File	Doc	Category	Size	Date	Package
MapELResolver.java	API Doc	Glassfish v2 API	16408	Thu May 04 14:31:34 BST 2006	javax.el

MapELResolver

• java.lang.Object
  • javax.el.ELResolver

Fields Summary
private static Class	theUnmodifiableMapClass
private boolean	isReadOnly

Constructors Summary
public MapELResolver() Creates a new read/write MapELResolver. this.isReadOnly = false;
public MapELResolver(boolean isReadOnly) Creates a new MapELResolver whose read-only status is determined by the given parameter. param isReadOnly true if this resolver cannot modify maps; false otherwise. this.isReadOnly = isReadOnly;

Methods Summary
public java.lang.Class	getCommonPropertyType(javax.el.ELContext context, java.lang.Object base) If the base object is a map, returns the most general type that this resolver accepts for the property argument. Otherwise, returns null. Assuming the base is a Map, this method will always return Object.class. This is because Maps accept any object as a key. param context The context of this evaluation. param base The map to analyze. Only bases of type Map are handled by this resolver. return null if base is not a Map; otherwise Object.class. if (base != null && base instanceof Map) { return Object.class; } return null;
public java.util.Iterator	getFeatureDescriptors(javax.el.ELContext context, java.lang.Object base) If the base object is a map, returns an Iterator containing the set of keys available in the Map. Otherwise, returns null. The Iterator returned must contain zero or more instances of {@link java.beans.FeatureDescriptor}. Each info object contains information about a key in the Map, and is initialized as follows: displayName - The return value of calling the toString method on this key, or "null" if the key is null. name - Same as displayName property. shortDescription - Empty string expert - false hidden - false preferred - true In addition, the following named attributes must be set in the returned FeatureDescriptors: {@link ELResolver#TYPE} - The return value of calling the getClass() method on this key, or null if the key is null. {@link ELResolver#RESOLVABLE_AT_DESIGN_TIME} - true param context The context of this evaluation. param base The map whose keys are to be iterated over. Only bases of type Map are handled by this resolver. return An Iterator containing zero or more (possibly infinitely more) FeatureDescriptor objects, each representing a key in this map, or null if the base object is not a map. if (base != null && base instanceof Map) { Map map = (Map) base; Iterator iter = map.keySet().iterator(); List<FeatureDescriptor> list = new ArrayList<FeatureDescriptor>(); while (iter.hasNext()) { Object key = iter.next(); FeatureDescriptor descriptor = new FeatureDescriptor(); String name = (key==null)? null: key.toString(); descriptor.setName(name); descriptor.setDisplayName(name); descriptor.setShortDescription(""); descriptor.setExpert(false); descriptor.setHidden(false); descriptor.setPreferred(true); descriptor.setValue("type", key==null? null: key.getClass()); descriptor.setValue("resolvableAtDesignTime", Boolean.TRUE); list.add(descriptor); } return list.iterator(); } return null;
public java.lang.Class	getType(javax.el.ELContext context, java.lang.Object base, java.lang.Object property) If the base object is a map, returns the most general acceptable type for a value in this map. If the base is a Map, the propertyResolved property of the ELContext object must be set to true by this resolver, before returning. If this property is not true after this method is called, the caller should ignore the return value. Assuming the base is a Map, this method will always return Object.class. This is because Maps accept any object as the value for a given key. param context The context of this evaluation. param base The map to analyze. Only bases of type Map are handled by this resolver. param property The key to return the acceptable type for. Ignored by this resolver. return If the propertyResolved property of ELContext was set to true, then the most general acceptable type; otherwise undefined. throws NullPointerException if context is null throws ELException if an exception was thrown while performing the property or variable resolution. The thrown exception must be included as the cause property of this exception, if available. if (context == null) { throw new NullPointerException(); } if (base != null && base instanceof Map) { context.setPropertyResolved(true); return Object.class; } return null;
public java.lang.Object	getValue(javax.el.ELContext context, java.lang.Object base, java.lang.Object property) If the base object is a map, returns the value associated with the given key, as specified by the property argument. If the key was not found, null is returned. If the base is a Map, the propertyResolved property of the ELContext object must be set to true by this resolver, before returning. If this property is not true after this method is called, the caller should ignore the return value. Just as in {@link java.util.Map#get}, just because null is returned doesn't mean there is no mapping for the key; it's also possible that the Map explicitly maps the key to null. param context The context of this evaluation. param base The map to be analyzed. Only bases of type Map are handled by this resolver. param property The key whose associated value is to be returned. return If the propertyResolved property of ELContext was set to true, then the value associated with the given key or null if the key was not found. Otherwise, undefined. throws ClassCastException if the key is of an inappropriate type for this map (optionally thrown by the underlying Map). throws NullPointerException if context is null, or if the key is null and this map does not permit null keys (the latter is optionally thrown by the underlying Map). throws ELException if an exception was thrown while performing the property or variable resolution. The thrown exception must be included as the cause property of this exception, if available. if (context == null) { throw new NullPointerException(); } if (base != null && base instanceof Map) { context.setPropertyResolved(true); Map map = (Map) base; return map.get(property); } return null;
public boolean	isReadOnly(javax.el.ELContext context, java.lang.Object base, java.lang.Object property) If the base object is a map, returns whether a call to {@link #setValue} will always fail. If the base is a Map, the propertyResolved property of the ELContext object must be set to true by this resolver, before returning. If this property is not true after this method is called, the caller should ignore the return value. If this resolver was constructed in read-only mode, this method will always return true. If a Map was created using {@link java.util.Collections#unmodifiableMap}, this method must return true. Unfortunately, there is no Collections API method to detect this. However, an implementation can create a prototype unmodifiable Map and query its runtime type to see if it matches the runtime type of the base object as a workaround. param context The context of this evaluation. param base The map to analyze. Only bases of type Map are handled by this resolver. param property The key to return the read-only status for. Ignored by this resolver. return If the propertyResolved property of ELContext was set to true, then true if calling the setValue method will always fail or false if it is possible that such a call may succeed; otherwise undefined. throws NullPointerException if context is null throws ELException if an exception was thrown while performing the property or variable resolution. The thrown exception must be included as the cause property of this exception, if available. if (context == null) { throw new NullPointerException(); } if (base != null && base instanceof Map) { context.setPropertyResolved(true); Map map = (Map) base; return isReadOnly || map.getClass() == theUnmodifiableMapClass; } return false;
public void	setValue(javax.el.ELContext context, java.lang.Object base, java.lang.Object property, java.lang.Object val) If the base object is a map, attempts to set the value associated with the given key, as specified by the property argument. If the base is a Map, the propertyResolved property of the ELContext object must be set to true by this resolver, before returning. If this property is not true after this method is called, the caller can safely assume no value was set. If this resolver was constructed in read-only mode, this method will always throw PropertyNotWritableException. If a Map was created using {@link java.util.Collections#unmodifiableMap}, this method must throw PropertyNotWritableException. Unfortunately, there is no Collections API method to detect this. However, an implementation can create a prototype unmodifiable Map and query its runtime type to see if it matches the runtime type of the base object as a workaround. param context The context of this evaluation. param base The map to be modified. Only bases of type Map are handled by this resolver. param property The key with which the specified value is to be associated. param val The value to be associated with the specified key. throws ClassCastException if the class of the specified key or value prevents it from being stored in this map. throws NullPointerException if context is null, or if this map does not permit null keys or values, and the specified key or value is null. throws IllegalArgumentException if some aspect of this key or value prevents it from being stored in this map. throws ELException if an exception was thrown while performing the property or variable resolution. The thrown exception must be included as the cause property of this exception, if available. throws PropertyNotWritableException if this resolver was constructed in read-only mode, or if the put operation is not supported by the underlying map. if (context == null) { throw new NullPointerException(); } if (base != null && base instanceof Map) { context.setPropertyResolved(true); Map map = (Map) base; if (isReadOnly || map.getClass() == theUnmodifiableMapClass) { throw new PropertyNotWritableException(); } try { map.put(property, val); } catch (UnsupportedOperationException ex) { throw new PropertyNotWritableException(); } }