MongoDB basic series -- Implement curd using MongoDB in Java

MongoDB supports multiple languages and is driven by multiple languages.

Java MongoDB operations to achieve curd: premise: Download the corresponding driver: download on the official website: http://central.maven.org/maven2/org/mongodb/mongo-java-driver/ I use mongo-2.10.1.jar version: the following code in detail, each method can be executed separately. In order to facilitate the operation, each method re-links the database, but does not mention it again, because the purpose here is to understand MongoDB.

Package COM. mongo. dao; import COM. mongoDB. basicdbobject; import COM. mongoDB. DB; import COM. mongoDB. dbcollection; import COM. mongoDB. dbcursor; import COM. mongoDB. mongo;/*** test the storage of basic entities * @ author LHY **/public class entitytest {public static void main (string [] ARGs) throws exception {Delete ();}/*** save object * @ throws exception */public static void saveentity () throws exception {// first: instantiate a mongo object, the connection to the MongoDB server contains all the databases // default constructor, which is connected to the local machine by default and port number. The default value is 27017 // equivalent to Mongo = new Mongo ("localhost", 27017) mongo = new Mongo (); // Second: connect to a specific database // The parameter is the name of the specific database. If the server does not exist, the database = Mongo is automatically created. getdb ("mymongo"); // third: the specific table for the Operation // does not have the table concept in MongoDB, but indicates the set // Where the parameter is the table in the database. If it does not exist, dbcollection collection = dB is automatically created. getcollection ("user"); // Add operation // no row concept in MongoDB, but it refers to the document basicdbobject document = new basicdbobject (); document. put ("ID", 1); document. put ("name", "James"); // save it to the collection /// collection. insert (document); // Of course, I can also save this JSON string/* {"ID": 1, "name", "James", "Address ": {"city": "Beijing", "code": "065000"} * // The preceding JSON string is implemented as follows: // The first method is similar to XML, add basicdbobject addressdocument = new basicdbobject (); addressdocument. put ("city", "Beijing"); addressdocument. put ("code", "065000"); document. put ("Address", addressdocument); // Save the collection in the database. insert (document); // type 2: directly store JSON in the database/* string jsontest = "{'id': 1, 'name': 'xiaoming ', "+" 'address': {'city': 'beijing', 'code': '000000'} "+"} "; dbobject dbobjct = (dbobject) JSON. parse (jsontest); Collection. insert (dbobjct); */}/*** traverse all the * @ throws exception */public static void selectall () throws exception {// first: instantiate the Mongo object, the connection to the MongoDB server contains all the databases // default constructor, which is connected to the local machine by default and port number. The default value is 27017 // equivalent to Mongo = new Mongo ("localhost", 27017) mongo = new Mongo (); // Second: connect to a specific database // The parameter is the name of the specific database. If the server does not exist, the database = Mongo is automatically created. getdb ("mymongo"); // third: the specific table for the Operation // does not have the table concept in MongoDB, but indicates the set // Where the parameter is the table in the database. If it does not exist, dbcollection collection = dB is automatically created. getcollection ("user"); // query operation // query all // similar to the cursor concept dbcursor cursor = collection in the Access Database. find (); system. out. println ("the result of the User table in MongoDB is as follows:"); While (cursor. hasnext () {system. out. println (cursor. next () ;}}/*** query by condition * @ throws exception */public static void selectpart () throws exception {// first: instantiate the Mongo object, the connection to the MongoDB server contains all the databases // default constructor, which is connected to the local machine by default and port number. The default value is 27017 // equivalent to Mongo = new Mongo ("localhost", 27017) mongo = new Mongo (); // Second: connect to a specific database // The parameter is the name of the specific database. If the server does not exist, the database = Mongo is automatically created. getdb ("mymongo"); // third: the specific table for the Operation // does not have the table concept in MongoDB, but indicates the set // Where the parameter is the table in the database. If it does not exist, dbcollection collection = dB is automatically created. getcollection ("user"); // you can directly put basicdbobject queryobject = new basicdbobject (); queryobject. put ("ID", 1); dbcursor querycursor = collection. find (queryobject); system. out. println ("condition query:"); While (querycursor. hasnext () {system. out. println (querycursor. next () ;}/ ***** update operation * updates a record * @ throws exception */public static void Update () throws exception {// first: instantiate the Mongo object, the connection to the MongoDB server contains all the databases // default constructor, which is connected to the local machine by default and port number. The default value is 27017 // equivalent to Mongo = new Mongo ("localhost", 27017) mongo = new Mongo (); // Second: connect to a specific database // The parameter is the name of the specific database. If the server does not exist, the database = Mongo is automatically created. getdb ("mymongo"); // third: the specific table for the Operation // does not have the table concept in MongoDB, but indicates the set // Where the parameter is the table in the database. If it does not exist, dbcollection collection = dB is automatically created. getcollection ("user"); // The updated object // The first update method basicdbobject newbasicdbobject = new basicdbobject (); newbasicdbobject. put ("ID", 2); newbasicdbobject. put ("name", "Xiaohong"); Collection. update (New basicdbobject (). append ("ID", 1), newbasicdbobject); // the second update method // update a field // basicdbobject newbasicdbobject = new basicdbobject (). append ("$ set", new basicdbobject (). append ("name", "Xiaohong"); // collection. update (New basicdbobject (). append ("ID", 1 ). append ("name", "James"), newbasicdbobject); dbcursor querycursor1 = collection. find (); system. out. println ("the updated result is as follows:"); While (querycursor1.hasnext () {system. out. println (querycursor1.next () ;}/ *** delete a document, including deleting all or some of the documents * @ throws exception */public static void Delete () throws exception {// first: instantiate the Mongo object. The connection to the MongoDB server contains all databases. // The default constructor is used to connect to the local machine and port number, the default value is 27017 // equivalent to Mongo = new Mongo ("localhost", 27017) Mongo = new Mongo (); // second: connect to a specific database // The parameter is the name of the specific database. If the server does not exist, the database DB = Mongo is automatically created. getdb ("mymongo"); // third: the specific table for the Operation // does not have the table concept in MongoDB, but indicates the set // Where the parameter is the table in the database. If it does not exist, dbcollection collection = dB is automatically created. getcollection ("user"); basicdbobject queryobject1 = new basicdbobject (); queryobject1.put ("ID", 2); queryobject1.put ("name", "Xiaohong "); // delete a collection record. remove (queryobject1); // Delete All // collection. drop (); dbcursor cursor1 = collection. find (); system. out. println ("the result after deletion is as follows:"); While (cursor1.hasnext () {system. out. println (cursor1.next ());}}}

Here, mongdb is executed using a JSON string. As for how to display the JSON string interface, the next blog will provide a demo for you to practice.