java 关于文件的读写操作
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();}}}}