generic reflection based MBean impl

bindings/java/src/org/hyperic/sigar/jmx/ReflectedMBean.java

@@ -0,0 +1,148 @@
+/* Copyright (C) [2004, 2005, 2006], Hyperic, Inc.
+ * This file is part of SIGAR.
+ * 
+ * SIGAR is free software; you can redistribute it and/or modify
+ * it under the terms version 2 of the GNU General Public License as
+ * published by the Free Software Foundation. This program is distributed
+ * in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
+ * even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA.
+ */
+
+package org.hyperic.sigar.jmx;
+
+import java.lang.reflect.Method;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import javax.management.AttributeNotFoundException;
+import javax.management.MBeanAttributeInfo;
+import javax.management.MBeanException;
+import javax.management.MBeanInfo;
+import javax.management.ReflectionException;
+
+import org.hyperic.sigar.Sigar;
+
+public class ReflectedMBean extends AbstractMBean {
+
+    private Method getter;
+    private Map methods;
+    private String type;
+
+    protected String getType() {
+        return this.type;
+    }
+
+    protected Class getMBeanClass() {
+        try {
+            return getGetter().getReturnType();
+        } catch (Exception e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+    
+    protected ReflectedMBean(Sigar sigar, String type) {
+        super(sigar, CACHELESS);
+        this.type = type;
+    }
+
+    public String getObjectName() {
+        return
+            SigarInvokerJMX.DOMAIN_NAME + ":" +
+            MBEAN_ATTR_TYPE + "=" + getType();
+    }
+
+    protected Method getGetter() throws Exception {
+        if (this.getter == null) {
+            String getName = "get" + getType();
+            Class[] params = getGetterParams();
+            this.getter =
+                this.sigarImpl.getClass().getDeclaredMethod(getName,
+                                                            params);
+        }
+        return this.getter;
+    }
+
+    protected Class[] getGetterParams() {
+        return new Class[0];
+    }
+
+    private Object getReflectedAttribute(String name)
+        throws Exception {
+
+        Method getter = getGetter();
+        Class[] params = getGetterParams();
+        Object obj = getter.invoke(this.sigarImpl, params);
+        Method method =
+            obj.getClass().getMethod("get" + name, new Class[0]);
+        return method.invoke(obj, new Object[0]);
+    }
+
+    public Object getAttribute(String name)
+        throws AttributeNotFoundException,
+               MBeanException, ReflectionException {
+        try {
+            return getReflectedAttribute(name);
+        } catch (Exception e) {
+            throw new ReflectionException(e);
+        }
+    }
+
+    private Map getMethods() {
+        if (this.methods != null) {
+            return this.methods;
+        }
+        this.methods = new LinkedHashMap();
+        Method[] methods = getMBeanClass().getDeclaredMethods();
+        for (int i=0; i<methods.length; i++) {
+            String name = methods[i].getName();
+            if (!name.startsWith("get")) {
+                continue;
+            }
+            name = name.substring(3);
+            this.methods.put(name, methods[i]);
+        }
+        return this.methods;
+    }
+
+    protected MBeanAttributeInfo[] getAttributeInfo() {
+        Map methods = getMethods();
+        MBeanAttributeInfo[] attrs =
+            new MBeanAttributeInfo[methods.size()];
+        int i=0;
+        for (Iterator it=methods.entrySet().iterator();
+             it.hasNext();)
+        {
+            Map.Entry entry = (Map.Entry)it.next();
+            String name = (String)entry.getKey();
+            Method method = (Method)entry.getValue();
+            attrs[i++] =
+                new MBeanAttributeInfo(name,
+                                       method.getReturnType().getName(),
+                                       name + " MBean",
+                                       true,   // isReadable
+                                       false,  // isWritable
+                                       false); // isIs
+        }        
+        return attrs;
+    }
+
+    public MBeanInfo getMBeanInfo() {
+        MBeanInfo info =
+            new MBeanInfo(getMBeanClass().getName(),
+                          "",
+                          getAttributeInfo(),
+                          null, //constructors
+                          null, //operations
+                          null); //notifications
+        return info;
+    }
+}