UTF-8转换成GBK

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;

public class FindAllTxtFile {

	private static String content;

	public static void main(String[] args) throws Exception {
		// 递归显示C盘下所有文件夹及其中文件
		File root = new File("c:/app");
		showAllFiles(root);
	}

	public static String PrintOut(String context, String encodeFormat) {
		if (encodeFormat == null || encodeFormat.equals(""))
			encodeFormat = "UTF-8";

		try {
			byte[] content = context.getBytes();

			String result = new String(content, encodeFormat);
			return result;
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}

		return "";
	}

	public static String readFile(String path, String encodeFormat) {

		try {
			String context = "";
			InputStreamReader is;
			is = new InputStreamReader(new FileInputStream(path), encodeFormat);
			BufferedReader br = new BufferedReader(is);
			String line;

			while ((line = br.readLine()) != null) {
				context += line + "\r\n";
				// System.out.println(line);
			}
			br.close();
			return context;
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return "";
	}

	/**
	 * 将内容输出为指定格式的文件保存到磁盘上
	 * 
	 * @param context
	 * @param path
	 * @param destEncode
	 */
	public static void writeFile(String context, String path, String destEncode) {
		File file = new File(path);
		if (file.exists())
			file.delete();
		BufferedWriter writer;

		try {
			FileOutputStream fos = new FileOutputStream(path);
			writer = new BufferedWriter(new OutputStreamWriter(fos, destEncode));
			writer.append(context);
			writer.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	final static void showAllFiles(File dir) throws Exception {
		File[] fs = dir.listFiles();
		for (int i = 0; i < fs.length; i++) {

			if (fs[i].isDirectory()) {
				try {
					showAllFiles(fs[i]);
				} catch (Exception e) {
				}
			} else {
				if (fs[i].getPath().endsWith(".java") || fs[i].getAbsolutePath().endsWith(".xml")) {
					String filePath;
					filePath = fs[i].getAbsolutePath();
					System.out.println(fs[i].getName());
					//System.out.println(filePath);
					content = readFile(filePath, "UTF-8");
					// System.out.println(content);
					writeFile(content, "c:/test/" + fs[i].getName(), "GBK");
				}
			}
		}
	}

}

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;

public class TxtFormatTransfer {
	public static String DefaultSrcEncodeFormat = "UTF-8";
	public static String DefaultDestEncodeFormat = "GBK";
	public static String UnsupportedEncodingExceptionError = "编码格式错误！";
	public static String FileNotFoundExceptionError = "文件不存在！";
	public static String IOExceptionError = "文件读写错误！";
	public static String IsUtf8File = "文件是UTF-8编码格式！";
	public static String IsNotUtf8File = "文件不是UTF-8编码格式！";

	public static String readFile(String path, String encodeFormat) {
		if ((encodeFormat == null || encodeFormat.equals(""))) {
			if (isUTF8File(path)) {
				encodeFormat = DefaultDestEncodeFormat;
			} else {
				encodeFormat = DefaultSrcEncodeFormat;
			}
		}

		try {
			String context = "";
			InputStreamReader isr;
			isr = new InputStreamReader(new FileInputStream(path), encodeFormat);
			BufferedReader br = new BufferedReader(isr);
			String line;

			while ((line = br.readLine()) != null) {
				context += line + "\r\n";
				System.out.println(line);
			}

			br.close();

			return context;
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			System.out.println(UnsupportedEncodingExceptionError);
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			System.out.println(FileNotFoundExceptionError);
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			System.out.println(IOExceptionError);
			e.printStackTrace();
		}
		;

		return "";
	}	
	/**
	 * Unicode、Unicode big endian和UTF-8编码的txt文件的开头会多出几个字节，
	 * 分别是FF、FE（Unicode）,FE、FF（Unicode bigendian）,EF、BB、BF（UTF-8）
	 * 
	 * @param path
	 * @return
	 */
	public static boolean isUTF8File(String path) {

		File file = new File(path);
		byte[] buf = new byte[3];
		FileInputStream is = null;

		try {
			is = new FileInputStream(file);
			int read = is.read(buf, 0, 3);
			System.out.println("" + buf[0] + " " + buf[1] + " " + buf[2]);
			return false;
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				is.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

		return false;
	}

	public static String transfer(String context, String encodeFormat) {
		if (encodeFormat == null || encodeFormat.equals(""))
			encodeFormat = DefaultDestEncodeFormat;

		try {
			byte[] content = context.getBytes();

			String result = new String(content, encodeFormat);
			return result;
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			System.out.println(UnsupportedEncodingExceptionError);
			e.printStackTrace();
		}

		return "";
	}

	public static void writeFile(String context, String path, String destEncode) {
		File file = new File(path);
		if (file.exists())
			file.delete();
		BufferedWriter writer;

		try {
			FileOutputStream fos = new FileOutputStream(path, true);
			writer = new BufferedWriter(new OutputStreamWriter(fos, destEncode));
			writer.append(context);
			writer.close();
		} catch (IOException e) {
			System.out.println(IOExceptionError);
			e.printStackTrace();
		}
	}

	public static void writeFile(String context, String path) {
		File file = new File(path);
		if (file.exists())
			file.delete();
		Writer writer;

		try {
			writer = new FileWriter(file, true);
			writer.append(context);
			writer.close();
		} catch (IOException e) {
			System.out.println(IOExceptionError);
			e.printStackTrace();
		}
	}

	public static void transfer(String srcPath, String destPath, String srcEncode, String destEncode) {
		if (destPath == null || destPath.equals(""))
			destPath = srcPath;

		String context = readFile(srcPath, srcEncode);

		context = transfer(context, destEncode);
		writeFile(context, destPath, destEncode);
	}

	public static void transfer(String srcPath, String destPath, String destEncode) {
		//if (isUTF8File(srcPath) == false) {
			transfer(srcPath, destPath, DefaultSrcEncodeFormat, "GBK");
		//}
	}

	public static void main(String args[]) {
		String path1 = "RetrofitSingleton.java";

		transfer(path1, path1, "GBK");
	}
}