adding prop holder

Signed-off-by: Rajendarreddy Jagapathi <rajendarreddyj@gmail.com>

java-projects/basics/src/main/java/com/rajendarreddyj/basics/pattern/singleton/PropertiesHolder.java

@@ -0,0 +1,57 @@
+package com.rajendarreddyj.basics.pattern.singleton;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.Serializable;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+
+public class PropertiesHolder implements Cloneable, Serializable {
+    private static final long serialVersionUID = 1007236647121448027L;
+    private static final String CONNECTION_FILE_WITH_PATH = "src/main/resources/dbconnection.properties";
+    private static PropertiesHolder PROPERTIES_HOLDER = null;
+    private final Properties properties = new Properties();
+
+    private PropertiesHolder() {
+    }
+
+    public static PropertiesHolder getInstance() throws IOException {
+        if (PROPERTIES_HOLDER == null) {
+            synchronized (PropertiesHolder.class) {
+                if (PROPERTIES_HOLDER == null) {
+                    InputStream file = new FileInputStream(new File(CONNECTION_FILE_WITH_PATH));
+                    PROPERTIES_HOLDER = new PropertiesHolder();
+                    PROPERTIES_HOLDER.properties.load(file);
+                }
+            }
+        }
+        return PROPERTIES_HOLDER;
+    }
+
+    @Override
+    protected Object clone() throws CloneNotSupportedException {
+        return PROPERTIES_HOLDER;
+    }
+
+    protected Object readResolve() {
+        return PROPERTIES_HOLDER;
+    }
+
+    public String getPropertyValue(final String propertyKey) {
+        if ((propertyKey != null) && !propertyKey.isEmpty()) {
+            return this.properties.getProperty(propertyKey);
+        }
+        return null;
+    }
+
+    public Map<String, String> getProperties() {
+        Map<String, String> propertyMap = new HashMap<>();
+        for (String propertyKey : this.properties.stringPropertyNames()) {
+            propertyMap.put(propertyKey, this.properties.getProperty(propertyKey));
+        }
+        return propertyMap;
+    }
+}

java-projects/basics/src/main/java/com/rajendarreddyj/basics/pattern/singleton/PropertiesHolderMono.java

@@ -0,0 +1,45 @@
+package com.rajendarreddyj.basics.pattern.singleton;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+
+/**
+ * @author rajendarreddy.jagapathi
+ */
+public class PropertiesHolderMono {
+    private static final String CONNECTION_FILE_WITH_PATH = "src/main/resources/dbconnection.properties";
+    private static Properties properties = new Properties();
+    static {
+        InputStream file;
+        try {
+            file = new FileInputStream(new File(CONNECTION_FILE_WITH_PATH));
+            properties.load(file);
+        } catch (FileNotFoundException exp) {
+            exp.printStackTrace();
+        } catch (IOException exp) {
+            exp.printStackTrace();
+        }
+    }
+
+    public static String getPropertyValue(final String propertyKey) {
+        if ((propertyKey != null) && !propertyKey.isEmpty()) {
+            return properties.getProperty(propertyKey);
+        }
+        return null;
+    }
+
+    public static Map<String, String> getProperties() {
+        Map<String, String> propertyMap = new HashMap<>();
+        for (String propertyKey : properties.stringPropertyNames()) {
+            propertyMap.put(propertyKey, properties.getProperty(propertyKey));
+        }
+        return propertyMap;
+    }
+
+}

java-projects/basics/src/main/resources/dbconnection.properties

@@ -0,0 +1,11 @@
+# DB Connection Properties.
+# Oracle DB properties
+#jdbc.driver=oracle.jdbc.driver.OracleDriver
+#jdbc.url=jdbc:oracle:thin:@localhost:1521:test
+#jdbc.username=admin
+#jdbc.password=admin
+# MySQL DB properties
+jdbc.driver=com.mysql.jdbc.Driver
+jdbc.url=jdbc:mysql://localhost:3306/sample
+jdbc.username=root
+jdbc.password=admin

java-projects/basics/src/test/java/com/rajendarreddyj/basics/pattern/singleton/PropertiesHolderMonoTest.java

@@ -0,0 +1,16 @@
+package com.rajendarreddyj.basics.pattern.singleton;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * @author rajendarreddy.jagapathi
+ */
+public class PropertiesHolderMonoTest {
+
+    @Test
+    public void test() {
+        Assert.assertNotNull(PropertiesHolderMono.getPropertyValue("jdbc.driver"));
+    }
+
+}

java-projects/basics/src/test/java/com/rajendarreddyj/basics/pattern/singleton/PropertiesHolderTest.java

@@ -0,0 +1,18 @@
+package com.rajendarreddyj.basics.pattern.singleton;
+
+import java.io.IOException;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * @author rajendarreddy.jagapathi
+ */
+public class PropertiesHolderTest {
+
+    @Test
+    public void test() throws IOException {
+        Assert.assertNotNull(PropertiesHolder.getInstance().getPropertyValue("jdbc.driver"));
+    }
+
+}