从头认识SpringBatch批处理框架---SkipListener

╰+哭是因爲堅強的太久メ 2022-08-20 13:22 174阅读 0赞

**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

<table> 
 <tbody> 
  <tr> 
   <td>方法</td> 
   <td>方法说明</td> 
   <td>注解定义</td> 
  </tr> 
  <tr> 
   <td>onSkipInRead(Throwable t)</td> 
   <td>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</td> 
   <td>@OnSkipInRead</td> 
  </tr> 
  <tr> 
   <td>onSkipInWrite(String item, Throwable t)</td> 
   <td>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</td> 
   <td>@OnSkipInWrite</td> 
  </tr> 
  <tr> 
   <td>onSkipInProcess(String item, Throwable t)</td> 
   <td>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</td> 
   <td>@OnSkipInProcess</td> 
  </tr> 
 </tbody> 
</table>

**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;
    	}
    
    }