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springboot based on a series of packaging framework. QmFramework to implements AOP, rewrite the requestBody, global exception catching,version checking, request body parameter symmetric encryption mechanism, controller packaging and the toolkit collection. thank you for using it.

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package com.starmcc.qmframework.tools.file;

import java.io.*;

/**
 * 文件读取工具
 *
 * @Author qm
 */
public class QmFileUtil {

    /**
     * 以字节为单位读取文件，通常用于读取二进制文件，如图片
     *
     * @param path
     * @return
     */
    public static String readByBytes(String path) {
        String content = null;

        try {
            InputStream inputStream = new FileInputStream(path);
            StringBuffer sb = new StringBuffer();
            int c = 0;
            byte[] bytes = new byte[1024];
            /*
             * InputStream.read(byte[] b)
             *
             * Reads some number of bytes from the input stream and stores them into the buffer array b. 从输入流中读取一些字节存入缓冲数组b中
             * The number of bytes actually read is returned as an integer.  返回实际读到的字节数
             * This method blocks until input data is available, end of file is detected, or an exception is thrown.
             * 该方法会一直阻塞，直到输入数据可以得到、或检测到文件结束、或抛出异常  -- 意思是得到数据就返回
             */
            while ((c = inputStream.read(bytes)) != -1) {
                sb.append(new String(bytes, 0, c, "utf-8"));
            }

            content = sb.toString();
            inputStream.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return content;
    }

    /**
     * 以行为单位读取文件，常用于读取面向行的格式化文件
     *
     * @param path
     * @return
     */
    public static String readByLines(String path) {
        String content = null;


        try {
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(path), "utf-8"));

            StringBuffer sb = new StringBuffer();
            String temp = null;
            while ((temp = bufferedReader.readLine()) != null) {
                sb.append(temp);
            }

            content = sb.toString();
            bufferedReader.close();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return content;
    }

    /**
     * 以字符为单位读取文件，常用于读取文本文件
     *
     * @param path
     * @return
     */
    public static String readByChars(String path) {
        String content = null;

        try {

            Reader reader = new InputStreamReader(new FileInputStream(path), "utf-8");
            StringBuffer sb = new StringBuffer();


            char[] tempchars = new char[1024];
            while (reader.read(tempchars) != -1) {
                sb.append(tempchars);
            }

            content = sb.toString();
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return content;
    }

    /**
     * 把内容content写的path文件中
     *
     * @param content
     * @param path
     * @return
     */
    public static boolean saveAs(String content, String path) {
        FileWriter fw = null;
        try {
            /**
             * Constructs a FileWriter object given a File object. 
             * If the second argument is true, then bytes will be written to the end of the file rather than the beginning.
             * 根据给定的File对象构造一个FileWriter对象。 如果append参数为true, 则字节将被写入到文件的末尾（向文件中追加内容）
             *
             *    Parameters:
             *        file,  a File object to write to 带写入的文件对象
             *        append,  if true, then bytes will be written to the end of the file rather than the beginning
             *    Throws:
             *        IOException - 
             *        if the file exists but is a directory rather than a regular file, 
             *            does not exist but cannot be created, 
             *            or cannot be opened for any other reason
             *      报异常的3种情况：
             *          file对象是一个存在的目录（不是一个常规文件）
             *          file对象是一个不存在的常规文件，但不能被创建
             *          file对象是一个存在的常规文件，但不能被打开
             *
             */
            fw = new FileWriter(new File(path), false);
            if (content != null) {
                fw.write(content);
            }
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        } finally {
            if (fw != null) {
                try {
                    fw.flush();
                    fw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return true;
    }
}