Java字符串与文件的互转

    Java中有时候需要读取一个文本类的文件，将其转换为字符串，然后做进一步处理。Java中没有现成的API方法，自己手动实现一个，大家来分享。

    一、字符串转换为文件

        /**
         * 将字符串写入指定文件(当指定的父路径中文件夹不存在时，会最大限度去创建，以保证保存成功！)
         *
         * @param res            原字符串
         * @param filePath 文件路径
         * @return 成功标记
         */
        public static boolean string2File(String res, String filePath) {
                boolean flag = true;
                BufferedReader bufferedReader = null;
                BufferedWriter bufferedWriter = null;
                try {
                        File distFile = new File(filePath);
                        if (!distFile.getParentFile().exists()) distFile.getParentFile().mkdirs();
                        bufferedReader = new BufferedReader(new StringReader(res));
                        bufferedWriter = new BufferedWriter(new FileWriter(distFile));
                        char buf[] = new char[1024];         //字符缓冲区
                        int len;
                        while ((len = bufferedReader.read(buf)) != -1) {
                                bufferedWriter.write(buf, 0, len);
                        }
                        bufferedWriter.flush();
                        bufferedReader.close();
                        bufferedWriter.close();
                } catch (IOException e) {
                        e.printStackTrace();
                        flag = false;
                        return flag;
                } finally {
                        if (bufferedReader != null) {
                                try {
                                        bufferedReader.close();
                                } catch (IOException e) {
                                        e.printStackTrace();
                                }
                        }
                }
                return flag;
        }

    二、文件转换为字符串

        /**
         * 文本文件转换为指定编码的字符串
         *
         * @param file         文本文件
         * @param encoding 编码类型
         * @return 转换后的字符串
         * @throws IOException
         */
        public static String file2String(File file, String encoding) {
                InputStreamReader reader = null;
                StringWriter writer = new StringWriter();
                try {
                        if (encoding == null || "".equals(encoding.trim())) {
                                reader = new InputStreamReader(new FileInputStream(file), encoding);
                        } else {
                                reader = new InputStreamReader(new FileInputStream(file));
                        }
                        //将输入流写入输出流
                        char[] buffer = new char[DEFAULT_BUFFER_SIZE];
                        int n = 0;
                        while (-1 != (n = reader.read(buffer))) {
                                writer.write(buffer, 0, n);
                        }
                } catch (Exception e) {
                        e.printStackTrace();
                        return null;
                } finally {
                        if (reader != null)
                                try {
                                        reader.close();
                                } catch (IOException e) {
                                        e.printStackTrace();
                                }
                }
                //返回转换结果
                if (writer != null)
                        return writer.toString();
                else return null;
        }

    不想抛出太多的检查异常，如果你需要捕捉，就抛出吧。

    注意：对于文件转换为字符串，存在一个编码问题。上面的file2String方法中，如果你不知道编码，调用时候方法设为null即可，此时使用系统默认的编码类型。