appl/util/GeneralUtil.java

package appl.util;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.URL;

import net.jini.loader.pref.PreferredClassLoader;

import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;

/**
 * General utility class. See method description for details.
 * 
 * @author Dominik Appl
 */
public class GeneralUtil {

        public static Logger LOG = LogManager.getLogger("appl.util.GeneralUtil");

        /**
         * Loads a class from the specified URL and returns an instance of this class.
         * @param location the URL of the rootDirectory/networkLocation
         * @param classname the fully qualified name of the class (the class must have a 
         * 
         * @return the instance of the class or <code>null</code> if loading fails
         */
        public static Object loadClassFromURL(URL location, String classname) {
                try {
                        URL[] locations = { location };
                        PreferredClassLoader classLoader = new PreferredClassLoader(
                                        locations, Thread.currentThread().getContextClassLoader(),
                                        null, false);
                        LOG.debug("Try to load " + classname.getClass().getName()
                                        + " from " + location);
                        Class classObject = classLoader.loadClass(classname);
                        return classObject.newInstance();
                } catch (Exception e) {
                        LOG.error("Could not load class for " + classname + " from "
                                        + location, e);
                        e.printStackTrace();
                }
                return null;
        }

        /**
         * Serializes the given object into the specified file. All exceptions are printed to console.
         * @param o the object
         * @param destFile the file to write to
         */
        public static void SerializeToFile(Object o, File destFile) {
                try {
                        destFile.createNewFile();
                        BufferedOutputStream fos = new BufferedOutputStream(
                                        new FileOutputStream(destFile));
                        ObjectOutputStream oos = new ObjectOutputStream(fos);
                        oos.writeObject(o);
                        oos.close();
                        fos.close();
                } catch (Exception e) {
                        e.printStackTrace();
                }
        }

        /**
         * Reads the first object out of the file
         * @param loadFile the file to read from
         * @return the object
         */
        public static Object readSerializedFrom(File loadFile) {
                Object loadedObject = null;
                try {
                        BufferedInputStream fis = new BufferedInputStream(
                                        new FileInputStream(loadFile));
                        ObjectInputStream ois = new ObjectInputStream(fis);
                        loadedObject = ois.readObject();
                        ois.close();
                        fis.close();
                        // remove File from Filesystem
                } catch (FileNotFoundException e) {
                        LOG.error(e);
                        e.printStackTrace();

                } catch (Exception e) {
                        LOG.error(e);
                        e.printStackTrace();
                }
                return loadedObject;
        }
}
1	package appl.util;
2
3	import java.io.BufferedInputStream;
4	import java.io.BufferedOutputStream;
5	import java.io.File;
6	import java.io.FileInputStream;
7	import java.io.FileNotFoundException;
8	import java.io.FileOutputStream;
9	import java.io.ObjectInputStream;
10	import java.io.ObjectOutputStream;
11	import java.net.URL;
12
13	import net.jini.loader.pref.PreferredClassLoader;
14
15	import org.apache.log4j.LogManager;
16	import org.apache.log4j.Logger;
17
18	/**
19	* General utility class. See method description for details.
20	*
21	* @author Dominik Appl
22	*/
23	public class GeneralUtil {
24
25	public static Logger LOG = LogManager.getLogger("appl.util.GeneralUtil");
26
27	/**
28	* Loads a class from the specified URL and returns an instance of this class.
29	* @param location the URL of the rootDirectory/networkLocation
30	* @param classname the fully qualified name of the class (the class must have a
31	*
32	* @return the instance of the class or <code>null</code> if loading fails
33	*/
34	public static Object loadClassFromURL(URL location, String classname) {
35	try {
36	URL[] locations = { location };
37	PreferredClassLoader classLoader = new PreferredClassLoader(
38	locations, Thread.currentThread().getContextClassLoader(),
39	null, false);
40	LOG.debug("Try to load " + classname.getClass().getName()
41	+ " from " + location);
42	Class classObject = classLoader.loadClass(classname);
43	return classObject.newInstance();
44	} catch (Exception e) {
45	LOG.error("Could not load class for " + classname + " from "
46	+ location, e);
47	e.printStackTrace();
48	}
49	return null;
50	}
51
52	/**
53	* Serializes the given object into the specified file. All exceptions are printed to console.
54	* @param o the object
55	* @param destFile the file to write to
56	*/
57	public static void SerializeToFile(Object o, File destFile) {
58	try {
59	destFile.createNewFile();
60	BufferedOutputStream fos = new BufferedOutputStream(
61	new FileOutputStream(destFile));
62	ObjectOutputStream oos = new ObjectOutputStream(fos);
63	oos.writeObject(o);
64	oos.close();
65	fos.close();
66	} catch (Exception e) {
67	e.printStackTrace();
68	}
69	}
70
71	/**
72	* Reads the first object out of the file
73	* @param loadFile the file to read from
74	* @return the object
75	*/
76	public static Object readSerializedFrom(File loadFile) {
77	Object loadedObject = null;
78	try {
79	BufferedInputStream fis = new BufferedInputStream(
80	new FileInputStream(loadFile));
81	ObjectInputStream ois = new ObjectInputStream(fis);
82	loadedObject = ois.readObject();
83	ois.close();
84	fis.close();
85	// remove File from Filesystem
86	} catch (FileNotFoundException e) {
87	LOG.error(e);
88	e.printStackTrace();
89
90	} catch (Exception e) {
91	LOG.error(e);
92	e.printStackTrace();
93	}
94	return loadedObject;
95	}
96	}