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spring batch 2.1.0 » org » springframework » batch » item » file » FlatFileItemReader.java
/*
 * 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.item.file;

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.charset.Charset;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.batch.item.ItemReader;
import org.springframework.batch.item.ReaderNotOpenException;
import org.springframework.batch.item.file.separator.RecordSeparatorPolicy;
import org.springframework.batch.item.file.separator.SimpleRecordSeparatorPolicy;
import org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.io.Resource;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;

/**
 * Restartable {@link ItemReader} that reads lines from input
 * {@link #setResource(Resource)}. Line is defined by the
 * {@link #setRecordSeparatorPolicy(RecordSeparatorPolicy)} and mapped to item
 * using {@link #setLineMapper(LineMapper)}.
 * 
 * @author Robert Kasanicky
 */
public class FlatFileItemReader<T> extends AbstractItemCountingItemStreamItemReader<T> implements
    ResourceAwareItemReaderItemStream<T>, InitializingBean {

  private static final Log logger = LogFactory.getLog(FlatFileItemReader.class);

  // default encoding for input files
  public static final String DEFAULT_CHARSET = Charset.defaultCharset().name();

  private RecordSeparatorPolicy recordSeparatorPolicy = new SimpleRecordSeparatorPolicy();

  private Resource resource;

  private BufferedReader reader;

  private int lineCount = 0;

  private String[] comments = new String[] { "#" };

  private boolean noInput = false;

  private String encoding = DEFAULT_CHARSET;

  private LineMapper<T> lineMapper;

  private int linesToSkip = 0;

  private LineCallbackHandler skippedLinesCallback;

  private boolean strict = true;

  private BufferedReaderFactory bufferedReaderFactory = new DefaultBufferedReaderFactory();

  public FlatFileItemReader() {
    setName(ClassUtils.getShortName(FlatFileItemReader.class));
  }

  /**
   * In strict mode the reader will throw an exception on
   * {@link #open(org.springframework.batch.item.ExecutionContext)} if the
   * input resource does not exist.
   * @param strict false by default
   */
  public void setStrict(boolean strict) {
    this.strict = strict;
  }

  /**
   * @param skippedLinesCallback will be called for each one of the initial
   * skipped lines before any items are read.
   */
  public void setSkippedLinesCallback(LineCallbackHandler skippedLinesCallback) {
    this.skippedLinesCallback = skippedLinesCallback;
  }

  /**
   * Public setter for the number of lines to skip at the start of a file. Can
   * be used if the file contains a header without useful (column name)
   * information, and without a comment delimiter at the beginning of the
   * lines.
   * 
   * @param linesToSkip the number of lines to skip
   */
  public void setLinesToSkip(int linesToSkip) {
    this.linesToSkip = linesToSkip;
  }

  /**
   * Setter for line mapper. This property is required to be set.
   * @param lineMapper maps line to item
   */
  public void setLineMapper(LineMapper<T> lineMapper) {
    this.lineMapper = lineMapper;
  }

  /**
   * Setter for the encoding for this input source. Default value is
   * {@link #DEFAULT_CHARSET}.
   * 
   * @param encoding a properties object which possibly contains the encoding
   * for this input file;
   */
  public void setEncoding(String encoding) {
    this.encoding = encoding;
  }

  /**
   * Factory for the {@link BufferedReader} that will be used to extract lines
   * from the file. The default is fine for plain text files, but this is a
   * useful strategy for binary files where the standard BufferedReaader from
   * java.io is limiting.
   * 
   * @param bufferedReaderFactory the bufferedReaderFactory to set
   */
  public void setBufferedReaderFactory(BufferedReaderFactory bufferedReaderFactory) {
    this.bufferedReaderFactory = bufferedReaderFactory;
  }

  /**
   * Setter for comment prefixes. Can be used to ignore header lines as well
   * by using e.g. the first couple of column names as a prefix.
   * 
   * @param comments an array of comment line prefixes.
   */
  public void setComments(String[] comments) {
    this.comments = new String[comments.length];
    System.arraycopy(comments, 0, this.comments, 0, comments.length);
  }

  /**
   * Public setter for the input resource.
   */
  public void setResource(Resource resource) {
    this.resource = resource;
  }

  /**
   * Public setter for the recordSeparatorPolicy. Used to determine where the
   * line endings are and do things like continue over a line ending if inside
   * a quoted string.
   * 
   * @param recordSeparatorPolicy the recordSeparatorPolicy to set
   */
  public void setRecordSeparatorPolicy(RecordSeparatorPolicy recordSeparatorPolicy) {
    this.recordSeparatorPolicy = recordSeparatorPolicy;
  }

  /**
   * @return string corresponding to logical record according to
   * {@link #setRecordSeparatorPolicy(RecordSeparatorPolicy)} (might span
   * multiple lines in file).
   */
  @Override
  protected T doRead() throws Exception {
    if (noInput) {
      return null;
    }

    String line = readLine();
    
    if (line == null) {
      return null;
    }
    else {
      try{
        return lineMapper.mapLine(line, lineCount);
      }
      catch(Exception ex){
        logger.error("Parsing error at line: " + lineCount + " in resource=" + 
            resource.getDescription() + ", input=[" + line + "]", ex);
        throw ex;
      }
    }
  }

  /**
   * @return next line (skip comments).
   */
  private String readLine() {

    if (reader == null) {
      throw new ReaderNotOpenException("Reader must be open before it can be read.");
    }

    String line = null;

    try {
      line = this.reader.readLine();
      if (line == null) {
        return null;
      }
      lineCount++;
      while (isComment(line)) {
        line = reader.readLine();
        if (line == null) {
          return null;
        }
        lineCount++;
      }
      
      line = applyRecordSeparatorPolicy(line);
    }
    catch (IOException e) {
      throw new FlatFileParseException("Unable to read from resource: [" + resource + "]", e, line, lineCount);
    }
    return line;
  }

  private boolean isComment(String line) {
    for (String prefix : comments) {
      if (line.startsWith(prefix)) {
        return true;
      }
    }
    return false;
  }

  @Override
  protected void doClose() throws Exception {
    lineCount = 0;
    if (reader != null) {
      reader.close();
    }
  }

  @Override
  protected void doOpen() throws Exception {
    Assert.notNull(resource, "Input resource must be set");
    Assert.notNull(recordSeparatorPolicy, "RecordSeparatorPolicy must be set");

    noInput = false;
    if (!resource.exists()) {
      if (strict) {
        throw new IllegalStateException("Input resource must exist (reader is in 'strict' mode): " + resource);
      }
      noInput = true;
      logger.warn("Input resource does not exist " + resource.getDescription());
      return;
    }

    if (!resource.isReadable()) {
      if (strict) {
        throw new IllegalStateException("Input resource must be readable (reader is in 'strict' mode): " + resource);
      }
      noInput = true;
      logger.warn("Input resource is not readable " + resource.getDescription());
      return;
    }

    reader = bufferedReaderFactory.create(resource, encoding);
    for (int i = 0; i < linesToSkip; i++) {
      String line = readLine();
      if (skippedLinesCallback != null) {
        skippedLinesCallback.handleLine(line);
      }
    }
  }

  public void afterPropertiesSet() throws Exception {
    Assert.notNull(lineMapper, "LineMapper is required");
  }
  
  @Override
  protected void jumpToItem(int itemIndex) throws Exception {
    for (int i = 0; i < itemIndex; i++) {
      readLine();
    }
  }
  
  private String applyRecordSeparatorPolicy(String line) throws IOException{
    
    String record = line;
    while (line != null && !recordSeparatorPolicy.isEndOfRecord(record)) {
      line = this.reader.readLine();
      if (line == null) {
        if (StringUtils.hasText(record)) {
          // A record was partially complete since it hasn't ended but
          // the line is null
          throw new FlatFileParseException("Unexpected end of file before record complete", record, lineCount);
        }
        else {
          // Record has no text but it might still be post processed
          // to something (skipping preProcess since that was already done)
          break;
        }
      } else {
        lineCount++;
            }
      record = recordSeparatorPolicy.preProcess(record) + line;
    }
    
    return recordSeparatorPolicy.postProcess(record);
    
  }


}
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