java读取文件并获得文件编码，转换为指定编码的工具类代码

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

public class Test {
    public static int fileCount = 0;
    public static String sourceFileRoot = "D:/workspace/test/src/com/zuidaima/"; // 将要转换文件所在的根目录
    public static String sourceCharset = "gbk"; // 源文件编码
    public static String targetCharset = "utf8"; // 目标文件编码

    public static void main(String[] args) throws IOException {
        File fileDir = new File(sourceFileRoot);
        convert(fileDir);
        System.out.println("Total Dealed : " + fileCount + "Files");
    }

    public static void convert(File file) throws IOException {
        // 如果是文件则进行编码转换，写入覆盖原文件
        if (file.isFile()) {
            // 只处理.java结尾的代码文件
            if (file.getPath().indexOf(".java") == -1) {
                return;
            }
            InputStreamReader isr = new InputStreamReader(new FileInputStream(
                    file), sourceCharset);
            BufferedReader br = new BufferedReader(isr);
            StringBuffer sb = new StringBuffer();
            String line = null;
            while ((line = br.readLine()) != null) {
                // 注意写入换行符
                sb.append(line + "\n");
            }
            br.close();
            isr.close();

            File targetFile = new File(file.getPath() + "." + targetCharset);
            OutputStreamWriter osw = new OutputStreamWriter(
                    new FileOutputStream(targetFile), targetCharset);
            BufferedWriter bw = new BufferedWriter(osw);
            // 以字符串的形式一次性写入
            bw.write(sb.toString());
            bw.close();
            osw.close();

            System.out.println("Deal:" + file.getPath());
            fileCount++;
        } else {
            for (File subFile : file.listFiles()) {
                convert(subFile);
            }
        }
    }

}