Java文件操作的方法

简介

本程序主要采用了FileInputStream和FileOutputStream两类对文件进行操作。具体包括通过相对路径打开文件，三种方法读取文件，查看文件属性，追加文件数据等。

效果图：

完整代码：

package Code.a;
import java.io.*;
public class FileInputStreamDemo {
    

    public static void main(String[] args) {
        //获取当前目录;
        File f = new File(".");
        System.out.print("absolute path:"+f.getAbsolutePath()+"\n");
        while(true)
        {
            try {
                //输入命令；
                System.out.print("Please input your order：");
                BufferedReader stdinBufferedReader;
                String str1 = null;
                stdinBufferedReader = new BufferedReader(new InputStreamReader(System.in));
                str1 = stdinBufferedReader.readLine();
                //相对路径打开文件；
                File file2 = new File(".\\src\\Code\\a\\Exception.java");
                FileInputStream fis2 = new FileInputStream(file2);
                
                根据不同的命令，执行不同操作；
                //一次性读取全部数据
                if(str1.equals("一次性读取全部数据"))
                {
                    byte[] buf = new byte[(int)(file2.length())];
                    fis2.read(buf);
                    String str = new String(buf);
                    System.out.print(str);
                    System.out.print("\n");
                }
                //分块读取
                else if(str1.equals("分块读取"))
                {
                    int n = 1024,count;
                    byte[] buf = new byte[n];
                    while((count = fis2.read(buf)) != -1)
                    {
                        System.out.print(new String(buf,0,count));
                    }
                    System.out.print("\n");
                }
                //逐字读取数据
                else if(str1.equals("逐字读取数据"))
                {
                    for(int i = 0; i < file2.length(); i++)
                    {
                        char ch = (char)(fis2.read());
                        System.out.print(ch);
                    }
                    System.out.print("\n");
                }
                //退出
                else if(str1.equals("退出"))
                {
                    System.out.print("已退出\n");
                    break;
                }
                //查看文件属性
                else if(str1.equals("查看文件属性"))
                {
                    System.out.print("If the file or catalog exists:"+file2.exists()+"\n");
                    System.out.print("If is it a file:"+file2.isFile()+"\n");
                    System.out.print("If is it a catalog:"+file2.isDirectory()+"\n");
                    System.out.print("FileName:"+file2.getName()+"\n");
                    System.out.print("absolute path:"+file2.getAbsolutePath()+"\n");
                    System.out.print("The last time that the file was changed:"+file2.lastModified()+"\n");
                    System.out.print("The size of the file:"+file2.length()+" bites\n");
                }
                //向文件追加数据
                else if(str1.equals("文件追加数据"))
                {
                    FileOutputStream fos2 = new FileOutputStream(file2,true);
                    System.out.println("Please input the content: ");
                    BufferedReader ContentReader;
                    String str2 = null;
                    ContentReader = new BufferedReader(new InputStreamReader(System.in));
                    str2 = ContentReader.readLine();
                    fos2.write(str2.getBytes());
                    fos2.close();
                }
                //关闭流对象；
                fis2.close();
            }
            //处理异常；
            catch(FileNotFoundException fnfe) {
                System.out.print("The file open unsuccessfully.");
            }catch(IOException ioe) {
                ioe.printStackTrace();
            }
        }
    }
    
}