JAVA语言的打开文件和写入文件

1   打开文件。
本例以FileInputStream的read(buffer)方法，每次从源程序文件OpenFile.java中读取512个字节，存储在缓冲区 buffer中，再将以buffer中的值构造的字符串new   String(buffer)显示在屏幕上。程序如下：
import   java.io.*;
public   class   OpenFile 
{
        public   static   void   main(String   args[])   throws   IOException
        {
                try
                {                                                                                     //创建文件输入流对象
                        FileInputStream     rf   =   new   FileInputStream( "OpenFile.java ");
                        int   n=512;
                        byte   buffer[]   =   new   byte[n];
                        while   ((rf.read(buffer,0,n)!=-1)   &&   (n> 0))       //读取输入流
                        {
                                System.out.print(new   String(buffer));
                        }
                        System.out.println();
                        rf.close();                                                         //关闭输入流
                }
                catch   (IOException   ioe)
                {
                        System.out.println(ioe);
                }
                catch   (Exception   e)
                {
                        System.out.println(e);
                }
        }
}
例     2     写入文件。
本例用System.in.read(buffer)从键盘输入一行字符，存储在缓冲区buffer中，再以FileOutStream的write(buffer)方法，将buffer中内容写入文件Write1.txt中，程序如下：
import   java.io.*;
public   class   Write1 
{
        public   static   void   main(String   args[])
        {
                try
                {
                        System.out.print( "Input:   ");
                        int   count,n=512;
                        byte   buffer[]   =   new   byte[n];
                        count   =   System.in.read(buffer);                 //读取标准输入流
                        FileOutputStream     wf   =   new   FileOutputStream( "Write1.txt ");
                                                                                                      //创建文件输出流对象
                        wf.write(buffer,0,count);                             //写入输出流
                        wf.close();                                                         //关闭输出流
                        System.out.println( "Save   to   Write1.txt! ");
                }
                catch   (IOException   ioe)
                {
                        System.out.println(ioe);
                }
                catch   (Exception   e)
                {
                        System.out.println(e);
                }
        }
}