Java判断文本文件编码的有用工具:juniversalchardet

一、juniversalchardet网盘下载

网盘下载：https://pan.baidu.com/s/1zuWq5JD2GzSf5rc6JZTb6g?pwd=yyds

二、文件工具类：FileUtils.java

文件工具类FileUtils.java

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;

public class FileUtils {

	public byte[] getContent(String filePath) throws IOException {
		File file = new File(filePath);
		long fileSize = file.length();
		if (fileSize > Integer.MAX_VALUE) {
			System.out.println("file too big...");
			return null;
		}
		FileInputStream fi = new FileInputStream(file);
		byte[] buffer = new byte[(int) fileSize];
		int offset = 0;
		int numRead = 0;
		while (offset < buffer.length && (numRead = fi.read(buffer, offset, buffer.length - offset)) >= 0) {
			offset += numRead;
		}
		// 确保所有数据均被读取
		if (offset != buffer.length) {
			throw new IOException("Could not completely read file " + file.getName());
		}
		fi.close();
		return buffer;
	}

	/**
	 * the traditional io way
	 * 
	 * @param filename
	 * @return
	 * @throws IOException
	 */
	public static byte[] toByteArray(String filename) throws IOException {
		File f = new File(filename);
		if (!f.exists()) {
			throw new FileNotFoundException(filename);
		}
		ByteArrayOutputStream bos = new ByteArrayOutputStream((int) f.length());
		BufferedInputStream in = null;
		try {
			in = new BufferedInputStream(new FileInputStream(f));
			int buf_size = 1024;
			byte[] buffer = new byte[buf_size];
			int len = 0;
			while (-1 != (len = in.read(buffer, 0, buf_size))) {
				bos.write(buffer, 0, len);
			}
			return bos.toByteArray();
		} catch (IOException e) {
			e.printStackTrace();
			throw e;
		} finally {
			try {
				in.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
			bos.close();
		}
	}

	/**
	 * NIO way
	 * 
	 * @param filename
	 * @return
	 * @throws IOException
	 */
	public static byte[] toByteArray2(String filename) throws IOException {
		File f = new File(filename);
		if (!f.exists()) {
			throw new FileNotFoundException(filename);
		}
		FileChannel channel = null;
		FileInputStream fs = null;
		try {
			fs = new FileInputStream(f);
			channel = fs.getChannel();
			ByteBuffer byteBuffer = ByteBuffer.allocate((int) channel.size());
			while ((channel.read(byteBuffer)) > 0) {
				// do nothing
				// System.out.println("reading");
			}
			return byteBuffer.array();
		} catch (IOException e) {
			e.printStackTrace();
			throw e;
		} finally {
			try {
				channel.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
			try {
				fs.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	/**
	 * Mapped File way MappedByteBuffer 可以在处理大文件时，提升性能
	 * 
	 * @param filename
	 * @return
	 * @throws IOException
	 */
	public static byte[] toByteArray3(String filename) throws IOException {
		FileChannel fc = null;
		try {
			fc = new RandomAccessFile(filename, "r").getChannel();
			MappedByteBuffer byteBuffer = fc.map(MapMode.READ_ONLY, 0, fc.size()).load();
			System.out.println(byteBuffer.isLoaded());
			byte[] result = new byte[(int) fc.size()];
			if (byteBuffer.remaining() > 0) {
				// System.out.println("remain");
				byteBuffer.get(result, 0, byteBuffer.remaining());
			}
			return result;
		} catch (IOException e) {
			e.printStackTrace();
			throw e;
		} finally {
			try {
				fc.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}

三、字符集检测工具类：CharsetDetectUtil.java

字符集检测工具类：CharsetDetectUtil.java

import org.mozilla.universalchardet.UniversalDetector;

import com.tzq.util.FileUtils;

public class CharsetDetectUtil {

	public static String detect(byte[] content) {
		UniversalDetector detector = new UniversalDetector(null);
		// 开始给一部分数据，让学习一下啊，官方建议是1000个byte左右（当然这1000个byte你得包含中文之类的）
		detector.handleData(content, 0, content.length);
		// 识别结束必须调用这个方法
		detector.dataEnd();
		// 神奇的时刻就在这个方法了，返回字符集编码。
		return detector.getDetectedCharset();
	}

	public static String guessEncoding(byte[] bytes) {
		String DEFAULT_ENCODING = "UTF-8";
		UniversalDetector detector = new UniversalDetector(null);
		detector.handleData(bytes, 0, bytes.length);
		detector.dataEnd();
		String encoding = detector.getDetectedCharset();
		detector.reset();
		if (encoding == null) {
			encoding = DEFAULT_ENCODING;
		}
		return encoding;
	}

	public static void main(String[] args) throws Exception {
		String filePath = "D:\\test\\2.sql";
		FileUtils fileUtils = new FileUtils();
		byte[] bytes = fileUtils.getContent(filePath);
		System.out.println(detect(bytes));
	}
}