第三章 MongoDb Java应用 3.1-优快云博客

本文介绍如何使用Java操作MongoDB数据库，包括连接服务器、创建数据库及集合、插入查询文档等基本操作，并演示了索引创建及使用游标获取数据的方法。

1、Java 应用示例

要使用Java操作MongoDB的话，要到官方网站下载一个驱动包，点击网站上的Drivers里面，可以看到目前支持的语言，非常的多……把包导入后，可以尝试来操作了（记得一定要开着服务器）

首先介绍一下比较常用的几个类

Mongo：连接服务器，执行一些数据库操作的选项，如新建立一个数据库等

DB：对应一个数据库，可以用来建立集合等操作

DBCollection：对应一个集合（类似表），可能是我们用得最多的，可以添加删除记录等

DBObjec：接口和BasicDBObject对象：表示一个具体的记录，BasicDBObject实现了DBObject，因为是key-value的数据结构，所以用起来其实和HashMap是基本一致的

DBCursor：用来遍历取得的数据，实现了Iterable和Iterator

接下来实际的操作一下，代码如下：

import java.net.UnknownHostException;

import java.util.List;

import java.util.Set;

import com.mongodb.BasicDBObject;

import com.mongodb.DB;

import com.mongodb.DBCollection;

import com.mongodb.DBCursor;

import com.mongodb.DBObject;

import com.mongodb.Mongo;

import com.mongodb.MongoException;

public class MongoDbTest {

public static void main(String[] args) throws UnknownHostException, MongoException {

//Mongo m = new Mongo();

//Mongo m = new Mongo("localhost");

Mongo m = new Mongo("localhost", 27017);

DB db = m.getDB("mytest");

Set<String> colls = db.getCollectionNames();

for (String s : colls) {

System.out.println(s);

}

DBCollection coll = db.getCollection("testCollection");

BasicDBObject doc = new BasicDBObject();

doc.put("name", "MongoDB");

doc.put("type", "database");

doc.put("count", 1);

BasicDBObject info = new BasicDBObject();

info.put("x", 203);

info.put("y", 102);

doc.put("info", info);

coll.insert(doc);

DBObject myDoc = coll.findOne();

System.out.println(myDoc);

//Adding Multiple Documents

for (int i=0; i < 100; i++) {

coll.insert(new BasicDBObject().append("i", i));

}

//Counting Documents in A Collection

System.out.println(coll.getCount());

//Using a Cursor to Get All the Documents

DBCursor cur = coll.find();

while(cur.hasNext()) {

System.out.println(cur.next());

}

System.out.println("-------------华丽分隔线----------------------");

//Getting A Single Document with A Query

BasicDBObject query = new BasicDBObject();

query.put("i", 71);

cur = coll.find(query);

System.out.println("查找i=71结果为:");

while(cur.hasNext()) {

System.out.println(cur.next());

}

System.out.println("查找i=71结束！");

System.out.println("-------------华丽分隔线----------------------");

query = new BasicDBObject();

query.put("i", new BasicDBObject("$gt", 90)); // e.g. find all where i > 50

cur = coll.find(query);

System.out.println("查找i>90结果为:");

while(cur.hasNext()) {

System.out.println(cur.next());

}

System.out.println("查找i>90结束！");

System.out.println("-------------华丽分隔线----------------------");

/**

* which should print the documents where i > 50.

* We could also get a range, say 20 < i <= 30 :

query = new BasicDBObject();

query.put("i", new BasicDBObject("$gt", 20).append("$lte", 25)); // i.e. 20 < i <= 30

cur = coll.find(query);

System.out.println("查找20 < i <= 25结果为:");

while(cur.hasNext()) {

System.out.println(cur.next());

}

System.out.println("查找20 < i <= 25结束！");

System.out.println("-------------华丽分隔线----------------------");

//Creating An Index

coll.createIndex(new BasicDBObject("i", 1)); // create index on "i", ascending

//Getting a List of Indexes on a Collection

List<DBObject> list = coll.getIndexInfo();

System.out.println("Getting a List of Indexes on a Collection start...");

for (DBObject o : list) {

System.out.println(o);

}

System.out.println("Getting a List of Indexes on a Collection end!");

System.out.println("-------------华丽分隔线----------------------");

System.out.println("Getting A List of Databases start...");

for (String s : m.getDatabaseNames()) {

System.out.println(s);

}

System.out.println("Getting A List of Databases end");

System.out.println("-------------华丽分隔线----------------------");

System.out.println("Dropping A Database start...");

//m.dropDatabase("my_new_db");

System.out.println("Dropping A Database end!");

}

本文转自jooben 51CTO博客，原文链接:http://blog.51cto.com/jooben/350740