java中的文件操作

package test;import java.io.BufferedReader;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.PrintWriter;import java.io.RandomAccessFile;import java.io.Reader;public class FileUtil {/** * 读取字节 * * @param fileName */public static void readFileByBytes(String fileName) {File file = new File(fileName);InputStream in = null;try {System.out.println("以字节为单位读取文件内容，一次读一个字节");in = new FileInputStream(file);int tempbyte;while ((tempbyte = in.read()) != -1) {System.out.write(tempbyte);}in.close();} catch (IOException e) {e.printStackTrace();return;}try {System.out.println("以字节为单位读取文件内容，一次读多个字节");byte[] tempbytes = new byte[100];int byteread = 0;in = new FileInputStream(fileName);FileUtil.showAvailableBytes(in);while ((byteread = in.read(tempbytes)) != -1) {System.out.write(tempbytes, 0, byteread);}} catch (Exception e) {e.printStackTrace();} finally {if (in != null) {try {in.close();} catch (IOException e) {e.printStackTrace();}}}}/** * 读取字符 * * @param fileName */public static void readFileByChars(String fileName) {File file = new File(fileName);Reader reader = null;try {System.out.println("以字符为单位读取文件内容，一次读一个字符");reader = new InputStreamReader(new FileInputStream(file));// 一次读一个字符int tempchar;while ((tempchar = reader.read()) != -1) {if (((char) tempchar) != '/r') {System.out.print((char) tempchar);}}reader.close();} catch (Exception e) {e.printStackTrace();}try {System.out.println("以字符为单位读取文件内容，一次读多个字符");reader = new InputStreamReader(new FileInputStream(file));char[] tempchars = new char[30];// 一次读一个字符int charread = 0;while ((charread = reader.read(tempchars)) != -1) {// 同样屏蔽掉/r不显示if ((charread == tempchars.length)&& (tempchars[tempchars.length - 1] != '/r')) {System.out.print(tempchars);} else {for (int i = 0; i < charread; i++) {if (tempchars[i] == '/r') {continue;} else {System.out.print(tempchars[i]);}}}}} catch (Exception e) {e.printStackTrace();} finally {if (reader != null) {try {reader.close();} catch (IOException e1) {e1.printStackTrace();}}}}/** * 读取行 * * @param fileName */public static void readFileByLines(String fileName) {File file = new File(fileName);BufferedReader reader = null;try {System.out.println("以行为单位读取文件内容");reader = new BufferedReader(new FileReader(file));// 一次读一个字符String tempString = null;int line = 1;while ((tempString = reader.readLine()) != null) {System.out.println("line " + line + ": " + tempString);line++;}reader.close();} catch (Exception e) {e.printStackTrace();} finally {if (reader != null) {try {reader.close();} catch (IOException e1) {e1.printStackTrace();}}}}/** * 随机读取 * * @param fileName */public static void readFileByRandomAccess(String fileName) {RandomAccessFile randomFile = null;try {System.out.println("随机读取一段文件内容");// 打开一个随机访问文件流，按只读方式randomFile = new RandomAccessFile(fileName, "r");// 文件长度，字节数long fileLength = randomFile.length();// 读文件的起始位置int beginIndex = (fileLength > 4) ? 4 : 0;// 将文件的开始位置移到beginIndex位置randomFile.seek(beginIndex);byte[] bytes = new byte[10];int byteread = 0;// 一次读10个字节，如果文件内容不足10个字节，则读剩下的字节。// 将一次读取的字节数赋给bytereadwhile ((byteread = randomFile.read(bytes)) != -1) {System.out.write(bytes, 0, byteread);}} catch (IOException e) {e.printStackTrace();} finally {if (randomFile != null) {try {randomFile.close();} catch (IOException e1) {e1.printStackTrace();}}}}/** * 通过随机访问追加内容 * * @param fileName * @param content */public static void appendToFileByRandomAccess(String fileName,String content) {try {RandomAccessFile randomFile = new RandomAccessFile(fileName, "rw");long fileLength = randomFile.length();randomFile.seek(fileLength);randomFile.writeBytes(content);randomFile.close();} catch (IOException e) {e.printStackTrace();}}/** * 通过FileWriter追加内容 * * @param fileName * @param content */public static void appendToFileByFileWriter(String fileName, String content) {try {FileWriter writer = new FileWriter(fileName, true);writer.write(content);writer.close();} catch (IOException e) {e.printStackTrace();}}private static void showAvailableBytes(InputStream in) {try {System.out.println("当前字节输入流中的字节数为" + in.available());} catch (IOException e) {e.printStackTrace();}}/** * 新建目录 * * @param a */public static void createFolder(String folderPath) {try {File filePath = new File(folderPath);if (!filePath.exists()) {filePath.mkdir();}System.out.println("新建目录成功");} catch (Exception e) {System.out.println("新建目录出错");e.printStackTrace();}}/** * 新建文件 * * @param a */public static void createFile(String filePathAndName, String fileContent) {try {File filePath = new File(filePathAndName);if (!filePath.exists()) {filePath.createNewFile();}FileWriter writer = new FileWriter(filePath);PrintWriter pw = new PrintWriter(writer);pw.println(fileContent);writer.close();System.out.println("新建目录成功");} catch (Exception e) {System.out.println("新建目录出错");e.printStackTrace();}}/** * 删除文件 * * @param a */public static void deleteFile(String filePathAndName) {try {File delFile = new File(filePathAndName);delFile.delete();System.out.println("删除文件成功");} catch (Exception e) {System.out.println("删除文件出错");e.printStackTrace();}}/** * 删除空文件夹 */public static void delFolder(String folderPath) {try {delAllFile(folderPath);File filePath = new File(folderPath);if (filePath.delete()) {System.out.println("删除文件夹" + folderPath + "操作 成功执行");} else {System.out.println("删除文件夹" + folderPath + "操作 执行失败");}} catch (Exception e) {System.out.println("删除文件夹操作出错");e.printStackTrace();}}/** * 删除文件夹里的所有文件 * * @param a */public static void delAllFile(String path) {File file = new File(path);if (!file.exists()) {return;}if (!file.isDirectory()) {return;}String[] tempList = file.list();File temp = null;for (int i = 0; i < tempList.length; i++) {if (path.endsWith(File.separator)) {temp = new File(path + tempList[i]);} else {temp = new File(path + File.separator + tempList[i]);}if (temp.isFile()) {temp.delete();}if (temp.isDirectory()) {delFolder(path + File.separatorChar + tempList[i]);}}}/** * 复制单个文件 * * @param a */public static void copyFile(String oldFile, String newFile) {try {int byteSum = 0;int byteRead = 0;File oFile = new File(oldFile);if (oFile.exists()) {InputStream inStream = new FileInputStream(oldFile);FileOutputStream fos = new FileOutputStream(newFile);byte[] buffer = new byte[1024];while ((byteRead = inStream.read(buffer)) != -1) {byteSum += byteRead;fos.write(buffer, 0, byteRead);}inStream.close();}} catch (Exception e) {e.printStackTrace();}}/** * 复制整个文件夹 * * @param a */public static void copyFolder(String oldPath, String newPath) {try {(new File(newPath)).mkdirs();File a = new File(oldPath);String[] file = a.list();File temp = null;for (int i = 0; i < file.length; i++) {if (oldPath.endsWith(File.separator)) {temp = new File(oldPath + file[i]);} else {temp = new File(oldPath + File.separator + file[i]);}if (temp.isFile()) {FileInputStream input = new FileInputStream(temp);FileOutputStream output = new FileOutputStream(newPath+ "/" + (temp.getName()).toString());byte[] b = new byte[1024 * 5];int len;while ((len = input.read(b)) != -1) {output.write(b, 0, len);}output.flush();output.close();input.close();}if (temp.isDirectory()) {copyFolder(oldPath + "/" + file[i], newPath + "/" + file[i]);}}} catch (Exception e) {e.printStackTrace();}}/** * 移动文件到目录 * * @param a */public static void moveFolder(String oldPath, String newPath) {copyFile(oldPath, newPath);deleteFile(oldPath);}} 

随机读取文件中的一部分文字~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/** * 随机读取 *  * @param fileName */public String readFileByRandomAccess(String fileName) {StringBuffer sb = new StringBuffer();RandomAccessFile randomFile = null;try {randomFile = new RandomAccessFile(fileName, "r");int fileLength = (int) randomFile.length();int beginIndex = random.nextInt(fileLength);randomFile.seek(beginIndex);int byteNum = 0;while (byteNum < 1) {byteNum = random.nextInt(10);}byte[] bytes = new byte[byteNum];int byteread = 0;while ((byteread = randomFile.read(bytes)) != -1) {sb.append(new String(bytes, 0, byteread));}} catch (IOException e) {e.printStackTrace();} finally {if (randomFile != null) {try {randomFile.close();} catch (IOException e1) {e1.printStackTrace();}}}return sb.toString();}