File操作-使用NIO进行文件的读写与复制

来源：互联网发布：我的世界1.7.10java 编辑：程序博客网时间：2024/05/22 13:03
Tips-1：并不是所有的IO流类都支持NIO操作的，支持的类有FileInputStream、FileOutputStream和RandomAccessFile.
/*文件读取，返回读取内容*/    public static String fileReader(File fileName){        String fileContent = null;        FileInputStream fis = null;        FileChannel fc = null;        ByteBuffer bb ;        try {            fis = new FileInputStream(fileName);            fc = fis.getChannel();            bb = ByteBuffer.allocate(10000);            /*读入到bb里面*/            fc.read(bb);            /*这里一定不要省略*/            bb.flip();            fileContent = new String(bb.array());        } catch (Exception e) {            e.printStackTrace();        }finally{            try {                fc.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            try {                fis.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        return fileContent;    }    /*    fileName:要写入的目标文件；    s:要写入的信息；     */    public static void fileWriter(File fileName,String s){        String fileContent = null;        FileOutputStream fos = null;        FileChannel fc = null;        byte[] bts = s.getBytes();        try {            fc = new FileOutputStream(fileName).getChannel();            ByteBuffer bb = ByteBuffer.allocate(bts.length);            /*将bts放入bb里面*/            bb.put(bts);            bb.flip();            /*从缓冲区块读出*/            fc.write(bb);        } catch (Exception e) {            e.printStackTrace();        }finally{            try {                fc.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            try {                fos.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }            }    }    /*进行文件复制*/    public static void copy(String srcFile,String destFile){        long begin = System.currentTimeMillis();        FileInputStream fis = null;        FileOutputStream fos = null;        FileChannel in = null;        FileChannel out =null;        ByteBuffer bb = null;        try {            /* get NIO read channel */            fis = new FileInputStream(srcFile);            in = fis.getChannel();            /* get NIO write channel*/            fos = new FileOutputStream(destFile);            out = fos.getChannel();            bb = ByteBuffer.allocate(100000);            int len = 0;            while((len = in.read(bb)) != -1){                /*在write前，set the limit and position*/                bb.flip();                /*write form position to limit */                out.write(bb);                /*init positon/limit/capcity,prepare to the next loop*/                bb.clear();            }            long end = System.currentTimeMillis();            System.out.println("use time ："+(end-begin));            out.close();            in.close();            fos.close();            fis.close();        } catch (Exception e) {            // TODO: handle exception            e.printStackTrace();        }    }
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