保存MongoDB集合后，如何将其加载到Java程序数据结构中？

我开始使用monogDB在java程序中保存和加载文件，但在将数据库加载回程序时遇到了问题。当我通过Mongo Compass进行检查时，我的save方法完全有效并创建了Mongo数据库，我的主要问题是我希望它将这些数据库值加载回我的数组中，该数组在运行代码时存储所有信息

现在，当我关闭并打开Java代码并输入load方法时，它不会检索保存的条目

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有人能帮我吗？

我更新了您的

加载文件

方法以获取名称数组

private static void loadFile(String[] name) {

    try (MongoClient mongoClient = MongoClients.create(System.getProperty("mongodb.uri"))) {

        MongoDatabase sampleTrainingDB = mongoClient.getDatabase("testDB");
        MongoCollection<Document> gradesCollection = sampleTrainingDB.getCollection("collection");

         // find one document with new Document
        Document document = gradesCollection.find(new Document("title", "Customer")).first();

        /** Code added from here to the end of the method      **/  
        /** Find all documents and get the names into an array **/

        // First we will load the documents in to a List collection
        List<Document> list = new ArrayList<>();
        gradesCollection.find(new Document("title", "Customer"))
                        .into(list);
        // From the list of we extract the name field and store in a string array
        String [] names = list.stream()
                               .map(doc -> doc.get("name"))
                               .toArray(String[]::new);
        System.out.println(Arrays.toString(names));
    }
}

私有静态void加载文件（字符串[]名称）{
try（MongoClient MongoClient=MongoClients.create（System.getProperty（“mongodb.uri”））{
MongoDatabase sampleTrainingDB=mongoClient.getDatabase（“testDB”）；
MongoCollection gradesCollection=sampleTrainingDB.getCollection（“collection”）；
//查找一个包含新文档的文档
Document Document=gradesCollection.find（新文档（“标题”、“客户”））.first（）；
/**从此处添加到方法末尾的代码**/
/**查找所有文档并将名称放入数组中**/
//首先，我们将把文档加载到列表集合中
列表=新的ArrayList（）；
gradesCollection.find（新文档（“标题”、“客户”））
.列入（名单）；
//从列表中，我们提取名称字段并存储在字符串数组中
字符串[]名称=list.stream（）
.map（doc->doc.get（“名称”））
.toArray（字符串[]：：新建）；
System.out.println（Arrays.toString（names））；
}
}

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请注意，我还对

MongoClient

创建方法进行了更改。

是否希望所有文档中的

name

字段值返回到一个数组中？加载方法为“是”

private static void saveFile(String[] name) {

        // Creating a Mongo client
        MongoClient mongo = new MongoClient("localhost", 27017);

        // Creating Credentials
        MongoCredential credential;
        credential = MongoCredential.createCredential("sampleUser", "trainDb",
                "password".toCharArray());
        System.out.println("Connected to the database successfully");

        //Accessing the database
        MongoDatabase database = mongo.getDatabase("testDB");

        //Creating a collection
        System.out.println("Collection created successfully");

        // Retrieving a collection
        MongoCollection<Document> collection = database.getCollection("collection");
        System.out.println("Collection myCollection selected successfully");

        for (int i = 0; i < 42; i++) {
            if (!name[i].equals("vacant") && (i == 0 || !name[i - 1].equals(name[i]))) {
                Document document = new Document("title", "Customer")
                        .append("Name", name[i])
                        .append("Seats", i + 1);
                collection.insertOne(document);
            }
        }
        System.out.println("Document inserted successfully");

    }

private static void loadFile(String[] name) {

    try (MongoClient mongoClient = MongoClients.create(System.getProperty("mongodb.uri"))) {

        MongoDatabase sampleTrainingDB = mongoClient.getDatabase("testDB");
        MongoCollection<Document> gradesCollection = sampleTrainingDB.getCollection("collection");

         // find one document with new Document
        Document document = gradesCollection.find(new Document("title", "Customer")).first();

        /** Code added from here to the end of the method      **/  
        /** Find all documents and get the names into an array **/

        // First we will load the documents in to a List collection
        List<Document> list = new ArrayList<>();
        gradesCollection.find(new Document("title", "Customer"))
                        .into(list);
        // From the list of we extract the name field and store in a string array
        String [] names = list.stream()
                               .map(doc -> doc.get("name"))
                               .toArray(String[]::new);
        System.out.println(Arrays.toString(names));
    }
}