Add bean configurator

Refactored PropertyConfiguration, but left the original class alone
until references to it have been removed from other policy repos.
Split the Property annotation out into its own file.  Cloned the
remaining code into BeanConfigurator, modifying its behavior so that,
instead of operating on its own subclass, it operates on a provided bean.
Also added an ability to copy the bean's fields to a Properties object.

Updated license dates.

Removed unneeded argument from functional interface.
Added comment about always checking default values.
Updated a few comments.

Change-Id: Iff36fd0524032d7630f9ee08f0eef7b05de100d1
Issue-ID: POLICY-1444
Signed-off-by: Jim Hahn <jrh3@att.com>

2 files changed, 626 insertions, 0 deletions

diff --git a/utils/src/main/java/org/onap/policy/common/utils/properties/BeanConfigurator.java b/utils/src/main/java/org/onap/policy/common/utils/properties/BeanConfigurator.java
new file mode 100644
index 00000000..9d02819a
--- /dev/null
+++ b/utils/src/main/java/org/onap/policy/common/utils/properties/BeanConfigurator.java
@@ -0,0 +1,567 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP - Common Modules
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.properties;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.Properties;
+import org.apache.commons.lang3.StringUtils;
+import org.onap.policy.common.utils.properties.exception.PropertyAccessException;
+import org.onap.policy.common.utils.properties.exception.PropertyException;
+import org.onap.policy.common.utils.properties.exception.PropertyInvalidException;
+import org.onap.policy.common.utils.properties.exception.PropertyMissingException;
+
+/**
+ * Configurator for beans whose fields are initialized by reading from a set of
+ * {@link Properties}, as directed by the {@link Property} annotations that appear on
+ * fields within the bean. The values of the fields are set via <i>setXxx()</i> methods.
+ * As a result, if a field is annotated and there is no corresponding <i>setXxx()</i>
+ * method, then an exception will be thrown.
+ *
+ * <p>It is possible that an invalid <i>defaultValue</i> is specified via the
+ * {@link Property} annotation. This could remain undetected until an optional property is
+ * left out of the {@link Properties}. Consequently, this class will always validate a
+ * {@link Property}'s default value, if the <i>defaultValue</i> is not empty or if
+ * <i>accept</i> includes the "empty" option.
+ */
+public class BeanConfigurator {
+
+    /**
+     * The "empty" option that may appear within the {@link Property}'s <i>accept</i>
+     * attribute.
+     */
+    public static final String ACCEPT_EMPTY = "empty";
+
+    /**
+     * Walks the class hierarchy of the bean, populating fields defined in each class,
+     * using values extracted from the given property set.
+     *
+     * @param bean bean whose fields are to be configured from the properties
+     * @param props properties from which to extract the values
+     * @throws PropertyException if an error occurs
+     */
+    public <T> T configureFromProperties(T bean, Properties props) throws PropertyException {
+        Class<?> clazz = bean.getClass();
+
+        while (clazz != Object.class) {
+            for (Field field : clazz.getDeclaredFields()) {
+                setValue(bean, field, props);
+            }
+
+            clazz = clazz.getSuperclass();
+        }
+
+        return bean;
+    }
+
+    /**
+     * Sets a field's value, within an object, based on what's in the properties.
+     *
+     * @param bean bean whose fields are to be configured from the properties
+     * @param field field whose value is to be set
+     * @param props properties from which to get the value
+     * @return {@code true} if the property's value was set, {@code false} otherwise
+     * @throws PropertyException if an error occurs
+     */
+    protected boolean setValue(Object bean, Field field, Properties props) throws PropertyException {
+        Property prop = field.getAnnotation(Property.class);
+        if (prop == null) {
+            return false;
+        }
+
+        checkModifiable(field, prop);
+
+        Method setter = getSetter(field, prop);
+        checkMethod(setter, prop);
+
+        if (setValue(bean, setter, field, props, prop)) {
+            return true;
+        }
+
+        throw new PropertyAccessException(prop.name(), field.getName(), "unsupported field type");
+    }
+
+    /**
+     * Sets a field's value from a particular property.
+     *
+     * @param bean bean whose fields are to be configured from the properties
+     * @param setter method to be used to set the field's value
+     * @param field field whose value is to be set
+     * @param props properties from which to get the value
+     * @param prop property of interest
+     * @return {@code true} if the property's value was set, {@code false} otherwise
+     * @throws PropertyException if an error occurs
+     */
+    protected boolean setValue(Object bean, Method setter, Field field, Properties props, Property prop)
+                    throws PropertyException {
+
+        try {
+            Object val = getValue(field, props, prop);
+            if (val == null) {
+                return false;
+
+            } else {
+                setter.invoke(bean, val);
+                return true;
+            }
+
+        } catch (IllegalArgumentException e) {
+            throw new PropertyInvalidException(prop.name(), field.getName(), e);
+
+        } catch (IllegalAccessException | InvocationTargetException e) {
+            throw new PropertyAccessException(prop.name(), setter.getName(), e);
+        }
+    }
+
+    /**
+     * Get the setter.
+     *
+     * @param field field whose value is to be set
+     * @param prop property of interest
+     * @return the method to be used to set the field's value
+     * @throws PropertyAccessException if a "set" method cannot be identified
+     */
+    private Method getSetter(Field field, Property prop) throws PropertyAccessException {
+        String nm = "set" + StringUtils.capitalize(field.getName());
+
+        try {
+            return field.getDeclaringClass().getMethod(nm, field.getType());
+
+        } catch (NoSuchMethodException | SecurityException e) {
+            throw new PropertyAccessException(prop.name(), nm, e);
+        }
+    }
+
+    /**
+     * Gets a property value, coercing it to the field's type.
+     *
+     * @param field field whose value is to be set
+     * @param props properties from which to get the value
+     * @param prop property of interest
+     * @return the value extracted from the property, or {@code null} if the field type is
+     *         not supported
+     * @throws PropertyException if an error occurs
+     */
+    protected Object getValue(Field field, Properties props, Property prop) throws PropertyException {
+
+        Class<?> clazz = field.getType();
+        String fieldName = field.getName();
+
+        // can still add support for short, float, double, enum
+
+        if (clazz == String.class) {
+            return getStringValue(fieldName, props, prop);
+
+        } else if (clazz == Boolean.class || clazz == boolean.class) {
+            return getBooleanValue(fieldName, props, prop);
+
+        } else if (clazz == Integer.class || clazz == int.class) {
+            return getIntegerValue(fieldName, props, prop);
+
+        } else if (clazz == Long.class || clazz == long.class) {
+            return getLongValue(fieldName, props, prop);
+
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * Verifies that the field can be modified, i.e., it's neither <i>static</i>, nor
+     * <i>final</i>.
+     *
+     * @param field field whose value is to be set
+     * @param prop property of interest
+     * @throws PropertyAccessException if the field is not modifiable
+     */
+    protected void checkModifiable(Field field, Property prop) throws PropertyAccessException {
+        int mod = field.getModifiers();
+
+        if (Modifier.isStatic(mod)) {
+            throw new PropertyAccessException(prop.name(), field.getName(), "'static' variable cannot be modified");
+        }
+
+        if (Modifier.isFinal(mod)) {
+            throw new PropertyAccessException(prop.name(), field.getName(), "'final' variable cannot be modified");
+        }
+    }
+
+    /**
+     * Verifies that the method is not <i>static</i>.
+     *
+     * @param method method to be checked
+     * @param prop property of interest
+     * @throws PropertyAccessException if the method is static
+     */
+    private void checkMethod(Method method, Property prop) throws PropertyAccessException {
+        int mod = method.getModifiers();
+
+        if (Modifier.isStatic(mod)) {
+            throw new PropertyAccessException(prop.name(), method.getName(), "method is 'static'");
+        }
+    }
+
+    /**
+     * Gets a property value, coercing it to a String.
+     *
+     * @param fieldName field whose value is to be set
+     * @param props properties from which to get the value
+     * @param prop property of interest
+     * @return the value extracted from the property
+     * @throws PropertyException if an error occurs
+     */
+    protected String getStringValue(String fieldName, Properties props, Property prop) throws PropertyException {
+
+        /*
+         * Note: the default value for a String type is always valid, thus no need to
+         * check it.
+         */
+
+        return getPropValue(fieldName, props, prop);
+    }
+
+    /**
+     * Gets a property value, coercing it to a Boolean.
+     *
+     * @param fieldName field whose value is to be set
+     * @param props properties from which to get the value
+     * @param prop property of interest
+     * @return the value extracted from the property
+     * @throws PropertyException if an error occurs
+     */
+    protected Boolean getBooleanValue(String fieldName, Properties props, Property prop) throws PropertyException {
+        // validate the default value
+        checkDefaultValue(fieldName, prop, () -> makeBoolean(fieldName, prop, prop.defaultValue()));
+
+        return makeBoolean(fieldName, prop, getPropValue(fieldName, props, prop));
+    }
+
+    /**
+     * Gets a property value, coercing it to an Integer.
+     *
+     * @param fieldName field whose value is to be set
+     * @param props properties from which to get the value
+     * @param prop property of interest
+     * @return the value extracted from the property
+     * @throws PropertyException if an error occurs
+     */
+    protected Integer getIntegerValue(String fieldName, Properties props, Property prop) throws PropertyException {
+        // validate the default value
+        checkDefaultValue(fieldName, prop, () -> makeInteger(fieldName, prop, prop.defaultValue()));
+
+        return makeInteger(fieldName, prop, getPropValue(fieldName, props, prop));
+    }
+
+    /**
+     * Gets a property value, coercing it to a Long.
+     *
+     * @param fieldName field whose value is to be set
+     * @param props properties from which to get the value
+     * @param prop property of interest
+     * @return the value extracted from the property
+     * @throws PropertyException if an error occurs
+     */
+    protected Long getLongValue(String fieldName, Properties props, Property prop) throws PropertyException {
+        // validate the default value
+        checkDefaultValue(fieldName, prop, () -> makeLong(fieldName, prop, prop.defaultValue()));
+
+        return makeLong(fieldName, prop, getPropValue(fieldName, props, prop));
+    }
+
+    /**
+     * Gets a value from the property set.
+     *
+     * @param fieldName field whose value is to be set
+     * @param props properties from which to get the value
+     * @param prop property of interest
+     * @return the value extracted from the property, or the <i>defaultValue</i> if the
+     *         value does not exist
+     * @throws PropertyMissingException if the property does not exist and the
+     *         <i>defaultValue</i> is empty and <i>emptyOk</i> is {@code false}
+     */
+    protected String getPropValue(String fieldName, Properties props, Property prop) throws PropertyMissingException {
+        String propnm = prop.name();
+
+        String val = props.getProperty(propnm);
+        if (val != null && isEmptyOk(prop, val)) {
+            return val;
+        }
+
+        val = prop.defaultValue();
+        if (val != null && isEmptyOk(prop, val)) {
+            return val;
+        }
+
+        throw new PropertyMissingException(prop.name(), fieldName);
+    }
+
+    /**
+     * Coerces a String value into a Boolean.
+     *
+     * @param fieldName field whose value is to be set
+     * @param prop property of interest
+     * @param value value to be coerced
+     * @return the Boolean value represented by the String value
+     * @throws PropertyInvalidException if the value does not represent a valid Boolean
+     */
+    private Boolean makeBoolean(String fieldName, Property prop, String value) throws PropertyInvalidException {
+        if ("true".equalsIgnoreCase(value)) {
+            return Boolean.TRUE;
+
+        } else if ("false".equalsIgnoreCase(value)) {
+            return Boolean.FALSE;
+
+        } else {
+            throw new PropertyInvalidException(prop.name(), fieldName, "expecting 'true' or 'false'");
+        }
+    }
+
+    /**
+     * Coerces a String value into an Integer.
+     *
+     * @param fieldName field whose value is to be set
+     * @param prop property of interest
+     * @param value value to be coerced
+     * @return the Integer value represented by the String value
+     * @throws PropertyInvalidException if the value does not represent a valid Integer
+     */
+    private Integer makeInteger(String fieldName, Property prop, String value) throws PropertyInvalidException {
+        try {
+            return Integer.valueOf(value);
+
+        } catch (NumberFormatException e) {
+            throw new PropertyInvalidException(prop.name(), fieldName, e);
+        }
+    }
+
+    /**
+     * Coerces a String value into a Long.
+     *
+     * @param fieldName field whose value is to be set
+     * @param prop property of interest
+     * @param value value to be coerced
+     * @return the Long value represented by the String value
+     * @throws PropertyInvalidException if the value does not represent a valid Long
+     */
+    private Long makeLong(String fieldName, Property prop, String value) throws PropertyInvalidException {
+        try {
+            return Long.valueOf(value);
+
+        } catch (NumberFormatException e) {
+            throw new PropertyInvalidException(prop.name(), fieldName, e);
+        }
+    }
+
+    /**
+     * Applies a function to check a property's default value. If the function throws an
+     * exception about an invalid property, then it's re-thrown as an exception about an
+     * invalid <i>defaultValue</i>.
+     *
+     * @param fieldName name of the field being checked
+     * @param prop property of interest
+     * @param func function to invoke to check the default value
+     */
+    private void checkDefaultValue(String fieldName, Property prop, CheckDefaultValueFunction func)
+                    throws PropertyInvalidException {
+
+        if (isEmptyOk(prop, prop.defaultValue())) {
+            try {
+                func.apply();
+
+            } catch (PropertyInvalidException ex) {
+                throw new PropertyInvalidException(ex.getPropertyName(), fieldName, "defaultValue is invalid", ex);
+            }
+        }
+    }
+
+    /**
+     * Determines if a value is OK, even if it's empty.
+     *
+     * @param prop property specifying what's acceptable
+     * @param value value to be checked
+     * @return {@code true} if the value is not empty or empty is allowed, {@code false}
+     *         otherwise
+     */
+    protected boolean isEmptyOk(Property prop, String value) {
+        return !value.isEmpty() || isEmptyOk(prop);
+    }
+
+    /**
+     * Determines if a {@link Property}'s <i>accept</i> attribute includes the "empty"
+     * option.
+     *
+     * @param prop property whose <i>accept</i> attribute is to be examined
+     * @return {@code true} if the <i>accept</i> attribute includes "empty"
+     */
+    protected boolean isEmptyOk(Property prop) {
+        for (String option : prop.accept().split(",")) {
+            if (ACCEPT_EMPTY.equals(option)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Copies the field values to a set of properties.
+     *
+     * @param bean bean whose fields are to be exported to the properties
+     * @param props properties into which the values should be added
+     * @param origPrefix prefix of the property names as they appear within the Property
+     *        annotations
+     * @param finalPrefix prefix to use instead, when adding to the set of properties
+     * @throws PropertyException if an error occurs
+     */
+    public void addToProperties(Object bean, Properties props, String origPrefix, String finalPrefix)
+                    throws PropertyException {
+
+        Class<?> clazz = bean.getClass();
+
+        String dottedOrig = (origPrefix.isEmpty() || origPrefix.endsWith(".") ? origPrefix : origPrefix + ".");
+        String dottedFinal = (finalPrefix.isEmpty() || finalPrefix.endsWith(".") ? finalPrefix : finalPrefix + ".");
+
+        while (clazz != Object.class) {
+            for (Field field : clazz.getDeclaredFields()) {
+                putProperty(bean, field, props, dottedOrig, dottedFinal);
+            }
+
+            clazz = clazz.getSuperclass();
+        }
+    }
+
+    /**
+     * Copies the field values to a set of properties.
+     *
+     * @param bean bean whose fields are to be exported to the properties
+     * @param field field whose value is to be copied
+     * @param props properties into which the values should be added
+     * @param origPrefix prefix of the property names as they appear within the Property
+     *        annotations. Includes a trailing "." (if non-empty)
+     * @param finalPrefix prefix to use instead, when adding to the set of properties.
+     *        Includes a trailing "." (if non-empty)
+     * @throws PropertyAccessException if an error occurs
+     */
+    private void putProperty(Object bean, Field field, Properties props, String origPrefix, String finalPrefix)
+                    throws PropertyAccessException {
+
+        Property prop = field.getAnnotation(Property.class);
+        if (prop == null) {
+            return;
+        }
+
+        Method getter = getGetter(field, prop);
+        checkMethod(getter, prop);
+
+        Object value = getBeanValue(bean, field, getter, prop);
+        if (value == null) {
+            return;
+        }
+
+        String name = prop.name();
+        if (name.startsWith(origPrefix)) {
+            name = finalPrefix + name.substring(origPrefix.length());
+        }
+
+        props.setProperty(name, value.toString());
+    }
+
+    /**
+     * Get the getter.
+     *
+     * @param field field whose value is to be gotten
+     * @param prop property of interest
+     * @return the method to be used to get the field's value
+     * @throws PropertyAccessException if a "get" method cannot be identified
+     */
+    private Method getGetter(Field field, Property prop) throws PropertyAccessException {
+        String capnm = StringUtils.capitalize(field.getName());
+
+        try {
+            return getGetter(field, "get" + capnm);
+
+        } catch (NoSuchMethodException e) {
+            if (field.getType() == Boolean.class || field.getType() == boolean.class) {
+                // boolean - check for "isXxx" method, too
+                try {
+                    return getGetter(field, "is" + capnm);
+
+                } catch (NoSuchMethodException | SecurityException e2) {
+                    throw new PropertyAccessException(prop.name(), "is" + capnm, e2);
+                }
+            }
+
+            throw new PropertyAccessException(prop.name(), "get" + capnm, e);
+
+        } catch (SecurityException e) {
+            // problem with "get" method
+            throw new PropertyAccessException(prop.name(), "get" + capnm, e);
+        }
+    }
+
+    /**
+     * Get the getter.  This may be overridden by junit tests.
+     *
+     * @param field field whose value is to be gotten
+     * @param methodName name of the method to return
+     * @return the method to be used to get the field's value
+     * @throws NoSuchMethodException if the method does not exist
+     * @throws SecurityException if the method cannot be accessed
+     */
+    protected Method getGetter(Field field, String methodName) throws NoSuchMethodException, SecurityException {
+        return field.getDeclaringClass().getMethod(methodName);
+    }
+
+    /**
+     * Gets a field's value for a particular property.
+     *
+     * @param bean bean whose fields are to be configured from the properties
+     * @param getter method to be used to get the field's value
+     * @param field field whose value is to be gotten
+     * @param prop property of interest
+     * @throws PropertyAccessException if an error occurs
+     */
+    private Object getBeanValue(Object bean, Field field, Method getter, Property prop)
+                    throws PropertyAccessException {
+        try {
+            return getter.invoke(bean);
+
+        } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
+            throw new PropertyAccessException(prop.name(), field.getName(), e);
+        }
+    }
+
+    /**
+     * Functions to check a default value.
+     */
+    @FunctionalInterface
+    private static interface CheckDefaultValueFunction {
+
+        /**
+         * Checks the default value.
+         *
+         * @throws PropertyInvalidException if an error occurs
+         */
+        public void apply() throws PropertyInvalidException;
+    }
+}
diff --git a/utils/src/main/java/org/onap/policy/common/utils/properties/Property.java b/utils/src/main/java/org/onap/policy/common/utils/properties/Property.java
new file mode 100644
index 00000000..bacedef9
--- /dev/null
+++ b/utils/src/main/java/org/onap/policy/common/utils/properties/Property.java
@@ -0,0 +1,59 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.properties;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.util.Properties;
+
+
+/**
+ * Annotation that declares a variable to be configured via {@link Properties}.
+ */
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+
+public @interface Property {
+
+    /**
+     * Name of the property.
+     *
+     * @return the property name
+     */
+    public String name();
+
+    /**
+     * Default value, used when the property does not exist.
+     *
+     * @return the default value
+     */
+    public String defaultValue() default "";
+
+    /**
+     * Comma-separated options identifying what's acceptable. The word, "empty",
+     * indicates that an empty string, "", is an acceptable value.
+     *
+     * @return options identifying what's acceptable
+     */
+    public String accept() default "";
+}