Java文件操作(一)

在读取文件的时候，为了避免乱码，我们需要按照文件的编码格式来读取文件，但是如何获取文件的编码格式，成了一大难题，查了资料终于搞定，现拿来与大家分享。

<span style="white-space:pre"></span>/** *  * @Description 获取文件编码格式  * @param fileName * @return * @throws IOException */public static String getCharset(File fileName) throws IOException{                BufferedInputStream bin = new BufferedInputStream(new FileInputStream(fileName));          int p = (bin.read() << 8) + bin.read();                  String code = null;                  switch (p) {              case 0xefbb:                  code = "UTF-8";                  break;              case 0xfffe:                  code = "Unicode";                  break;              case 0xfeff:                  code = "UTF-16BE";                  break;              default:                  code = "GBK";          }          if(bin!= null) bin.close();        return code;}

读文件操作：

/** *  * @Description 读文件 （路径下不存在，则创建文件） * @param fileRoot 文件路径 * @param fileName 文件名 * @return */public static String readFile(String fileRoot, String fileName) {        try {            if (!new File(fileRoot).isDirectory()) new File(fileRoot).mkdirs();            File file = new File(fileRoot, fileName);            return readFile(file);        }        catch (Exception e) {            return "";        }    }/** *  * @Description  读文件 * @param file 文件 * @return 文件内容 */private static String readFile(File file) {        try {        if (!file.exists()) file.createNewFile();//        BufferedReader br = new BufferedReader(new FileReader(file));        // 指定读取文件的编码格式，要和写入的格式一致，以免出现中文乱码,//        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8"));        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(file), getCharset(file)));            String line = br.readLine();            StringBuffer sb = new StringBuffer();            while (line != null) {                sb.append(line + "\n");                line = br.readLine();            }            br.close();            System.out.println(sb.toString());            return sb.toString();} catch (IOException e) {e.printStackTrace();}return "";}

写文件操作,按指定格式写入，这里是UTF-8:

/** *  * @Description 写入文件  * @param fileRoot 文件路径 * @param fileName 文件名 * @param fileInfo 写入内容 */public static void writeFile(String fileRoot, String fileName, String fileInfo) {if(!new File(fileRoot).isDirectory()){new File(fileRoot).mkdirs();//创建此抽象路径名指定的目录，包括所有必需但不存在的父目录}//创建文件File file = new File(fileRoot, fileName);//写入文件writeFile(file, fileInfo);}/** *  * @Description 写入文件 * @param file 文件 * @param fileInfo 写入内容 */private static void writeFile(File file, String fileInfo) {try {if(!file.exists()){file.createNewFile();}//BufferedWriter bw = new BufferedWriter(new FileWriter(file));// 指定编码格式，以免读取时中文字符异常BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), "UTF-8"));bw.write(fileInfo);bw.flush();bw.close();} catch (IOException e) {e.printStackTrace();}}

创建文件：

/** * 创建文件  * @Description  * @author zhangjinmiao * @return */public static boolean createFile(File fileName){boolean flag = false;if(!fileName.exists()){try {fileName.createNewFile();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}flag = true;}return flag;}

删除文件：

/** * 删除文件 * @Description  * @param sPath * @return */public static boolean deleteFile(String sPath) {boolean flag = false;File file = new File(sPath);// 路径为文件且不为空则进行删除if(file.isFile()&& file.exists()){file.delete();flag = true;}return flag;}

追加内容到文件：

/** *  * @Description 向文件中追加内容  * @param filePath 文件路径 F:/a/zz.txt * @param content 追加的内容 */public static void contentToTxt(String filePath,String content){String str = new String(); //原有txt内容          String s1 = new String();//内容更新 try {File file = new File(filePath);if(file.exists()){System.out.println("文件存在");}else {System.out.println("文件不存在");file.createNewFile();//创建文件}//开始读文件//BufferedReader input = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8"));BufferedReader input = new BufferedReader(new InputStreamReader(new FileInputStream(file), getCharset(file)));while ((str = input.readLine()) != null) {                  s1 += str + "\n";              }              System.out.println("原有内容：\n"+s1);              input.close();              s1 += "\r\n"+ content;//新添内容换行加入    //          BufferedWriter output = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file),"UTF-8"));              BufferedWriter output = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file),getCharset(file)));              output.write(s1);              output.close();  } catch (Exception e) {e.printStackTrace();}}