NoSql之MongoDB的常用类管理

1、DBCollection的管理

package com.boonya.mongo;
import java.util.Set;
import com.mongodb.DBCollection;
public class CollectionManager {
	
	public static DBCollection  getDbCollection(String collectionName){
		return DBConnection.getInstance().getCollection(collectionName.equals("")?"myCollection":collectionName);
	}
	
	public String getCollectionNames(){
		String strNames="";
		Set<String> colls =DBConnection.getInstance().getCollectionNames();
		for (String cname : colls) {
			strNames+=cname+",";
		}
		return strNames;
	}

}

2、并发操作管理

package com.boonya.mongo;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBObject;
import com.mongodb.WriteConcern;

public class ConcurrencyManager {
	
	private static DBCollection coll= CollectionManager.getDbCollection("myCollection");
	
	/**
	 * If you want to ensure complete consistency in a “session” (maybe an http request), 
	 * you would want the driver to use the same socket, which you can achieve by using a
	 * “consistent request”. Call requestStart() before your operations and requestDone()
	 * to release the connection back to the pool:
	 * DB and DBCollection are completely thread safe. In fact, they are cached so you get
	 * the same instance no matter what
	 */
	public void insertData(){
		DB db=DBConnection.getInstance();
		db.requestStart();
		try {
			db.requestEnsureConnection();
			//do something
		} finally {
			db.requestDone();
		}

	}
	
	/**
	 * Since by default a connection is given back to the pool after each request, you may 
	 * wonder how calling getLastError() works after a write. You should actually use a 
	 * write concern like WriteConcern.SAFE instead of calling getLastError() manually. 
	 * The driver will then call getLastError() before putting the connection back in the pool.
	 * 
	 * WriteConcern.NONE            No exceptions thrown. 
     * WriteConcern.NORMAL          Exceptions are only thrown when the primary node is unreachable for
     *                              a read, or the full replica set is unreachable. 
     * WriteConcern.SAFE            Same as the above, but exceptions thrown when there is a server error
     *                              on writes or reads. Calls getLastError(). 
     * WriteConcern.REPLICAS_SAFE   Tries to write to two separate nodes. Same as the above, but
     *                              will throw an exception if two writes are not possible. 
     * WriteConcern.FSYNC_SAFE      Same  as WriteConcern.SAFE, but also waits for write to be written to disk. 
     *
	 */
	public void writeConcern(){
		coll.insert(new BasicDBObject("name","boonya").append("age", 21), WriteConcern.SAFE);

		// is equivalent to

		DB db=DBConnection.getInstance();
		DBCollection coll=CollectionManager.getDbCollection("myCollection");
		db.requestStart();
		try {
		   coll.insert(new BasicDBObject("name","boonya").append("age", 21));
		   DBObject err = db.getLastError();
		   System.out.println(err);
		} finally {
		   db.requestDone();
		}

	}

}

3、数据库管理

package com.boonya.mongo;
import java.net.UnknownHostException;
import com.mongodb.MongoClient;
public class DatabaseManager {
	
	public String getDatabaseNames() throws UnknownHostException{
		String strNames="";
		MongoClient mongoClient;
		mongoClient = new MongoClient();
		for (String name : mongoClient.getDatabaseNames()) {
			  strNames+=name+",";
		}
		return strNames;
	}
	
	public void  dropDatabase(String databaseName) throws UnknownHostException{
	     MongoClient mongoClient = new MongoClient();
	     mongoClient.dropDatabase(databaseName);
	}

}

4、文档管理

package com.boonya.mongo;
import java.util.ArrayList;
import java.util.List;
import com.mongodb.BasicDBObject;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
public class DocumentManager {
	
	private static DBCollection coll= CollectionManager.getDbCollection("myCollection");
	
	public void insertADocument(){
		BasicDBObject doc = new BasicDBObject("name", "MongoDB").append("type", "database")
			.append("count", 1)
			.append("info", new BasicDBObject("x", 203).append("y", 102));
         coll.insert(doc);
	}
	
	/**
	 * PRINT BELOW:
	 * { "_id" : "49902cde5162504500b45c2c" ,
     * "name" : "MongoDB" ,
     * "type" : "database" ,
     *  "count" : 1 ,
     *  "info" : { "x" : 203 , "y" : 102}}
	 * @return
	 */
	public DBObject findTheFirstDocument(){
		System.out.println("collection count:"+coll.getCount());
		DBObject myDoc = coll.findOne();
		System.out.println(myDoc);
        return myDoc;
	}
	
    public List<DBObject> getADocumentsByCursor(){
    	List<DBObject> docs=new ArrayList<DBObject>();
    	DBCursor cursor =coll.find();
    	try {
    	   while(cursor.hasNext()) {
    		   DBObject obj=cursor.next();
    	       System.out.println(obj);
    	       docs.add(obj);
    	   }
    	   return docs;
    	} finally {
    	   cursor.close();
    	}
	}
    
    /**
     * PRINT LIKE THIS:
     * { "_id" : "49903677516250c1008d624e" , "i" : 71 }
     */
    public void queryADocument(){
    	BasicDBObject query = new BasicDBObject("i", 71);
    	DBCursor cursor =coll.find();
    	cursor = coll.find(query);
    	try {
    	   while(cursor.hasNext()) {
    	       System.out.println(cursor.next());
    	   }
    	} finally {
    	   cursor.close();
    	}
    }
    
    public void  editQueryRegular(){
    	//db.things.find({j: {$ne: 3}, k: {$gt: 10} });
    	BasicDBObject query = new BasicDBObject("j", new BasicDBObject("$ne", 3)
    	       .append("k", new BasicDBObject("$gt", 10)));
    	DBCursor cursor = coll.find(query);
        try {
        	while(cursor.hasNext()) {
        	  System.out.println(cursor.next());
            }
        } finally {
        	cursor.close();
        }
    }
    
    public void getAsetDocument(){
    	BasicDBObject query = new BasicDBObject("i", new BasicDBObject("$gt", 50));  // e.g. find all where i > 50
//    	query = new BasicDBObject("i", new BasicDBObject("$gt", 20).
//                append("$lte", 30));  // i.e.   20 < i <= 30
    	DBCursor  cursor = coll.find(query);
    	try {
    	   while(cursor.hasNext()) {
    	       System.out.println(cursor.next());
    	   }
    	} finally {
    	   cursor.close();
    	}
    }
	

}

5、索引管理

package com.boonya.mongo;
import java.util.List;
import com.mongodb.BasicDBObject;
import com.mongodb.DBCollection;
import com.mongodb.DBObject;

public class IndexManager {
	
	private static DBCollection coll= CollectionManager.getDbCollection("myCollection");
	
	public void createIndex(){
		// create index on "i", ascending
		coll.createIndex(new BasicDBObject("i", 1));
	}
	
	public List<DBObject> getIndexList(){
		List<DBObject> list = coll.getIndexInfo();
		for (DBObject o : list) {
		   System.out.println(o);
		   list.add(o);
		}
		return list;
	}

}

6、预读取机制

package com.boonya.mongo;
import com.mongodb.BasicDBObject;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.ReadPreference;
public class ReadPreferences {
	
	private static DBCollection coll= CollectionManager.getDbCollection("myCollection");
	
	/**
	 * ReadPreference.primary();
     * ReadPreference.primaryPreferred();
     * ReadPreference.secondary();
     * ReadPreference.secondaryPreferred();
     * ReadPreference.nearest();
	 */
	public void read(){
		DBObject query = new BasicDBObject("name", "simple doc");
		
		//Read from primary if available, otherwise a secondary.
		ReadPreference preference = ReadPreference.primaryPreferred();
		DBCursor cur = new DBCursor(coll, query, (DBObject) preference);
		
		//Read from any member node from the set of nodes which respond the fastest. 
		//The responsiveness of a node is measured with pings. Any node whose ping 
		//time is within 15 milliseconds of the node with the lowest ping time is considered near.
		DBObject result =coll.findOne(query, (DBObject) ReadPreference.nearest());
		
		
		// initialize a properly tagged read preference
		ReadPreference tagged_pref =ReadPreference.secondaryPreferred(new BasicDBObject("datacenter", "Los Angeles"));

		// include the tagged read preference in this request}}
		DBObject result1=coll.findOne(new BasicDBObject("name", "simple doc"), (DBObject) tagged_pref);
        
		// read from either LA or US_West
		DBObject tagSetOne = new BasicDBObject("datacenter", "Los Angeles");
		DBObject tagSetTwo = new BasicDBObject("region", "US_West");
		ReadPreference pref =ReadPreference.primaryPreferred(tagSetOne, tagSetTwo);

	}

}