added web binder

org.springframework.context/src/main/java/org/springframework/ui/binding/Binding.java

@@ -25,7 +25,7 @@ public interface Binding {
 	 * The formatted value to display in the user interface.
 	 */
 	String getValue();
-	
+
 	/**
 	 * Set the property associated with this binding to the value provided.
 	 * The value may be a formatted String, a formatted String[] if a collection binding, or an Object of a type that can be coersed to the underlying property type.
@@ -51,5 +51,6 @@ public interface Binding {
 	 * When a collection binding, the formatted values to display in the user interface.
 	 */
 	String[] getCollectionValues();
-	
+
+
 }

org.springframework.context/src/main/java/org/springframework/ui/binding/support/GenericBinder.java

@@ -55,7 +55,7 @@ import org.springframework.ui.format.Formatter;
  * Binds user-entered values to properties of a model object.
  * @author Keith Donald
  *
- * @param <T> The type of model object this binder binds to
+ * @param <M> The type of model object this binder binds to
  * @see #add(BindingConfiguration)
  * @see #bind(Map)
  */
@@ -214,12 +214,7 @@ public class GenericBinder<M> implements Binder<M> {
 		}
 
 		public boolean isCollection() {
-			Class type;
-			try { 
-				type = getValueType();
-			} catch (EvaluationException e) {
-				throw new IllegalArgumentException("Failed to get property expression value type - this should not happen", e);
-			}
+			Class type = getValueType();
 			TypeDescriptor<?> typeDesc = TypeDescriptor.valueOf(type);
 			return typeDesc.isCollection() || typeDesc.isArray();
 		}
@@ -248,7 +243,19 @@ public class GenericBinder<M> implements Binder<M> {
 			}
 			return formattedValues;
 		}
-
+		
+		// public impl only
+		
+		public Class getValueType() {
+			Class type;
+			try { 
+				type = property.getValueType(createEvaluationContext());
+			} catch (EvaluationException e) {
+				throw new IllegalArgumentException("Failed to get property expression value type - this should not happen", e);
+			}
+			return type;
+		}
+		
 		// internal helpers
 		
 		private BindingResult setStringValue(String formatted) {
@@ -303,7 +310,7 @@ public class GenericBinder<M> implements Binder<M> {
 			if (formatter != null) {
 				return formatter;
 			} else {
-				Class<?> type = getValueType();
+				Class<?> type = property.getValueType(createEvaluationContext());
 				Formatter<?> formatter = typeFormatters.get(type);
 				if (formatter != null) {
 					return formatter;
@@ -320,9 +327,6 @@ public class GenericBinder<M> implements Binder<M> {
 			}
 		}
 
-		private Class<?> getValueType() throws EvaluationException {
-			return property.getValueType(createEvaluationContext());
-		}
 
 		private Annotation[] getAnnotations() throws EvaluationException {
 			return property.getValueTypeDescriptor(createEvaluationContext()).getAnnotations();

org.springframework.context/src/main/java/org/springframework/ui/binding/support/WebBinder.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright 2004-2009 the original author or authors.
+ *
+ * Licensed 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.springframework.ui.binding.support;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.ui.binding.UserValue;
+
+/**
+ * A binder designed for use in HTTP (web) environments.
+ * Suited for binding user-provided HTTP query parameters to model properties.
+ * @author Keith Donald
+ * @param <M> The type of model object this binder binds to
+ * @see #setFieldDefaultPrefix(String)
+ * @see #setFieldMarkerPrefix(String)
+ */
+public class WebBinder<M> extends GenericBinder<M> {
+
+	private String fieldMarkerPrefix = "_";
+
+	private String fieldDefaultPrefix = "!";
+
+	/**
+	 * Creates a new web binder for the model object.
+	 * @param model the model object containing properties this binder will bind to
+	 */
+	public WebBinder(M model) {
+		super(model);
+	}
+
+	/**
+	 * Configure the prefix for determining default field values.
+	 * Default is '!'.
+	 */
+	public void setFieldDefaultPrefix(String fieldDefaultPrefix) {
+		this.fieldDefaultPrefix = fieldDefaultPrefix;
+	}
+
+	/**
+	 * Configure the prefix for determining empty fields.
+	 * Default is '_'.
+	 */
+	public void setFieldMarkerPrefix(String fieldMarkerPrefix) {
+		this.fieldMarkerPrefix = fieldMarkerPrefix;
+	}
+
+	@Override
+	public List<UserValue> createUserValues(Map<String, ? extends Object> userMap) {
+		List<UserValue> values = new ArrayList<UserValue>();
+		for (Map.Entry<String, ? extends Object> entry : userMap.entrySet()) {
+			String field = entry.getKey();
+			Object value = entry.getValue();
+			if (field.startsWith(fieldDefaultPrefix)) {
+				field = field.substring(fieldDefaultPrefix.length());
+				if (!userMap.containsKey(field)) {
+					values.add(new UserValue(field, value));
+				}
+			} else if (field.startsWith(fieldMarkerPrefix)) {
+				field = field.substring(fieldMarkerPrefix.length());
+				if (!userMap.containsKey(field) && !userMap.containsKey(fieldDefaultPrefix + field)) {
+					value = getEmptyValue((BindingImpl) getBinding(field));
+					values.add(new UserValue(field, value));
+				}
+			} else {
+				values.add(new UserValue(entry.getKey(), entry.getValue()));
+			}
+		}
+		return values;
+	}
+
+	protected Object getEmptyValue(BindingImpl binding) {
+		Class<?> type = binding.getValueType();
+		if (boolean.class.equals(type) || Boolean.class.equals(type)) {
+			return Boolean.FALSE;
+		} else {
+			return null;
+		}
+	}
+
+}