Adding config support.

1 files changed, 148 insertions, 0 deletions

diff --git a/src/com/p4square/grow/config/Config.java b/src/com/p4square/grow/config/Config.java
new file mode 100644
index 0000000..f5ebe3c
--- /dev/null
+++ b/src/com/p4square/grow/config/Config.java
@@ -0,0 +1,148 @@
+/*
+ * Copyright 2013 Jesse Morgan
+ */
+
+package com.p4square.grow.config;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.io.IOException;
+import java.util.Properties;
+
+import org.apache.log4j.Logger;
+
+/**
+ * Manage configuration for an application.
+ *
+ * Config reads one or more property files as the application config. Duplicate
+ * properties loaded later override properties loaded earlier. Config has the
+ * concept of a domain to distinguish settings for development and production.
+ * The default domain is prod for production. Domain can be any String such as
+ * dev for development or test for testing.
+ *
+ * The property files are processed like java.util.Properties except that the
+ * keys are specified as DOMAIN.KEY. An asterisk (*) can be used in place of a
+ * domain to indicate it should apply to all domains. If a domain specific entry
+ * exists for the current domain, it will override any global config.
+ *
+ * @author Jesse Morgan <jesse@jesterpm.net>
+ */
+public class Config {
+    private static Logger cLog = Logger.getLogger(Config.class);
+
+    private String mDomain;
+    private Properties mProperties;
+
+    /**
+     * Construct a new Config object. Domain defaults to prod.
+     */
+    public Config() {
+        mDomain = "prod";
+        mProperties = new Properties();
+
+    }
+
+    /**
+     * Change the domain from the default string "prod".
+     *
+     * @param domain The new domain.
+     */
+    public void setDomain(String domain) {
+        mDomain = domain;
+    }
+
+    /**
+     * Load properties from a file.
+     * Any exceptions are logged and suppressed.
+     */
+    public void updateConfig(String propertyFilename) {
+        final File propFile = new File(propertyFilename);
+
+        cLog.info("Loading properties from " + propFile);
+
+        try {
+            InputStream in = new FileInputStream(propFile);
+            updateConfig(in);
+
+        } catch (IOException e) {
+            cLog.error("Could not load properties file: " + e.getMessage(), e);
+        }
+    }
+
+    /**
+     * Load properties from an InputStream.
+     * This method closes the InputStream when it completes.
+     *
+     * @param in The InputStream
+     */
+    public void updateConfig(InputStream in) throws IOException {
+        mProperties.load(in);
+        in.close();
+    }
+
+    /**
+     * Get a String from the config.
+     *
+     * @return The config value or null if it is not found.
+     */
+    public String getString(String key) {
+        return getString(key, null);
+    }
+
+    /**
+     * Get a String from the config.
+     *
+     * @return The config value or defaultValue if it can not be found.
+     */
+    public String getString(String key, String defaultValue) {
+        String result;
+
+        final String domainKey = mDomain + "." + key;
+        result = mProperties.getProperty(domainKey, defaultValue);
+        if (result != null) {
+            return result;
+        }
+
+        final String globalKey = "*." + key;
+        result = mProperties.getProperty(globalKey, defaultValue);
+        if (result != null) {
+            return result;
+        }
+
+        return defaultValue;
+    }
+
+    /**
+     * Get an integer from the config.
+     *
+     * @return The config value or Integer.MIN_VALUE if the key is not present or the
+     *         config can not be parsed.
+     */
+    public int getInt(String key) {
+        return getInt(key, Integer.MIN_VALUE);
+    }
+
+    /**
+     * Get an integer from the config.
+     *
+     * @return The config value or defaultValue if the key is not present or the
+     *         config can not be parsed.
+     */
+    public int getInt(String key, int defaultValue) {
+        final String propertyValue = getString(key);
+
+        if (propertyValue != null) {
+            try {
+                final int result = Integer.valueOf(propertyValue);
+                return result;
+
+            } catch (NumberFormatException e) {
+                cLog.warn("Expected property to be an integer: "
+                        + key + " = { " + propertyValue + " }");
+            }
+        }
+
+        return defaultValue;
+    }
+}