Java重定向System.out和System.err

 

继承PrintStream类：

     public   class  TeeStream  extends  PrintStream {
        PrintStream out;
         public  TeeStream(PrintStream out1, PrintStream out2) {
             super (out1);
             this .out  =  out2;
        }
         public   void  write( byte  buf[],  int  off,  int  len) {
             try  {
                 super .write(buf, off, len);
                out.write(buf, off, len);
            }  catch  (Exception e) {
            }
        }
         public   void  flush() {
             super .flush();
            out.flush();
        }
    }

  使用示例：

     try  {
        PrintStream out  =   new  PrintStream( new  FileOutputStream( " out.log " ));
        PrintStream tee  =   new  TeeStream(System.out, out);
    
        System.setOut(tee);
    
        PrintStream err  =   new  PrintStream( new  FileOutputStream( " err.log " ));
        tee  =   new  TeeStream(System.err, err);
    
        System.setErr(tee);
    }  catch  (FileNotFoundException e) {
    }
    
    System.out.println( " welcome " );
    System.err.println( " error " );