Implement computed attributes

1 files changed, 78 insertions, 0 deletions

diff --git a/src/org/traccar/processing/ComputedAttributesHandler.java b/src/org/traccar/processing/ComputedAttributesHandler.java
new file mode 100644
index 000000000..ea7c0aa1d
--- /dev/null
+++ b/src/org/traccar/processing/ComputedAttributesHandler.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2017 Anton Tananaev (anton@traccar.org)
+ * Copyright 2017 Andrey Kunitsyn (andrey@traccar.org)
+ *
+ * Licensed 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.traccar.processing;
+
+import java.util.Collection;
+
+import org.apache.commons.jexl2.JexlEngine;
+import org.apache.commons.jexl2.JexlException;
+import org.apache.commons.jexl2.MapContext;
+import org.traccar.BaseDataHandler;
+import org.traccar.Context;
+import org.traccar.helper.Log;
+import org.traccar.model.Attribute;
+import org.traccar.model.Position;
+
+public class ComputedAttributesHandler extends BaseDataHandler {
+
+    private JexlEngine engine;
+
+    public ComputedAttributesHandler() {
+        engine = new JexlEngine();
+        engine.setStrict(true);
+    }
+
+    public Object computeAttribute(Attribute attribute, Position position) throws JexlException {
+        MapContext expressionContext = new MapContext();
+        expressionContext.set("position", position);
+        return engine.createExpression(attribute.getExpression()).evaluate(expressionContext);
+    }
+
+    @Override
+    protected Position handlePosition(Position position) {
+        Collection<Attribute> attributes = Context.getAttributesManager().getAttributes(
+                Context.getAttributesManager().getAllDeviceAttributes(position.getDeviceId()));
+        for (Attribute attribute : attributes) {
+            if (attribute.getAttribute() != null) {
+                Object result = null;
+                try {
+                    result = computeAttribute(attribute, position);
+                } catch (JexlException error) {
+                    Log.warning(error);
+                }
+                if (result != null) {
+                    try {
+                        switch (attribute.getType()) {
+                            case "number":
+                                position.getAttributes().put(attribute.getAttribute(), (Number) result);
+                                break;
+                            case "boolean":
+                                position.getAttributes().put(attribute.getAttribute(), (Boolean) result);
+                                break;
+                            default:
+                                position.getAttributes().put(attribute.getAttribute(), result.toString());
+                        }
+                    } catch (ClassCastException error) {
+                        Log.warning(error);
+                    }
+                }
+            }
+        }
+        return position;
+    }
+
+}