java 关于文件的读写操作

你的名字 2021-02-12 17:31 616阅读 0赞

**今天在此做一个总结，关于文件的读写操作：**

package com.phj.file.read;
    
    import java.io.BufferedReader;
    import java.io.BufferedWriter;
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.FileReader;
    import java.io.FileWriter;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.io.OutputStream;
    import java.io.PrintWriter;
    import java.io.Reader;
    import java.io.StringReader;
    import java.util.Scanner;
    
    public class ObjectFileReadAndWrite {
    
    	/**
    	 * @author feihong
    	 * @throws Exception
    	 */
    	public static void main(String[] args) throws Exception {
    		String path = "D:/TestFile/MathUtil.java";
    		// ReadByByte(path);
    		// ReadByBytes(path);
    		// ReadByChars(path);
    		// ReadByLine(path);
    		File file = new File(path) ;
    		readFromFile(file);
    		// writeFile();
    		// writeFileToMemory(path);
    		// writeFile2(path);
    		 writeFile3();
    //		File file = new File("D:" + File.separator + "test");
    //		printFile(file);
    //		deleFile(file);
    		double num = 12.213213;
    		System.out.printf("%f", num);
    		System.out.println("操作成功！");
    	}
    
    	public static void ReadByByte(String filePath) throws Exception {
    
    		File file = new File(filePath);
    		InputStream is = new FileInputStream(file);
    		int temp;
    		while ((temp = is.read()) != -1) {
    			System.out.write(temp);
    		}
    
    		File file1 = new File("D:/test.txt");
    		OutputStream os = new FileOutputStream(file1);
    		os.write(is.read());
    
    		is.close();
    		os.close();
    	}
    
    	public static void ReadByBytes(String filePath) throws Exception {
    		File file = new File(filePath);
    		InputStream is = new FileInputStream(file);
    		byte[] temp = new byte[1024];
    		int flag = 0;
    		is.available();
    		while ((flag = is.read(temp)) != -1) {
    			System.out.write(temp, 0, flag);
    		}
    		is.close();
    	}
    
    	public static void ReadByChar(String filePath) throws Exception {
    		File file = new File(filePath);
    		Reader reader = new FileReader(file);
    		int temp = 0;
    		while ((temp = reader.read()) != -1) {
    			if ((char) temp != '\r') {
    				System.out.print((char) temp);
    			}
    
    		}
    		reader.close();
    	}
    
    	public static void ReadByChars(String filePath) throws Exception {
    		File file = new File(filePath);
    		Reader reader = new FileReader(file);
    		char[] temp = new char[1024];
    		int length = reader.read(temp);
    		String str = new String(temp, 0, length);
    		System.out.println(str);
    		reader.close();
    	}
    
    	public static void ReadByLine(String filePath) throws Exception {
    		File file = new File(filePath);
    		BufferedReader br = new BufferedReader(new FileReader(file));
    		String str = null;
    		while ((str = br.readLine()) != null) {
    			System.out.println(str);
    		}
    	}
    
    	public static void readFromFile(File file) throws Exception{
    		Scanner scan = new Scanner(file) ;
    		StringBuffer sb = new StringBuffer();
    		while(scan.hasNext()){
    			sb.append(scan.next()).append("\n");
    		}
    		System.out.println(sb);
    	}
    	
    	// 输入即返回
    	public static void writeFile() throws Exception {
    		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    		System.out.println("Enter a line: ");
    		boolean flag = true;
    		while (flag) {
    			System.out.println(br.readLine().concat("====="));
    			flag = true;
    		}
    		br.close();
    	}
    
    	public static void writeFileToMemory(String filePath) throws Exception {
    		BufferedReader br = new BufferedReader(new FileReader(filePath));
    		String temp, file = null;
    		while ((temp = br.readLine()) != null) {
    			file += temp + '\n';
    		}
    		br.close();
    		StringReader sr = new StringReader(file);
    		int csr = 0;
    		while ((csr = sr.read()) != -1) {
    			System.out.print((char) csr);
    		}
    		sr.close();
    	}
    
    	// 文件写入
    	public static void writeFile2(String filePath) throws Exception {
    
    		BufferedReader br = new BufferedReader(new FileReader(filePath));
    		String temp, file = null;
    		while ((temp = br.readLine()) != null) {
    			file += temp + '\n';
    		}
    		br.close();
    
    		BufferedReader brWrite = new BufferedReader(new StringReader(file));
    		PrintWriter pwOut = new PrintWriter(new BufferedWriter(new FileWriter(
    				"D:/IODemo.txt")));
    		int lintCount = 1;
    		String s = "";
    		try {
    			while ((s = brWrite.readLine()) != null) {
    				pwOut.println(lintCount + "--->" + s);
    				lintCount++;
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    		pwOut.close();
    	}
    
    	public static void writeFile3() throws Exception {      //这个操作就相当于是复制一份文件到另一个文件中
    		File file = new File("D:/TestFile/MathUtil.java");
    		FileOutputStream fos = null;
    		FileInputStream fis = null;
    		File wFile = new File("D:" + File.separator + "TestFile" + File.separator + "Hello.txt") ;
    		try {
    			fos = new FileOutputStream(wFile);
    			fis = new FileInputStream(file);
    			int temp = 0;
    			while((temp = fis.read()) != -1){
    				fos.write(temp);
    			}
    			fos.close();
    			fis.close();
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
    
    	public static void printFile(File file) {  //写出全部文件
    		if (file != null) {
    			if (file.isDirectory()) {
    				File[] f = file.listFiles();
    				if (f != null) {
    					for (int i = 0; i < f.length; i++) {
    						printFile(f[i]);
    					}
    				}
    			} else {
    				System.out.println(file);
    			}
    		}
    	}
    
    	public static void deleFile(File file) {  //删除相应文件夹以及相应全部文件
    		if (file != null) {
    			if (file.isDirectory()) {
    				File[] f = file.listFiles();
    				for (int i = 0; i < f.length; i++) {
    					deleFile(f[i]);
    				}
    				file.delete();
    			} else {
    				file.delete();
    			}
    		}
    	}
    }