shapefile中dbf的数据格式（转载）

来源：http://www.clicketyclick.dk/databases/xbase/format/db2_dbf.html#DB2_DBF_NOTE_4_SOURCE

Xbase: dBASE II data files (*.dbf)

    _______________________  _______
 0 | Version number      *1|  ^
   |-----------------------|  |
 1 | Number of records     | Record
 2 | in data file (16 bit) | header
   |-----------------------|  |            _  |=======================| _______
 3 | Date of last update   |  |           /  0| Field name in ASCII   |  ^
 4 |      YYMMDD           |  |          /    : (terminated by 00h)   :  |
 5 |                       |  |         |     |                       |  |
   |-----------------------|  |         |   10|                       |  |
 6 | Length of each record |  |         |     |-----------------------| For
 7 | ( 16 bits )         *2|  |         |   11| Field type in ASCII *4| each
   |-----------------------|--|---      |     |-----------------------| field
 8 |                       |  |  ^      |   12| Field length  (binary)|  |
 9 | Field descriptor      |  |  | ____/      |-----------------------|  |
   : Array             *5  :  |  |          13| Field adress in memory|  |
   : (Terminated by 0Dh)   :  |  |          14|                       |  |
   :                       :  |  | ______     |-----------------------|  |
   :                       :  |  |       \  15| Field decimal count   |  |
   :                       :  |  |        \_  |=======================| _v_____
   |                       |  |  |
519|                       |  |  |
   |-----------------------|  |  |
520| Terminator          *3|__v__v_
   |=======================|    |
521| Records               |    |
   :                       :    |
   :                       :    |
   :                       :    |
   :                       :    |
  n|                       |    |
   |__End_of_File__________| ___v____  End of file ( 1Ah )  *11

1. dBASE II version no: 02h

1. Sum of lengths of all fields + 1 (deletion flag). Max. length is 1,000 bytes

1. Terminator: 0Dh if all 32 fields present, otherwise 00h.

1. Field type Field type: C, N or L

1. Field descriptor array Max. 32 fields

1. Field lenght: 0 - ffh. Logical fields = 1, decimal no ( = no of digits)
2. Field name can be undefined (= 1 x 00h)

1. Field address in memory can be ignored.
2. Deleted flag. Blanks (20h) are valid! "*" = deleted.

Note that records remain in the datafile when deleted (i.e. are marked with "*") The deleted record are moved out of the valid range of records by the pack command. But is still present in the data file!!! This means that the file size is unchanged!

 Deleted     	 Packed
 =========== 	 ===========
|Header     |	|Header     |
|-----------|	|-----------|
|Valid 1    |	|Valid 1    |
|-----------|	|-----------|
|Deleted 1  |	|Valid 2    |
|-----------|	|-----------|
|Valid 2    |	|Valid 3    |
|-----------|	|===========|
|Deleted 2  |	|EOF        |
|-----------|	|===========|
|Deleted 3  |	|Deleted 1  |
|-----------|	|-----------|
|Valid 3    |	|Deleted 2  |
|===========|	|-----------|
|EOF        |	|Deleted 3  |
 ===========	 ===========