Java tutorial
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See the License for the specific language governing permissions and limitations under the License. */ package com.ecyrd.management; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.Iterator; import javax.management.*; import org.apache.commons.lang.StringUtils; /** * A simple MBean which does not require an interface class unlike * the StandardMBean class. The methods are exposed through a method * call, which in turn then calls the methods using the Reflection API. * <p> * This class is similar to the javax.management.StandardMBean, but it does * require the API interface to be declared, so it's simpler. It's not as * powerful, but it does not require you to declare two classes (and keep * them in sync). * * @since 2.6 */ // FIXME: This class should really use Annotations instead of a method call. // FIXME: Exception handling is not probably according to spec... public abstract class SimpleMBean implements DynamicMBean { protected MBeanInfo m_beanInfo; private static Method findGetterSetter(Class<?> clazz, String name, Class<?> parm) { try { Class<?>[] params = { parm }; Class<?>[] emptyparms = {}; Method m = clazz.getDeclaredMethod(name, parm != null ? params : emptyparms); return m; } catch (Exception e) { // There's nothing to do, really - we just return a null. } return null; } /** * Create a new SimpleMBean * * @throws NotCompliantMBeanException {@inheritDoc} */ protected SimpleMBean() throws NotCompliantMBeanException { // // Create attributes // String[] attlist = getAttributeNames(); MBeanAttributeInfo[] attributes = null; if (attlist != null) { attributes = new MBeanAttributeInfo[attlist.length]; for (int i = 0; i < attlist.length; i++) { String name = attlist[i]; name = StringUtils.capitalize(name); Method getter = findGetterSetter(getClass(), "get" + name, null); if (getter == null) getter = findGetterSetter(getClass(), "is" + name, null); Method setter = null; if (getter != null) { setter = findGetterSetter(getClass(), "set" + name, getter.getReturnType()); } // // Check, if there's a description available // Method descriptor = findGetterSetter(getClass(), "get" + name + "Description", null); String description = ""; if (descriptor != null) { try { description = (String) descriptor.invoke(this, (Object[]) null); } catch (Exception e) { description = "Exception: " + e.getMessage(); } } MBeanAttributeInfo info; try { info = new MBeanAttributeInfo(attlist[i], description, getter, setter); } catch (IntrospectionException e) { throw new NotCompliantMBeanException(e.getMessage()); } attributes[i] = info; } } // // Create operations. // String[] oplist = getMethodNames(); MBeanOperationInfo[] operations = new MBeanOperationInfo[oplist.length]; Method[] methods = getClass().getMethods(); for (int i = 0; i < oplist.length; i++) { Method method = null; for (int m = 0; m < methods.length; m++) { if (methods[m].getName().equals(oplist[i])) { method = methods[m]; } } if (method == null) { throw new NotCompliantMBeanException( "Class declares method " + oplist[i] + ", yet does not implement it!"); } MBeanOperationInfo info = new MBeanOperationInfo(method.getName(), method); operations[i] = info; } // // Create the actual BeanInfo instance. // MBeanConstructorInfo[] constructors = null; MBeanNotificationInfo[] notifications = null; m_beanInfo = new MBeanInfo(getClass().getName(), getDescription(), attributes, constructors, operations, notifications); } /** * Customization hook: Override this to get a description for your MBean. By default, * this is an empty string. * * @return A description for the MBean. */ protected String getDescription() { return ""; } /** * Gets an attribute using reflection from the MBean. * * @param name Name of the attribute to find. * @return The value returned by the corresponding getXXX() call * @throws AttributeNotFoundException If there is not such attribute * @throws MBeanException * @throws ReflectionException */ public Object getAttribute(String name) throws AttributeNotFoundException, MBeanException, ReflectionException { Method m; Object res = null; try { String mname = "get" + StringUtils.capitalize(name); m = findGetterSetter(getClass(), mname, null); if (m == null) throw new AttributeNotFoundException(name); res = m.invoke(this, (Object[]) null); } catch (SecurityException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalArgumentException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InvocationTargetException e) { // TODO Auto-generated catch block e.printStackTrace(); } return res; } /** * Gets multiple attributes at the same time. * * @param arg0 The attribute names to get * @return A list of attributes */ public AttributeList getAttributes(String[] arg0) { AttributeList list = new AttributeList(); for (int i = 0; i < arg0.length; i++) { try { list.add(new Attribute(arg0[i], getAttribute(arg0[i]))); } catch (AttributeNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (MBeanException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ReflectionException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return list; } /** * Return the MBeanInfo structure. * * @return the MBeanInfo */ public MBeanInfo getMBeanInfo() { return m_beanInfo; } /** * Invokes a particular method. * * @param arg0 Method name * @param arg1 A list of arguments for the invocation */ public Object invoke(String arg0, Object[] arg1, String[] arg2) throws MBeanException, ReflectionException { Method[] methods = getClass().getMethods(); for (int i = 0; i < methods.length; i++) { if (methods[i].getName().equals(arg0)) { try { return methods[i].invoke(this, arg1); } catch (IllegalArgumentException e) { throw new ReflectionException(e, "Wrong arguments"); } catch (IllegalAccessException e) { throw new ReflectionException(e, "No access"); } catch (InvocationTargetException e) { throw new ReflectionException(e, "Wrong target"); } } } throw new ReflectionException(null, "There is no such method " + arg0); // TODO: Can you put a null exception? } public void setAttribute(Attribute attr) throws AttributeNotFoundException, InvalidAttributeValueException, MBeanException, ReflectionException { Method m; String mname = "set" + StringUtils.capitalize(attr.getName()); m = findGetterSetter(getClass(), mname, attr.getValue().getClass()); if (m == null) throw new AttributeNotFoundException(attr.getName()); Object[] args = { attr.getValue() }; try { m.invoke(this, args); } catch (IllegalArgumentException e) { throw new InvalidAttributeValueException("Faulty argument: " + e.getMessage()); } catch (IllegalAccessException e) { throw new ReflectionException(e, "Cannot access attribute " + e.getMessage()); } catch (InvocationTargetException e) { throw new ReflectionException(e, "Cannot invoke attribute " + e.getMessage()); } } public AttributeList setAttributes(AttributeList arg0) { AttributeList result = new AttributeList(); for (Iterator i = arg0.iterator(); i.hasNext();) { Attribute attr = (Attribute) i.next(); // // Attempt to set the attribute. If it succeeds (no exception), // then we just add it to the list of successfull sets. // try { setAttribute(attr); result.add(attr); } catch (AttributeNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InvalidAttributeValueException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (MBeanException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ReflectionException e) { // TODO Auto-generated catch block e.printStackTrace(); } } return result; } /** * This method must return a list of attributes which are * exposed by the SimpleMBean. If there's a getXXX() method * available, it'll be exposed as a getter, and if there's a * setXXX() method available, it'll be exposed as a setter. * For example: * <pre> * public void setFoo( String foo ) ... * public String getFoo() ... * * public String[] getAttributeNames() * { * String[] attrs = { "foo" }; * * return attrs; * } * </pre> * Also, methods starting with "is" are also recognized as getters * (e.g. <code>public boolean isFoo()</code>.) * * @return An array of attribute names that can be get and optionally set. */ public abstract String[] getAttributeNames(); /** * This method must return a list of operations which * are to be exposed by the SimpleMBean. Note that using overloaded * method names is not supported - only one will be exposed as a JMX method * at random. * * @return An array of method names that should be exposed as * JMX operations. */ public abstract String[] getMethodNames(); }