java 6 IO读取txt文件内容

逐行读取。

首先获取文件的编码格式；

读取文件内容。

 

log4j-1.2.17.jar

slf4j-api-1.4.3.jar

slf4j-log4j12-1.4.0.jar

 

1. 获取文件的编码格式

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

public class TxtCommonMethods {

	private static final Logger log = LoggerFactory
			.getLogger(TxtCommonMethods.class);

	/**
	 * @Title: getFileCharset
	 * @Description: 判断文件的编码格式
	 * @param filePath
	 *            文件绝对路径
	 * @return String
	 * @author 
	 * @date 2015年12月26日
	 */
	public static String getFileCharset(String filePath) {

		File file = new File(filePath);

		if (!file.exists()) {
			System.out.println("File not found.");
		}
		// 默认编码格式为GBK
		String charset = "GBK";

		FileInputStream is = null;
		BufferedInputStream bis = null;

		try {
			byte[] first3Bytes = new byte[3];

			boolean checked = false;

			is = new FileInputStream(file);

			bis = new BufferedInputStream(is);

			bis.mark(0);

			int read = bis.read(first3Bytes, 0, 3);

			if (-1 == read) {
				charset = "GBK";
			} else if (first3Bytes[0] == (byte) 0xFF
					&& first3Bytes[1] == (byte) 0xFE) {
				charset = "UTF-16LE";
				checked = true;
			} else if (first3Bytes[0] == (byte) 0xFE
					&& first3Bytes[1] == (byte) 0xFF) {
				charset = "UTF-16BE";
				checked = true;
			} else if (first3Bytes[0] == (byte) 0xEF
					&& first3Bytes[1] == (byte) 0xBB
					&& first3Bytes[2] == (byte) 0xBF) {
				charset = "UTF-8";
				checked = true;
			}
			bis.reset();

			if (!checked) {

				int loc = 0;

				while ((read = bis.read()) != -1) {

					loc++;

					if (read >= 0xF0) {
						break;
					}

					if (0x80 <= read && read <= 0xBF) {
						// 单独出现BF以下的,也算GBK
						break;
					}

					if (0x80 <= read && read <= 0xDF) {
						read = bis.read();
						if (0x80 <= read && read <= 0xBF) {
							// GBK
							continue;
						} else {
							break;
						}
					} else if (0xE0 <= read && read <= 0xEF) {
						read = bis.read();
						if (0x80 <= read && read <= 0xBF) {
							read = bis.read();
							if (0x80 <= read && read <= 0xBF) {
								charset = "UTF-8";
								break;
							} else {
								break;
							}
						} else {
							break;
						}
					}
				}
			}

		} catch (FileNotFoundException e) {
			log.error(
					"Get charset of '" + filePath + "' fail:" + e.getMessage(),
					e);
		} catch (IOException e) {
			log.error(
					"Get charset of '" + filePath + "' fail:" + e.getMessage(),
					e);
		} catch (Exception e) {
			log.error(
					"Get charset of '" + filePath + "' fail:" + e.getMessage(),
					e);
		} finally {
			TxtIOUtils.closeStream(bis, null);
			TxtIOUtils.closeStream(is, null);
		}

		return charset;
	}
}

 

2. 读取文件内容

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ReadLoadTxtFileRunnable implements Runnable {

	private static final Logger log = LoggerFactory
			.getLogger(ReadLoadTxtFileRunnable.class);

	private String filePath;
	
	public ReadLoadTxtFileRunnable(String filePath) {
		this.filePath = filePath;
	}

	@Override
	public void run() {
		this.read(filePath);
	}

	/**
	 * @Title: read
	 * @Description: 读取txt文件内容
	 * @param filePath
	 *            文件绝对路径
	 * @return List
	 * @author 
	 * @date 2015年12月26日
	 */
	private void read(String filePath) {

		log.info("Read Whole Grid Load txt file,filePath=" + filePath);

		filePath = null == filePath ? null : filePath.trim();

		if (null == filePath || "".equals(filePath)) {
			log.error("The filePath is null.");
			return null;
		}

		InputStream is = null;
		Reader reader = null;
		BufferedReader bufRead = null;

		try {
			is = new FileInputStream(filePath);

			// 判断文件的编码格式
			String charset = TxtCommonMethods.getFileCharset(filePath);

			log.info("The charset of '" + filePath + "' is:" + charset);

			reader = new InputStreamReader(is, charset);

			bufRead = new BufferedReader(reader);

			String line = null;

			String[] arrs = null;

			while ((line = bufRead.readLine()) != null) {

				System.out.println(line);
			}

		} catch (FileNotFoundException e) {
			log.error("Read file '" + filePath + "' fail:" + e.getMessage(), e);
		} catch (UnsupportedEncodingException e) {
			log.error("Read file '" + filePath + "' fail:" + e.getMessage(), e);
		} catch (IOException e) {
			log.error("Read file '" + filePath + "' fail:" + e.getMessage(), e);
		} catch (Exception e) {
			log.error("Read file '" + filePath + "' fail:" + e.getMessage(), e);
		} finally {
			TxtIOUtils.closeReader(bufRead);
			TxtIOUtils.closeReader(reader);
			TxtIOUtils.closeStream(is, null);
		}

		log.info("End of Read Whole Grid Load txt file");
	}
}

 

3.TxtIOUtils.java

public class TxtIOUtils {

	private static final Logger log = LoggerFactory.getLogger(TxtIOUtils.class);

	public static void closeStream(InputStream is, OutputStream out) {

		if (null != out) {
			try {
				out.close();
			} catch (IOException e) {
				log.error("Close OutputStream fail:" + e.getMessage(), e);
			}
			out = null;
		}

		if (null != is) {
			try {
				is.close();
			} catch (IOException e) {
				log.error("Close InputStream fail:" + e.getMessage(), e);
			}
			is = null;
		}
	}

	public static void closeReader(Reader reader) {

		if (null != reader) {
			try {
				reader.close();
			} catch (IOException e) {
				log.error("Close Reader fail:" + e.getMessage(), e);
			}
			reader = null;
		}
	}

	public static void closeWriter(Writer writer) {

		if (null != writer) {
			try {
				writer.close();
			} catch (IOException e) {
				log.error("Close Reader fail:" + e.getMessage(), e);
			}
			writer = null;
		}
	}

	public static void closeChannel(Channel c) {

		if (null != c) {
			try {
				c.close();
			} catch (IOException e) {
				log.error("Close Channel fail:" + e.getMessage(), e);
			}
			c = null;
		}
	}
}