Editing Server level.dat (section)

=== Accessing the array of bytes ===

One generally has two options for accessing the byte array of blocks: 

The [[player]] could deserialize the compressed .dat file directly back into an instance of a Level object inside of Java, thus having access to the instance of the Level object in exactly the same way the Minecraft Server does. This would allow the player to set the blocks, dimensions, spawn point and other aspects of the map directly by calling the methods on the instantiated Level object. Manual decompression is not needed before loading, because Java can compress and decompress gzipped files on the fly. To load the datafile back into an instance of the Level class, the player would need the class definition for the Level class. This is included with the minecraft-server.jar file. An example of this can be seen in the [[Development resources/Example Minecraft Classic Level Editing Class]].

Others have read and modified the map's data by simply accessing the raw byte array in the datafile file. To do this, the player would decompress it, make changes to the bytes where the byte array is stored, and then compress it again. Since the player is editing it raw, the player must keep the first 344 (14E in HEX) bytes intact. The next 256×256×64 bytes are where the byte array is stored. Additionally, it is also possible to alter the spawn location coordinates this way if the player knows where to look: there are 3 integer values starting at byte 284 and thus overwriting the next 12 bytes (3 integers) allow the player to change the spawn location.

{{Java Edition}}

[[Category:Server]]

[[pt:server level.dat]]
[[zh:server level.dat]]