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

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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。為了避免冗長的篇幅，分為增刪改、查詢、彙總、地理索引等幾部分。

先看用於示範的類的基本代碼

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和連接埠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: 將在這裡填充更多查詢樣本}//列印查詢的結果集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()方法中示範，並且在執行後列印結果集以觀察查詢結果。下面來填充show()方法

//建立單欄位索引mc.createIndex(new Document("words", 1));//建立複合式索引(同樣遵循最左首碼原則)mc.createIndex(new Document("title", 1).append("owner", -1));//建立全文索引mc.createIndex(new Document("title", "text"));//查詢全部FindIterable<Document> iterable = mc.find();printResult("find all", iterable);//查詢title=gooditerable = mc.find(new Document("title", "good"));printResult("find title=good", iterable);        //查詢title=good and owner=tomiterable = mc.find(new Document("title", "good").append("owner", "tom"));printResult("find title=good and owner=tom", iterable);        //查詢title like %good% and owner=tomiterable = 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>350iterable = 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欄位iterable = mc.find().projection(include("title", "owner"));printResult("find all include (title,owner)", iterable);        //返回除title外的其他欄位iterable = mc.find().projection(exclude("title"));printResult("find all exclude title", iterable);        //不返回_id欄位iterable = mc.find().projection(excludeId());printResult("find all excludeId", iterable);        //返回title和owner欄位且不返回_id欄位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);        //一個錯誤的樣本, 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("$gt", 2)));printResult("find comments.author=white and comments.score>2 (wrong)", iterable);        //上面的需求正確的寫法iterable = mc.find(Projections.elemMatch("comments", Filters.and(Filters.eq("author", "white"), Filters.gt("score", 2))));printResult("find comments.author=white and comments.score>2 using elemMatch", iterable);        //尋找title以good開頭的, 並且comments只保留一個元素iterable = mc.find(Filters.regex("title", "^good")).projection(slice("comments", 1));printResult("find regex ^good and slice comments 1", iterable);        //全文索引尋找iterable = mc.find(text("good"));printResult("text good", iterable);//用Filters構建的title=gooditerable = mc.find(eq("title", "good"));printResult("Filters: title eq good", iterable);//$in 等同於sql的initerable = mc.find(in("owner", "joe", "john", "william"));printResult("Filters: owner in joe,john,william", iterable);//$nin 等同於sql的not initerable = mc.find(nin("owner", "joe", "john", "tom"));printResult("Filters: owner nin joe,john,tom", iterable);//查詢內嵌文檔iterable = mc.find(in("comments.author", "joe", "tom"));printResult("Filters: comments.author in joe,tom", iterable);//$ne 不等於iterable = mc.find(ne("words", 300));printResult("Filters: words ne 300", iterable);//$and 組合條件iterable = mc.find(and(eq("owner", "tom"), gt("words", 300)));printResult("Filters: owner eq tom and words gt 300", iterable);//較複雜的組合iterable = mc.find(and(or(eq("words", 300), eq("words", 400)), or(eq("owner", "joe"), size("comments", 2))));printResult("Filters: (words=300 or words=400) and (owner=joe or size(comments)=2)", iterable);//查詢第2個元素值為2的數組iterable = mc.find(eq("tag.1", 2));printResult("Filters: tag.1 eq 2", iterable);//查詢匹配全部值的數組iterable = mc.find(all("tag", Arrays.asList(1, 2, 3, 4)));printResult("Filters: tag match all (1, 2, 3, 4)", iterable);//$existsiterable = mc.find(exists("tag"));printResult("Filters: exists tag", iterable);iterable = mc.find(type("words", BsonType.INT32));printResult("Filters: type words is int32", iterable);

這裡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。

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