Java文件与流-练习

﹏ヽ暗。殇╰゛Y 2024-04-18 08:56 26阅读 0赞

**1、在本机的磁盘系统中，找一个文件夹，利用File类的提供方法，列出该文件夹中的所有文件的文件名和文件的路径，执行效果如下：  
路径是xxx的文件夹内的文件有：  
文件名：abc.txt  
路径名：d:\\temp\\abc.txt  
\--------------------------------------------  
文件名：def.txt  
路径名：d:\\temp\\def.txt**

public class test {
    	public static void main(String[] args) {
    		File file1 = new File("d:/temp/abc.txt");
    		if(file1.exists()) {
    			System.out.println("文件已存在");
    		}else {
    			try {
    				System.out.println("创建成功:"+file1.createNewFile());
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		File file2 = new File("d:/temp/def.txt");
    		if(file2.exists()) {
    			System.out.println("文件已存在");
    		}else {
    			try {
    				System.out.println("创建成功:"+file2.createNewFile());
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		File file = new File("d:/temp");
    		printFile(file);
    	}
    	public static void printFile(File file) {
    		System.out.println("路径是d:/temp的文件夹内的文件有:");
    		File[] fileList = file.listFiles();
    		for (File f : fileList) {
    			System.out.println("文件名:"+f.getName());
    			System.out.println("路径名:"+f.getAbsolutePath());
    		}
    	}
    }

**改进版:输出该目录下的所有内容,包括子目录中的内容**

public class test2 {
    	public static void main(String[] args) {
    		File file1 = new File("d:/temp/abc.txt");
    		if(file1.exists()) {
    			System.out.println("文件已存在");
    		}else {
    			try {
    				System.out.println("创建成功:"+file1.createNewFile());
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		File file2 = new File("d:/temp/def.txt");
    		if(file2.exists()) {
    			System.out.println("文件已存在");
    		}else {
    			try {
    				System.out.println("创建成功:"+file2.createNewFile());
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		File file = new File("d:/temp");
    		printFile(file);
    	}
    	public static void printFile(File file) {
    		System.out.println("路径是d:/temp的文件夹内的文件有:");
    		File[] fileList = file.listFiles();
    		for (File f : fileList) {
    			System.out.println("文件名:"+f.getName());
    			System.out.println("路径名:"+f.getAbsolutePath());
    			System.out.println("是否文件夹:"+f.isDirectory());//判断是否为文件夹
    			//如果为文件夹,输出文件夹中的内容
    			if(f.isDirectory()) {
    				printFile(f);
    			}
    		}
    	}
    }

结果:

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3hpYW9qeF8_size_16_color_FFFFFF_t_70]

**2、创建c:/test.txt文件并在其中输入"hello world"  
创建一个输入流读取该文件中的文本  
并且把小写的l变成大写L再利用输出流写入到d:\\test.txt中  
3.1 实现步骤：  
3.1.1 在本地硬盘C盘下创建一个文件test.txt  
3.1.2 创建一个包含main()方法的类，并在main中编写代码  
3.1.3 运行代码并且测试结果  
3.2 实现过滤器的功能**

public static void main(String[] args) {
    
    		FileReader reader = null;
    		FileWriter writer = null;
    		try {
    			reader = new FileReader("c:/test.txt");
    			writer = new FileWriter("d:/test.txt");
    			char[] c = new char[3];
    			int length;
    			while((length=reader.read(c))!=-1) {
    			
    				System.out.println(length+Arrays.toString(c));
    				c = new String(c).replace("l","L").toCharArray();				
    				writer.write(c,0,length);
    		
    			}
    			writer.flush();
    			
    		} catch (FileNotFoundException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}finally {
    			try {
    				reader.close();
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    			try {
    				writer.close();
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		
    	}
    
    }

结果:  
![在这里插入图片描述][20190904195432718.png]

![在这里插入图片描述][20190904195442599.png]

**3、在程序中创建一个Student类型的对象，并把对象信息保存到  
d:/io/student.txt文件中，然后再从文件中把Student  
对象的信息读出显示在控制台上，Student类的描述如下：**  
![在这里插入图片描述][20190905175111898.png]

//创建Student类实现可用于序列化操作的Serializable接口
    
    public class Student implements Serializable{
    	private int id;
    	private String name;
    	private String birth;
    	
    	public Student() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    	
    	public Student(int id, String name, String birth) {
    		super();
    		this.id = id;
    		this.name = name;
    		this.birth = birth;
    	}
    	
    	@Override
    	public String toString() {
    		return "Student [id=" + id + ", name=" + name + ", birth=" + birth + "]";
    	}
    	
    }

public class test {
    
    	public static void main(String[] args) {
    		
    		Serialization();
    		deSerialization();
    		
    	}
    	public static void Serialization() {
    		ObjectOutputStream output = null;
    		
    		try {
    			Student stu = new Student(1,"小明","2000年1月1号");
    			
    			FileOutputStream out = new FileOutputStream("d:/io/student.txt");
    			
    			output = new ObjectOutputStream(out);
    			
    			output.writeObject(stu);
    			
    			output.flush();
    			
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}finally {
    		
    			try {
    				if(output!=null) {
    					output.close();
    				}
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    			
    		}
    	}
    	public static void deSerialization() {
    		ObjectInputStream input = null;
    		
    		try {
    			
    			FileInputStream in = new FileInputStream("d:/io/student.txt");
    			
    			input =new ObjectInputStream(in);
    			
    			Student stu = (Student) input.readObject();
    			
    			System.out.println(stu.toString());
    			
    		} catch (FileNotFoundException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		} catch (ClassNotFoundException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}finally {
    		
    			try {
    				if(input!=null) {
    					input.close();
    				}
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    			
    		}		
    	}		
    }

结果:  
![在这里插入图片描述][20190905175449517.png]

**4、编写一个java程序实现文件复制功能，要求将d:/io/copysrc.doc中的内容复制到d:/io/copydes.doc中。**

public class BufferedTest {
    	public static void main(String[] args) {
    		BufferedReader reader = null;
    		BufferedWriter writer = null;
    		
    		try {
    			FileReader r = new FileReader("d:/io/copysrc.doc");
    			reader = new BufferedReader(r);
    			
    			FileWriter w = new FileWriter("d:/io/copydes.doc");
    			writer = new BufferedWriter(w);
    			
    			String length = "";
    			while((length=reader.readLine())!=null) {
    				System.out.println(length);
    				writer.write(length);
    				writer.newLine();
    				
    			}
    			writer.flush();
    			
    		} catch (FileNotFoundException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}finally {
    			try {
    				if(reader!=null) {
    					reader.close();
    				}
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    			try {
    				if(writer!=null) {
    					writer.close();
    				}
    			} catch (IOException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		
    	}
    }

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[20190904195432718.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/17/1e09e71ec7b247e59204a6f553c885cf.png
[20190904195442599.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/17/df02b1145a6d43b2a1e503885b919232.png
[20190905175111898.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/17/be0fa69e935b498ebd525bd30496bbcc.png
[20190905175449517.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/04/17/21b520984aa546a8b1eb043437a3e739.png