java sout写到文本文件里

PrintStream fileStream = new PrintStream("filename.txt");
System.setOut(fileStream);

 以后所有的sout都变成记录日志了

然后一个小技巧

//这里开始写日志，启动日志记录
try{
   Date cData = new Date(System.currentTimeMillis());
   SimpleDateFormat ft = new SimpleDateFormat ("yyyy-MM-dd-hh-mm-ss");
   String cDataStr = ft.format(cData);
   PrintStream fileStream = new PrintStream("log_"+cDataStr+"_"+myProjectHelper.ProjectDest.substring(0, myProjectHelper.ProjectDest.length()-1)+".txt");
   System.setOut(fileStream);
}catch (Exception e11){
   e11.printStackTrace();
   e11.getCause();
}
System.out.println("---------------------日志功能开启---------------------");