3.1 MongoDB through the Java

http://mongodb.github.io/mongo-java-driver/3.12/driver/getting-started/quick-start/

3.1.1 connecting

        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongodb-driver</artifactId>
            <version>3.12.7</version>
        </dependency>

    private ServerAddress serverAddress = new ServerAddress("101.132.251.198", 27017);
    private MongoCredential credential = MongoCredential.createCredential("root", "tutorial", "root".toCharArray());
    private MongoClient mongoClient = new MongoClient(serverAddress, credential, MongoClientOptions.builder().build());
    private MongoDatabase database = mongoClient.getDatabase("tutorial");
    private MongoCollection<Document> users = database.getCollection("users");

Create a Document

  {
   "name" : "MongoDB",
   "type" : "database",
   "count" : 1,
   "versions": [ "v3.2", "v3.0", "v2.6" ],
   "info" : { x : 203, y : 102 }
  }

        Document doc = new Document("name", "MongoDB").append("type", "database")
                .append("count", 1)
                .append("versions", Arrays.asList("v3.2", "v3.0", "v2.6"))
                .append("info", new Document("x", 203).append("y", 102));

Insert a Document

users.insertOne(doc);

Insert Multiple Documents

@Test
    public void testInsertMultiple(){
        ArrayList<Document> documents = new ArrayList<>();
        for (int i = 0; i < 100; i++) {
            documents.add(new Document("i", i));
        }
        users.insertMany(documents);
    }

Count Documents in A Collection

    @Test
    public void testCount() {
        System.out.println(users.countDocuments());
    }

Query the Collection

Find the First Document in a Collection

    @Test
    public void testQuery() {
        Document myDoc = users.find().first();
        System.out.println(myDoc.toJson());
    }

Find All Documents in a Collection

    @Test
    public void testQuery() {
        MongoCursor<Document> cursor = users.find().iterator();
        try {
            while (cursor.hasNext()){
                System.out.println(cursor.next().toJson());
            }
        }finally {
            cursor.close();
        }
    }

避免用foreach循环迭代遍历，因为如果循环提前结束，应用程序可能会泄露游标

Specify a Query Filter

Get A Single Document That Matches a Filter

    @Test
    public void testQueryFilter() {
        Document myDoc = users.find(Filters.eq("i", 71)).first();
        System.out.println(myDoc.toJson());
    }

Get All Documents That Match a Filter

    @Test
    public void testQueryFilter() {
        Block<Document> printBlock = new Block<Document>(){
            @Override
            public void apply(Document document) {
                System.out.println(document.toJson());
            }
        };
        users.find(Filters.gt("i", 50)).forEach(printBlock);
        users.find(Filters.and(Filters.gt("i", 50), Filters.lte("i", 100))).forEach(printBlock);
    }

Update Documents

• updateOne
• updateMany

返回值为UpdateResult，提供了关于文档更新的数量信息

Update a Single Document

    @Test
    public void testUpdate() {
        users.updateOne(Filters.eq("i", 10), new Document("$set", new Document("i", 110)));
        Document documents = users.find(new Document("i", 110)).first();
        System.out.println(documents.toJson());
    }

Update Multiple Documents

    @Test
    public void testUpdate() {
        // 下面的例子将所有文件的i值增加100，其中i小于100的值:
        UpdateResult updateResult = users.updateMany(lt("i", 100), Updates.inc("i", 100));
        System.out.println(updateResult.getModifiedCount());
    }

Delete Documents

• deleteOne

• deleteMany

    @Test
    public void testDelete() {
        DeleteResult deleteResult = users.deleteMany(gte("i", 100));
        System.out.println(deleteResult.getDeletedCount());
    }

  Create Indexes

• For an ascending index type, specify 1 for .

• For a descending index type, specify -1 for .

    @Test
    public void testCreateIndexes() {
        users.createIndex(new Document("i", 1));
    }