Add Builder for RepositoryItemReader
resolves BATCH-2606
This commit is contained in:
Glenn Renfro
committed by
Michael Minella
Michael Minella
parent
4d9b13ce92
commit
6950318bab
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/*
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* Copyright 2017 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.batch.item.data.builder;
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import java.lang.reflect.Method;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Map;
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import org.springframework.batch.item.builder.AbstractItemCountingItemStreamItemReaderBuilder;
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import org.springframework.batch.item.data.RepositoryItemReader;
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import org.springframework.cglib.proxy.Enhancer;
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import org.springframework.cglib.proxy.MethodInterceptor;
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import org.springframework.cglib.proxy.MethodProxy;
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import org.springframework.data.domain.Sort;
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import org.springframework.data.repository.PagingAndSortingRepository;
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import org.springframework.util.Assert;
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import org.springframework.util.StringUtils;
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/**
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* A builder implementation for the {@link RepositoryItemReader}.
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*
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* @author Glenn Renfro
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* @since 4.0
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* @see RepositoryItemReader
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*/
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public class RepositoryItemReaderBuilder<T>
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extends AbstractItemCountingItemStreamItemReaderBuilder<RepositoryItemReaderBuilder<T>> {
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private PagingAndSortingRepository<?, ?> repository;
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private Map<String, Sort.Direction> sorts;
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private List<?> arguments;
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private int pageSize = 10;
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private String methodName;
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private RepositoryMethodReference repositoryMethodReference;
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/**
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* Arguments to be passed to the data providing method.
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*
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* @param arguments list of method arguments to be passed to the repository.
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* @return The current instance of the builder.
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* @see RepositoryItemReader#setArguments(List)
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*/
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public RepositoryItemReaderBuilder<T> arguments(List<?> arguments) {
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this.arguments = arguments;
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return this;
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}
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/**
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* Provides ordering of the results so that order is maintained between paged queries.
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*
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* @param sorts the fields to sort by and the directions.
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* @return The current instance of the builder.
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* @see RepositoryItemReader#setSort(Map)
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*/
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public RepositoryItemReaderBuilder<T> sorts(Map<String, Sort.Direction> sorts) {
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this.sorts = sorts;
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return this;
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}
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/**
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* Establish the pageSize for the generated RepositoryItemReader.
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*
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* @param pageSize The number of items to retrieve per page.
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* @return The current instance of the builder.
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* @see RepositoryItemReader#setPageSize(int)
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*/
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public RepositoryItemReaderBuilder<T> pageSize(int pageSize) {
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this.pageSize = pageSize;
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return this;
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}
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/**
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* The {@link org.springframework.data.repository.PagingAndSortingRepository}
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* implementation used to read input from.
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*
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* @param repository underlying repository for input to be read from.
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* @return The current instance of the builder.
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* @see RepositoryItemReader#setRepository(PagingAndSortingRepository)
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*/
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public RepositoryItemReaderBuilder<T> repository(PagingAndSortingRepository<?, ?> repository) {
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this.repository = repository;
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return this;
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}
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/**
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* Specifies what method on the repository to call. This method must take
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* {@link org.springframework.data.domain.Pageable} as the <em>last</em> argument.
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*
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* @param methodName name of the method to invoke.
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* @return The current instance of the builder.
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* @see RepositoryItemReader#setMethodName(String)
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*/
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public RepositoryItemReaderBuilder<T> methodName(String methodName) {
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this.methodName = methodName;
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return this;
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}
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/**
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* Specifies a repository and the type-safe method to call for the reader. This method
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* must take {@link org.springframework.data.domain.Pageable} as the <em>last</em>
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* argument. This method can be used in place of {@link #methodName(String)},
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* {@link #arguments(List)} and {@link #repository(PagingAndSortingRepository)}. The
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* repository that is used by the repositoryMethodReference must be non-final.
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*
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* @param repositoryMethodReference of the used to get a repository and type-safe
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* method for use by the reader.
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* @return The current instance of the builder.
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* @see RepositoryItemReader#setMethodName(String)
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* @see RepositoryItemReader#setRepository(PagingAndSortingRepository)
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*
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*/
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public RepositoryItemReaderBuilder<T> repository(RepositoryMethodReference repositoryMethodReference) {
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this.repositoryMethodReference = repositoryMethodReference;
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return this;
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}
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/**
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* Builds the {@link RepositoryItemReader}.
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*
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* @return a {@link RepositoryItemReader}
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*/
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public RepositoryItemReader<T> build() {
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if (this.repositoryMethodReference != null) {
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this.methodName = this.repositoryMethodReference.getMethodName();
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this.repository = this.repositoryMethodReference.getRepository();
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this.arguments = this.repositoryMethodReference.getArguments();
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}
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Assert.notNull(this.sorts, "sorts map is required.");
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Assert.notNull(this.repository, "repository is required.");
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Assert.hasText(this.methodName, "methodName is required.");
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if (this.saveState) {
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Assert.state(StringUtils.hasText(this.name), "A name is required when saveState is set to true.");
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}
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RepositoryItemReader<T> reader = new RepositoryItemReader<>();
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reader.setArguments(this.arguments);
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reader.setRepository(this.repository);
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reader.setMethodName(this.methodName);
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reader.setPageSize(this.pageSize);
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reader.setCurrentItemCount(this.currentItemCount);
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reader.setMaxItemCount(this.maxItemCount);
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reader.setSaveState(this.saveState);
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reader.setSort(this.sorts);
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reader.setName(this.name);
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return reader;
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}
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/**
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* Establishes a proxy that will capture a the Repository and the associated
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* methodName that will be used by the reader.
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* @param <T> The type of repository that will be used by the reader.
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*/
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public static class RepositoryMethodReference<T> {
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private RepositoryMethodIterceptor repositoryInvocationHandler;
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private PagingAndSortingRepository<?, ?> repository;
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public RepositoryMethodReference(PagingAndSortingRepository<?, ?> repository) {
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this.repository = repository;
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this.repositoryInvocationHandler = new RepositoryMethodIterceptor();
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}
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/**
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* The proxy returned prevents actual method execution and is only used to gather,
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* information about the method.
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* @return T is a proxy of the object passed in in the constructor
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*/
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public T methodIs() {
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Enhancer enhancer = new Enhancer();
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enhancer.setSuperclass(this.repository.getClass());
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enhancer.setCallback(this.repositoryInvocationHandler);
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return (T) enhancer.create();
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}
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public PagingAndSortingRepository<?, ?> getRepository() {
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return this.repository;
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}
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public String getMethodName() {
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return this.repositoryInvocationHandler.getMethodName();
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}
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public List<Object> getArguments() {
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return this.repositoryInvocationHandler.getArguments();
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}
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}
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private static class RepositoryMethodIterceptor implements MethodInterceptor {
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private String methodName;
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private List<Object> arguments;
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@Override
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public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
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this.methodName = method.getName();
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if (objects != null && objects.length > 1) {
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arguments = new ArrayList<>(Arrays.asList(objects));
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// remove last entry because that will be provided by the
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// RepositoryItemReader
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arguments.remove(objects.length - 1);
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}
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return null;
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}
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public String getMethodName() {
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return this.methodName;
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}
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public List<Object> getArguments() {
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return arguments;
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}
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}
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}
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