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java/org/apache/jasper/runtime/JspApplicationContextImpl.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.jasper.runtime;
+
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.el.CompositeELResolver;
+import javax.el.ELContext;
+import javax.el.ELContextEvent;
+import javax.el.ELContextListener;
+import javax.el.ELResolver;
+import javax.el.ExpressionFactory;
+import javax.servlet.ServletContext;
+import javax.servlet.jsp.JspApplicationContext;
+import javax.servlet.jsp.JspContext;
+
+import org.apache.jasper.Constants;
+import org.apache.jasper.el.ELContextImpl;
+import org.apache.jasper.el.JasperELResolver;
+
+/**
+ * Implementation of JspApplicationContext
+ *
+ * @author Jacob Hookom
+ */
+public class JspApplicationContextImpl implements JspApplicationContext {
+
+    private static final String KEY = JspApplicationContextImpl.class.getName();
+
+    private final ExpressionFactory expressionFactory =
+            ExpressionFactory.newInstance();
+
+    private final List<ELContextListener> contextListeners = new ArrayList<>();
+
+    private final List<ELResolver> resolvers = new ArrayList<>();
+
+    private boolean instantiated = false;
+
+    private ELResolver resolver;
+
+    public JspApplicationContextImpl() {
+
+    }
+
+    @Override
+    public void addELContextListener(ELContextListener listener) {
+        if (listener == null) {
+            throw new IllegalArgumentException("ELContextListener was null");
+        }
+        this.contextListeners.add(listener);
+    }
+
+    public static JspApplicationContextImpl getInstance(ServletContext context) {
+        if (context == null) {
+            throw new IllegalArgumentException("ServletContext was null");
+        }
+        JspApplicationContextImpl impl = (JspApplicationContextImpl) context
+                .getAttribute(KEY);
+        if (impl == null) {
+            impl = new JspApplicationContextImpl();
+            context.setAttribute(KEY, impl);
+        }
+        return impl;
+    }
+
+    public ELContextImpl createELContext(JspContext context) {
+        if (context == null) {
+            throw new IllegalArgumentException("JspContext was null");
+        }
+
+        // create ELContext for JspContext
+        final ELResolver r = this.createELResolver();
+        ELContextImpl ctx;
+        if (Constants.IS_SECURITY_ENABLED) {
+            ctx = AccessController.doPrivileged(
+                    new PrivilegedAction<ELContextImpl>() {
+                        @Override
+                        public ELContextImpl run() {
+                            return new ELContextImpl(r);
+                        }
+                    });
+        } else {
+            ctx = new ELContextImpl(r);
+        }
+        ctx.putContext(JspContext.class, context);
+
+        // alert all ELContextListeners
+        fireListeners(ctx);
+
+        return ctx;
+    }
+
+    protected void fireListeners(ELContext elContext) {
+        ELContextEvent event = new ELContextEvent(elContext);
+        for (int i = 0; i < this.contextListeners.size(); i++) {
+            this.contextListeners.get(i).contextCreated(event);
+        }
+    }
+
+    private ELResolver createELResolver() {
+        this.instantiated = true;
+        if (this.resolver == null) {
+            CompositeELResolver r = new JasperELResolver(this.resolvers,
+                    expressionFactory.getStreamELResolver());
+            this.resolver = r;
+        }
+        return this.resolver;
+    }
+
+    @Override
+    public void addELResolver(ELResolver resolver) throws IllegalStateException {
+        if (resolver == null) {
+            throw new IllegalArgumentException("ELResolver was null");
+        }
+        if (this.instantiated) {
+            throw new IllegalStateException(
+                    "cannot call addELResolver after the first request has been made");
+        }
+        this.resolvers.add(resolver);
+    }
+
+    @Override
+    public ExpressionFactory getExpressionFactory() {
+        return expressionFactory;
+    }
+
+}