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+/*
+ * ============LICENSE_START=======================================================
+ * ONAP Policy Engine - Common Modules
+ * ================================================================================
+ * Copyright (C) 2018 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.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.util.Properties;
+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;
+
+/**
+ * Configuration 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
+ * subclass.
+ * <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 PropertyConfiguration {
+
+ /**
+ * The "empty" option that may appear within the {@link Property}'s <i>accept</i>
+ * attribute.
+ */
+ public static final String ACCEPT_EMPTY = "empty";
+
+ /**
+ * Constructs a configuration, without populating any fields; fields should be
+ * populated later by invoking {@link #setAllFields(Properties)}.
+ */
+ public PropertyConfiguration() {
+ super();
+ }
+
+ /**
+ * Initializes each "@Property" field with its value, as found in the properties.
+ *
+ * @param props properties from which to extract the values
+ * @throws PropertyException if an error occurs
+ */
+ public PropertyConfiguration(Properties props) throws PropertyException {
+ setAllFields(props);
+ }
+
+ /**
+ * Walks the class hierarchy of "this" object, populating fields defined in each
+ * class, using values extracted from the given property set.
+ *
+ * @param props properties from which to extract the values
+ * @throws PropertyException if an error occurs
+ */
+ public void setAllFields(Properties props) throws PropertyException {
+ Class<?> clazz = getClass();
+
+ while (clazz != PropertyConfiguration.class) {
+ for (Field field : clazz.getDeclaredFields()) {
+ setValue(field, props);
+ }
+
+ clazz = clazz.getSuperclass();
+ }
+ }
+
+ /**
+ * Sets a field's value, within an object, based on what's in 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(Field field, Properties props) throws PropertyException {
+ Property prop = field.getAnnotation(Property.class);
+ if (prop == null) {
+ return false;
+ }
+
+ checkModifiable(field, prop);
+
+ if (setValue(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 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(Field field, Properties props, Property prop) throws PropertyException {
+
+ try {
+ Object val = getValue(field, props, prop);
+ if (val == null) {
+ return false;
+
+ } else {
+
+ /*
+ * According to java docs & blogs, "field" is our own copy, so we're free
+ * to change the flags without impacting the real permissions of the field
+ * within the real class.
+ */
+ field.setAccessible(true);
+
+ field.set(this, val);
+ return true;
+ }
+
+ } catch (IllegalArgumentException e) {
+ throw new PropertyInvalidException(prop.name(), field.getName(), e);
+
+ } catch (IllegalAccessException e) {
+ throw new PropertyAccessException(prop.name(), field.getName(), 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");
+ }
+ }
+
+ /**
+ * 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, xxx -> 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, xxx -> 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, xxx -> 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 = getRawPropertyValue(props, 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);
+ }
+
+ /**
+ * Gets the property value, straight from the property set.
+ *
+ * @param props properties from which to get the value
+ * @param propnm name of the property of interest
+ * @return
+ */
+ protected String getRawPropertyValue(Properties props, String propnm) {
+ return props.getProperty(propnm);
+ }
+
+ /**
+ * 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".equals(value.toLowerCase())) {
+ return Boolean.TRUE;
+
+ } else if ("false".equals(value.toLowerCase())) {
+ 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(null);
+
+ } catch (PropertyInvalidException ex) {
+ throw new PropertyInvalidException(ex.getPropertyName(), fieldName, "defaultValue is invalid",
+ ex.getCause());
+ }
+ }
+ }
+
+ /**
+ * 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;
+ }
+
+ /**
+ * Functions to check a default value.
+ */
+ @FunctionalInterface
+ private static interface CheckDefaultValueFunction {
+
+ /**
+ * Checks the default value.
+ *
+ * @param arg always {@code null}
+ * @throws PropertyInvalidException if an error occurs
+ */
+ public void apply(Void arg) throws PropertyInvalidException;
+ }
+
+ /**
+ * Annotation that declares a variable to be configured via {@link Properties}.
+ */
+ @Target(ElementType.FIELD)
+ @Retention(RetentionPolicy.RUNTIME)
+
+ protected static @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 "";
+
+ }
+}