使用Java将MongoDB数据转换为CSV [英] Convert MongoDB data into csv using java

问题描述

我已经使用MongoDb创建了一些数据.我想使用Java程序将该数据导出到csv文件中.

I have used MongoDb to create some data. I want to export that data into csv file using java program.

推荐答案

您可以在文件上书写，而不是在屏幕上书写.这段代码会写出您的数据库( Your_Db_Name )中存在的每个集合.

Instead to write on screen you can write on a file. This code writes every collection present in your db (Your_Db_Name).

MongoClient mongoClient = new MongoClient("localhost", 27017);
MongoDatabase db = mongoClient.getDatabase("YOUR_DB_NAME");

ListCollectionsIterable collections = db.listCollections();

MongoCursor collectionsCursor = collections.iterator();

while (collectionsCursor.hasNext()) {
    Document collectionDocument = (Document) collectionsCursor.next();

    String name = collectionDocument.getString("name");
    if (!name.equalsIgnoreCase("system.indexes")) {
        MongoCollection collectionTemp = db.getCollection(name);

        boolean collectionFirst = true;
        MongoCursor < Document > cursorDoc = collectionTemp.find().iterator();
        while (cursorDoc.hasNext()) {

            Document collectionElement = cursorDoc.next();
            boolean first = true;
            Set < String > keySet = collectionElement.keySet();
            if (collectionFirst) {
                for (String key: keySet)
                if (first) {
                    System.out.print(key);
                    first = !first;
                } else System.out.print("," + key);

                collectionFirst = !collectionFirst;
                System.out.println("");
            }
            first = true;
            for (String key: keySet)
            if (first) {
                System.out.print(collectionElement.get(key));
                first = !first;
            } else System.out.print("," + collectionElement.get(key));

            System.out.println("");
        }
    }
}

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