要使用FileOutputStream覆盖文件foo.log，请执行以下操作：

File myFoo = new File("foo.log");
FileOutputStream fooStream = new FileOutputStream(myFoo, false); // true to append
                                                                 // false to overwrite.
byte[] myBytes = "New Contents\n".getBytes(); 
fooStream.write(myBytes);
fooStream.close();

或使用FileWriter：

File myFoo = new File("foo.log");
FileWriter fooWriter = new FileWriter(myFoo, false); // true to append
                                                     // false to overwrite.
fooWriter.write("New Contents\n");
fooWriter.close();