File-CRD-KeyValue-DS

Background

This project is build on top of mapdb. MapDB combines embedded database engine and Java collections. MapDB is extensively unit-tested By default.

We can directly pass JSON String to it. We get JSON String which string, with the help of Jackson one can make use of it.

File extension in this project is db.

Features

• Create, can be easily done by put(key, value).
• Read, by get(key)
• Delete, by remove(key)
• As it is based on java collection, many more features are copied with the same.
• for more features refer mapdb-docs.

How to use

Create Database

import in.toin.DB;

DB with standard project directory

DB customDb = new DB("example");

DB with custom location

DB customDb1 = new DB("E:\\", "example");

Code Example

import com.fasterxml.jackson.databind.ObjectMapper;
import in.toin.DB;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;

public class Example {
    public static void main(String[] args) {
        
        // DB with standard project directory
        DB customDb = new DB("random");
        
        // DB with custom location
        // DB customDb1 = new DB("E:\", "hello");
        
        // ObjectMapper provides functionality for reading and writing JSON,
        ObjectMapper mapper = new ObjectMapper();
        
        // Map of DS
        ConcurrentMap<String, String> map = null;
        
        try {
            // Here Value is sample object
            Value value = new Value("Apple", "Fruit as well as trillion dollar company.");
            
            // Java objects to JSON string - compact-print
            String jsonString = mapper.writeValueAsString(value);
            
            // Get the from the data base.
            map  = customDb.getMap();
    
            // Insert
            map.put("brand", jsonString);
            map.put("location", jsonString);
            map.put("animals", jsonString);
            // Remove
            map.remove("location");
            
            // Iteration through the map
            for (Map.Entry<String, String> entry: map.entrySet())
                System.out.println(entry.getKey() + " " + entry.getValue());
        
        } catch (IOException e) {
            e.printStackTrace();
        }
        
        customDb.close();
    }
}

Note

Always close the DB once operations have been performed, or else the DB will get corrupted. As it is meant for single user at a time.

db.close();

Sources

Build on top of mapdb.