Java 连接MongoDB
package mymaven;import java.net.UnknownHostException;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 Test { /** * @author ithomer.net * @datetime 2013-11-11 */ public static void main(String[] args) throws UnknownHostException, MongoException { Mongo mongo = new Mongo("172.27.9.104", 27017); // 连接数据库 DB db = mongo.getDB("mytestdb"); // 数据库 Set<String> cols = db.getCollectionNames(); // 获取数据库中所有的集合（类似于获取关系数据库中的表） // 打印出数据库中的集合，这里应当为null for (String s : cols) { System.out.println(s); } DBCollection collection = db.getCollection("mytestcoll"); // 创建一个集合 collection.drop(); // 删除集合，插入数据时自动重建 BasicDBObject obj = new BasicDBObject(); // 初始化一个基本DB对象，插入数据库的就是DB对象 obj.put("from", "blog.ithomer.net"); // 放入几个键值对 obj.put("to", "forum.ithomer.net"); obj.put("subject", "ithomer.net"); collection.insert(obj); // 插入对象 DBObject dbobj = collection.findOne(); // 查看一条记录，findOne()=find().limit(1); System.out.println(dbobj); // 打印出刚才插入的数据 // 插入10条{ranking:i}的数据 for (int i = 0; i < 10; i++) { collection.insert(new BasicDBObject().append("ranking", i)); } System.out.println("count: " + collection.getCount()); // 打印集合中的数据总数 DBCursor cursor = collection.find(); // 然后我们使用这个游标来遍历集合 while (cursor.hasNext()) { System.out.println(cursor.next()); } // 简单的条件查询，查询ranking为1的记录 BasicDBObject query = new BasicDBObject(); query.put("ranking", 1); cursor = collection.find(query); System.out.println("collection find({\"ranking\":1}):"); while (cursor.hasNext()) { System.out.println(cursor.next()); } // 复杂的条件查询，查询ranking大于等于5小于9的记录 query = new BasicDBObject(); query.put("ranking", new BasicDBObject("$gte", 5).append("$lt", 9)); cursor = collection.find(query); System.out.println("collection find({\"ranking\":[5-9)}):"); while (cursor.hasNext()) { System.out.println(cursor.next()); } // mongo.dropDatabase("mytestdb"); // 最后删除我们的测试数据库 }}运行结果：
mytestcollsystem.indexes{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10107"} , "from" : "blog.ithomer.net" , "to" : "forum.ithomer.net" , "subject" : "ithomer.net"}count: 11{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10107"} , "from" : "blog.ithomer.net" , "to" : "forum.ithomer.net" , "subject" : "ithomer.net"}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10108"} , "ranking" : 0}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10109"} , "ranking" : 1}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010a"} , "ranking" : 2}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010b"} , "ranking" : 3}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010c"} , "ranking" : 4}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010d"} , "ranking" : 5}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010e"} , "ranking" : 6}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010f"} , "ranking" : 7}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10110"} , "ranking" : 8}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10111"} , "ranking" : 9}collection find({"ranking":1}):{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10109"} , "ranking" : 1}collection find({"ranking":[5-9)}):{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010d"} , "ranking" : 5}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010e"} , "ranking" : 6}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd1010f"} , "ranking" : 7}{ "_id" : { "$oid" : "52c62ed8e4b0f4de3dd10110"} , "ranking" : 8}源码下载（maven）
@SuppressWarnings("unchecked") public static void loadMediaTags(List<MediaEntity> mediaEntityList) { mediaEntityList.clear(); try { Mongo mongo = new Mongo(CosineCluster.gMongo_HOST, CosineCluster.gMongo_PORT); DB db = mongo.getDB(CosineCluster.gMongo_DB); DBCollection collection = db.getCollection(CosineCluster.gMongo_Coll_Media); DBCursor cursor = collection.find(); int index = 0; long startTime = System.currentTimeMillis(); while(cursor.hasNext()){ BasicDBObject obj = (BasicDBObject) cursor.next(); long id = obj.getLong("_id"); ArrayList<String> tagList = (ArrayList<String>) obj.get("tag"); // tag ArrayList<String> keywordList = (ArrayList<String>)obj.get("keyword"); // keyword ArrayList<Integer> copyrightList = (ArrayList<Integer>)obj.get("copyright"); // copyright MediaEntity mediaEntity = new MediaEntity(); mediaEntity.setId(id); // tag for(int j=0; j<tagList.size(); j++) { mediaEntity.addTag(tagList.get(j)); int tagId = getTagInt(tagList.get(j)); mediaEntity.addTag(tagId); } // actors ArrayList<DBObject> actorsObjList = (ArrayList<DBObject>)obj.get("actors"); // actors for(int j=0; j<actorsObjList.size(); j++) { mediaEntity.addActor((String) actorsObjList.get(j).get("name")); int actorId = getActorInt((String)actorsObjList.get(j).get("name")); mediaEntity.addActor(actorId); } // director ArrayList<DBObject> directorObjList = (ArrayList<DBObject>)obj.get("director"); // director for(int j=0; j<directorObjList.size(); j++) { mediaEntity.addDirector((String) directorObjList.get(j).get("name")); int directorId = getDirectorInt((String) directorObjList.get(j).get("name")); mediaEntity.addDirector(directorId); } // keyword for(int j=0; j<keywordList.size(); j++) { mediaEntity.addKeyword(keywordList.get(j)); int keywordId = getKeywordInt(keywordList.get(j)); mediaEntity.addKeyword(keywordId); } // copyright for(int j=0; j<copyrightList.size(); j++) { mediaEntity.addCopyright(copyrightList.get(j)); } mediaEntityList.add(mediaEntity); index++; if(index > 100) { break; } System.out.println(index + " --- mediaEntity : " + mediaEntity.toString()); } long costTime = System.currentTimeMillis() - startTime; System.out.println("load data costTime = " + index + "; costTime = " + costTime/1000f); } catch (Exception e) { e.printStackTrace(); } } public static int getTagInt(String tag) { int tagIntId = -1; try { MongoClient mongo = new MongoClient(CosineCluster.gMongo_HOST, CosineCluster.gMongo_PORT); DB db = mongo.getDB(CosineCluster.gMongo_DB); DBCollection tagmapCollection = db.getCollection("recommend_tag_map"); DBCursor cursor = tagmapCollection.find(new BasicDBObject("name", tag)); if(cursor == null || cursor.toArray().size() <= 0) { // 处理小于2或n的映射关键字，下同 return tagIntId; } DBObject obj = cursor.toArray().get(0); String name = tag; tagIntId = (Integer) obj.get("id"); int num = (Integer) obj.get("num"); mongo.close(); } catch (UnknownHostException e) { e.printStackTrace(); } return tagIntId; } public static int getActorInt(String actor) { int actorIntId = -1; try { MongoClient mongo = new MongoClient(CosineCluster.gMongo_HOST, CosineCluster.gMongo_PORT); DB db = mongo.getDB(CosineCluster.gMongo_DB); DBCollection tagmapCollection = db.getCollection("recommend_actor_map"); DBCursor cursor = tagmapCollection.find(new BasicDBObject("name", actor)); if(cursor == null || cursor.toArray().size() <= 0) { return actorIntId; } DBObject obj = cursor.toArray().get(0); String name = actor; actorIntId = (Integer) obj.get("id"); int num = (Integer) obj.get("num"); mongo.close(); } catch (UnknownHostException e) { e.printStackTrace(); } return actorIntId; }参考推荐：
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