mongodb在java中常见的查询(一)

mongodb是非关系型数据库,对于数据的操作跟关系型数据库有很大的区别,非通用sql,

那么在java中是如何进行数据读取呢?详情如下:

(聚合函数部分见下期<mongodb在java中常见的查询(二)>)

ps: mongodb不适合做业务系统,,只适合做缓存为主的key-value读取形式存放的  或者是静态缓存数据,或者 不太重要的数据(mongodb不支持事务处理)

和java的契合度不好,一样会写大量繁琐的代码,还不如两三行sql来得痛快,不过话说回来如果只是用key来取值确实方便.,..

package com.9203.mongo;

import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.regex.Pattern;

import org.junit.Test;

import com.mongodb.AggregationOutput;
import com.mongodb.BasicDBList;
import com.mongodb.BasicDBObject;
import com.mongodb.BasicDBObjectBuilder;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.MapReduceCommand;
import com.mongodb.MapReduceOutput;
import com.mongodb.Mongo;
import com.mongodb.QueryBuilder;
import com.mongodb.WriteConcern;

public class TestCase {

	@Test
	/**
	 * 获取所有数据库实例
	 */
	public void testGetDBS() {
		List<String> dbnames = MongoUtil.getMong().getDatabaseNames();
		for (String dbname : dbnames) {
			System.out.println("dbname:" + dbname);
		}
	}

	@Test
	/**
	 * 删除数据库
	 */
	public void dropDatabase() {
		MongoUtil.getMong().dropDatabase("my_new_db");
	}

	@Test
	/**
	 * 查询所有表名
	 */
	public void getAllCollections() {
		Set<String> colls = MongoUtil.getDB().getCollectionNames();
		for (String s : colls) {
			System.out.println(s);
		}
	}

	@Test
	public void dropCollection() {
		MongoUtil.getColl("jellonwu").drop();
	}

	/**
	 * 添加一条记录
	 */
	@Test
	public void addData() {
		DBCollection coll = MongoUtil.getColl("wujintao");
		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);
		// 设定write concern，以便操作失败时得到提示
		coll.setWriteConcern(WriteConcern.SAFE);
	}

	@Test
	/**
	 * 创建索引
	 */
	public void createIndex() {
		MongoUtil.getColl("wujintao").createIndex(new BasicDBObject("i", 1));
	}

	@Test
	/**
	 * 获取索引信息
	 */
	public void getIndexInfo() {
		List<DBObject> list = MongoUtil.getColl("hems_online").getIndexInfo();
		for (DBObject o : list) {
			System.out.println(o);
		}
	}

	@Test
	/**
	 * 添加多条记录
	 */
	public void addMultiData() {
		for (int i = 0; i < 100; i++) {
			MongoUtil.getColl("wujintao").insert(
					new BasicDBObject().append("i", i));
		}

		List<DBObject> docs = new ArrayList<DBObject>();
		for (int i = 0; i < 50; i++) {
			docs.add(new BasicDBObject().append("i", i));
		}
		MongoUtil.getColl("wujintao").insert(docs);
		// 设定write concern，以便操作失败时得到提示
		MongoUtil.getColl("wujintao").setWriteConcern(WriteConcern.SAFE);
	}

	@Test
	/**
	 * 查找第一条记录
	 */
	public void findOne() {
		DBObject myDoc = MongoUtil.getColl("wujintao").findOne();
		System.out.println(myDoc);
	}

	@Test
	/**
	 * 获取表中所有记录条数
	 */
	public void count() {
		System.out.println(MongoUtil.getColl("wujintao").getCount());
		System.out.println(MongoUtil.getColl("wujintao").count());
	}

	@Test
	/**
	 * 获取查询结果集的记录数
	 */
	public void getCount() {
		DBObject query = new BasicDBObject("name", "a");
		long count = MongoUtil.getColl("wujintao").count(query);
		System.out.println(count);
	}

	@Test
	/**
	 * 查询所有结果
	 */
	public void getAllDocuments() {
		DBCursor cursor = MongoUtil.getColl("wujintao").find();
		try {
			while (cursor.hasNext()) {
				System.out.println(cursor.next());
			}
		} finally {
			cursor.close();
		}
	}

	@Test
	/**
	 * 按照一个条件查询
	 */
	public void queryByConditionOne() {
		BasicDBObject query = new BasicDBObject();
		query.put("name", "MongoDB");
		DBCursor cursor = MongoUtil.getColl("wujintao").find(query);

		try {
			while (cursor.hasNext()) {
				System.out.println(cursor.next());
			}
		} finally {
			cursor.close();
		}
	}

	@Test
	/**
	 * AND多条件查询,区间查询
	 */
	public void queryMulti() {
		BasicDBObject query = new BasicDBObject();
		// 查询j不等于3,k大于10的结果集
		query.put("j", new BasicDBObject("$ne", 3));
		query.put("k", new BasicDBObject("$gt", 10));
		DBCursor cursor = MongoUtil.getColl("wujintao").find(query);
		try {
			while (cursor.hasNext()) {
				System.out.println(cursor.next());
			}
		} finally {
			cursor.close();
		}
	}

	@Test
	/**
	 * 区间查询
	 * select * from table where i >50
	 */
	public void queryMulti2() {
		BasicDBObject query = new BasicDBObject();
		query = new BasicDBObject();
		query.put("i", new BasicDBObject("$gt", 50)); // e.g. find all where i >
		DBCursor cursor = MongoUtil.getColl("wujintao").find(query);
		try {
			while (cursor.hasNext()) {
				System.out.println(cursor.next());
			}
		} finally {
			cursor.close();
		}
	}

	@Test
	/**
	 * 区间查询
	 * select * from table where 20 < i <= 30
	    //比较符   
	    //"$gt"： 大于   
	    //"$gte"：大于等于   
	    //"$lt"： 小于   
	    //"$lte"：小于等于   
	    //"$in"： 包含   
	 */
	public void queryMulti3() {
		BasicDBObject query = new BasicDBObject();
		query = new BasicDBObject();

		query.put("i", new BasicDBObject("$gt", 20).append("$lte", 30));
		DBCursor cursor = MongoUtil.getColl("wujintao").find(query);
		try {
			while (cursor.hasNext()) {
				System.out.println(cursor.next());
			}
		} finally {
			cursor.close();
		}
	}

	/**
	 * 组合in和and select * from test_Table where (a=5 or b=6) and (c=5 or d = 6)
	 */
	public void queryMulti4() {
		BasicDBObject query11 = new BasicDBObject();
		query11.put("a", 1);
		BasicDBObject query12 = new BasicDBObject();
		query12.put("b", 2);
		List<BasicDBObject> orQueryList1 = new ArrayList<BasicDBObject>();
		orQueryList1.add(query11);
		orQueryList1.add(query12);
		BasicDBObject orQuery1 = new BasicDBObject("$or", orQueryList1);

		BasicDBObject query21 = new BasicDBObject();
		query21.put("c", 5);
		BasicDBObject query22 = new BasicDBObject();
		query22.put("d", 6);
		List<BasicDBObject> orQueryList2 = new ArrayList<BasicDBObject>();
		orQueryList2.add(query21);
		orQueryList2.add(query22);
		BasicDBObject orQuery2 = new BasicDBObject("$or", orQueryList2);

		List<BasicDBObject> orQueryCombinationList = new ArrayList<BasicDBObject>();
		orQueryCombinationList.add(orQuery1);
		orQueryCombinationList.add(orQuery2);

		BasicDBObject finalQuery = new BasicDBObject("$and",
				orQueryCombinationList);
		DBCursor cursor = MongoUtil.getColl("wujintao").find(finalQuery);
	}

	@Test
	/**
	 * IN查询
	 * if i need to query name in (a,b); just use { name : { $in : ['a', 'b'] } }
	 * select * from things where name='a' or name='b'
	 * @param coll
	 */
	public void queryIn() {
		BasicDBList values = new BasicDBList();
		values.add("a");
		values.add("b");
		BasicDBObject in = new BasicDBObject("$in", values);
		DBCursor cursor = MongoUtil.getColl("wujintao").find(
				new BasicDBObject("name", in));
		try {
			while (cursor.hasNext()) {
				System.out.println(cursor.next());
			}
		} finally {
			cursor.close();
		}
	}

	@Test
	/**
	 * 或查询
	 * select * from table where name  = '12' or title = 'p'
	 * @param coll
	 */
	public void queryOr() {
		QueryBuilder query = new QueryBuilder();
		query.or(new BasicDBObject("name", 12), new BasicDBObject("title", "p"));
		DBCursor cursor = MongoUtil.getColl("wujintao").find(query.get()).addSpecial("$returnKey", "");
		try {
			while (cursor.hasNext()) {
				System.out.println(cursor.next());
			}
		} finally {
			cursor.close();
		}
	}
	
	@Test
	public void customQueryField() throws UnknownHostException{
        Mongo mongo = new Mongo("localhost", 27017);
        DB db = mongo.getDB("zhongsou_ad");
        BasicDBObjectBuilder bulder = new BasicDBObjectBuilder();
        bulder.add("times",1);
        bulder.add("aid",1);
        DBCursor cusor =  db.getCollection("ad_union_ad_c_1").find(new BasicDBObject(),bulder.get());
        for (DBObject dbObject : cusor) {
            System.out.println(dbObject);
        }
	}
	
	@Test
	public void mapReduce() throws UnknownHostException{
        Mongo mongo = new Mongo("localhost", 27017);
        DB db = mongo.getDB("zhongsou_ad");
     
        try {

            DBCollection books = db.getCollection("books");

            BasicDBObject book = new BasicDBObject();
            book.put("name", "Understanding JAVA");
            book.put("pages", 100);
            books.insert(book);
            
            book = new BasicDBObject();  
            book.put("name", "Understanding JSON");
            book.put("pages", 200);
            books.insert(book);
            
            book = new BasicDBObject();
            book.put("name", "Understanding XML");
            book.put("pages", 300);
            books.insert(book);
            
            book = new BasicDBObject();
            book.put("name", "Understanding Web Services");
            book.put("pages", 400);
            books.insert(book);
          
            book = new BasicDBObject();
            book.put("name", "Understanding Axis2");
            book.put("pages", 150);
            books.insert(book);
            
            String map = "function() { "+ 
                      "var category; " +  
                      "if ( this.pages >= 250 ) "+  
                      "category = 'Big Books'; " +
                      "else " +
                      "category = 'Small Books'; "+  
                      "emit(category, {name: this.name});}";
            
            String reduce = "function(key, values) { " +
                                     "var sum = 0; " +
                                     "values.forEach(function(doc) { " +
                                     "sum += 1; "+
                                     "}); " +
                                     "return {books: sum};} ";
            
            MapReduceCommand cmd = new MapReduceCommand(books, map, reduce,
              null, MapReduceCommand.OutputType.INLINE, null);

            MapReduceOutput out = books.mapReduce(cmd);

            for (DBObject o : out.results()) {
             System.out.println(o.toString());
            }
           } catch (Exception e) {
             e.printStackTrace();
           }
	}
	
	@Test
    public void GroupByManyField() throws UnknownHostException{
	    //此方法没有运行成功
        Mongo mongo = new Mongo("localhost", 27017);
        DB db = mongo.getDB("libary");
        DBCollection books = db.getCollection("books");
        BasicDBObject groupKeys = new BasicDBObject();
        groupKeys.put("total", new BasicDBObject("$sum","pages"));
        
        BasicDBObject condition = new BasicDBObject();
        condition.append("pages", new BasicDBObject().put("$gt", 0));
   
        
        String reduce = "function(key, values) { " +
                "var sum = 0; " +
                "values.forEach(function(doc) { " +
                "sum += 1; "+
                "}); " +
                "return {books: sum};} ";
        /**
         BasicDBList basicDBList = (BasicDBList)db.getCollection("mongodb中集合编码或者编码")
                   .group(DBObject key,   --分组字段，即group by的字段
                DBObject cond,        --查询中where条件
                DBObject initial,     --初始化各字段的值
                String reduce,        --每个分组都需要执行的Function
                String finial         --终结Funciton对结果进行最终的处理
         */
        DBObject obj = books.group(groupKeys, condition,  new BasicDBObject(), reduce);
        System.out.println(obj);
        
        AggregationOutput ouput = books.aggregate(new BasicDBObject("$group",groupKeys));
        System.out.println(ouput.getCommandResult());
        System.out.println(books.find(new BasicDBObject("$group",groupKeys)));
    }	
	

	@Test
	/**
	 * 分页查询   
	 */
	public void pageQuery() {
		DBCursor cursor = MongoUtil.getColl("wujintao").find().skip(0)
				.limit(10);
		while (cursor.hasNext()) {
			System.out.println(cursor.next());
		}
	}

	/**
	 * 模糊查询
	 */
	public void likeQuery() {
		Pattern john = Pattern.compile("joh?n");
		BasicDBObject query = new BasicDBObject("name", john);

		// finds all people with "name" matching /joh?n/i
		DBCursor cursor = MongoUtil.getColl("wujintao").find(query);
	}

	@Test
	/**
	 * 条件删除   
	 */
	public void delete() {
		BasicDBObject query = new BasicDBObject();
		query.put("name", "xxx");
		// 找到并且删除，并返回删除的对象
		DBObject removeObj = MongoUtil.getColl("wujintao").findAndRemove(query);
		System.out.println(removeObj);
	}

	@Test
	/**
	 * 更新
	 */
	public void update() {
		BasicDBObject query = new BasicDBObject();
		query.put("name", "liu");
		DBObject stuFound = MongoUtil.getColl("wujintao").findOne(query);
		stuFound.put("name", stuFound.get("name") + "update_1");
		MongoUtil.getColl("wujintao").update(query, stuFound);
	}


}