Apache commons VFS 文件操作 源代码示例

通过VFS对文件进行一些操作，包括写入、读取文件，判断文件是否可读可写等示例。Apache commons VFS包和apache commons的其他基础性类有非常密切的关系。

整理了一些常用的方法，源代码如下：

package test.ffm83.commons.VFS;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.text.SimpleDateFormat;

import org.apache.commons.io.IOUtils;

import org.apache.commons.lang.StringUtils;

import org.apache.commons.vfs2.FileObject;

import org.apache.commons.vfs2.FileSystemException;

import org.apache.commons.vfs2.FileSystemManager;

import org.apache.commons.vfs2.FileType;

import org.apache.commons.vfs2.VFS;

/**

 * 通过VFS对文件进行一些操作，包括写入、读取文件，判断文件是否可读可写等使用2.0版本实现

 *

 * @author范芳铭

 */

public classVFSUtils {

    private static FileSystemManager fsManager = null;

    // 静态处理块

    static {

        try {

            fsManager = VFS.getManager();

        }catch(FileSystemException e) {

            e.printStackTrace();

        }

    }

    /**

     * <读取文件内容>

     */

    public static StringreadFileToString(String filePath, String encoding)

            throws IOException {

        if (StringUtils.isEmpty(filePath)){

            throw new IOException("File ‘"+ filePath + "‘ is empty.");

        }

        FileObjectfileObj = null;

        InputStreamin = null;

        try {

            fileObj= fsManager.resolveFile(filePath);

            if (fileObj.exists()) {

                if (FileType.FOLDER.equals(fileObj.getType())){

                    throw new IOException("File ‘"+ filePath

                            +"‘ exists but is a directory");

                }else{

                    in= fileObj.getContent().getInputStream();

                    return IOUtils.toString(in,encoding);

                    // 返回List<String>，通过 IOUtils.readLines(in, encoding)的形式；

                    // 返回byte[]，通过IOUtils.toByteArray(in)的形式;

                }

            }else{

                throw new FileNotFoundException("File ‘"+ filePath

                        +"‘ does not exist");

            }

        }catch(FileSystemException e) {

            throw new IOException("File ‘"+ filePath + "‘ resolveFile fail.");

        }finally{

            IOUtils.closeQuietly(in);

            if (fileObj != null) {

                fileObj.close();

            }

        }

    }

    /**

     * <将内容写入文件中,如果文件不存在，那么创建。> <功能详细描述>

     */

    public static voidwriteStringToFile(String filePath, String data,

            Stringencoding) throwsIOException {

        if (StringUtils.isEmpty(filePath)){

            throw new IOException("File ‘"+ filePath + "‘ is empty.");

        }

        FileObjectfileObj = null;

        OutputStreamout = null;

        try {

            fileObj= fsManager.resolveFile(filePath);

            if (!fileObj.exists()) {

                fileObj.createFile();

            }else{

                if (FileType.FOLDER.equals(fileObj.getType())){

                    throw new IOException("Write fail. File ‘"+ filePath

                            +"‘ exists but is a directory");

                }

            }

            // 处理文件不可写的异常

            if(!fileObj.isWriteable()) {

                throw new IOException("Write fail. File ‘"+ filePath

                        +"‘ exists but isWriteable is false.");

            }

            out= fileObj.getContent().getOutputStream();

            // commons io里的方法

            IOUtils.write(data,out, encoding);

        }catch(FileSystemException e) {

            throw new IOException("File ‘"+ filePath + "‘ resolveFile fail.");

        }finally{

            IOUtils.closeQuietly(out);

            if (fileObj != null) {

                fileObj.close();

            }

        }

    }

    /**

     * <修改文件的最后修改时间,将文件做旧。> <功能详细描述>

     */

    public static void_changeLastModificationTime(String filePath,

            StringlastTime) throwsException {

        if (StringUtils.isEmpty(filePath)|| StringUtils.isEmpty(lastTime)) {

            throw new IOException("File ‘"+ filePath + " or "+ lastTime

                    +"‘ is empty.");

        }

        SimpleDateFormatsdf = newSimpleDateFormat("yyyy/MM/dd HH:mm:ss");

        long lastModifyTime =sdf.parse(lastTime).getTime();

        FileObjectfileObj = null;

        try {

            fileObj= fsManager.resolveFile(filePath);

            fileObj.getContent().setLastModifiedTime(lastModifyTime);

        }catch(Exception e) {

            e.printStackTrace();

        }

    }

    public static void main(String[] args) throws Exception {

        Stringfile_encode = "D:\\ffm83\\ffm_encode.txt";

        Stringdata = "范芳铭在做Apache commons VFS简介的测试，关于ffm等";

        // write

        writeStringToFile(file_encode,data, "utf-8");

        System.out.println(StringUtils.center("write file "+ file_encode, 50,

                "-"));

        // read

        System.out.println(StringUtils.center("read file "+ file_encode, 50,

                "-"));

        StringreadStr = readFileToString(file_encode, "utf-8");

        System.out.println("读取的内容为：" + readStr);

        System.out.println(file_encode + ",可读？"

                +fsManager.resolveFile(file_encode).isReadable());

        System.out.println(file_encode + ",可写？"

                +fsManager.resolveFile(file_encode).isWriteable());

        //修改文件的最后的修改时间

        _changeLastModificationTime(file_encode,"2012/1/1 12:12:12");

        System.out.println(StringUtils.center("edit lastModifyTime: "+ file_encode, 50,

                "-"));

    }

}

运行结果如下：

--------write fileD:\ffm83\ffm_encode.txt--------

--------read file D:\ffm83\ffm_encode.txt---------

读取的内容为：范芳铭在做Apachecommons VFS简介的测试，关于ffm等

D:\ffm83\ffm_encode.txt,可读？true

D:\ffm83\ffm_encode.txt,可写？true

---edit lastModifyTime: D:\ffm83\ffm_encode.txt---

打开文件一看，文件的修改时间如期变成了2012年。