Spark Java Article BAEL-498 (#912)

* Initial Commit for Spark Java Article BAEL-498

* reverting main pom.xml and rollbacking accidental changes.

* Changes as per review:

1. Added UserService
2. Renamed UserStore to UserServiceMapImpl
3. Removed Empty spaces in User.java
4. Removed AppTest
5. Changes in SparkRestExample for using UserServiceMapImp instead of
UserStore static functions.

* Suggested changes in print messages.

* Changes as per comments on github... for PR:
https://github.com/eugenp/tutorials/pull/912

* Changes in editUser function as per guidance by Kevin.

* Clean up

* added 1.8 config for pom.xml

* Clean up.

* Removed junit dep.

* Added Application/json in response type.

pom.xml

@@ -94,6 +94,7 @@
         <module>resteasy</module>
 
         <module>selenium-junit-testng</module>
+        <module>spark-java</module>
         <module>spring-akka</module>
         <module>spring-amqp</module>
         <module>spring-all</module>

spark-java/pom.xml

@@ -0,0 +1,29 @@
+<?xml version="1.0"?>
+<project
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+	xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>com.baeldung</groupId>
+	<artifactId>spark-java</artifactId>
+	<version>0.1.0-SNAPSHOT</version>
+	<name>spark-java</name>
+	<url>http://maven.apache.org</url>
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<maven.compiler.source>1.8</maven.compiler.source>
+		<maven.compiler.target>1.8</maven.compiler.target>
+	</properties>
+	<dependencies>
+		<dependency>
+			<groupId>com.sparkjava</groupId>
+			<artifactId>spark-core</artifactId>
+			<version>2.5.4</version>
+		</dependency>
+		<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson -->
+		<dependency>
+			<groupId>com.google.code.gson</groupId>
+			<artifactId>gson</artifactId>
+			<version>2.8.0</version>
+		</dependency>
+	</dependencies>
+</project>

spark-java/src/main/java/com/baeldung/sparkjava/HelloWorldService.java

@@ -0,0 +1,12 @@
+package com.baeldung.sparkjava;
+import static spark.Spark.*;
+
+public class HelloWorldService {
+    public static void main(String[] args) {
+        get("/hello", (req,res)->"Hello, Baeldung");
+        
+        get("/hello/:name", (req,res)->{
+            return "Hello: "+ req.params(":name");
+        });
+    }
+}

spark-java/src/main/java/com/baeldung/sparkjava/SparkRestExample.java

@@ -0,0 +1,76 @@
+package com.baeldung.sparkjava;
+
+import static spark.Spark.delete;
+import static spark.Spark.get;
+import static spark.Spark.options;
+import static spark.Spark.post;
+import static spark.Spark.put;
+
+import com.google.gson.Gson;
+
+public class SparkRestExample {
+    public static void main(String[] args) {
+        final UserService userService = new UserServiceMapImpl();
+        
+        post("/users", (request, response) -> {
+            response.type("application/json");
+            
+            User user = new Gson().fromJson(request.body(), User.class);
+            userService.addUser(user);
+
+            return new Gson().toJson(new StandardResponse(StatusResponse.SUCCESS));
+        });
+
+        get("/users", (request, response) -> {
+            response.type("application/json");
+            
+            return new Gson().toJson(
+                new StandardResponse(StatusResponse.SUCCESS,new Gson()
+                    .toJsonTree(userService.getUsers())));
+        });
+
+        get("/users/:id", (request, response) -> {
+            response.type("application/json");
+            
+            return new Gson().toJson(
+                new StandardResponse(StatusResponse.SUCCESS,new Gson()
+                  .toJsonTree(userService.getUser(request.params(":id")))));
+        });
+
+        put("/users/:id", (request, response) -> {
+            response.type("application/json");
+            
+            User toEdit = new Gson().fromJson(request.body(), User.class);
+            User editedUser = userService.editUser(toEdit);
+                
+            if (editedUser != null) {
+                return new Gson().toJson(
+                    new StandardResponse(StatusResponse.SUCCESS,new Gson()
+                        .toJsonTree(editedUser)));
+            }else  {
+                return new Gson().toJson(
+                    new StandardResponse(StatusResponse.ERROR,new Gson()
+                        .toJson("User not found or error in edit")));
+            }
+        });
+
+        delete("/users/:id", (request, response) -> {
+            response.type("application/json");
+            
+            userService.deleteUser(request.params(":id"));
+            return new Gson().toJson(
+                new StandardResponse(StatusResponse.SUCCESS, "user deleted"));
+        });
+
+        options("/users/:id", (request, response) -> {
+            response.type("application/json");
+            
+            return new Gson().toJson(
+                new StandardResponse(StatusResponse.SUCCESS, 
+                    (userService.userExist(
+                        request.params(":id"))) ? "User exists" : "User does not exists" ));
+        });
+
+    }
+
+}

spark-java/src/main/java/com/baeldung/sparkjava/StandardResponse.java

@@ -0,0 +1,47 @@
+package com.baeldung.sparkjava;
+
+import com.google.gson.JsonElement;
+
+public class StandardResponse {
+    private StatusResponse status;
+    private String message;
+    private JsonElement data;
+
+    public StandardResponse(StatusResponse status) {
+        this.status = status;
+    }
+
+    public StandardResponse(StatusResponse status, String message) {
+        this.status = status;
+        this.message = message;
+    }
+
+    public StandardResponse(StatusResponse status, JsonElement data) {
+        this.status = status;
+        this.data = data;
+    }
+
+    public StatusResponse getStatus() {
+        return status;
+    }
+
+    public void setStatus(StatusResponse status) {
+        this.status = status;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public JsonElement getData() {
+        return data;
+    }
+
+    public void setData(JsonElement data) {
+        this.data = data;
+    }
+}

spark-java/src/main/java/com/baeldung/sparkjava/StatusResponse.java

@@ -0,0 +1,17 @@
+package com.baeldung.sparkjava;
+
+public enum StatusResponse {
+    SUCCESS ("Success"),
+    ERROR ("Error");
+    
+    final private String status;
+   
+    StatusResponse(String status) {
+        this.status = status;
+    }
+    
+    public String getStatus() {
+        return status;
+    }
+
+}

spark-java/src/main/java/com/baeldung/sparkjava/User.java

@@ -0,0 +1,59 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package com.baeldung.sparkjava;
+
+class User {
+
+    private String id;
+    private String firstName;
+    private String lastName;
+    private String email;
+
+    public User(String id, String firstName, String lastName, String email) {
+        super();
+        this.id = id;
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.email = email;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    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;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+    
+    @Override
+    public String toString() {
+        return new StringBuffer().append(getEmail()).toString();
+    }
+}

spark-java/src/main/java/com/baeldung/sparkjava/UserException.java

@@ -0,0 +1,13 @@
+package com.baeldung.sparkjava;
+
+public class UserException extends Exception{
+    
+    public UserException() {
+        super();
+    }
+    
+    public UserException(String message) {
+        super(message);
+    }
+
+}

spark-java/src/main/java/com/baeldung/sparkjava/UserService.java

@@ -0,0 +1,12 @@
+package com.baeldung.sparkjava;
+
+import java.util.Collection;
+
+public interface UserService {
+    public void addUser (User user) ;
+    public Collection<User> getUsers () ;
+    public User getUser (String id) ;
+    public User editUser (User user) throws UserException;
+    public void deleteUser (String id) ;
+    public boolean userExist (String id);
+}

spark-java/src/main/java/com/baeldung/sparkjava/UserServiceMapImpl.java

@@ -0,0 +1,68 @@
+package com.baeldung.sparkjava;
+
+import java.util.Collection;
+import java.util.HashMap;
+
+public class UserServiceMapImpl  implements UserService{
+    private HashMap<String, User> userMap;
+    
+    public UserServiceMapImpl() {
+        userMap = new HashMap<>();
+    }
+
+    @Override
+    public void addUser (User user) {
+        userMap.put(user.getId(), user);
+    }
+    
+    @Override
+    public Collection<User> getUsers () {
+        return  userMap.values();
+    }
+    
+    @Override
+    public User getUser (String id) {
+        return userMap.get(id);
+    }
+    
+    @Override
+    public User editUser (User forEdit) throws UserException{
+        try{
+            if (forEdit.getId() == null) 
+                throw new UserException("ID cannot be blank");
+            
+            User toEdit = userMap.get(forEdit.getId());
+            
+            if (toEdit == null )
+                throw new UserException("User not found");
+            
+            if (forEdit.getEmail()!=null) {
+                toEdit.setEmail(forEdit.getEmail());
+            }
+            if (forEdit.getFirstName()!=null) {
+                toEdit.setFirstName(forEdit.getFirstName());
+            }
+            if (forEdit.getLastName()!=null) {
+                toEdit.setLastName(forEdit.getLastName());
+            }
+            if (forEdit.getId()!=null) {
+                toEdit.setId(forEdit.getId());
+            }
+
+            return toEdit;
+        }catch (Exception ex) {
+            throw new UserException(ex.getMessage());
+        }
+    }
+    
+    @Override
+    public void deleteUser (String id) {
+        userMap.remove(id);
+    }
+    
+    @Override
+    public boolean userExist (String id) {
+        return userMap.containsKey(id);
+    }
+
+}