先得出某个路径:
String resultsDir=getServletConfig().getServletContext().getRealPath("\\");
FileWriter resultsFile=new FileWriter(resultsDir+"flatresult.txt",true);
File myFile=new File(resultsDir+"flatresult.txt");
FileInputStream tfile=new FileInputStream(resultsDir+"flatresult.txt");
if(tfile.read()==你的条件){
RandomAccessFile savefile = new RandomAccessFile(resultsDir+"dd.txt","rw");
savefile.writeBytes(“修改的内容”);
savefile.close();
}
tfile.close();