文件处理常用方法

1.通过递归算法查找指定文件

public class FileSearch {

    /**
     * 
     * @param args
     * @Description: 测试该类
     */
    public static void main(String[] args) {
        FileFilter filter = new FileFilter() {

            public boolean accept(File pathname) {
              
                return pathname.getName().equals("aa.xml");
            }
        };
        List<File> list = search("./sjs/xml", filter);

        for (File file : list) {
            System.out.println(file.getName());
        }

    }

    public static List<File> search(String filePath, FileFilter filter) {
        return search(new File(filePath), filter);
    }

    // 递归算法遍历指定文件
    public static List<File> search(File file, FileFilter filter) {
        List<File> result = new LinkedList<File>();
        if (!file.exists()) {
            return null;
        }

        if (file.isDirectory()) {
            File[] subs = file.listFiles();
            if (subs != null) {
                for (File sub : subs) {
                    result.addAll(search(sub, filter));
                }
            }
        }
        if (filter.accept(file)) {
            result.add(file);
        }
        return result;

    }
}

 2.通过递归算法删除指定文件

 

public class FileDelete {
    
    //删除指定目录下以".txt"结尾的文件
    public static void main(String...filter) {
        deleteFile("./sjs/xml", new FileFilter(){
            public boolean accept(File pathname) {
                return pathname.getName().endsWith(".txt");
            }
            
        });
    }

    public static void deleteFile(String filePath,FileFilter filter) {
        if(filePath == null || "".equals(filePath)) {
            return  ;
        }
        //如果过滤器为空，为了防止删去所有的文件，故不做删除操作
        if(filter == null ) {
            return ;
        }
        deleteFile(new File(filePath), filter) ;
    }
    
    private static void deleteFile(File file,FileFilter filter) {
        if(!file.exists()) {
            return ;
        }
        if(file.isDirectory()) {
            File[] subs = file.listFiles(filter) ;
            if(subs != null ) {
                for(File sub : subs ) {
                    deleteFile(sub, filter) ;
                }
            }
        }
        if(filter.accept(file)) {
            file.delete() ;
        }
    }
}

 3.文件切割器

public class FileSplit {
    
    public static void main(String...output) {
        long start = System.currentTimeMillis() ;
        split("C:\\fileparse\\nohup.out","C:\\logs",1024*1024*4L) ;
        System.out.println(System.currentTimeMillis() - start) ;
    }
    
    
    public static void split(String source, String output, long capcity) {
        File sourceFile = new File(source);
        long length = sourceFile.length();
        if (length <= 0) {
            return;
        }
        if (capcity <= 0) {
            capcity = 1024 * 1024L;
        }
        long size = (length % capcity == 0) ? length / capcity : length / capcity + 1;
        InputStream is = null;
        OutputStream out = null;
        try {
            is = new FileInputStream(sourceFile);
            byte[] once = new byte[(int) capcity];
            int readReally = 0;
            for (int start = (int) size; start > 0; start--) {
                try {
                    readReally = is.read(once);
                    byte[] really = new byte[readReally];
                    System.arraycopy(once, 0, really, 0, readReally);
                    out = new FileOutputStream(new File(output, sourceFile.getName()+"-" + start), false);
                    out.write(really);
                    out.flush();
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    if (out != null) {
                        try {
                            out.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }

            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}