MongoDB-JAVA-Driver 3.2版本常用代碼全整理(2) - 查詢

MongoDB的3.x版本Java驅動相對2.x做了全新的設計，類庫和使用方法上有很大區別。例如用Document替換BasicDBObject、通過Builders類構建Bson替代直接輸入$命令等，本文整理了基於3.2版本的常用增刪改查操作的使用方法。爲了避免冗長的篇幅，分爲增刪改、查詢、聚合、地理索引等幾部分。

先看用於演示的類的基本代碼

import static com.mongodb.client.model.Filters.*;
import static com.mongodb.client.model.Projections.*;
import static com.mongodb.client.model.Sorts.*;

import java.text.ParseException;
import java.util.Arrays;

import org.bson.BsonType;
import org.bson.Document;

import com.mongodb.Block;
import com.mongodb.MongoClient;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;
import com.mongodb.client.model.Projections;

public class FindExamples {

    public static void main(String[] args) throws ParseException {
        //根據實際環境修改ip和端口
        MongoClient mongoClient = new MongoClient("localhost", 27017);
        MongoDatabase database = mongoClient.getDatabase("lesson");

        FindExamples client = new FindExamples(database);
        client.show();
        mongoClient.close();
    }

    private MongoDatabase database;
    public FindExamples(MongoDatabase database) {
        this.database = database;
    }

    public void show() {
        MongoCollection<Document> mc = database.getCollection("blog");
        //每次執行前清空集合以方便重複運行
        mc.drop();

        //插入用於測試的文檔
        Document doc1 = new Document("title", "good day").append("owner", "tom").append("words", 300)
                .append("comments", Arrays.asList(new Document("author", "joe").append("score", 3).append("comment", "good"), new Document("author", "white").append("score", 1).append("comment", "oh no")));
        Document doc2 = new Document("title", "good").append("owner", "john").append("words", 400)
                .append("comments", Arrays.asList(new Document("author", "william").append("score", 4).append("comment", "good"), new Document("author", "white").append("score", 6).append("comment", "very good")));
        Document doc3 = new Document("title", "good night").append("owner", "mike").append("words", 200)
                .append("tag", Arrays.asList(1, 2, 3, 4));
        Document doc4 = new Document("title", "happiness").append("owner", "tom").append("words", 1480)
                .append("tag", Arrays.asList(2, 3, 4));
        Document doc5 = new Document("title", "a good thing").append("owner", "tom").append("words", 180)
                .append("tag", Arrays.asList(1, 2, 3, 4, 5));
        mc.insertMany(Arrays.asList(doc1, doc2, doc3, doc4, doc5));

        //測試: 查詢全部
        FindIterable<Document> iterable = mc.find();
        printResult("find all", iterable);

        //TODO: 將在這裏填充更多查詢示例
    }

    //打印查詢的結果集
    public void printResult(String doing, FindIterable<Document> iterable) {
        System.out.println(doing);
        iterable.forEach(new Block<Document>() {
            public void apply(final Document document) {
                System.out.println(document);
            }
        });
        System.out.println("------------------------------------------------------");
        System.out.println();
    }
}

如上面代碼所示，把所有的查詢操作集中在show()方法中演示，並且在執行後打印結果集以觀察查詢結果。下面來填充show()方法

//創建單字段索引
mc.createIndex(new Document("words", 1));
//創建組合索引(同樣遵循最左前綴原則)
mc.createIndex(new Document("title", 1).append("owner", -1));
//創建全文索引
mc.createIndex(new Document("title", "text"));

//查詢全部
FindIterable<Document> iterable = mc.find();
printResult("find all", iterable);

//查詢title=good
iterable = mc.find(new Document("title", "good"));
printResult("find title=good", iterable);

//查詢title=good and owner=tom
iterable = mc.find(new Document("title", "good").append("owner", "tom"));
printResult("find title=good and owner=tom", iterable);

//查詢title like %good% and owner=tom
iterable = mc.find(and(regex("title", "good"), eq("owner", "tom")));
printResult("find title like %good% and owner=tom", iterable);

//查詢全部按title排序
iterable = mc.find().sort(ascending("title"));
printResult("find all and ascending title", iterable);

//查詢全部按owner,title排序
iterable = mc.find().sort(ascending("owner", "title"));
printResult("find all and ascending owner,title", iterable);

//查詢全部按words倒序排序
iterable = mc.find().sort(descending("words"));
printResult("find all and descending words", iterable);

//查詢owner=tom or words>350
iterable = mc.find(new Document("$or", Arrays.asList(new Document("owner", "tom"), new Document("words", new Document("$gt", 350)))));
printResult("find owner=tom or words>350", iterable);

//返回title和owner字段
iterable = mc.find().projection(include("title", "owner"));
printResult("find all include (title,owner)", iterable);

//返回除title外的其他字段
iterable = mc.find().projection(exclude("title"));
printResult("find all exclude title", iterable);

//不返回_id字段
iterable = mc.find().projection(excludeId());
printResult("find all excludeId", iterable);

//返回title和owner字段且不返回_id字段
iterable = mc.find().projection(fields(include("title", "owner"), excludeId()));
printResult("find all include (title,owner) and excludeId", iterable);

//內嵌文檔匹配
iterable = mc.find(new Document("comments.author", "joe"));
printResult("find comments.author=joe", iterable);

//一個錯誤的示例, 想查詢評論中包含作者是white且分值>2的, 返回結果不符合預期
iterable = mc.find(new Document("comments.author", "white").append("comments.score", new Document("$gt", 2)));
printResult("find comments.author=white and comments.score>2 (wrong)", iterable);

//上面的需求正確的寫法
iterable = mc.find(Projections.elemMatch("comments", Filters.and(Filters.eq("author", "white"), Filters.gt("score", 2))));
printResult("find comments.author=white and comments.score>2 using elemMatch", iterable);

//查找title以good開頭的, 並且comments只保留一個元素
iterable = mc.find(Filters.regex("title", "^good")).projection(slice("comments", 1));
printResult("find regex ^good and slice comments 1", iterable);

//全文索引查找
iterable = mc.find(text("good"));
printResult("text good", iterable);

//用Filters構建的title=good
iterable = mc.find(eq("title", "good"));
printResult("Filters: title eq good", iterable);

//$in 等同於sql的in
iterable = mc.find(in("owner", "joe", "john", "william"));
printResult("Filters: owner in joe,john,william", iterable);

//$nin 等同於sql的not in
iterable = mc.find(nin("owner", "joe", "john", "tom"));
printResult("Filters: owner nin joe,john,tom", iterable);

//查詢內嵌文檔
iterable = mc.find(in("comments.author", "joe", "tom"));
printResult("Filters: comments.author in joe,tom", iterable);

//$ne 不等於
iterable = mc.find(ne("words", 300));
printResult("Filters: words ne 300", iterable);

//$and 組合條件
iterable = mc.find(and(eq("owner", "tom"), gt("words", 300)));
printResult("Filters: owner eq tom and words gt 300", iterable);

//較複雜的組合
iterable = mc.find(and(or(eq("words", 300), eq("words", 400)), or(eq("owner", "joe"), size("comments", 2))));
printResult("Filters: (words=300 or words=400) and (owner=joe or size(comments)=2)", iterable);

//查詢第2個元素值爲2的數組
iterable = mc.find(eq("tag.1", 2));
printResult("Filters: tag.1 eq 2", iterable);

//查詢匹配全部值的數組
iterable = mc.find(all("tag", Arrays.asList(1, 2, 3, 4)));
printResult("Filters: tag match all (1, 2, 3, 4)", iterable);

//$exists
iterable = mc.find(exists("tag"));
printResult("Filters: exists tag", iterable);

iterable = mc.find(type("words", BsonType.INT32));
printResult("Filters: type words is int32", iterable);

這裏列出的查詢方式可以覆蓋到大部分開發需求，更多查詢需求請參考官方文檔。

(完)

個人補充--參考代碼：

			// 先從collection中取出最後的日期
			if (queryFields.indexOf("datetime") > -1) {
				FindIterable<Document> iter = null;
				String datetime = getParam("datetime").toString();
				
				if ("last".equals(datetime)) {
					iter = collection.find().projection(Projections.include("datetime")).sort(Sorts.descending("datetime")).limit(1);
				} else {
					iter = collection.find(Filters.lte("datetime", Integer.parseInt(datetime))).projection(Projections.include("datetime")).sort(Sorts.descending("datetime")).limit(1);
				}
				
				iter.forEach(new Block<Document>() {
					public void apply(Document doc) {
						setParams("datetime", doc.getInteger("datetime"));
					}
				});
			}
			
			// 生成查詢條件
			Bson[] filters = new Bson[queryFields.size()];
			for (int i=0; i<queryFields.size(); i++) {
				String field = queryFields.get(i);
				if ("objs".equals(field)) {
					List<String> objSet = getParam("objs");
					objsLen = objSet.size();
					filters[i] = Filters.in("objs", objSet);
				} else {
					switch (DataType.toData(dataTypeMap.get(field).toUpperCase())) {
						case LONG :
							filters[i] = Filters.eq(field, Long.parseLong(getParam(field).toString()));
							break;
						case DOUBLE :
							filters[i] = Filters.eq(field, Double.parseDouble(getParam(field).toString()));
							break;
						case INT :
							filters[i] = Filters.eq(field, Integer.parseInt(getParam(field).toString()));
							break;
						default :
							filters[i] = Filters.eq(field, getParam(field));
					}
				}
			}
			
			// 生成查詢列名
			Bson[] projections = new Bson[2];
			fidSet = getParam("fids");
			projections[0] = Projections.include(new ArrayList<String>(fidSet));
			projections[1] = Projections.include(queryFields);
			
			// 查詢mongo
			FindIterable<Document> iter = collection.find(Filters.and(filters)).projection(Projections.fields(projections));
			
			final Map<String, JSONArray> map = new HashMap<String, JSONArray>();
			
			iter.forEach(new Block<Document>() {
				public void apply(Document doc) {
					for (String seqid : seqMap.keySet()) {
						Set<String> fidSet = seqMap.get(seqid);


						JSONObject object = new JSONObject();
						object.put("objs", doc.get("objs"));
						for (String fid : fidSet) {
							if (fid.indexOf("#") > -1) {
								object.put(fid.split("#")[0], doc.get(fid));
							} else {
								object.put(fid, doc.get(fid));
							}
						}
						
						if (map.containsKey(seqid)) {
							JSONArray array = map.get(seqid);
							array.add(object);
						} else {
							JSONArray array = new JSONArray();
							array.add(object);
							map.put(seqid, array);
						}
					}
				}
			});

原文地址：

http://blog.csdn.net/autfish/article/details/51366839