java实现文件编码转换的方法

package com.mikan.stuff;  import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.FilenameFilter; import java.io.InputStream; import java.io.InputStreamReader; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.nio.charset.Charset; import java.nio.charset.UnsupportedCharsetException;  public class FileCharsetConverter {    public static void main(String[] args) throws Exception {     convert("D://stuff//src//main//java//com//mikan//stuff//test.txt",         "GBK", "UTF-8", new FilenameFilter() {           @Override           public boolean accept(File dir, String name) {             return name.endsWith("txt");           }         });   }    /**    * 把指定文件或目录转换成指定的编码    *    * @param fileName    *      要转换的文件    * @param fromCharsetName    *      源文件的编码    * @param toCharsetName    *      要转换的编码    * @throws Exception    */   public static void convert(String fileName, String fromCharsetName,       String toCharsetName) throws Exception {     convert(new File(fileName), fromCharsetName, toCharsetName, null);   }    /**    * 把指定文件或目录转换成指定的编码    *    * @param file    *      要转换的文件或目录    * @param fromCharsetName    *      源文件的编码    * @param toCharsetName    *      要转换的编码    * @throws Exception    */   public static void convert(File file, String fromCharsetName,       String toCharsetName) throws Exception {     convert(file, fromCharsetName, toCharsetName, null);   }    /**    * 把指定文件或目录转换成指定的编码    *    * @param file    *      要转换的文件或目录    * @param fromCharsetName    *      源文件的编码    * @param toCharsetName    *      要转换的编码    * @param filter    *      文件名过滤器    * @throws Exception    */   public static void convert(String fileName, String fromCharsetName,       String toCharsetName, FilenameFilter filter) throws Exception {     convert(new File(fileName), fromCharsetName, toCharsetName, filter);   }    /**    * 把指定文件或目录转换成指定的编码    *    * @param file    *      要转换的文件或目录    * @param fromCharsetName    *      源文件的编码    * @param toCharsetName    *      要转换的编码    * @param filter    *      文件名过滤器    * @throws Exception    */   public static void convert(File file, String fromCharsetName,       String toCharsetName, FilenameFilter filter) throws Exception {     if (file.isDirectory()) {       File[] fileList = null;       if (filter == null) {         fileList = file.listFiles();       } else {         fileList = file.listFiles(filter);       }       for (File f : fileList) {         convert(f, fromCharsetName, toCharsetName, filter);       }     } else {       if (filter == null           || filter.accept(file.getParentFile(), file.getName())) {         String fileContent = getFileContentFromCharset(file,             fromCharsetName);         saveFile2Charset(file, toCharsetName, fileContent);       }     }   }    /**    * 以指定编码方式读取文件，返回文件内容    *    * @param file    *      要转换的文件    * @param fromCharsetName    *      源文件的编码    * @return    * @throws Exception    */   public static String getFileContentFromCharset(File file,       String fromCharsetName) throws Exception {     if (!Charset.isSupported(fromCharsetName)) {       throw new UnsupportedCharsetException(fromCharsetName);     }     InputStream inputStream = new FileInputStream(file);     InputStreamReader reader = new InputStreamReader(inputStream,         fromCharsetName);     char[] chs = new char[(int) file.length()];     reader.read(chs);     String str = new String(chs).trim();     reader.close();     return str;   }    /**    * 以指定编码方式写文本文件，存在会覆盖    *    * @param file    *      要写入的文件    * @param toCharsetName    *      要转换的编码    * @param content    *      文件内容    * @throws Exception    */   public static void saveFile2Charset(File file, String toCharsetName,       String content) throws Exception {     if (!Charset.isSupported(toCharsetName)) {       throw new UnsupportedCharsetException(toCharsetName);     }     OutputStream outputStream = new FileOutputStream(file);     OutputStreamWriter outWrite = new OutputStreamWriter(outputStream,         toCharsetName);     outWrite.write(content);     outWrite.close();   } }