DataBinder uses a default limit of 256 for array/collection auto-growing (SPR-7842)

org.springframework.beans/src/main/java/org/springframework/beans/BeanWrapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2009 the original author or authors.
+ * Copyright 2002-2011 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.
@@ -92,4 +92,15 @@ public interface BeanWrapper extends ConfigurablePropertyAccessor {
 	 */
 	boolean isAutoGrowNestedPaths();
 
+	/**
+	 * Specify a limit for array and collection auto-growing.
+	 * <p>Default is unlimited on a plain BeanWrapper.
+	 */
+	void setAutoGrowCollectionLimit(int autoGrowCollectionLimit);
+
+	/**
+	 * Return the limit for array and collection auto-growing.
+	 */
+	int getAutoGrowCollectionLimit();
+
 }

org.springframework.beans/src/main/java/org/springframework/beans/BeanWrapperImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2011 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.
@@ -37,6 +37,7 @@ import java.util.Set;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+
 import org.springframework.core.CollectionFactory;
 import org.springframework.core.GenericCollectionTypeResolver;
 import org.springframework.core.MethodParameter;
@@ -119,6 +120,8 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 
 	private boolean autoGrowNestedPaths = false;
 
+	private int autoGrowCollectionLimit = Integer.MAX_VALUE;
+
 
 	/**
 	 * Create new empty BeanWrapperImpl. Wrapped instance needs to be set afterwards.
@@ -183,6 +186,7 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 		setWrappedInstance(object, nestedPath, superBw.getWrappedInstance());
 		setExtractOldValueForEditor(superBw.isExtractOldValueForEditor());
 		setAutoGrowNestedPaths(superBw.isAutoGrowNestedPaths());
+		setAutoGrowCollectionLimit(superBw.getAutoGrowCollectionLimit());
 		setConversionService(superBw.getConversionService());
 		setSecurityContext(superBw.acc);
 	}
@@ -250,22 +254,38 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 	}
 
 	/**
-	 * If this BeanWrapper should "auto grow" nested paths.
-	 * When true, auto growth is triggered on nested paths when null values are encountered.
-	 * When true, auto growth is triggered on collection properties when out of bounds indexes are accessed.
-	 * Default is false.
+	 * Set whether this BeanWrapper should attempt to "auto-grow" a nested path that contains a null value.
+	 * <p>If "true", a null path location will be populated with a default object value and traversed
+	 * instead of resulting in a {@link NullValueInNestedPathException}. Turning this flag on also
+	 * enables auto-growth of collection elements when accessing an out-of-bounds index.
+	 * <p>Default is "false" on a plain BeanWrapper.
 	 */
 	public void setAutoGrowNestedPaths(boolean autoGrowNestedPaths) {
 		this.autoGrowNestedPaths = autoGrowNestedPaths;
 	}
 
 	/**
-	 * If this BeanWrapper should "auto grow" nested paths.
+	 * Return whether "auto-growing" of nested paths has been activated.
 	 */
 	public boolean isAutoGrowNestedPaths() {
 		return this.autoGrowNestedPaths;
 	}
 
+	/**
+	 * Specify a limit for array and collection auto-growing.
+	 * <p>Default is unlimited on a plain BeanWrapper.
+	 */
+	public void setAutoGrowCollectionLimit(int autoGrowCollectionLimit) {
+		this.autoGrowCollectionLimit = autoGrowCollectionLimit;
+	}
+
+	/**
+	 * Return the limit for array and collection auto-growing.
+	 */
+	public int getAutoGrowCollectionLimit() {
+		return this.autoGrowCollectionLimit;
+	}
+
 	/**
 	 * Set the security context used during the invocation of the wrapped instance methods.
 	 * Can be null.
@@ -832,7 +852,7 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 			return array;
 		}
 		int length = Array.getLength(array);
-		if (index >= length) {
+		if (index >= length && index < this.autoGrowCollectionLimit) {
 			Class<?> componentType = array.getClass().getComponentType();
 			Object newArray = Array.newInstance(componentType, index + 1);
 			System.arraycopy(array, 0, newArray, 0, length);
@@ -855,7 +875,8 @@ public class BeanWrapperImpl extends AbstractPropertyAccessor implements BeanWra
 		if (!this.autoGrowNestedPaths) {
 			return;
 		}
-		if (index >= collection.size()) {
+		int size = collection.size();
+		if (index >= size && index < this.autoGrowCollectionLimit) {
 			Class elementType = GenericCollectionTypeResolver.getCollectionReturnType(pd.getReadMethod(), nestingLevel);
 			if (elementType != null) {
 				for (int i = collection.size(); i < index + 1; i++) {