对txt文件内容修改存入新txt文件

package com;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
public class OutputBySort {

public String readFromFile(File file) throws IOException {//读取文件并且转化
FileInputStream fis = null;
try {
fis = new FileInputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
}

InputStreamReader ipsr = new InputStreamReader(fis);
BufferedReader br = new BufferedReader(ipsr);//创建bufferReader对象
String str = null;
String str1 = null;
String str2 = null;
String str3 = null;
int pos,length;
StringBuffer sb = new StringBuffer();//创建stringBuffer
try {
while ((str = br.readLine()) != null) {//读一行
sb.append(str);//将读到的一行str加入到string缓冲区
sb.append("/r/n");//读入换行符
}
} catch (IOException e) {
e.printStackTrace();
}
str1 = sb.toString();//转化为String
str1 = str1.replaceAll("//D"+"/w","");//去标点
str1 = str1.replaceAll("/[a-zA-Z]+", "");//将/w类似的子串去掉
pos = str1.indexOf("html");//html的位置
length = str1.length();
str2 = str1.substring(0, pos+5);//网址
str2 = str2.replaceAll("//s+","");
str3 = str1.substring(pos+4, length);//网址以后的内容
str3 = str3.replaceAll("//s+", "/r/n");//将空格转化为换行
str3 = str2 + str3;
return str3;
}
public void writeIntoFile(File file,String str)throws IOException{//写入到文件,str为要写入的String

try{
String str1 = str;
RandomAccessFile dos = new RandomAccessFile(file, "rw");//打开以便读取和写入。如果该文件尚不存在，则尝试创建该文件
dos.seek(dos.length());
dos.write(str1.getBytes());
}catch(IOException e){
e.printStackTrace();
}
}
public void creatFolder(String folderPath){//创建新目录
try {
File myFilePath = new File(folderPath);
if (!myFilePath.exists()) {//不存在则重新创建一个
myFilePath.mkdir();
}
}
catch (Exception e) {
e.printStackTrace();
}
}
public void Transformation(String oldFolderPath,String newFolderPath)throws IOException{//转化方法
String oldPath = oldFolderPath;//原有文件夹路径
String newPath = newFolderPath;//新文件路径
String str,string;//str用于接收readFromFile返回字符，string用于写入文件的文件路径
File file = new File(oldPath);//原来文件夹的对象
File[] childs = file.listFiles();//获得文件夹下所有子文件
creatFolder(newPath);//创建新目录
for(int i = 0;i<childs.length;i++)
{
string = childs[i].getName();//原名
string = newPath +"/"+ string;//写入的文件路径（新路径+原名）
str = readFromFile(childs[i]);
File f = new File(string);
writeIntoFile(f,str);
}
}
public static void main(String[] args) throws IOException{
OutputBySort out = new OutputBySort();
out.Transformation("E:/a", "E:/c");
}
}