[ISSUE49]Fix KeyValue merge problem

openmessaging-api/src/main/java/io/openmessaging/KeyValue.java

@@ -135,6 +135,17 @@ public interface KeyValue {
      */
     int getInt(String key);
 
+    /**
+     * Searches for the {@code int} property with the specified key in this {@code KeyValue} object. If the key is not
+     * found in this property list, the default value argument is returned.
+     *
+     * @param key the property key
+     * @param defaultValue a default value
+     * @return the value in this {@code KeyValue} object with the specified key value
+     * @see #put(String, int)
+     */
+    int getInt(String key, int defaultValue);
+
     /**
      * Searches for the {@code long} property with the specified key in this {@code KeyValue} object. If the key is not
      * found in this property list, zero is returned.
@@ -166,6 +177,17 @@ public interface KeyValue {
      */
     double getDouble(String key);
 
+    /**
+     * Searches for the {@code double} property with the specified key in this {@code KeyValue} object. If the key is
+     * not found in this property list, the default value argument is returned.
+     *
+     * @param key the property key
+     * @param defaultValue a default value
+     * @return the value in this {@code KeyValue} object with the specified key value
+     * @see #put(String, double)
+     */
+    double getDouble(String key, double defaultValue);
+
     /**
      * Searches for the {@code String} property with the specified key in this {@code KeyValue} object. If the key is
      * not found in this property list, {@code null} is returned.
@@ -176,6 +198,17 @@ public interface KeyValue {
      */
     String getString(String key);
 
+    /**
+     * Searches for the {@code String} property with the specified key in this {@code KeyValue} object. If the key is
+     * not found in this property list, the default value argument is returned.
+     *
+     * @param key the property key
+     * @param defaultValue a default value
+     * @return the value in this {@code KeyValue} object with the specified key value
+     * @see #put(String, String)
+     */
+    String getString(String key, String defaultValue);
+
     /**
      * Returns a {@link Set} view of the keys contained in this {@code KeyValue} object.
      * <p>

openmessaging-api/src/main/java/io/openmessaging/internal/DefaultKeyValue.java

@@ -105,6 +105,11 @@ public int getInt(String key) {
         return Integer.valueOf(properties.get(key));
     }
 
+    @Override
+    public int getInt(final String key, final int defaultValue) {
+        return properties.containsKey(key) ? getInt(key) : defaultValue;
+    }
+
     @Override
     public long getLong(String key) {
         if (!properties.containsKey(key)) {
@@ -126,11 +131,21 @@ public double getDouble(String key) {
         return Double.valueOf(properties.get(key));
     }
 
+    @Override
+    public double getDouble(final String key, final double defaultValue) {
+        return properties.containsKey(key) ? getDouble(key) : defaultValue;
+    }
+
     @Override
     public String getString(String key) {
         return properties.get(key);
     }
 
+    @Override
+    public String getString(final String key, final String defaultValue) {
+        return properties.containsKey(key) ? getString(key) : defaultValue;
+    }
+
     @Override
     public Set<String> keySet() {
         return properties.keySet();