Nosql-common MongoDB Class Management

1. dbcollection Management

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. Concurrent Operation Management

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. Database Management

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. Document Management

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. index management

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. Pre-read Mechanism

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); }}