Author: niallp
Date: Sat Nov 4 18:49:09 2006
New Revision: 471345
URL: http://svn.apache.org/viewvc?view=rev&rev=471345
Log:
BEANUTILS-258 - Add new AbstractConverter base implementation
Added:
jakarta/commons/proper/beanutils/trunk/src/java/org/apache/commons/beanutils/converters/AbstractConverter.java
(with props)
Added:
jakarta/commons/proper/beanutils/trunk/src/java/org/apache/commons/beanutils/converters/AbstractConverter.java
URL:
http://svn.apache.org/viewvc/jakarta/commons/proper/beanutils/trunk/src/java/org/apache/commons/beanutils/converters/AbstractConverter.java?view=auto&rev=471345
==============================================================================
---
jakarta/commons/proper/beanutils/trunk/src/java/org/apache/commons/beanutils/converters/AbstractConverter.java
(added)
+++
jakarta/commons/proper/beanutils/trunk/src/java/org/apache/commons/beanutils/converters/AbstractConverter.java
Sat Nov 4 18:49:09 2006
@@ -0,0 +1,387 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.beanutils.converters;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.commons.beanutils.ConversionException;
+import org.apache.commons.beanutils.Converter;
+
+/**
+ * Base [EMAIL PROTECTED] Converter} implementation that provides the structure
+ * for handling conversion <b>to</b> and <b>from</b> a specified type.
+ * <p>
+ * This implementation provides the basic structure for
+ * converting to/from a specified type optionally using a default
+ * value or throwing a [EMAIL PROTECTED] ConversionException} if a
+ * conversion error occurs.
+ * <p>
+ * Implementations should provide conversion to the specified
+ * type and from the specified type to a <code>String</code> value
+ * by implementing the following methods:
+ * <ul>
+ * <li><code>convertToString(value)</code> - convert to a String
+ * (default implementation uses the objects <code>toString()</code>
+ * method).</li>
+ * <li><code>convertToType(Class, value)</code> - convert
+ * to the specified type</li>
+ * </ul>
+ *
+ * @version $Revision$ $Date$
+ * @since 1.8.0
+ */
+public abstract class AbstractConverter implements Converter {
+
+ /**
+ * Logging for this instance.
+ */
+ private Log log = LogFactory.getLog(getClass());
+
+ /**
+ * The default type this <code>Converter</code> handles.
+ */
+ private Class defaultType = null;
+
+ /**
+ * Should we return the default value on conversion errors?
+ */
+ private boolean useDefault = false;
+
+ /**
+ * The default value specified to our Constructor, if any.
+ */
+ private Object defaultValue = null;
+
+ // ----------------------------------------------------------- Constructors
+
+ /**
+ * Construct a <i>Converter</i> that throws a
+ * <code>ConversionException</code> if an error occurs.
+ *
+ * @param defaultType The default type this <code>Converter</code>
+ * handles
+ */
+ public AbstractConverter(Class defaultType) {
+ this.defaultType = defaultType;
+ if (defaultType == null) {
+ throw new IllegalArgumentException("Default type is missing.");
+ }
+ }
+
+ /**
+ * Construct a <i>Converter</i> that returns a default
+ * value if an error occurs.
+ *
+ * @param defaultType The default type this <code>Converter</code>
+ * handles
+ * @param defaultValue The default value to be returned
+ * if the value to be converted is missing or an error
+ * occurs converting the value.
+ */
+ public AbstractConverter(Class defaultType, Object defaultValue) {
+ this(defaultType);
+ setDefaultValue(defaultValue);
+ }
+
+ // --------------------------------------------------------- Public Methods
+
+ /**
+ * Set the default value, converting as required.
+ * <p>
+ * If the default value is different from the type the
+ * <code>Converter</code> handles, it will be converted
+ * to the handled type.
+ *
+ * @param defaultValue The default value to be returned
+ * if the value to be converted is missing or an error
+ * occurs converting the value.
+ * @throws ConversionException if an error occurs converting
+ * the default value
+ */
+ public void setDefaultValue(Object defaultValue) {
+ useDefault = false;
+ if (log.isDebugEnabled()) {
+ log.debug("Setting default value: " + defaultValue);
+ }
+ if (defaultValue == null) {
+ this.defaultValue = null;
+ } else {
+ this.defaultValue = convert(getDefaultType(), defaultValue);
+ }
+ useDefault = true;
+ }
+
+ /**
+ * Convert the input object into an output object of the
+ * specified type.
+ *
+ * @param type Data type to which this value should be converted
+ * @param value The input value to be converted
+ * @return The converted value.
+ * @throws ConversionException if conversion cannot be performed
+ * successfully and no default is specified.
+ */
+ public Object convert(Class type, Object value) {
+
+ Class sourceType = value == null ? null : value.getClass();
+ Class targetType = primitive(type == null ? getDefaultType() : type);
+
+ if (log.isDebugEnabled()) {
+ log.debug("Converting value '" + value + "'"
+ + (value == null ? "" : ", type[" +
toString(sourceType) + "]")
+ + " to type " + toString(targetType));
+ }
+
+ // Missing Value
+ if (value == null) {
+ return handleMissing(targetType);
+
+ // Convert --> String
+ } else if (targetType.equals(String.class)) {
+ return convertToString(value);
+
+ // No conversion necessary
+ } else if (targetType.equals(sourceType)) {
+ if (log.isDebugEnabled()) {
+ log.debug(" No conversion required, value is already a "
+ + toString(targetType));
+ }
+ return value;
+
+ // Convert --> Type
+ } else {
+ try {
+ Object result = convertToType(targetType, value);
+ if (log.isDebugEnabled()) {
+ log.debug(" Converted to " + toString(targetType) +
+ " value '" + result + "'");
+ }
+ return result;
+ } catch (Exception ex) {
+ return handleError(targetType, value, ex);
+ }
+ }
+
+ }
+
+ /**
+ * Convert the input object into a String.
+ * <p>
+ * <b>N.B.</b>This implementation simply uses the value's
+ * <code>toString()</code> method and should be overriden if a
+ * more sophisticated mechanism for <i>conversion to a String</i>
+ * is required.
+ *
+ * @param value The input value to be converted.
+ * @return the converted String value.
+ */
+ protected String convertToString(Object value) {
+ return value.toString();
+ }
+
+ /**
+ * Convert the input object into an output object of the
+ * specified type.
+ * <p>
+ * Typical implementations will provide a minimum of
+ * <code>String --> type</code> conversion.
+ *
+ * @param type Data type to which this value should be converted.
+ * @param value The input value to be converted.
+ * @return The converted value.
+ * @throws Exception if an error occurs converting to the specified type
+ */
+ protected abstract Object convertToType(Class type, Object value) throws
Exception;
+
+ /**
+ * Handle Conversion Errors.
+ * <p>
+ * If a default value has been specified then it is returned
+ * otherwise a ConversionException is thrown.
+ *
+ * @param type Data type to which this value should be converted.
+ * @param value The input value to be converted
+ * @param ex The exception thrown by the <code>convert</code> method
+ * @return The default value.
+ * @throws ConversionException if no default value has been
+ * specified for this [EMAIL PROTECTED] Converter}.
+ */
+ protected Object handleError(Class type, Object value, Exception ex) {
+ if (log.isDebugEnabled()) {
+ if (ex instanceof ConversionException) {
+ log.debug(" Conversion threw ConversionException: " +
ex.getMessage());
+ } else {
+ log.debug(" Conversion threw " + ex);
+ }
+ }
+
+ if (useDefault) {
+ return handleMissing(type);
+ }
+
+ ConversionException cex = null;
+ if (ex instanceof ConversionException) {
+ cex = (ConversionException)ex;
+ if (log.isDebugEnabled()) {
+ log.debug(" Re-throwing ConversionException: " +
cex.getMessage());
+ }
+ } else {
+ String msg = "Error converting type[" + toString(value.getClass())
+
+ "], value '" + value + "' to [" + toString(type) + "]";
+ cex = new ConversionException(msg, ex);
+ if (log.isDebugEnabled()) {
+ log.debug(" Throwing ConversionException: " + msg);
+ }
+ }
+
+ throw cex;
+
+ }
+
+ /**
+ * Handle missing values.
+ * <p>
+ * If a default value has been specified then it is returned
+ * otherwise a ConversionException is thrown.
+ *
+ * @param type Data type to which this value should be converted.
+ * @return The default value.
+ * @throws ConversionException if no default value has been
+ * specified for this [EMAIL PROTECTED] Converter}.
+ */
+ protected Object handleMissing(Class type) {
+
+ if (useDefault || type.equals(String.class)) {
+ Object value = getDefault(type);
+ if (useDefault && value != null &&
!(type.equals(value.getClass()))) {
+ try {
+ value = convertToType(type, defaultValue);
+ } catch (Exception e) {
+ // default conversion shouldn't fail
+ }
+ }
+ if (log.isDebugEnabled()) {
+ log.debug(" Using default "
+ + (value == null ? "" : toString(value.getClass()) + "
")
+ + "value '" + defaultValue + "'");
+ }
+ return value;
+ }
+
+ ConversionException cex = new ConversionException("No value
specified.");
+ if (log.isDebugEnabled()) {
+ log.debug(" Throwing ConversionException: " + cex.getMessage());
+ }
+ throw cex;
+
+ }
+
+ /**
+ * Return the default type this <code>Converter</code> handles.
+ *
+ * @return The default type this <code>Converter</code> handles.
+ */
+ protected Class getDefaultType() {
+ return defaultType;
+ }
+
+ /**
+ * Return the default value for conversions to the specified
+ * type.
+ * @param type Data type to which this value should be converted.
+ * @return The default value for the specified type.
+ */
+ protected Object getDefault(Class type) {
+ return (type.equals(String.class) ? null : defaultValue);
+ }
+
+ // ----------------------------------------------------------- Package
Methods
+
+ /**
+ * Accessor method for Log instance.
+ * <p>
+ * The Log instance variable is transient and
+ * accessing it through this method ensures it
+ * is re-initialized when this instance is
+ * de-serialized.
+ *
+ * @return The Log instance.
+ */
+ Log log() {
+ return log;
+ }
+
+ /**
+ * Change primitve Class types to the associated wrapper class.
+ * @param type The class type to check.
+ * @return The converted type.
+ */
+ Class primitive(Class type) {
+ if (type == null || !type.isPrimitive()) {
+ return type;
+ }
+
+ if (type == Integer.TYPE) {
+ return Integer.class;
+ } else if (type == Double.TYPE) {
+ return Double.class;
+ } else if (type == Long.TYPE) {
+ return Long.class;
+ } else if (type == Boolean.TYPE) {
+ return Boolean.class;
+ } else if (type == Float.TYPE) {
+ return Float.class;
+ } else if (type == Short.TYPE) {
+ return Short.class;
+ } else if (type == Byte.TYPE) {
+ return Byte.class;
+ } else if (type == Character.TYPE) {
+ return Character.class;
+ } else {
+ return type;
+ }
+ }
+
+ /**
+ * Provide a String representation of a <code>java.lang.Class</code>.
+ * @param type The <code>java.lang.Class</code>.
+ * @return The String representation.
+ */
+ String toString(Class type) {
+ String typeName = null;
+ if (type == null) {
+ typeName = "null";
+ } else if (type.isArray()) {
+ Class elementType = type.getComponentType();
+ int count = 1;
+ while (elementType.isArray()) {
+ elementType = elementType .getComponentType();
+ count++;
+ }
+ typeName = elementType.getName();
+ for (int i = 0; i < count; i++) {
+ typeName += "[]";
+ }
+ } else {
+ typeName = type.getName();
+ }
+ if (typeName.startsWith("java.lang.")) {
+ typeName = typeName.substring("java.lang.".length());
+ }
+ return typeName;
+ }
+}
Propchange:
jakarta/commons/proper/beanutils/trunk/src/java/org/apache/commons/beanutils/converters/AbstractConverter.java
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svn:eol-style = native
Propchange:
jakarta/commons/proper/beanutils/trunk/src/java/org/apache/commons/beanutils/converters/AbstractConverter.java
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svn:keywords = Date Author Id Revision HeadURL
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