javax.el.ImportHandler Maven / Gradle / Ivy
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package javax.el;
import java.util.Map;
import java.util.List;
import java.util.HashMap;
import java.util.ArrayList;
import java.util.HashSet;
import java.lang.reflect.Modifier;
/**
* Handles imports of class names and package names. An imported package
* name implicitly imports all the classes in the package. A class that has
* been imported can be used without its package name.
* The name is resolved to its full (package and class) name
* at evaluation time.
*/
public class ImportHandler {
private Map classNameMap = new HashMap();
private Map> classMap = new HashMap>();
private Map staticNameMap = new HashMap();
private HashSet notAClass = new HashSet();
private List packages = new ArrayList();
{
importPackage("java.lang");
}
/**
* Import a static field or method.
* @param name The static member name, including the full class name,
* to be imported
* @throws ELException if the name does not include a ".".
*/
public void importStatic(String name) throws ELException {
int i = name.lastIndexOf('.');
if (i <= 0) {
throw new ELException(
"The name " + name + " is not a full static member name");
}
String memberName = name.substring(i+1);
String className = name.substring(0, i);
staticNameMap.put(memberName, className);
}
/**
* Import a class.
* @param name The full class name of the class to be imported
* @throws ELException if the name does not include a ".".
*/
public void importClass(String name) throws ELException {
int i = name.lastIndexOf('.');
if (i <= 0) {
throw new ELException(
"The name " + name + " is not a full class name");
}
String className = name.substring(i+1);
classNameMap.put(className, name);
}
/**
* Import all the classes in a package.
* @param packageName The package name to be imported
*/
public void importPackage(String packageName) {
packages.add(packageName);
}
/**
* Resolve a class name.
*
* @param name The name of the class (without package name) to be resolved.
* @return If the class has been imported previously, with
* {@link #importClass} or {@link #importPackage}, then its
* Class instance. Otherwise null.
* @throws ELException if the class is abstract or is an interface, or
* not public.
*/
public Class resolveClass(String name) {
String className = classNameMap.get(name);
if (className != null) {
return resolveClassFor(className);
}
for (String packageName: packages) {
String fullClassName = packageName + "." + name;
Classc = resolveClassFor(fullClassName);
if (c != null) {
classNameMap.put(name, fullClassName);
return c;
}
}
return null;
}
/**
* Resolve a static field or method name.
*
* @param name The name of the member(without package and class name)
* to be resolved.
* @return If the field or method has been imported previously, with
* {@link #importStatic}, then the class object representing the class that
* declares the static field or method.
* Otherwise null.
* @throws ELException if the class is not public, or is abstract or
* is an interface.
*/
public Class resolveStatic(String name) {
String className = staticNameMap.get(name);
if (className != null) {
Class c = resolveClassFor(className);
if (c != null) {
return c;
}
}
return null;
}
private Class resolveClassFor(String className) {
Class c = classMap.get(className);
if (c != null) {
return c;
}
c = getClassFor(className);
if (c != null) {
checkModifiers(c.getModifiers());
classMap.put(className, c);
}
return c;
}
private Class getClassFor(String className) {
if (!notAClass.contains(className)) {
try {
return Class.forName(className, false, getClass().getClassLoader());
} catch (ClassNotFoundException ex) {
notAClass.add(className);
}
}
return null;
}
private void checkModifiers(int modifiers) {
if (Modifier.isAbstract(modifiers) || Modifier.isInterface(modifiers)
|| ! Modifier.isPublic((modifiers))) {
throw new ELException("Imported class must be public, and cannot be abstract or an interface");
}
}
}
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