文件复制public static void main(String[] args)throws IOException{    String str=new String();    try{        BufferedReader in=new BufferedReader(new FileReader("c:\\7\\1.txt"));        BufferedWriter out = new BufferedWriter(new FileWriter("c:\\7\\8.txt"));        while((str=in.readLine())!=null){            System.out.println(str);            out.write(str);            out.newLine();        }        out.flush();        in.close();        out.close( );    }catch(IOException ex){        System.out.println("错误！"+ex);    }}对文件的随机访问    类 RandomAccessFile    构造函数：    RandomAccessFile(String name,String mode)        参数name:确定一个文件名，给出流的源（目的地），参数mode取r(只读)、rw(可读写)    RandomAccessFile(File name,String mode)        参数File：是一个File对象，给出流的源（目的地），提供一个方法：    seek(long a)        定位RandomAccessFile流的读写位置。参数a为读写位置距离文件开头的字节个数。    getFilePoint( )方法获得流的当前读写位置。    public static void main(String[] args) throws IOException {        try{            RandomAccessFile in;            int data[]={1,2,3,4,5,6,7,8,9,10};            in=new RandomAccessFile("c:\\tom.out","rw");            for(int i=0;i<data.length;i++)                in.writeInt(data[i]);            for(long j=data.length-1;j>=0;j--){                in.seek(j*4);                System.out.print(","+in.readInt());            }            in.close( );        }catch(Exception ex){                }        try{            RandomAccessFile in;            in=new  RandomAccessFile("c:\\FileInputStreamDemo.java","rw");            long filePoint=0;            long fileLength=in.length();            while(filePoint<fileLength){                String s=in.readLine();                System.out.println(s);                filePoint=in.getFilePointer();            }            in.close( );        }catch(Exception ex){               }    }    DataInputStream 和 DataOutputStream            构造方法        DataInputStream(InputStream in)        DataOutputStream(OutputStream out)Serialization串行化（序列化）            当对象保存到文件或从文件中读取对象时，对象必须实现Serialization序列化。    对象必须实现接口 java.io.Serializable    public class Date extends Object implements Serializable, Cloneable, ComparableObjectInputStream 和 ObjectOutputStream    可以传对象    构造方法        ObjectInputStream(InputStream in)        ObjectOutputStream(OutputStream out)    方法：readObject()/writeObject()        class Student implements Serializable{        String name;        double height;        Student(String name,double height){           this.name=name;           this.height=height;        }        public void setHeight(double c){           this.height=c;        }    }    public static void main(String[] args) throws IOException {      Student stu=new Student("张三",1.65);      try{      FileOutputStream out=new FileOutputStream("c:\\k.txt");      ObjectOutputStream object_out=new ObjectOutputStream(out);      object_out.writeObject(stu);      FileInputStream in=new FileInputStream("c:\\k.txt");      ObjectInputStream object_in=new ObjectInputStream(in);      Student li=(Student)object_in.readObject();      li.setHeight(1.78);      li.name="李四";      System.out.println(stu.name+stu.height);      System.out.println(li.name+li.height);      }catch(Exception ex){      }对象的复制        public static void main(String[] args) throws IOException {        Student stu=new Student("张三",1.65);        try{            ByteArrayOutputStream outone=new ByteArrayOutputStream( );            ObjectOutputStream object_out=new ObjectOutputStream(outone);            object_out.writeObject(stu);            ByteArrayInputStream inone=new       ByteArrayInputStream(outone.toByteArray());            ObjectInputStream intwo=new ObjectInputStream(inone);            Student li=(Student)intwo.readObject();            System.out.println(stu.name+stu.height);            System.out.println(li.name+li.height);         }catch(Exception ex){                }    }    java文件的管理创建文件夹：在指定的目录下创建文件夹temp     File file2=new File("c:\\r","temp");     file2.mkdir( );     在temp目录中创建文件     File file3=new File(file2,"temp1.txt");     file3.createNewFile( );     删除文件     file3.delete( );               获取文件夹中的所有文件和子文件夹    String [ ] filename = file2.list( );        显示文件名和目录名通常使用getCanonicalPath( )和getName( )，         前者返回包含规范化路径名的字符串，后者返回文件名字符串        static BufferedReader  stdIn =  new BufferedReader(new InputStreamReader(System.in));    public static void main(String[] args) {       try{            String s=stdIn.readLine( );            File t=new File(s);            listSubDir(t);        }catch(IOException e){         }    static void listSubDir( File currentPath ){        String [ ] filenames=currentPath.list( );           try{                for(int i=0;i<filenames.length;i++){                    File f=new File(currentPath.getPath( ) ,filenames[i]);                    if(f.isDirectory( )){                        System.out.println(f.getCanonicalPath());                        listSubDir(f);                            //递归调用实现遍历目录中的所有文件和文件夹                    }else{                        System.out.println(f.getName());                    }                }            }catch(IOException e){                System.out.println("IOException");            }        }            }