Java access to MongoDB files

MongoDB has been a constant concern. What is the legendary document database better than MySQL every day? All of this requires data to be used to talk about it. Let's talk nonsense. Let's take a look at a piece of code first. Please ignore the skills and rigor of code writing. Thank you. Packagecom.cn. javabloger; importjava. io. File; importjava. io. iow.t

MongoDB has been a constant concern. What is the legendary document database better than MySQL every day? All of this requires data to be used to talk about it. Let's talk nonsense. Let's take a look at a piece of code first. Please ignore the skills and rigor of code writing. Thank you. Package com.cn. javabloger; import java. io. File; import java. io. IOExcept

MongoDB has been a constant concern. What is the legendary document database better than MySQL every day? All of this requires data,
To put it bluntly, read a piece of code first,Please ignore the skills and rigor of my code writing. Thank you..
Package com.cn. javabloger;

Import java. io. File;
Import java. io. IOException;
Import java. util. Date;
Import java. util. List;

Import com. mongodb. DB;
Import com. mongodb. Mongo;
Import com. mongodb. gridfs. GridFS;
Import com. mongodb. gridfs. GridFSDBFile;
Import com. mongodb. gridfs. GridFSFile;

Public class MongoDBFileTest {

Static DB imgDB = null;
Static GridFS gridFS = null;

Public static void main (String [] args) throws Exception {
Long start = System. currentTimeMillis ();
Mongo mongo = new Mongo ("192.168.50.215", 27017); // database address, Port Number
ImgDB = mongo. getDB ("imgs"); // Database Name
GridFS = new GridFS (imgDB );

String fileName = "android-sdk-windows.rar"; // read 428 M Files
String fileNameO = "spring.zip"; // name of the written file
MongoDBFileTest mon = new MongoDBFileTest ();
File fileIN = new File ("c:/" + fileName );
File fileOUT = new File ("c:/" + fileNameO );

/**
* Save the file to the MongoDB database.
*/
Mon. saveFile (fileIN, fileName );
Long end = System. currentTimeMillis ();
System. out. println (end-start );

/**
* Read data from MongoDB and write data to disk
*/
List List = mon. findFilesByName (fileName );
GridFSDBFile gridFSDBFile = (GridFSDBFile) list. get (0 );
GridFSDBFile. writeTo (fileOUT );
System. out. println (list. size ());
}

/**
* Writing files
* @ Param fileName
*/
Public void saveFile (File file, String fileName ){
Try {
GridFSFile same file = gridFS. createFile (file );
Using file. put ("filename", fileName );
Using file. put ("uploadDate", new Date ());
Using file. put ("contentType", fileName. substring (fileName. lastIndexOf (".")));
Using file. save ();
} Catch (IOException e ){
E. printStackTrace ();
}
}

/**
* Reading files
* @ Param fileName
*/
Public List FindFilesByName (String fileName ){
List List = gridFS. find (fileName );
Return list;
}
}

I started MongoDB on a 32-bit machine,And addedSmallfilesAndNssizeStartup parameters, Find a 428M android-sdk-windows.rar file, write the MongoDB database four times, each write consumes time is87360/69485/105595/40094The memory usage for each insert is higher than once. The mongod process occupies 256 MB, and the mongod process occupies MB of memory. When I write the fifth time, the following error message is displayed:
Tue May 18 00:36:59 Caught Assertion in insert, continuing
Tue May 18 00:36:59 insert imgs. fs. chunks exception userassert: can't map file memory-mongo requires 64 bit build for larger datasets 0 ms
Mmap () failed for/work/fetch data/imgs.7 len: 536870912 errno: 12 Cannot allocate memory
Mmap failed with out of memory, if you're using 32-bits, then you probably need to upgrade to 64

There is no 64-bit system at the moment, and one will be prepared in the near future.

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