extendedproperties.java

初级java程序员如果想要更深一步提高自己的实力

    public ExtendedProperties subset(String prefix) {
        ExtendedProperties c = new ExtendedProperties();
        Iterator keys = getKeys();
        boolean validSubset = false;

        while (keys.hasNext()) {
            Object key = keys.next();

            if (key instanceof String && ((String) key).startsWith(prefix)) {
                if (!validSubset) {
                    validSubset = true;
                }

                /*
                 * Check to make sure that c.subset(prefix) doesn't
                 * blow up when there is only a single property
                 * with the key prefix. This is not a useful
                 * subset but it is a valid subset.
                 */
                String newKey = null;
                if (((String) key).length() == prefix.length()) {
                    newKey = prefix;
                } else {
                    newKey = ((String) key).substring(prefix.length() + 1);
                }

                /*
                 *  use addPropertyDirect() - this will plug the data as 
                 *  is into the Map, but will also do the right thing
                 *  re key accounting
                 */
                c.addPropertyDirect(newKey, get(key));
            }
        }

        if (validSubset) {
            return c;
        } else {
            return null;
        }
    }

    /**
     * Display the configuration for debugging purposes to System.out.
     */
    public void display() {
        Iterator i = getKeys();

        while (i.hasNext()) {
            String key = (String) i.next();
            Object value = get(key);
            System.out.println(key + " => " + value);
        }
    }

    /**
     * Get a string associated with the given configuration key.
     *
     * @param key The configuration key.
     * @return The associated string.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a String.
     */
    public String getString(String key) {
        return getString(key, null);
    }

    /**
     * Get a string associated with the given configuration key.
     *
     * @param key The configuration key.
     * @param defaultValue The default value.
     * @return The associated string if key is found,
     * default value otherwise.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a String.
     */
    public String getString(String key, String defaultValue) {
        Object value = get(key);

        if (value instanceof String) {
            return interpolate((String) value);
            
        } else if (value == null) {
            if (defaults != null) {
                return interpolate(defaults.getString(key, defaultValue));
            } else {
                return interpolate(defaultValue);
            }
        } else if (value instanceof List) {
            return interpolate((String) ((List) value).get(0));
        } else {
            throw new ClassCastException('\'' + key + "' doesn't map to a String object");
        }
    }

    /**
     * Get a list of properties associated with the given
     * configuration key.
     *
     * @param key The configuration key.
     * @return The associated properties if key is found.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a String/List.
     * @throws IllegalArgumentException if one of the tokens is
     * malformed (does not contain an equals sign).
     */
    public Properties getProperties(String key) {
        return getProperties(key, new Properties());
    }

    /**
     * Get a list of properties associated with the given
     * configuration key.
     *
     * @param key The configuration key.
     * @return The associated properties if key is found.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a String/List.
     * @throws IllegalArgumentException if one of the tokens is
     * malformed (does not contain an equals sign).
     */
    public Properties getProperties(String key, Properties defaults) {
        /*
         * Grab an array of the tokens for this key.
         */
        String[] tokens = getStringArray(key);

        // Each token is of the form 'key=value'.
        Properties props = new Properties(defaults);
        for (int i = 0; i < tokens.length; i++) {
            String token = tokens[i];
            int equalSign = token.indexOf('=');
            if (equalSign > 0) {
                String pkey = token.substring(0, equalSign).trim();
                String pvalue = token.substring(equalSign + 1).trim();
                props.put(pkey, pvalue);
            } else {
                throw new IllegalArgumentException('\'' + token + "' does not contain " + "an equals sign");
            }
        }
        return props;
    }

    /**
     * Get an array of strings associated with the given configuration
     * key.
     *
     * @param key The configuration key.
     * @return The associated string array if key is found.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a String/List.
     */
    public String[] getStringArray(String key) {
        Object value = get(key);

        List values;
        if (value instanceof String) {
            values = new Vector(1);
            values.add(value);
            
        } else if (value instanceof List) {
            values = (List) value;
            
        } else if (value == null) {
            if (defaults != null) {
                return defaults.getStringArray(key);
            } else {
                return new String[0];
            }
        } else {
            throw new ClassCastException('\'' + key + "' doesn't map to a String/List object");
        }

        String[] tokens = new String[values.size()];
        for (int i = 0; i < tokens.length; i++) {
            tokens[i] = (String) values.get(i);
        }

        return tokens;
    }

    /**
     * Get a Vector of strings associated with the given configuration
     * key.
     *
     * @param key The configuration key.
     * @return The associated Vector.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a Vector.
     */
    public Vector getVector(String key) {
        return getVector(key, null);
    }

    /**
     * Get a Vector of strings associated with the given configuration key.
     * <p>
     * The list is a copy of the internal data of this object, and as
     * such you may alter it freely.
     *
     * @param key The configuration key.
     * @param defaultValue The default value.
     * @return The associated Vector.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a Vector.
     */
    public Vector getVector(String key, Vector defaultValue) {
        Object value = get(key);

        if (value instanceof List) {
            return new Vector((List) value);
            
        } else if (value instanceof String) {
            Vector values = new Vector(1);
            values.add(value);
            put(key, values);
            return values;
            
        } else if (value == null) {
            if (defaults != null) {
                return defaults.getVector(key, defaultValue);
            } else {
                return ((defaultValue == null) ? new Vector() : defaultValue);
            }
        } else {
            throw new ClassCastException('\'' + key + "' doesn't map to a Vector object");
        }
    }

    /**
     * Get a List of strings associated with the given configuration key.
     * <p>
     * The list is a copy of the internal data of this object, and as
     * such you may alter it freely.
     *
     * @param key The configuration key.
     * @return The associated List object.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a List.
     * @since Commons Collections 3.2
     */
    public List getList(String key) {
        return getList(key, null);
    }

    /**
     * Get a List of strings associated with the given configuration key.
     * <p>
     * The list is a copy of the internal data of this object, and as
     * such you may alter it freely.
     *
     * @param key The configuration key.
     * @param defaultValue The default value.
     * @return The associated List.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a List.
     * @since Commons Collections 3.2
     */
    public List getList(String key, List defaultValue) {
        Object value = get(key);

        if (value instanceof List) {
            return new ArrayList((List) value);
            
        } else if (value instanceof String) {
            List values = new ArrayList(1);
            values.add(value);
            put(key, values);
            return values;
            
        } else if (value == null) {
            if (defaults != null) {
                return defaults.getList(key, defaultValue);
            } else {
                return ((defaultValue == null) ? new ArrayList() : defaultValue);
            }
        } else {
            throw new ClassCastException('\'' + key + "' doesn't map to a List object");
        }
    }

    /**
     * Get a boolean associated with the given configuration key.
     *
     * @param key The configuration key.
     * @return The associated boolean.
     * @throws NoSuchElementException is thrown if the key doesn't
     * map to an existing object.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a Boolean.
     */
    public boolean getBoolean(String key) {
        Boolean b = getBoolean(key, null);
        if (b != null) {
            return b.booleanValue();
        } else {
            throw new NoSuchElementException('\'' + key + "' doesn't map to an existing object");
        }
    }

    /**
     * Get a boolean associated with the given configuration key.
     *
     * @param key The configuration key.
     * @param defaultValue The default value.
     * @return The associated boolean.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a Boolean.
     */
    public boolean getBoolean(String key, boolean defaultValue) {
        return getBoolean(key, new Boolean(defaultValue)).booleanValue();
    }

    /**
     * Get a boolean associated with the given configuration key.
     *
     * @param key The configuration key.
     * @param defaultValue The default value.
     * @return The associated boolean if key is found and has valid
     * format, default value otherwise.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a Boolean.
     */
    public Boolean getBoolean(String key, Boolean defaultValue) {

        Object value = get(key);

        if (value instanceof Boolean) {
            return (Boolean) value;
            
        } else if (value instanceof String) {
            String s = testBoolean((String) value);
            Boolean b = new Boolean(s);
            put(key, b);
            return b;
            
        } else if (value == null) {
            if (defaults != null) {
                return defaults.getBoolean(key, defaultValue);
            } else {
                return defaultValue;
            }
        } else {
            throw new ClassCastException('\'' + key + "' doesn't map to a Boolean object");
        }
    }

    /**
     * Test whether the string represent by value maps to a boolean
     * value or not. We will allow <code>true</code>, <code>on</code>,
     * and <code>yes</code> for a <code>true</code> boolean value, and
     * <code>false</code>, <code>off</code>, and <code>no</code> for
     * <code>false</code> boolean values.  Case of value to test for
     * boolean status is ignored.
     *
     * @param value  the value to test for boolean state
     * @return <code>true</code> or <code>false</code> if the supplied
     * text maps to a boolean value, or <code>null</code> otherwise.
     */
    public String testBoolean(String value) {
        String s = value.toLowerCase();

        if (s.equals("true") || s.equals("on") || s.equals("yes")) {
            return "true";
        } else if (s.equals("false") || s.equals("off") || s.equals("no")) {
            return "false";
        } else {
            return null;
        }
    }

    /**
     * Get a byte associated with the given configuration key.
     *
     * @param key The configuration key.
     * @return The associated byte.
     * @throws NoSuchElementException is thrown if the key doesn't
     * map to an existing object.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a Byte.
     * @throws NumberFormatException is thrown if the value mapped
     * by the key has not a valid number format.
     */
    public byte getByte(String key) {
        Byte b = getByte(key, null);
        if (b != null) {
            return b.byteValue();
        } else {
            throw new NoSuchElementException('\'' + key + " doesn't map to an existing object");
        }
    }

    /**
     * Get a byte associated with the given configuration key.
     *
     * @param key The configuration key.
     * @param defaultValue The default value.
     * @return The associated byte.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a Byte.
     * @throws NumberFormatException is thrown if the value mapped
     * by the key has not a valid number format.
     */
    public byte getByte(String key, byte defaultValue) {
        return getByte(key, new Byte(defaultValue)).byteValue();
    }

    /**
     * Get a byte associated with the given configuration key.
     *
     * @param key The configuration key.
     * @param defaultValue The default value.
     * @return The associated byte if key is found and has valid
     * format, default value otherwise.
     * @throws ClassCastException is thrown if the key maps to an
     * object that is not a Byte.
     * @throws NumberFormatException is thrown if the value mapped
     * by the key has not a valid number format.
     */
    public Byte getByte(String key, Byte defaultValue) {
        Object value = get(key);