批量删除UTF-8文件头BOM

批量移除UTF-8的BOM，其实质就是删除带有BOM信息的UTF-8文件的前三字节

先引入apache commons-io.jar包

import java.io.File;  
import java.io.IOException;  
import java.util.Collection;  
import org.apache.commons.io.DirectoryWalker;  
import org.apache.commons.io.FileUtils;  
import org.apache.commons.io.FilenameUtils;  
@SuppressWarnings("rawtypes")  
public class Utf8BomRemover extends DirectoryWalker {  
    public static void main(String[] args) throws IOException {  
        //删除指定文件夹下（含子文件夹）所有java文件的BOM，若构造器中参数为null则删除所有文件头部BOM  
        new Utf8BomRemover("java").start(new File("E:/workspace/Test/src"));  
    }  
    private String extension = null;  
    public Utf8BomRemover(String extension) {  
        super();  
        this.extension = extension;  
    }  
    /** 启动对某个文件夹的筛选 */  
    @SuppressWarnings("unchecked")  
    public void start(File rootDir) throws IOException {  
        walk(rootDir, null);  
    }  
    protected void handleFile(File file, int depth, Collection results) throws IOException {  
        if (extension == null  
                || extension.equalsIgnoreCase(FilenameUtils.getExtension(file.toString()))) {  
            //调用具体业务逻辑，其实这里不仅可以实现删除BOM，还可以做很多想干的事情。  
            remove(file);  
        }  
    }  
    /** 移除UTF-8的BOM */  
    private void remove(File file) throws IOException {  
        byte[] bs = FileUtils.readFileToByteArray(file);  
        if (bs[0] == -17 && bs[1] == -69 && bs[2] == -65) {  
            byte[] nbs = new byte[bs.length - 3];  
            System.arraycopy(bs, 3, nbs, 0, nbs.length);  
            FileUtils.writeByteArrayToFile(file, nbs);  
            System.out.println("Remove BOM: " + file);  
        }  
    }  
}