDAOFactory {

    private static final Properties props = new Properties();

    static {
        try (InputStream input = MovieDAOFactory.class.getClassLoader()
        											  .getResourceAsStream("application.properties")) {
            
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

}

The Factory

If the InputStream is null, that means the properties file cannot be found.
If the properties file is found, we pass the InputStream object to the load() method of the Properties class.

package edu.kirkwood.dao;

import edu.kirkwood.dao.impl.*;

import java.io.InputStream;
import java.util.Properties;

public class MovieDAOFactory {

    private static final Properties props = new Properties();

    static {
        try (InputStream input = MovieDAOFactory.class.getClassLoader()
        											  .getResourceAsStream("application.properties")) {
            if (input == null) {
                System.out.println("Unable to find application.properties");
            }
            props.load(input);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

}

The Factory

Create a method to get the DAO specified in the properties file.

package edu.kirkwood.dao;

import edu.kirkwood.dao.impl.*;

import java.io.InputStream;
import java.util.Properties;

public class MovieDAOFactory {

    private static final Properties props = new Properties();

    static {
        try (InputStream input = MovieDAOFactory.class.getClassLoader().getResourceAsStream("application.properties")) {
            if (input == null) {
                System.out.println("Unable to find application.properties");
            }
            props.load(input);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static MovieDAO getMovieDAO() {
        String sourceType = props.getProperty("datasource.type");

        switch (sourceType.toUpperCase()) {
            case "XML":
                break;

            // other cases for JSON, MYSQL, MongoDB, etc.

            default:
                throw new IllegalArgumentException("Invalid data source type specified: " + sourceType);
        }
    }
}

The Factory

Now, create the factory class to read the application.properties file.
]Create a "MovieDAOFactory" class in the "dao" package.

package edu.kirkwood.dao;

import edu.kirkwood.dao.impl.*;

import java.io.InputStream;
import java.util.Properties;

public class MovieDAOFactory {

    private static final Properties props = new Properties();

    static {
        try (InputStream input = MovieDAOFactory.class.getClassLoader().getResourceAsStream("application.properties")) {
            if (input == null) {
                System.out.println("Unable to find application.properties");
            }
            props.load(input);
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

    public static MovieDAO getMovieDAO() {
        String sourceType = props.getProperty("datasource.type");

        switch (sourceType.toUpperCase()) {
            case "XML":
            	String apiURL = props.getProperty("xml.apiURL");
                if (apiURL == null) {
                    throw new IllegalArgumentException("XML API URL is not configured in application.properties");
                }
                return new XmlMovieDAO(apiURL);

            // other cases for JSON, MYSQL, MongoDB, etc.

            default:
                throw new IllegalArgumentException("Invalid data source type specified: " + sourceType);
        }
    }
}

Movie App Main class

Create a "MovieApp" class containing a main method.
Your main application logic can now get the MovieDAOXml and call the new method.

package edu.kirkwood;

import edu.kirkwood.dao.MovieDAO;
import edu.kirkwood.dao.MovieDAOFactory;
import edu.kirkwood.dao.impl.MovieDAOXml;
import edu.kirkwood.model.xml.MovieSearchResult;

import java.util.List;

public class MovieApp {
    public static void main(String[] args) {
        MovieDAO movieDAO = MovieDAOFactory.getMovieDAO();

        String search = "Batman";

        if (movieDAO instanceof XmlMovieDAO) {
            XmlMovieDAO xmlMovieDao = (XmlMovieDAO) movieDAO;
            List<MovieSearchResult> results = xmlMovieDao.search(search);

            System.out.println("Found " + results.size() + " results for '" + search + "':");
            results.forEach(System.out::println);
        }
    }
}