从头认识SpringBatch批处理框架---SkipListener

SkipListener在chunk处理阶段抛出跳过定义的异常时触发，在chunk的读、处理、写阶段发生的异常都会触发该拦截器

SkipListener接口声明:

/*
 * Copyright 2006-2007 the original author or authors.
 *
 * 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.springframework.batch.core;

/**
 * Interface for listener to skipped items. Callbacks will be called by
 * {@link Step} implementations at the appropriate time in the step lifecycle.
 * Implementers of this interface should not assume that any method will be 
 * called immediately after an error has been encountered.  Because there 
 * may be errors later on in processing the chunk, this listener will not be
 * called until just before committing.
 * 
 * @author Dave Syer
 * @author Robert Kasanicky
 * 
 */
public interface SkipListener<T,S> extends StepListener {

	/**
	 * Callback for a failure on read that is legal, so is not going to be
	 * re-thrown. In case transaction is rolled back and items are re-read, this
	 * callback will occur repeatedly for the same cause.  This will only happen
	 * if read items are not buffered.
	 * 
	 * @param t cause of the failure
	 */
	void onSkipInRead(Throwable t);

	/**
	 * This item failed on write with the given exception, and a skip was called
	 * for. 
	 * 
	 * @param item the failed item
	 * @param t the cause of the failure
	 */
	void onSkipInWrite(S item, Throwable t);

	/**
	 * This item failed on processing with the given exception, and a skip was called
	 * for. 
	 * 
	 * @param item the failed item
	 * @param t the cause of the failure
	 */
	void onSkipInProcess(T item, Throwable t);

}

SkipListener方法说明及注解定义

方法	方法说明	注解定义
onSkipInRead(Throwable t)	在读阶段发生异常并且配置了异常可以跳过时触发该操作	@OnSkipInRead
onSkipInWrite(String item, Throwable t)	在写阶段发生异常并且配置了异常可以跳过时触发该操作	@OnSkipInWrite
onSkipInProcess(String item, Throwable t)	在处理阶段发生异常并且配置了异常可以跳过时触发该操作	@OnSkipInProcess

SkipListener的默认实现接口

CompositeSkipListener ---组合跳过拦截器

MulticasterBatchListener--组合策略跳过拦截器

SkipListenerSupport----跳过拦截器默认实现

自定义SkipListener实现示例：

/**
 * 
 */
package com.juxtapose.example.ch05.step.listener;

import org.springframework.batch.core.SkipListener;
import org.springframework.batch.core.annotation.OnSkipInProcess;
import org.springframework.batch.item.file.FlatFileParseException;
import org.springframework.jdbc.core.JdbcTemplate;

/**
 * 自定义SkipListener
 * @author wbw
 *
 */
public class DBSkipListener implements SkipListener<String, String> {
	private JdbcTemplate jdbcTemplate;

	@OnSkipInProcess
	public void onSkipInRead(Throwable t) {
		if (t instanceof FlatFileParseException) {
			jdbcTemplate.update("insert into skipbills "
					+ "(line,content) values (?,?)",
					((FlatFileParseException) t).getLineNumber(),
					((FlatFileParseException) t).getInput());
		}
	}

	public void onSkipInWrite(String item, Throwable t) {
	}

	public void onSkipInProcess(String item, Throwable t) {
	}

	public JdbcTemplate getJdbcTemplate() {
		return jdbcTemplate;
	}

	public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
		this.jdbcTemplate = jdbcTemplate;
	}

}