如何在不知道json文件属性的情况下，用Java代码动态上传同一个文件夹下的多个json文件到MongoDB。

Question

我得到了错误信息。

在线程 "main "中出现异常 org.bson.BsonInvalidOperationException: readStartDocument can only be called when CurrentBSONType is DOCUMENT, not when CurrentBSONType is ARRAY.

下面的代码我只想插入一个json文件。请你帮助我好吗？

   public class hallo {

    public static void main( String args[] ) {

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


        // Accessing the database
        MongoDatabase database = mongo.getDatabase("dumpJsonFiles");
        //System.out.println("Credentials ::"+ credential);

        //Creating a collection
        //database.createCollection("sampleCollection1");
        System.out.println("Collection created successfully");
        MongoCollection<Document> collection = database.getCollection("new_name");
        System.out.println("Collection myCollection selected successfully");
        Document document = new Document("title", "MongoDB")
                .append("description", "database")
                .append("likes", 100)
                .append("url", "http://www.tutorialspoint.com/mongodb/")
                .append("by", "tutorials point");

        //Inserting document into the collection
        collection.insertOne(document);
        System.out.println("Document inserted successfully");
        List<InsertOneModel<Document>> docs = new ArrayList<>();
        int count = 0;
        int batch = 100;
        try (BufferedReader br = new BufferedReader(new FileReader("sample.json"))) {
            String line;
            while ((line = br.readLine()) != null) {
                System.out.println("line is "+line);
                docs.add(new InsertOneModel<>(Document.parse(line)));
                count++;
                if (count == batch) {
                    collection.bulkWrite(docs, new BulkWriteOptions().ordered(false));
                    docs.clear();
                    count = 0;
                }
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        if (count > 0) {
            collection.bulkWrite(docs, new BulkWriteOptions().ordered(false));
        }
        //DBObject dbObject = (DBObject)JSON.parse("sample.json");

        System.out.println("Document inserted 2 successfully");

    }
}

---

输入的json文件示例内容（从注释中复制）。

{
   "Details":{
      "Name":"AC",
      "Rollno":"5978",
      "section":"",
      "Maths":"10",
      "Science":"20",
      "social":"20",
      "English":"30"
   }
}

另一个json文件是：

[
   {
      "Name":"Table",
      "Description":"Used",
      "Marks":[
         {
            "Social":"10",
            "Science":"20",
            "Maths":"30",
            "English":"40",
            "Hindi":"50",
            "Computers":[
               {
                  "Lab":"10",
                  "Theory":"20"
               }
            ]
         }
      ]
   }
]

Answer 1

你得到的错误是因为输入的JSON数据文件有问题。很可能是文件中的JSON文件的格式是 阵列;例如一个有两个文件的文件。

[{ "type": "fruits", "items": [ "apple", "orange"] },
{ "type": "objects", "item": { "property": "color", "value": "green" } }]

如果你运行你的代码(你的Java代码工作正常)，就会出现和你一样的错误。

Exception in thread "main" org.bson.BsonInvalidOperationException: readStartDocument can only be called when CurrentBSON Type is DOCUMENT, not when CurrentBSONType is ARRAY...。

正确的格式化方式是如下所示的两行，每行代表一个JSON。

{ "type": "fruits", "items": [ "apple", "orange"] }
{ "type": "objects", "item": { "property": "color", "value": "green" } }

这样的结果是在集合中出现了两个文件。

{
        "_id" : ObjectId("5ee06cfe7bd8631234d4c283"),
        "type" : "fruits",
        "items" : [
                "apple",
                "orange"
        ]
}
{
        "_id" : ObjectId("5ee06cfe7bd8631234d4c284"),
        "type" : "objects",
        "item" : {
                "property" : "color",
                "value" : "green"
        }
}

---

NOTES。

• 您可能需要使用较新版本的 MongoDB Java 驱动程序.
• 较新的创建方式 MongoClient 正在使用 MongoClients.create() 方法。
• 总是关闭 MongoClient 对象后，它与MongoClint#close 方法 - 释放资源。参见例子.