rollerruntimeconfig.java

这个weblogging 设计得比较精巧

/*
 * RollerRuntimeConfig.java
 *
 * Created on May 4, 2005, 3:00 PM
 */

package org.roller.config;

import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StringWriter;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.roller.config.runtime.RuntimeConfigDefs;
import org.roller.config.runtime.RuntimeConfigDefsParser;
import org.roller.model.PropertiesManager;
import org.roller.model.RollerFactory;

/**
 * This class acts as a convenience gateway for getting property values
 * via the PropertiesManager.  We do this because most calls to the
 * PropertiesManager are just to get the value of a specific property and
 * thus the caller doesn't need the full RollerPropertyData object.
 *
 * We also provide some methods for converting to different data types.
 *
 * @author Allen Gilliland
 */
public class RollerRuntimeConfig {
    
    private static String runtime_config = "/rollerRuntimeConfigDefs.xml";
    private static RuntimeConfigDefs configDefs = null;
    
    private static Log mLogger = 
        LogFactory.getFactory().getInstance(RollerRuntimeConfig.class);
    
    
    // prevent instantiations
    private RollerRuntimeConfig() {}
    
    
    /**
     * Retrieve a single property from the PropertiesManager ... returns null
     * if there is an error
     **/
    public static String getProperty(String name) {
        
        String value = null;
        try {
            PropertiesManager pmgr = RollerFactory.getRoller().getPropertiesManager();
            value = pmgr.getProperty(name).getValue();
        } catch(Exception e) {
            mLogger.warn("Trouble accessing property: "+name, e);
        }
        
        mLogger.debug("fetched property ["+name+"="+value+"]");
        
        return value;
    }
    
    
    /**
     * Retrieve a property as a boolean ... defaults to false if there is an error
     **/
    public static boolean getBooleanProperty(String name) {
        
        // get the value first, then convert
        String value = RollerRuntimeConfig.getProperty(name);
        
        if(value == null)
            return false;
        
        return (new Boolean(value)).booleanValue();
    }
    
    
    /**
     * Retrieve a property as an int ... defaults to -1 if there is an error
     **/
    public static int getIntProperty(String name) {
        
        // get the value first, then convert
        String value = RollerRuntimeConfig.getProperty(name);
        
        if(value == null)
            return -1;
        
        int intval = -1;
        try {
            intval = Integer.parseInt(value);
        } catch(Exception e) {
            mLogger.warn("Trouble converting to int: "+name, e);
        }
        
        return intval;
    }
    
    
    public static RuntimeConfigDefs getRuntimeConfigDefs() {
        
        if(configDefs == null) {
            
            // unmarshall the config defs file
            try {
                InputStream is = 
                        RollerConfig.class.getResourceAsStream(runtime_config);
                
                RuntimeConfigDefsParser parser = new RuntimeConfigDefsParser();
                configDefs = parser.unmarshall(is);
                
            } catch(Exception e) {
                // error while parsing :(
                mLogger.error("Error parsing runtime config defs", e);
            }
            
        }
        
        return configDefs;
    }
    
    
    /**
     * Get the runtime configuration definitions XML file as a string.
     *
     * This is basically a convenience method for accessing this file.
     * The file itself contains meta-data about what configuration
     * properties we change at runtime via the UI and how to setup
     * the display for editing those properties.
     */
    public static String getRuntimeConfigDefsAsString() {
        
        mLogger.debug("Trying to load runtime config defs file");
        
        try {
            InputStreamReader reader =
                    new InputStreamReader(RollerConfig.class.getResourceAsStream(runtime_config));
            StringWriter configString = new StringWriter();
            
            char[] buf = new char[8196];
            int length = 0;
            while((length = reader.read(buf)) > 0)
                configString.write(buf, 0, length);
            
            reader.close();
            
            return configString.toString();
        } catch(Exception e) {
            mLogger.error("Error loading runtime config defs file", e);
        }
        
        return "";
    }
    
}