用java修改文件的编码

1、将本地的文件转换成另外一种编码输出，主要逻辑代码如下：

  /**
      * 将本地文件以哪种编码输出
      * @param inputfile 输入文件的路径
      * @param outfile 输出文件的路径
      * @param code 输出文件的编码
      * @throws IOException
      */
     public  void convert(String inputfile,String outfile,String code) throws IOException {
         StringBuffer sb = new StringBuffer();
         //得到当前文件的编码
         String ch=getCharset(inputfile);
         InputStreamReader isr=null;
         OutputStreamWriter osw =null;
         //根据当前文件编码进行解码
         if(ch.equals("UTF8")){
             isr= new InputStreamReader(new FileInputStream(inputfile), "UTF-8");
         }else if(ch.equals("Unicode")){
             isr= new InputStreamReader(new FileInputStream(inputfile), "Unicode");
         }else {
             isr= new InputStreamReader(new FileInputStream(inputfile), "GB2312");
         }
         //将字符串存入StringBuffer中
         BufferedReader br = new BufferedReader(isr);
         String line = null;
         while ((line = br.readLine()) != null) {
             sb.append(line + "\n");
         }
         br.close();
         isr.close();

         //以哪种方式写入文件
         if("UTF-8".equals(code)){
             osw = new OutputStreamWriter(new FileOutputStream(outfile), "UTF-8");
         }else if("GB2312".equals(code)){
             osw = new OutputStreamWriter(new FileOutputStream(outfile), "GB2312");
         }else if("Unicode".equals(code)){
             osw = new OutputStreamWriter(new FileOutputStream(outfile), "Unicode");
         }else{
             osw = new OutputStreamWriter(new FileOutputStream(outfile), "UTF-8");
         }
         BufferedWriter bw = new BufferedWriter(osw);
         bw.write(sb.toString());
         bw.close();
         osw.close();
     }

 /**
      * 根据文件路径判断编码
      * @param str
      * @return
      * @throws IOException
      */
     private String getCharset(String str) throws IOException{
         BytesEncodingDetect s = new BytesEncodingDetect();
         String code = BytesEncodingDetect.javaname[s.detectEncoding(new File(str))];
         return code;
     } 

2、将远程的文件转换成自己想要的编码，然后写入本地

 /**
      * 将远程文件以哪种编码输出到本地
      * @param fileurl 远程文件的URL
      * @param outfile 输出文件的路径
      * @param code 以哪种编码输出
      * @throws Exception
      */
     public void Remote(String fileurl,String outfile,String code) throws Exception{
         //        String str="http://172.18.1.103:8080/kms/text.txt";
         URL url =new URL(fileurl);
         HttpURLConnection urlCon = (HttpURLConnection)url.openConnection();
         //设置连接超时和读取超时
         urlCon.setConnectTimeout(5000);
         urlCon.setReadTimeout(5000);
         //得到远程文件的编码
         String ch=getCharset_Remote(fileurl);
         //文件写入流
         OutputStreamWriter osw =null;
         BufferedReader br=null;
         //将字符串保存到临时的StringBuffer中
         StringBuffer sb = new StringBuffer();
         if(ch.equals("UTF8")){
             br =new BufferedReader(new InputStreamReader( urlCon.getInputStream(),"UTF-8"));
             String line = null;
             while ((line = br.readLine()) != null) {
                 sb.append(line + "\n");
             }
         }
         else if(ch.equals("Unicode")){
             br =new BufferedReader(new InputStreamReader( urlCon.getInputStream(),"Unicode"));
             String line = null;
             while ((line = br.readLine()) != null) {
                 sb.append(line + "\n");
             }
         }
         else{
             br =new BufferedReader(new InputStreamReader( urlCon.getInputStream(),"GB2312"));
             String line = null;
             while ((line = br.readLine()) != null) {
                 sb.append(line + "\n");
             }
         }
         br.close();    

         //以哪种方式写入文件
         if("UTF-8".equals(code)){
             osw = new OutputStreamWriter(new FileOutputStream(outfile), "UTF-8");
         }else if("GB2312".equals(code)){
             osw = new OutputStreamWriter(new FileOutputStream(outfile), "GB2312");
         }else if("Unicode".equals(code)){
             osw = new OutputStreamWriter(new FileOutputStream(outfile), "Unicode");
         }else{
             osw = new OutputStreamWriter(new FileOutputStream(outfile), "UTF-8");
         }
         BufferedWriter bw = new BufferedWriter(osw);
         bw.write(sb.toString());
         bw.close();
         osw.close();
     } 

 /**
      * 根据文件路径判断远程文件编码
      * @param str
      * @return
      * @throws IOException
      */
     private String getCharset_Remote(String str) throws IOException{
         URL url =new URL(str);
         BytesEncodingDetect s = new BytesEncodingDetect();
         String fileCode = BytesEncodingDetect.javaname[s.detectEncoding(url)];
         return fileCode;
     }

3、测试代码：

 package com.zhang.test;

 public class test {
     public static void main(String[] args) {
         String inputfile="D:/gbk.txt";
         String outfile="D:/utf8.txt";
         String outfileurl="D:/utf8url.txt";
         String fileurl="http://127.0.0.1:8080/jsp/gbk.txt";
 //        String file="D:/unicode.txt";
         Convert_Code code=new Convert_Code();
         try {
             code.convert(inputfile,outfile,"UTF-8");
             code.Remote(fileurl, outfileurl, "UTF-8");
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }

注意：这两个方法引用了BytesEncodingDetect.java文件

此案例的下载链接：http://download.csdn.net/detail/u013865056/9908100