convertutilsbean.java

这是一个有关common beanutils 的源码

     * Register the provided converters with the specified defaults.
     *
     * @param throwException <code>true</code> if the converters should
     * throw an exception when a conversion error occurs, otherwise <code>
     * <code>false</code> if a default value should be used.
     * @param defaultNull <code>true</code>if the <i>standard</i> converters
     * (see {@link ConvertUtilsBean#registerStandard(boolean, boolean)})
     * should use a default value of <code>null</code>, otherwise <code>false</code>.
     * N.B. This values is ignored if <code>throwException</code> is <code>true</code>
     * @param defaultArraySize The size of the default array value for array converters
     * (N.B. This values is ignored if <code>throwException</code> is <code>true</code>).
     * Specifying a value less than zero causes a <code>null<code> value to be used for
     * the default.
     */
    public void register(boolean throwException, boolean defaultNull, int defaultArraySize) {
        registerPrimitives(throwException);
        registerStandard(throwException, defaultNull);
        registerOther(throwException);
        registerArrays(throwException, defaultArraySize);
    }

    /**
     * Register the converters for primitive types.
     * </p>
     * This method registers the following converters:
     * <ul>
     *     <li><code>Boolean.TYPE</code> - {@link BooleanConverter}</li>
     *     <li><code>Byte.TYPE</code> - {@link ByteConverter}</li>
     *     <li><code>Character.TYPE</code> - {@link CharacterConverter}</li>
     *     <li><code>Double.TYPE</code> - {@link DoubleConverter}</li>
     *     <li><code>Float.TYPE</code> - {@link FloatConverter}</li>
     *     <li><code>Integer.TYPE</code> - {@link IntegerConverter}</li>
     *     <li><code>Long.TYPE</code> - {@link LongConverter}</li>
     *     <li><code>Short.TYPE</code> - {@link ShortConverter}</li>
     * </ul>
     * @param throwException <code>true</code> if the converters should
     * throw an exception when a conversion error occurs, otherwise <code>
     * <code>false</code> if a default value should be used.
     */
    private void registerPrimitives(boolean throwException) {
        register(Boolean.TYPE,   throwException ? new BooleanConverter()    : new BooleanConverter(Boolean.FALSE));
        register(Byte.TYPE,      throwException ? new ByteConverter()       : new ByteConverter(ZERO));
        register(Character.TYPE, throwException ? new CharacterConverter()  : new CharacterConverter(SPACE));
        register(Double.TYPE,    throwException ? new DoubleConverter()     : new DoubleConverter(ZERO));
        register(Float.TYPE,     throwException ? new FloatConverter()      : new FloatConverter(ZERO));
        register(Integer.TYPE,   throwException ? new IntegerConverter()    : new IntegerConverter(ZERO));
        register(Long.TYPE,      throwException ? new LongConverter()       : new LongConverter(ZERO));
        register(Short.TYPE,     throwException ? new ShortConverter()      : new ShortConverter(ZERO));
    }

    /**
     * Register the converters for standard types.
     * </p>
     * This method registers the following converters:
     * <ul>
     *     <li><code>BigDecimal.class</code> - {@link BigDecimalConverter}</li>
     *     <li><code>BigInteger.class</code> - {@link BigIntegerConverter}</li>
     *     <li><code>Boolean.class</code> - {@link BooleanConverter}</li>
     *     <li><code>Byte.class</code> - {@link ByteConverter}</li>
     *     <li><code>Character.class</code> - {@link CharacterConverter}</li>
     *     <li><code>Double.class</code> - {@link DoubleConverter}</li>
     *     <li><code>Float.class</code> - {@link FloatConverter}</li>
     *     <li><code>Integer.class</code> - {@link IntegerConverter}</li>
     *     <li><code>Long.class</code> - {@link LongConverter}</li>
     *     <li><code>Short.class</code> - {@link ShortConverter}</li>
     *     <li><code>String.class</code> - {@link StringConverter}</li>
     * </ul>
     * @param throwException <code>true</code> if the converters should
     * throw an exception when a conversion error occurs, otherwise <code>
     * <code>false</code> if a default value should be used.
     * @param defaultNull <code>true</code>if the <i>standard</i> converters
     * (see {@link ConvertUtilsBean#registerStandard(boolean, boolean)})
     * should use a default value of <code>null</code>, otherwise <code>false</code>.
     * N.B. This values is ignored if <code>throwException</code> is <code>true</code>
     */
    private void registerStandard(boolean throwException, boolean defaultNull) {

        Number     defaultNumber     = defaultNull ? null : ZERO;
        BigDecimal bigDecDeflt       = defaultNull ? null : new BigDecimal("0.0");
        BigInteger bigIntDeflt       = defaultNull ? null : new BigInteger("0");
        Boolean    booleanDefault    = defaultNull ? null : Boolean.FALSE;
        Character  charDefault       = defaultNull ? null : SPACE;
        String     stringDefault     = defaultNull ? null : "";

        register(BigDecimal.class, throwException ? new BigDecimalConverter() : new BigDecimalConverter(bigDecDeflt));
        register(BigInteger.class, throwException ? new BigIntegerConverter() : new BigIntegerConverter(bigIntDeflt));
        register(Boolean.class,    throwException ? new BooleanConverter()    : new BooleanConverter(booleanDefault));
        register(Byte.class,       throwException ? new ByteConverter()       : new ByteConverter(defaultNumber));
        register(Character.class,  throwException ? new CharacterConverter()  : new CharacterConverter(charDefault));
        register(Double.class,     throwException ? new DoubleConverter()     : new DoubleConverter(defaultNumber));
        register(Float.class,      throwException ? new FloatConverter()      : new FloatConverter(defaultNumber));
        register(Integer.class,    throwException ? new IntegerConverter()    : new IntegerConverter(defaultNumber));
        register(Long.class,       throwException ? new LongConverter()       : new LongConverter(defaultNumber));
        register(Short.class,      throwException ? new ShortConverter()      : new ShortConverter(defaultNumber));
        register(String.class,     throwException ? new StringConverter()     : new StringConverter(stringDefault));
        
    }

    /**
     * Register the converters for other types.
     * </p>
     * This method registers the following converters:
     * <ul>
     *     <li><code>Class.class</code> - {@link ClassConverter}</li>
     *     <li><code>java.util.Date.class</code> - {@link DateConverter}</li>
     *     <li><code>java.util.Calendar.class</code> - {@link CalendarConverter}</li>
     *     <li><code>File.class</code> - {@link FileConverter}</li>
     *     <li><code>java.sql.Date.class</code> - {@link SqlDateConverter}</li>
     *     <li><code>java.sql.Time.class</code> - {@link SqlTimeConverter}</li>
     *     <li><code>java.sql.Timestamp.class</code> - {@link SqlTimestampConverter}</li>
     *     <li><code>URL.class</code> - {@link URLConverter}</li>
     * </ul>
     * @param throwException <code>true</code> if the converters should
     * throw an exception when a conversion error occurs, otherwise <code>
     * <code>false</code> if a default value should be used.
     */
    private void registerOther(boolean throwException) {
        register(Class.class,         throwException ? new ClassConverter()        : new ClassConverter(null));
        register(java.util.Date.class, throwException ? new DateConverter()        : new DateConverter(null));
        register(Calendar.class,      throwException ? new CalendarConverter()     : new CalendarConverter(null));
        register(File.class,          throwException ? new FileConverter()         : new FileConverter(null));
        register(java.sql.Date.class, throwException ? new SqlDateConverter()      : new SqlDateConverter(null));
        register(java.sql.Time.class, throwException ? new SqlTimeConverter()      : new SqlTimeConverter(null));
        register(Timestamp.class,     throwException ? new SqlTimestampConverter() : new SqlTimestampConverter(null));
        register(URL.class,           throwException ? new URLConverter()          : new URLConverter(null));
    }

    /**
     * Register array converters.
     *
     * @param throwException <code>true</code> if the converters should
     * throw an exception when a conversion error occurs, otherwise <code>
     * <code>false</code> if a default value should be used.
     * @param defaultArraySize The size of the default array value for array converters
     * (N.B. This values is ignored if <code>throwException</code> is <code>true</code>).
     * Specifying a value less than zero causes a <code>null<code> value to be used for
     * the default.
     */
    private void registerArrays(boolean throwException, int defaultArraySize) {

        // Primitives
        registerArrayConverter(Boolean.TYPE,   new BooleanConverter(),   throwException, defaultArraySize);
        registerArrayConverter(Byte.TYPE,      new ByteConverter(),      throwException, defaultArraySize);
        registerArrayConverter(Character.TYPE, new CharacterConverter(), throwException, defaultArraySize);
        registerArrayConverter(Double.TYPE,    new DoubleConverter(),    throwException, defaultArraySize);
        registerArrayConverter(Float.TYPE,     new FloatConverter(),     throwException, defaultArraySize);
        registerArrayConverter(Integer.TYPE,   new IntegerConverter(),   throwException, defaultArraySize);
        registerArrayConverter(Long.TYPE,      new LongConverter(),      throwException, defaultArraySize);
        registerArrayConverter(Short.TYPE,     new ShortConverter(),     throwException, defaultArraySize);

        // Standard
        registerArrayConverter(BigDecimal.class, new BigDecimalConverter(), throwException, defaultArraySize);
        registerArrayConverter(BigInteger.class, new BigIntegerConverter(), throwException, defaultArraySize);
        registerArrayConverter(Boolean.class,    new BooleanConverter(),    throwException, defaultArraySize);
        registerArrayConverter(Byte.class,       new ByteConverter(),       throwException, defaultArraySize);
        registerArrayConverter(Character.class,  new CharacterConverter(),  throwException, defaultArraySize);
        registerArrayConverter(Double.class,     new DoubleConverter(),     throwException, defaultArraySize);
        registerArrayConverter(Float.class,      new FloatConverter(),      throwException, defaultArraySize);
        registerArrayConverter(Integer.class,    new IntegerConverter(),    throwException, defaultArraySize);
        registerArrayConverter(Long.class,       new LongConverter(),       throwException, defaultArraySize);
        registerArrayConverter(Short.class,      new ShortConverter(),      throwException, defaultArraySize);
        registerArrayConverter(String.class,     new StringConverter(),     throwException, defaultArraySize);

        // Other
        registerArrayConverter(Class.class,          new ClassConverter(),        throwException, defaultArraySize);
        registerArrayConverter(java.util.Date.class, new DateConverter(),         throwException, defaultArraySize);
        registerArrayConverter(Calendar.class,       new DateConverter(),         throwException, defaultArraySize);
        registerArrayConverter(File.class,           new FileConverter(),         throwException, defaultArraySize);
        registerArrayConverter(java.sql.Date.class,  new SqlDateConverter(),      throwException, defaultArraySize);
        registerArrayConverter(java.sql.Time.class,  new SqlTimeConverter(),      throwException, defaultArraySize);
        registerArrayConverter(Timestamp.class,      new SqlTimestampConverter(), throwException, defaultArraySize);
        registerArrayConverter(URL.class,            new URLConverter(),          throwException, defaultArraySize);

    }

    /**
     * Register a new ArrayConverter with the specified element delegate converter
     * that returns a default array of the specified size in the event of conversion errors.
     *
     * @param componentType The component type of the array
     * @param componentConverter The converter to delegate to for the array elements
     * @param throwException Whether a conversion exception should be thrown or a default
     * value used in the event of a conversion error
     * @param defaultArraySize The size of the default array
     */
    private void registerArrayConverter(Class componentType, Converter componentConverter,
            boolean throwException, int defaultArraySize) {
        Class arrayType = Array.newInstance(componentType, 0).getClass();
        Converter arrayConverter = null;
        if (throwException) {
            arrayConverter = new ArrayConverter(arrayType, componentConverter);
        } else {
            arrayConverter = new ArrayConverter(arrayType, componentConverter, defaultArraySize);
        }
        register(arrayType, arrayConverter);
    }

    /** strictly for convenience since it has same parameter order as Map.put */
    private void register(Class clazz, Converter converter) {
        register(new ConverterFacade(converter), clazz);
    }

    /**
     * Remove any registered {@link Converter} for the specified destination
     * <code>Class</code>.
     *
     * @param clazz Class for which to remove a registered Converter
     */
    public void deregister(Class clazz) {

        converters.remove(clazz);

    }


    /**
     * Look up and return any registered {@link Converter} for the specified
     * destination class; if there is no registered Converter, return
     * <code>null</code>.
     *
     * @param clazz Class for which to return a registered Converter
     * @return The registered {@link Converter} or <code>null</code> if not found
     */
    public Converter lookup(Class clazz) {

        return ((Converter) converters.get(clazz));

    }

    /**
     * Look up and return any registered {@link Converter} for the specified
     * source and destination class; if there is no registered Converter,
     * return <code>null</code>.
     *
     * @param sourceType Class of the value being converted
     * @param targetType Class of the value to be converted to
     * @return The registered {@link Converter} or <code>null</code> if not found
     */
    public Converter lookup(Class sourceType, Class targetType) {

        if (targetType == null) {
            throw new IllegalArgumentException("Target type is missing");
        }
        if (sourceType == null) {
            return lookup(targetType);
        }

        Converter converter = null;
        // Convert --> String 
        if (targetType == String.class) {
            converter = lookup(sourceType);
            if (converter == null && (sourceType.isArray() ||
                        Collection.class.isAssignableFrom(sourceType))) {
                converter = lookup(String[].class);
            }
            if (converter == null) {
                converter = lookup(String.class);
            }
            return converter;
        }

        // Convert --> String array 
        if (targetType == String[].class) {
            if (sourceType.isArray() || Collection.class.isAssignableFrom(sourceType)) {
                converter = lookup(sourceType);
            }
            if (converter == null) {
                converter = lookup(String[].class);
            }
            return converter;
        }

        return lookup(targetType);

    }

    /**
     * Register a custom {@link Converter} for the specified destination
     * <code>Class</code>, replacing any previously registered Converter.
     *
     * @param converter Converter to be registered
     * @param clazz Destination class for conversions performed by this
     *  Converter
     */
    public void register(Converter converter, Class clazz) {

        converters.put(clazz, converter);

    }
}