org.jclouds.rest.InputParamValidator.java Source code

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Here is the source code for org.jclouds.rest.InputParamValidator.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.jclouds.rest;

import static com.google.common.base.Preconditions.checkNotNull;

import java.util.List;

import javax.inject.Inject;

import org.jclouds.predicates.Validator;
import org.jclouds.reflect.Invocation;
import org.jclouds.rest.annotations.ParamValidators;

import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.reflect.Parameter;
import com.google.inject.Injector;

/**
 * Validates method parameters.
 * 
 * Checks the {@link ParamValidators} annotation for validators. There can be method-level validators that apply to all
 * parameters, and parameter-level validators. When validation on at least one parameter doesn't pass, throws
 * {@link IllegalStateException}.
 * 
 * @author Oleksiy Yarmula
 */
public class InputParamValidator {

    private final Injector injector;

    @Inject
    public InputParamValidator(Injector injector) {
        this.injector = injector;
    }

    public InputParamValidator() {
        injector = null;
    }

    /**
     * Validates that method parameters are correct, according to {@link ParamValidators}.
     * 
     * @param method
     *           method with optionally set {@link ParamValidators}
     * @param args
     *           method arguments with optionally set {@link ParamValidators}
     * @see ParamValidators
     * @see Validator
     * 
     * @throws IllegalStateException
     *            if validation failed
     */
    public void validateMethodParametersOrThrow(Invocation invocation) {
        try {
            performMethodValidation(checkNotNull(invocation, "invocation"));
            performParameterValidation(invocation);
        } catch (IllegalArgumentException e) {
            throw new IllegalArgumentException(
                    String.format("Validation on '%s' didn't pass:%n Reason: %s.", invocation, e.getMessage()), e);
        }
    }

    /**
     * Returns if all the method parameters passed all of the method-level validators or throws an
     * {@link IllegalArgumentException}.
     * 
     * @param method
     *           method with optionally set {@link ParamValidators}. This can not be null.
     * @param args
     *           method's parameters
     */
    private void performMethodValidation(Invocation invocation) {
        ParamValidators paramValidatorsAnnotation = invocation.getInvokable().getAnnotation(ParamValidators.class);
        if (paramValidatorsAnnotation == null)
            return; // by contract

        List<Validator<?>> methodValidators = getValidatorsFromAnnotation(paramValidatorsAnnotation);

        runPredicatesAgainstArgs(methodValidators, invocation.getArgs());
    }

    /**
     * Returns if all the method parameters passed all of their corresponding validators or throws an
     * {@link IllegalArgumentException}.
     * 
     * @param parameters
     *           annotations for method's arguments
     * @param args
     *           arguments that correspond to the array of annotations
     */
    private void performParameterValidation(Invocation invocation) {
        for (Parameter param : invocation.getInvokable().getParameters()) {
            ParamValidators annotation = param.getAnnotation(ParamValidators.class);
            if (annotation == null)
                continue;
            List<Validator<?>> parameterValidators = getValidatorsFromAnnotation(annotation);
            // TODO position guava issue 1243
            runPredicatesAgainstArg(parameterValidators, invocation.getArgs().get(param.hashCode()));
        }
    }

    private List<Validator<?>> getValidatorsFromAnnotation(ParamValidators paramValidatorsAnnotation) {
        List<Validator<?>> validators = Lists.newArrayList();
        for (Class<? extends Validator<?>> validator : paramValidatorsAnnotation.value()) {
            validators.add(checkNotNull(injector.getInstance(validator)));
        }
        return validators;
    }

    @SuppressWarnings("unchecked")
    private void runPredicatesAgainstArg(List<Validator<?>> predicates, Object arg) {
        for (@SuppressWarnings("rawtypes")
        Validator validator : predicates) {
            validator.apply(arg);
        }
    }

    @SuppressWarnings("unchecked")
    private void runPredicatesAgainstArgs(List<Validator<?>> predicates, List<Object> args) {
        for (@SuppressWarnings("rawtypes")
        Validator validator : predicates) {
            Iterables.all(args, validator);
        }
    }

}