Java文件操作练习题

朱雀 2022-12-21 02:27 103阅读 0赞

## 1、已知一个文件路径“C:\\ProgramData\\Kugou\\2.txt”，截取文件名称，然后在D:\\a下创建同名的文件。然后使用键盘输入一首诗，保存在该文件中。 ##

package com.Java文件操作练习题;
    
    import java.io.FileWriter;
    import java.io.IOException;
    import java.util.Scanner;
    
    public class demo1 { 
    	public static void main(String[] args) throws IOException{ 
    		String s = "C:\\ProgramData\\Kugou\\2.txt";
    		String fileName = s.substring(21,26);
    		FileWriter filterWriter = new FileWriter("D:\\a\\"+ fileName);
    		Scanner input = new Scanner(System.in);
    		System.out.println("请输入古诗：");
    		String poet = input.next();
    		filterWriter.write(poet);
    		filterWriter.close();
    	}
    }

![在这里插入图片描述][20201113190824756.png_pic_center]  
运行结果：  
![在这里插入图片描述][20201113191619599.png_pic_center]

## 2、已知一个目录，使用递归方法，遍历出所有包含的文件和目录。 ##

package com.Java文件操作练习题;
    
    import java.io.File;
    
    public class demo2 { 
    
    	public static void main(String[] args) { 
    		File dir = new File("C:\\Users\\Desktop");
    		lists(dir);
    	}
    	public static void lists(File dir) { 
    		if (dir.isFile()) { 
    			return;
    		} else { 
    			System.out.println("当前目录为：" + dir.getAbsolutePath());
    			File[] files = dir.listFiles();
    			for (File file : files) { 
    				if (file.isDirectory()) { 
    					lists(file);
    				} else { 
    					System.out.println("文件：" + file.getAbsolutePath());
    				}
    			}
    		}
    	}
    }

## 3、从一个文件中，一行一行的读取出所有内容，然后打印在控制台上。 ##

package com.Java文件操作练习题;
    
    import java.io.BufferedReader;
    import java.io.FileReader;
    import java.io.IOException;
    
    public class demo3 { 
    
    	public static void main(String[] args) throws IOException{ 
    		FileReader fileReader = new FileReader("C:\\Users\\Desktop\\test.txt");
    		BufferedReader bufferedOut = new BufferedReader(fileReader);
    		String line = bufferedOut.readLine();
    		while(line!=null) { 
    			System.out.println(line);
    			line = bufferedOut.readLine();
    		}
    	}
    }

运行结果：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNTI2Ng_size_16_color_FFFFFF_t_70_pic_center]

## 4、输入两个文件的名称，将文件a中的数据全部拷贝到文件b中。 ##

package com.Java文件操作练习题;
    
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.util.Scanner;
    
    public class demo4 { 
    
    	public static void main(String[] args) throws IOException{ 
    		Scanner input = new Scanner(System.in);
    		
    		System.out.println("请输入a的文件名：");//"C:\\Users\\Desktop\\a.txt"
    		String file_a_name = input.next();
    		
    		System.out.println("请输入b的文件名：");//"C:\\Users\\Desktop\\b.txt"
    		String file_b_name = input.next();
    	
    		FileInputStream fileInputStream = new FileInputStream(file_a_name);
    		FileOutputStream fileOutputStream = new FileOutputStream(file_b_name,true);
    		
    		byte[] bs = new byte[10];
    		int i = fileInputStream.read(bs);
    		while(i!=-1) { 
    			fileOutputStream.write(bs, 0 , i);
    			i = fileInputStream.read(bs);
    		}
    		fileOutputStream.close();
    		fileInputStream.close();
    	}
    }

a与b两个文件存的数据如下：

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNTI2Ng_size_16_color_FFFFFF_t_70_pic_center 1]  
运行结果为：  
![在这里插入图片描述][20201113203656357.png_pic_center]

## 5、读取一个文本文件，统计里面所有字符出现的个数，保存在map中。 ##

package com.Java文件操作练习题;
    
    import java.io.FileInputStream;
    import java.io.IOException;
    import java.util.HashMap;
    import java.util.Map;
    public class demo5 { 
    	public static void main(String[] args) throws IOException{ 
    		FileInputStream fileInputStream = new FileInputStream("C:\\Users\\Desktop\\test.txt");
    		int i = fileInputStream.read();
    		Map<Character, Integer> map = new HashMap<Character, Integer>();
    		while(i!=-1) { 
    			map.put((char)i, map.containsKey((char)i) ? map.get((char)i) + 1 : 1);
    			i = fileInputStream.read();
    		}
    		map.forEach((k,v)->{ 
    			System.out.println("字符：" + k + " 个数：" + v);
    		});
    	}
    }

运行结果为：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNTI2Ng_size_16_color_FFFFFF_t_70_pic_center 2]

## 6、从c盘剪切一个图片文件到d盘下。 ##

package com.Java文件操作练习题;
    
    import java.io.BufferedInputStream;
    import java.io.BufferedOutputStream;
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.IOException;
    
    public class demo6 { 
    
    	public static void main(String[] args) throws IOException{ 
    		File file = new File("C:\\Users\\Pictures\\1.jpg");
    		FileInputStream fileInputStream = new FileInputStream("C:\\Users\\Pictures\\1.jpg");
    		FileOutputStream fileOutputStream = new FileOutputStream("C:\\Users\\Desktop\\1.jpg");
    		
    		byte[] bs = new byte[1024];
    		int i = fileInputStream.read(bs);
    		while(i!=-1) { 
    			fileOutputStream.write(bs, 0 , i);
    			System.out.println(i);
    			i = fileInputStream.read(bs);
    		}
    		fileOutputStream.close();
    		fileInputStream.close();
    		file.delete();
    	}
    }

[20201113190824756.png_pic_center]: /images/20221120/f8f487d66d7e457fa98332519a0431ca.png
[20201113191619599.png_pic_center]: /images/20221120/7c93c476fcf342c0a986c9e6da2743c0.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNTI2Ng_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/10dd19d5a307419ca47ad247d0063087.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNTI2Ng_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221120/c1c38b3abf25420fa82ea4d59489b917.png
[20201113203656357.png_pic_center]: /images/20221120/4598d728ece045c191690c7d081a2139.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzYwNTI2Ng_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221120/8982c1123c734b3394b71fe66c7327c4.png