将Firestore查询的结果保存到ArrayList并将每个结果添加到CSV文件

import com.google.api.core.ApiFuture;
import com.google.cloud.firestore.DocumentSnapshot;
import com.google.cloud.firestore.Firestore;
import com.google.cloud.firestore.Query;
import com.google.cloud.firestore.QueryDocumentSnapshot;
import com.google.cloud.firestore.QuerySnapshot;
import com.google.cloud.firestore.FirestoreOptions;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

FirestoreOptions firestoreOptions = FirestoreOptions.getDefaultInstance().toBuilder()
    .setProjectId("your-project-id")
    .build();
Firestore firestore = firestoreOptions.getService();

List<DocumentSnapshot> documents = new ArrayList<>();
ApiFuture<QuerySnapshot> future = firestore.collection("your-collection").get();
QuerySnapshot querySnapshot = future.get();
for (QueryDocumentSnapshot document : querySnapshot.getDocuments()) {
    documents.add(document);
}

try (FileWriter writer = new FileWriter("output.csv")) {
    for (DocumentSnapshot document : documents) {
        // 从document中获取所需的字段值
        String field1 = document.getString("field1");
        int field2 = document.getLong("field2").intValue();
        // 将字段值写入CSV文件
        writer.write(field1 + "," + field2 + "\n");
    }
} catch (IOException e) {
    e.printStackTrace();
}