java操作mongodb示例分享

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 {      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      }  }