various improvements

Author: HolgerDoerner

Diff for: mock_data.sql

@@ -7,22 +7,27 @@
 import com.example.bean.EmployeeBean;
 import com.google.gson.Gson;
 
+import spark.Service.StaticFiles;
+
 /**
  * Main application class
  */
 public final class App {
-    private static Gson gson = new Gson();
-    private static RestService service;
+    private static final RestService service;
+
+    private static final Gson gson = new Gson();
 
     static {
         try {
-            DatabaseUtil.initDatabase();
-
-            // Replace this with yout own implementation of RestService.
-            service = new MyRestService();
+            DatabaseProvider.initDatabase();
         } catch (SQLException e) {
-            e.printStackTrace();
+            System.err.println("Error setting up database: " + e.getMessage());
+            System.err.println("Exiting...");
+            System.exit(1);
         }
+
+        // Replace this with yout own implementation of RestService.
+        service = new MyRestService();
     }
 
     /**
@@ -32,7 +37,6 @@ public final class App {
      * @throws Exception
      */
     public static void main(String[] args) throws Exception {
-        
         // returns a list of all employees
         get("/users", (request, response) -> service.getEmployees(), gson::toJson);
 
@@ -52,7 +56,7 @@ public static void main(String[] args) throws Exception {
             (request, response) -> service.updateEmployee(gson.fromJson(request.body(), EmployeeBean.class)),
             gson::toJson);
 
-        // set default content-type to json for all endpoints
+        // set default content-type to json for response from all endpoints.
         after((request, response) -> response.header("Content-type", "application/json"));
     }
 }

Diff for: src/main/java/com/example/App.java

@@ -0,0 +1,65 @@
+package com.example;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.Objects;
+
+import org.h2.jdbcx.JdbcDataSource;
+import org.h2.tools.Server;
+
+/**
+ * Implementation encapsulates an H2 in-memmory database.
+ */
+public class DatabaseProvider {
+    private static Server db;
+    private static JdbcDataSource ds = new JdbcDataSource();
+
+    private static final Object lock = new Object();
+
+    private DatabaseProvider() {
+    }
+
+    public static void initDatabase() throws SQLException {
+        if (Objects.isNull(db)) {
+            synchronized (lock) {
+                if (Objects.isNull(db)) {
+                    db = Server.createTcpServer().start();
+
+                    ds.setURL("jdbc:h2:mem:mockdb;DB_CLOSE_DELAY=-1");
+                    // ds.setUser("user");
+                    // ds.setPassword("password");
+
+                    try (Connection conn = ds.getConnection(); Statement stmt = conn.createStatement()) {
+
+                        Files.lines(Paths.get("mock_data.sql")).filter(line -> !line.isEmpty()).forEach(line -> {
+                            try {
+                                stmt.executeUpdate(line);
+                            } catch (SQLException e) {
+                                System.err.println("Error setting up database: " + e.getMessage());
+                                System.err.println("Exiting...");
+                                System.exit(1);
+                            }
+                        });
+                    } catch (IOException e) {
+                        System.err.println("Unable to read SQL file: " + e.getMessage());
+                        System.err.println("Make sure it is placedin the same directory as the JAR file!");
+                        System.err.println("Exiting...");
+                        System.exit(1);
+                    }
+                }
+            }
+        }
+    }
+
+    public static Connection getConnection() throws SQLException {
+        if (Objects.isNull(db)) {
+            initDatabase();
+        }
+
+        return ds.getConnection();
+    }
+}

Diff for: src/main/java/com/example/DatabaseProvider.java

@@ -1,11 +1,11 @@
 package com.example;
 
-import java.time.LocalDateTime;
 import java.util.Collection;
 
 public class ResponseMessage <T> {
     private String status;
-    private LocalDateTime timeStamp;
+    private String timeStamp;
+    private Integer count;
     private Collection<T> msg;
 
     public String getStatus() {
@@ -16,14 +16,22 @@ public void setStatus(String status) {
         this.status = status;
     }
 
-    public LocalDateTime getTimeStamp() {
+    public String getTimeStamp() {
         return timeStamp;
     }
 
-    public void setTimeStamp(LocalDateTime timeStamp) {
+    public void setTimeStamp(String timeStamp) {
         this.timeStamp = timeStamp;
     }
 
+    public Integer getCount() {
+        return count;
+    }
+
+    public void setCount(Integer count) {
+        this.count = count;
+    }
+
     public Collection<T> getMsg() {
         return msg;
     }

Diff for: src/main/java/com/example/DatabaseUtil.java

@@ -7,25 +7,28 @@
 import java.sql.Statement;
 import java.time.LocalDateTime;
 import java.util.ArrayList;
+import java.util.List;
 
 import com.example.bean.EmployeeBean;
 
 public interface RestService {
     public default ResponseMessage<EmployeeBean> getEmployees() {
         ResponseMessage<EmployeeBean> message = new ResponseMessage<>();
 
-        try (Connection conn = DatabaseUtil.getConnection();
-            Statement stmt = conn.createStatement();
-            ResultSet res = stmt.executeQuery("select * from employees;")) {
+        try (Connection conn = DatabaseProvider.getConnection();
+                Statement stmt = conn.createStatement();
+                ResultSet res = stmt.executeQuery("select * from employees;")) {
 
-            message.setTimeStamp(LocalDateTime.now());
-            message.setStatus("SUCCESS");
-            message.setMsg(EmployeeBean.ofResultSet(res));
+            message.setTimeStamp(LocalDateTime.now().toString());
+            message.setStatus("Ok");
+            List<EmployeeBean> tmp = EmployeeBean.ofResultSet(res);
+            message.setCount(tmp.size());
+            message.setMsg(tmp);
         } catch (SQLException e) {
             e.printStackTrace();
 
-            message.setTimeStamp(LocalDateTime.now());
-            message.setStatus("ERROR");
+            message.setTimeStamp(LocalDateTime.now().toString());
+            message.setStatus("Error");
             message.setMsg(new ArrayList<>());
         }
 
@@ -36,23 +39,28 @@ public default ResponseMessage<EmployeeBean> getEmployeeById(Integer id) {
         ResponseMessage<EmployeeBean> message = new ResponseMessage<>();
         String sql = "select * from employees where id=?;";
 
-        try (Connection conn = DatabaseUtil.getConnection();
-            PreparedStatement stmt = conn.prepareStatement(sql)) {
-            
+        try (Connection conn = DatabaseProvider.getConnection(); PreparedStatement stmt = conn.prepareStatement(sql)) {
+
             stmt.setInt(1, id);
             ResultSet res = stmt.executeQuery();
 
+            EmployeeBean e = EmployeeBean.ofSingleResult(res);
+
             ArrayList<EmployeeBean> tmp = new ArrayList<>();
-            tmp.add(EmployeeBean.ofSingleResult(res));
 
-            message.setTimeStamp(LocalDateTime.now());
-            message.setStatus("OK");
+            if (e.getId() != -1) {
+                tmp.add(e);
+            }
+
+            message.setTimeStamp(LocalDateTime.now().toString());
+            message.setStatus("Ok");
             message.setMsg(tmp);
+            message.setCount(tmp.size());
         } catch (SQLException e) {
             e.printStackTrace();
 
-            message.setTimeStamp(LocalDateTime.now());
-            message.setStatus("ERROR");
+            message.setTimeStamp(LocalDateTime.now().toString());
+            message.setStatus("Error");
             message.setMsg(new ArrayList<>());
         }
 
@@ -63,19 +71,18 @@ public default ResponseMessage<EmployeeBean> deleteEmployee(Integer id) {
         ResponseMessage<EmployeeBean> message = new ResponseMessage<>();
         String sql = "delete from employees where id=?;";
 
-        try (Connection conn = DatabaseUtil.getConnection();
-            PreparedStatement stmt = conn.prepareStatement(sql)) {
+        try (Connection conn = DatabaseProvider.getConnection(); PreparedStatement stmt = conn.prepareStatement(sql)) {
             stmt.setInt(1, id);
             stmt.executeUpdate();
 
-            message.setTimeStamp(LocalDateTime.now());
-            message.setStatus("deleted");
+            message.setTimeStamp(LocalDateTime.now().toString());
+            message.setStatus("Ok");
             message.setMsg(new ArrayList<>());
         } catch (SQLException e) {
             e.printStackTrace();
 
-            message.setTimeStamp(LocalDateTime.now());
-            message.setStatus("error");
+            message.setTimeStamp(LocalDateTime.now().toString());
+            message.setStatus("Error");
             message.setMsg(new ArrayList<>());
         }
 
@@ -85,33 +92,24 @@ public default ResponseMessage<EmployeeBean> deleteEmployee(Integer id) {
     public default ResponseMessage<EmployeeBean> updateEmployee(EmployeeBean employee) {
         ResponseMessage<EmployeeBean> message = new ResponseMessage<>();
         EmployeeBean current = new EmployeeBean();
-        
+
         String sql1 = "select * from employees where id=?;";
-        try (Connection conn = DatabaseUtil.getConnection();
-            PreparedStatement stmt = conn.prepareStatement(sql1)) {
-            
+        try (Connection conn = DatabaseProvider.getConnection(); PreparedStatement stmt = conn.prepareStatement(sql1)) {
+
             stmt.setInt(1, employee.getId());
             ResultSet res = stmt.executeQuery();
 
             current = EmployeeBean.ofSingleResult(res);
         } catch (SQLException e) {
             e.printStackTrace();
         }
-        
+
         current.update(employee);
-        
-        String sql2 = "update employees set firstName=?,"
-                    + "lastName=?,"
-                    + "birthDate=?,"
-                    + "gender=?,"
-                    + "company=?,"
-                    + "department=?,"
-                    + "employerId=?,"
-                    + "email=? "
-                    + "where id=?;";
-
-        try (Connection conn = DatabaseUtil.getConnection();
-            PreparedStatement stmt = conn.prepareStatement(sql2)) {
+
+        String sql2 = "update employees set firstName=?," + "lastName=?," + "birthDate=?," + "gender=?," + "company=?,"
+                + "department=?," + "employerId=?," + "email=? " + "where id=?;";
+
+        try (Connection conn = DatabaseProvider.getConnection(); PreparedStatement stmt = conn.prepareStatement(sql2)) {
 
             stmt.setString(1, current.getFirstName());
             stmt.setString(2, current.getLastName());
@@ -125,12 +123,13 @@ public default ResponseMessage<EmployeeBean> updateEmployee(EmployeeBean employe
 
             stmt.executeUpdate();
 
-            message.setTimeStamp(LocalDateTime.now());
+            message.setTimeStamp(LocalDateTime.now().toString());
             message.setStatus("Ok");
 
             ArrayList<EmployeeBean> tmp = new ArrayList<>();
             tmp.add(current);
             message.setMsg(tmp);
+            message.setCount(tmp.size());
         } catch (SQLException e) {
             e.printStackTrace();
         }