Implement Derby database implementation for unit testing

.gitignore

@@ -1,3 +1,23 @@
+
+# Idea files #
+################
+/.idea/
+
+
+# bat files #
+################
+/bin/
+
+# Gradle files #
+################
+.gradle
+
+
+# Files in the build folder #
+#############################
+/build/
+
+
 # Compiled source #
 ###################
 *.com

build.gradle

@@ -67,7 +67,6 @@ dependencies {
 
 }
 
-
 jar {
 
    manifest {

src/main/java/excel2db/excel2db.java

@@ -6,14 +6,12 @@
 import java.util.HashSet;
 import java.util.concurrent.TimeUnit;
 
-import excel2db.ApplicationException;
 import excel2db.service.CreateTable;
 import excel2db.service.DBConnection;
 import excel2db.service.GenerateFileList;
 import excel2db.service.InitConstants;
 import excel2db.service.InitInputFiles;
 import excel2db.service.PopulateTable;
-import excel2db.Excel2dbTask;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.context.ApplicationContext;
@@ -85,31 +83,32 @@ public static void main(String[] args) {
             //this way we call methods for objects that is already initialized by the Spring
             app.dbConnection.establishDBConnection();
 
-            // iterate through file name values in properties file,
-            // for each file start a new thread
-            for (String fileNameValue : fileList) {
-
-                File fileName = new File(fileNameValue);
-                //check if the file really exists
-                if (fileName.exists() == false) {
-                    logger.error("The file " + fileNameValue + " doesn't exist");
-                } else {
-                    taskExecutor.execute(new Excel2dbTask(app, fileName));
+            // in case the connection established
+            // iterate through file name values in properties file, for each file start a new thread
+            if (connection != null) {
+                for (String fileNameValue : fileList) {
+
+                    File fileName = new File(fileNameValue);
+                    //check if the file really exists
+                    if (fileName.exists() == false) {
+                        logger.error("The file " + fileNameValue + " doesn't exist");
+                    } else {
+                        taskExecutor.execute(new Excel2dbTask(app, fileName));
+                    }
                 }
 
-            }
-
-            //TODO : This is just as a workaround to wait till the thread has been really started
-            //TODO : Need to use the ScheduledThreadPoolExecutor to customize delays on starting threads
-            TimeUnit.SECONDS.sleep(1);
-            // Wait until all threads are finished
-            logger.info("Waiting until active threads exist");
-            while (taskExecutor.getActiveCount() != 0) {
-            }
-            logger.info("All threads are inactive");
 
-            app.closeConnections();
+                //TODO : This is just as a workaround to wait till the thread has been really started
+                //TODO : Need to use the ScheduledThreadPoolExecutor to customize delays on starting threads
+                TimeUnit.SECONDS.sleep(1);
+                // Wait until all threads are finished
+                logger.info("Waiting until active threads exist");
+                while (taskExecutor.getActiveCount() != 0) {
+                }
+                logger.info("All threads are inactive");
 
+                app.closeConnections();
+            }
         } catch (Exception e) {
             logger.error("An exception occurred while running application", e);
             System.exit(1);

src/main/java/excel2db/service/DBConnection.java

@@ -1,7 +1,10 @@
 package excel2db.service;
 
+import java.sql.Connection;
+import java.sql.SQLException;
+
 public interface DBConnection {
 
-    public void establishDBConnection();
+    public void establishDBConnection() throws SQLException;
 
 }

src/main/java/excel2db/service/impl/CreateTableDerbyImpl.java

@@ -4,8 +4,14 @@
  * Created by Andrey on 6/21/2017.
  */
 
+import java.sql.DatabaseMetaData;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.util.LinkedHashMap;
+import java.util.Map;
 
+import excel2db.excel2db;
 import excel2db.service.CreateTable;
 import excel2db.service.PopulateTable;
 import org.apache.poi.ss.usermodel.Sheet;
@@ -15,15 +21,55 @@
 
 public class CreateTableDerbyImpl implements CreateTable {
 
-    public static final Logger logger = LoggerFactory.getLogger(PopulateTableOracleImpl.class);
+    public static final Logger logger = LoggerFactory.getLogger(CreateTableDerbyImpl.class);
 
-    private Integer numOfProcessedRows = 0;
+    public void createTable(Sheet sheet, String tableName) throws SQLException {
 
-    public void createTable(Sheet sheet, String tableName)
-            throws SQLException {
+        Map<String, Integer> header = new LinkedHashMap<>();
+        header = InitInputFilesImpl.readSheetHeader(sheet);
+
+        //dropping statement
+        String sqlTableDropStatement = "DROP TABLE \"" +
+                tableName + "\"";
+
+        //creating statement
+        StringBuilder sqlTableCreateStatement = new StringBuilder();
+        sqlTableCreateStatement.append("CREATE TABLE \"" +
+                tableName + "\"(");
+        for (String headerColumnName : header.keySet()) {
+            sqlTableCreateStatement.append("\"" + headerColumnName + "\"" + " VARCHAR(100), ");
+        }
+
+        sqlTableCreateStatement.setLength(sqlTableCreateStatement.length() - 2);
+        sqlTableCreateStatement.append(")");
+
+
+        //Derby doesn't support the "DROP IF EXISTS" SQL statement
+        //Thus, checking the table and dropping if the table exists
+        logger.info("Checking if the table " + tableName + " already exists");
+        DatabaseMetaData dbm = excel2db.connection.getMetaData();
+        ResultSet tables = dbm.getTables(null, null, tableName, null);
+        if (tables.next()) {
+            // Table exists, dropping
+            logger.info("The table " + tableName + " exists, dropping ...");
+            PreparedStatement pstmtDrop = excel2db.connection.prepareStatement(sqlTableDropStatement);
+            pstmtDrop.execute();
+            logger.info("The table " + tableName + " has been dropped");
+        }
+        else {
+            // Table does not exist, skipp dropping
+            logger.info("The table " + tableName + " doesn't exist, skip dropping");
+        }
+
+
+        //creating
+        logger.info("The table " + tableName + " is being created ...");
+        PreparedStatement pstmtCreate = excel2db.connection.prepareStatement(sqlTableCreateStatement.toString());
+        pstmtCreate.execute();
+        logger.info("The table " + tableName + " has been created");
 
-        logger.info("Create table method : Derby implementation is not covered yet");
 
     }
 
+
 }

src/main/java/excel2db/service/impl/CreateTableOracleImpl.java

@@ -31,7 +31,7 @@ public void createTable(Sheet sheet, String tableName) throws SQLException {
         sqlTableCreateStatement.append("CREATE TABLE \"" +
                 tableName + "\"(");
         for (String headerColumnName : header.keySet()) {
-            sqlTableCreateStatement.append("\"" + headerColumnName + "\"" + " VARCHAR2(20), ");
+            sqlTableCreateStatement.append("\"" + headerColumnName + "\"" + " VARCHAR2(100), ");
         }
 
         sqlTableCreateStatement.setLength(sqlTableCreateStatement.length() - 2);

src/main/java/excel2db/service/impl/CreateTablePostgresImpl.java

@@ -19,7 +19,6 @@ public class CreateTablePostgresImpl implements CreateTable {
 
     public void createTable(Sheet sheet, String tableName) throws SQLException {
 
-        //sheetEntityManager = new SheetEntityManager(sheet);
         //initializing var for a header
         Map<String, Integer> header = new LinkedHashMap<>();
         header = InitInputFilesImpl.readSheetHeader(sheet);

src/main/java/excel2db/service/impl/DBConnectionDerbyImpl.java

@@ -4,62 +4,34 @@
  * Created by Andrey on 6/21/2017.
  */
 
+import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
+import java.util.Properties;
 
 import excel2db.excel2db;
 import excel2db.service.DBConnection;
+import org.apache.derby.jdbc.EmbeddedDriver;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Value;
 
 
-
-
-
 public class DBConnectionDerbyImpl implements DBConnection {
 
-    // connection parameters
-    @Value("${db.derby.server}")
-    String dbServer;
-
-    @Value("${db.derby.user}")
-    String dbUser;
-
-    @Value("${db.derby.password}")
-    String dbPassword;
-
-    @Value("${db.derby.port}")
-    String dbPort;
-
-    @Value("${db.derby.database}")
-    String dbName;
-
-
     public static final Logger logger = LoggerFactory.getLogger(DBConnectionDerbyImpl.class);
 
     public void establishDBConnection() {
         {
-
             try {
-                excel2db.connection = DriverManager.getConnection(
-                        //"jdbc:derby//" + dbServer + ":" + dbPort + "/" + dbName + ";create=true;user=" + dbUser + ";password=" + dbPassword
-                        "jdbc:derby://localhost:1527/testDB;create=true"
-                );
+                //initialize an In-Memory Derby database
+                EmbeddedDriver driver = new EmbeddedDriver();
+                excel2db.connection = driver.connect("jdbc:derby:memory:testdb;create=true", new Properties());
+                logger.info("Derby connection is established");
 
             } catch (SQLException e) {
                 logger.error("Derby Connection Failed! Check output console");
-                e.printStackTrace();
-                return;
-            }
-            if (excel2db.connection != null) {
-                logger.info("Derby connection is established");
-            } else {
-                logger.error("Failed to make the Derby connection!");
             }
-
         }
-
     }
-
 }

src/main/java/excel2db/service/impl/DBConnectionOracleImpl.java

@@ -38,20 +38,11 @@ public void establishDBConnection() {
 
             try {
                 excel2db.connection = DriverManager.getConnection(
-                        "jdbc:oracle:thin:@//" + dbServer + ":" + dbPort + "/" + dbSid, dbUser, dbPassword)
-                ;
-
+                        "jdbc:oracle:thin:@//" + dbServer + ":" + dbPort + "/" + dbSid, dbUser, dbPassword);
+                logger.info("Oracle connection is established");
             } catch (SQLException e) {
                 logger.error("Oracle Connection Failed! Check output console");
-                e.printStackTrace();
-                return;
             }
-            if (excel2db.connection != null) {
-                logger.info("Oracle connection is established");
-            } else {
-                logger.error("Failed to make the Oracle connection!");
-            }
-
         }
 
     }

src/main/java/excel2db/service/impl/DBConnectionPostgresImpl.java

@@ -1,5 +1,6 @@
 package excel2db.service.impl;
 
+import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.SQLException;
 
@@ -29,21 +30,18 @@ public class DBConnectionPostgresImpl implements DBConnection {
 
     public static final Logger logger = LoggerFactory.getLogger(DBConnectionPostgresImpl.class);
 
-    public void establishDBConnection() {
+
+    public void establishDBConnection() throws SQLException {
+
+        //TODO : try to use the try-catch-resource construction, connection object should be closed as soon as the program stops working with this object
         try {
             excel2db.connection = DriverManager.getConnection(
-                    "jdbc:postgresql://" + dbServer + ":" + dbPort + "/" + dbDatabase, dbUser, dbPassword)
-            ;
-
-        } catch (SQLException e) {
-            logger.error("Connection Failed! Check output console");
-            e.printStackTrace();
-            return;
-        }
-        if (excel2db.connection != null) {
+                    "jdbc:postgresql://" + dbServer + ":" + dbPort + "/" + dbDatabase, dbUser, dbPassword);
             logger.info("Postgres connection is established");
-        } else {
-            logger.error("Failed to make connection!");
+        } catch (SQLException e) {
+            logger.error("Postgres Connection Failed! Check output console.");
         }
+
     }
+
 }

src/main/java/excel2db/service/impl/InitInputFilesImpl.java

@@ -42,6 +42,9 @@ public void setInputSheetFile(File inputSheetFile) {
 
     public static final Logger logger = LoggerFactory.getLogger(InitInputFilesImpl.class);
 
+    //fabric method for
+    //fabric method pattern, we don't know which object should be created
+    //in advance and define the object type based on an extension
     @Override
     public Sheet initInputFiles(File inputFile)
             throws ApplicationException, IOException {

src/main/resources/excel2db.properties

@@ -1,5 +1,8 @@
-#db implementation: Postgres, Oracle
-db.implementation=Postgres
+#db implementation: Postgres, Oracle, Derby
+#use Derby if you run Unit tests and have no Postgres and Oracle installed on you laptop
+#in this case the Derby In-Memory database will be created and used during
+#the UnitTest execution
+db.implementation=Derby
 
 # names of input tables
 input.files=test.xlsx,test1.xlsx
@@ -21,15 +24,8 @@ db.oracle.password=oracle
 
 
 # DON'T TOUCH : 
-
 # set db implementation classes based on the db.implementation 
 dbConnectionImplenentation=excel2db.service.impl.DBConnection${db.implementation}Impl
 createTableImplenentation=excel2db.service.impl.CreateTable${db.implementation}Impl
 
-# derby connection parameters
-db.derby.server=localhost
-db.derby.database=excel2db
-db.derby.port=5433
-db.derby.user=postgres
-db.derby.password=postgres