jembeanhelper.java

这是个爬虫和lucece相结合最好了

                               "Get environment statistics.",
                               statParams,
                               "java.lang.String",
                               MBeanOperationInfo.INFO);

    private static final MBeanOperationInfo OP_LOCK_STAT_INFO = 
        new MBeanOperationInfo(OP_LOCK_STAT,
                               "Get locking statistics.",
                               statParams,
                               "com.sleepycat.je.LockStats",
                               MBeanOperationInfo.INFO);
    
    private static final MBeanOperationInfo OP_LOCK_STAT_STR_INFO = 
        new MBeanOperationInfo(OP_LOCK_STAT_STR,
                               "Get locking statistics.",
                               statParams,
                               "java.lang.String",
                               MBeanOperationInfo.INFO);

    private static final MBeanOperationInfo OP_TXN_STAT_INFO = 
        new MBeanOperationInfo(OP_TXN_STAT,
                               "Get transactional statistics.",
                               statParams,
                               "com.sleepycat.je.TransactionStats",
                               MBeanOperationInfo.INFO);

    private static final MBeanOperationInfo OP_DB_NAMES_INFO = 
        new MBeanOperationInfo(OP_DB_NAMES,
                              "Get the names of databases in the environment.",
                               new MBeanParameterInfo[0], // no params
                               "java.lang.String",
                               MBeanOperationInfo.INFO);

    private static final MBeanOperationInfo OP_DB_STAT_INFO = 
        new MBeanOperationInfo(OP_DB_STAT,
                               "Get database statistics.",
                               statParams,
                               "com.sleepycat.je.TransactionStats",
                               MBeanOperationInfo.INFO);
/*
    private static final MBeanParameterInfo [] dbStatParams = {
        new MBeanParameterInfo ("clear", "java.lang.Boolean",
                                "If true, reset statistics after reading."),
        new MBeanParameterInfo ("fast", "java.lang.Boolean",
                                "If true, only return statistics which do " +
                                "not require expensive computation."),
        new MBeanParameterInfo ("databaseName", "java.lang.String",
                                "database name")

    };
*/
    /* target JE environment home directory. */
    private File environmentHome;  

    /* 
     * If canConfigure is true, this helper will make environment configuration
     * attributes available in the mbean metadata. Configuration attributes
     * will be saved in the openConfig instance.
     */
    private boolean canConfigure;
    private EnvironmentConfig openConfig;

    /* true if the mbean metadata needs to be refreshed. */
    private boolean needReset;

    /*
     * Save whether the environment was open the last time we fetched
     * mbean attributes. Use to detect a change in environment status.
     */
    private boolean envWasOpen;
    
    /**
     * Instantiate a helper, specifying environment home and open capabilities.
     *
     * @param environmentHome home directory of the target JE environment.
     * @param canConfigure If true, the helper will show environment
     * configuration attributes.
     */
    public JEMBeanHelper(EnvironmentConfig config,
            File environmentHome, boolean canConfigure) {

        if (environmentHome == null) {
            throw new IllegalArgumentException(
                                        "Environment home cannot be null");
        }
        this.environmentHome = environmentHome;
        this.canConfigure = canConfigure;
        if (canConfigure) {
            openConfig = config;
        }
    }

    /**
     * Return the target environment directory. 
     * @return the environment directory.
     */
    public File getEnvironmentHome() {
        return environmentHome;
    }

    /**
     * If the helper was instantiated with canConfigure==true, it shows
     * environment configuration attributes. Those attributes are returned
     * within this EnvironmentConfig object for use in opening environments.
     * 
     * @return EnvironmentConfig object which saves configuration attributes
     * recorded through MBean attributes.
     */
    public EnvironmentConfig getEnvironmentOpenConfig() {
        return openConfig;
    }

    /**
     * Return an Environment only if the environment has already been opened
     * in this process. A helper method for MBeans which want to only access
     * open environments. 
     * @return Environment if already open, null if not open.
     */
    public Environment getEnvironmentIfOpen() {
        if (environmentHome == null) {
            return null;
        }

        return DbInternal.getEnvironmentShell(environmentHome);
    }

    /**
     * Tell the MBean if the available set of functionality has changed.
     *
     * @return true if the MBean should regenerate its JE metadata.
     */
    public synchronized boolean getNeedReset() {
        return needReset;
    }

    /********************************************************************/
    /* MBean Attributes                                                 */
    /********************************************************************/

    /**
     * Get MBean attribute metadata for this environment.
     * @param targetEnv The target JE environment. May be null if the
     * environment is not open.
     * @return list of MBeanAttributeInfo objects describing the available
     * attributes.
     */
    public List<MBeanAttributeInfo> getAttributeList(Environment targetEnv) {

        /* Turn off reset because the mbean metadata is being refreshed. */
        setNeedReset(false);

        ArrayList<MBeanAttributeInfo> attrList 
         = new ArrayList<MBeanAttributeInfo>();
        
        /* Add attributes for all JE environments. */
        for (int i = 0; i < COMMON_ATTR.length; i++) {
            attrList.add(COMMON_ATTR[i]);
        }

        if (targetEnv == null) {
            if (canConfigure) {
                /* Add attributes for configuring an environment. */
                for (int i = 0; i < CREATE_ATTR.length; i++) {
                    attrList.add(CREATE_ATTR[i]);
                }
            }
        } else {
            /* Add attributes for an open environment. */
            for (int i = 0; i < OPEN_ATTR.length; i++) {
                attrList.add(OPEN_ATTR[i]);
            }

            /* Add attributes for an open, transactional environment. */
            try {
                EnvironmentConfig config = targetEnv.getConfig();
                if (config.getTransactional()) {
                    for (int i = 0; i < TRANSACTIONAL_ATTR.length; i++) {
                        attrList.add(TRANSACTIONAL_ATTR[i]);
                    }
                }
            } catch (DatabaseException ignore) {
            	/* ignore */
            }
        }

        return attrList;
    }

    /**
     * Get an attribute value for the given environment. Check
     * JEMBeanHelper.getNeedReset() after this call because the helper may
     * detect that the environment has changed and that the MBean metadata
     * should be reset.
     *
     * @param targetEnv The target JE environment. May be null if the
     * environment is not open.
     * @param attributeName attribute name.
     * @return attribute value.
     */
    public Object getAttribute(Environment targetEnv,
                               String attributeName) 
        throws AttributeNotFoundException,
               MBeanException {

        /* Sanity check. */
        if (attributeName == null) {
            throw new AttributeNotFoundException(
                                            "Attribute name cannot be null");
        }

        /* These attributes are available regardless of environment state. */
        try {
            if (attributeName.equals(ATT_ENV_HOME)) {
                return environmentHome.getCanonicalPath();
            } else if (attributeName.equals(ATT_OPEN)) {
                boolean envIsOpen = (targetEnv != null);
                resetIfOpenStateChanged(envIsOpen);
                return new Boolean(envIsOpen);
            } else if (attributeName.equals(ATT_SET_READ_ONLY)) {
                return new Boolean(openConfig.getReadOnly());
            } else if (attributeName.equals(ATT_SET_TRANSACTIONAL)) {
                return new Boolean(openConfig.getTransactional());
            } else if (attributeName.equals(ATT_SET_SERIALIZABLE)) {
                return new Boolean(openConfig.getTxnSerializableIsolation());
            } else {
                /* The rest are JE environment attributes. */
                if (targetEnv != null) {

                    EnvironmentConfig config = targetEnv.getConfig();

                    if (attributeName.equals(ATT_IS_READ_ONLY)) {
                        return new Boolean(config.getReadOnly());
                    } else if (attributeName.equals(ATT_IS_TRANSACTIONAL)) {
                        return new Boolean(config.getTransactional());
                    } else if (attributeName.equals(ATT_CACHE_SIZE)) {
                        return new Long(config.getCacheSize());
                    } else if (attributeName.equals(ATT_CACHE_PERCENT)) {
                        return new Integer(config.getCachePercent());
                    } else if (attributeName.equals(ATT_LOCK_TIMEOUT)) {
                        return new Long(config.getLockTimeout());
                    } else if (attributeName.equals(ATT_IS_SERIALIZABLE)) {
                        return new
                            Boolean(config.getTxnSerializableIsolation());
                    } else if (attributeName.equals(ATT_TXN_TIMEOUT)) {
                        return new Long(config.getTxnTimeout());
                    } else {
                        throw new AttributeNotFoundException("attribute " +
                                                             attributeName +
                                                             " is not valid.");
                    }
                } 
                return null; 
            }
        } catch (Exception e) {
            /*
             * Add both the message and the exception for easiest deciphering
             * of the problem. Sometimes the original exception stacktrace gets
             * hidden in server logs.
             */
            throw new MBeanException(e, e.getMessage());
        }
    }

    /**
     * Set an attribute value for the given environment.
     *
     * @param targetEnv The target JE environment. May be null if the