package javax.el;
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.UnsupportedEncodingException;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
import java.util.Properties;
/**
*/
public abstract class ExpressionFactory {
+ private static final String SERVICE_RESOURCE_NAME =
+ "META-INF/services/javax.el.ExpressionFactory";
+
+ private static final String SEP = System.getProperty("file.separator");
+ private static final String PROPERTY_FILE =
+ System.getProperty("java.home") + "jre" + SEP + "lib" + SEP +
+ "el.properties";
+ private static final String PROPERTY_NAME = "javax.el.ExpressionFactory";
+
public abstract Object coerceToType(Object obj, Class<?> expectedType)
throws ELException;
String expression, Class<?> expectedReturnType,
Class<?>[] expectedParamTypes) throws ELException,
NullPointerException;
-
+
+ /**
+ * Create a new {@link ExpressionFactory}. The class to use is determined by
+ * the following search order:
+ * <ol>
+ * <li>services API (META-INF/services/javax.el.ExpressionFactory)</li>
+ * <li>$JRE_HOME/lib/el.properties - key javax.el.ExpressionFactory</li>
+ * <li>javax.el.ExpressionFactory</li>
+ * <li>Platform default implementation -
+ * org.apache.el.ExpressionFactoryImpl</li>
+ * </ol>
+ * @return
+ */
public static ExpressionFactory newInstance() {
return newInstance(null);
}
+ /**
+ * Create a new {@link ExpressionFactory} passing in the provided
+ * {@link Properties}. Search order is the same as {@link #newInstance()}.
+ *
+ * @param properties
+ * @return
+ */
public static ExpressionFactory newInstance(Properties properties) {
- // TODO
+ String className = null;
+ ExpressionFactory result = null;
+
+ ClassLoader tccl = Thread.currentThread().getContextClassLoader();
+
+ // First services API
+ className = getClassNameServices(tccl);
+ if (className == null) {
+ // Second el.properties file
+ className = getClassNameJreDir();
+ }
+ if (className == null) {
+ // Third system property
+ className = getClassNameSysProp();
+ }
+ if (className == null) {
+ // Fourth - default
+ className = "org.apache.el.ExpressionFactoryImpl";
+ }
+
+ try {
+ Class<?> clazz = null;
+ if (tccl == null) {
+ clazz = Class.forName(className);
+ } else {
+ clazz = tccl.loadClass(className);
+ }
+ Constructor<?> constructor = null;
+ // Do we need to look for a constructor that will take properties?
+ if (properties != null) {
+ try {
+ constructor = clazz.getConstructor(Properties.class);
+ } catch (SecurityException se) {
+ throw new ELException(se);
+ } catch (NoSuchMethodException nsme) {
+ // This can be ignored
+ // This is OK for this constructor not to exist
+ }
+ }
+ if (constructor == null) {
+ result = (ExpressionFactory) clazz.newInstance();
+ } else {
+ result =
+ (ExpressionFactory) constructor.newInstance(properties);
+ }
+
+ } catch (ClassNotFoundException e) {
+ throw new ELException(
+ "Unable to find ExpressionFactory of type: " + className,
+ e);
+ } catch (InstantiationException e) {
+ throw new ELException(
+ "Unable to create ExpressionFactory of type: " + className,
+ e);
+ } catch (IllegalAccessException e) {
+ throw new ELException(
+ "Unable to create ExpressionFactory of type: " + className,
+ e);
+ } catch (IllegalArgumentException e) {
+ throw new ELException(
+ "Unable to create ExpressionFactory of type: " + className,
+ e);
+ } catch (InvocationTargetException e) {
+ throw new ELException(
+ "Unable to create ExpressionFactory of type: " + className,
+ e);
+ }
+
+ return result;
+ }
+
+ private static String getClassNameServices(ClassLoader tccl) {
+ InputStream is = null;
+
+ if (tccl == null) {
+ is = ClassLoader.getSystemResourceAsStream(SERVICE_RESOURCE_NAME);
+ } else {
+ is = tccl.getResourceAsStream(SERVICE_RESOURCE_NAME);
+ }
+
+ if (is != null) {
+ String line = null;
+ try {
+ BufferedReader br =
+ new BufferedReader(new InputStreamReader(is, "UTF-8"));
+ line = br.readLine();
+ if (line != null && line.trim().length() > 0) {
+ return line.trim();
+ }
+ } catch (UnsupportedEncodingException e) {
+ // Should never happen with UTF-8
+ // If it does - ignore & return null
+ } catch (IOException e) {
+ throw new ELException("Failed to read " + SERVICE_RESOURCE_NAME,
+ e);
+ } finally {
+ try {
+ is.close();
+ } catch (IOException ioe) {
+ // Ignore
+ }
+ }
+ }
+
+ return null;
+ }
+
+ private static String getClassNameJreDir() {
+ File file = new File(PROPERTY_FILE);
+ if (file.canRead()) {
+ InputStream is = null;
+ try {
+ is = new FileInputStream(file);
+ Properties props = new Properties();
+ props.load(is);
+ String value = props.getProperty(PROPERTY_NAME);
+ if (value != null && value.trim().length() > 0) {
+ return value.trim();
+ }
+ } catch (FileNotFoundException e) {
+ // Should not happen - ignore it if it does
+ } catch (IOException e) {
+ throw new ELException("Failed to read " + PROPERTY_FILE, e);
+ } finally {
+ if (is != null) {
+ try {
+ is.close();
+ } catch (IOException e) {
+ // Ignore
+ }
+ }
+ }
+ }
+ return null;
+ }
+
+ private static final String getClassNameSysProp() {
+ String value = System.getProperty(PROPERTY_NAME);
+ if (value != null && value.trim().length() > 0) {
+ return value.trim();
+ }
return null;
}
}
projects / tomcat7.0 / commitdiff