如何使用键值从 Firebase 中检索数据？答案

【问题标题】：How to retrieve data from firebase with the key value?如何使用键值从 Firebase 中检索数据？
【发布时间】：2016-11-28 23:43:20
【问题描述】：

{-KVsGKFs_VfPKYNylmH0={entryDate=11/14/2016, markerColor=30, daysSick=2, userId=ABCD, sickness=Flu, severity=Medium, longitude=-75.57221984863281, latitude=38.38811111450195, type=Viral}, 
15fKhOQizabN0EL6ZAq7SOk3Gqb2={entryDate=11/8/2016, markerColor=210, daysSick=5, userId=15fKhOQizabN0EL6ZAq7SOk3Gqb2, sickness=Pneumonia, severity=High, longitude=-77.1867304, latitude=38.80375897, type=Bacterial}, 
2SfN7GkHsjXHFuGGYQJAQoRCOho1={-KXLF4gT9wUfvgRuYxWI={entryDate=11/24/2016, markerColor=210, daysSick=3, userId=2SfN7GkHsjXHFuGGYQJAQoRCOho1, sickness=Anthrax, severity=Medium, longitude=0, latitude=0, type=Bacterial}}

对于以下上述 json 响应，我必须检索“sickness”的所有关键值的数据。如何找回？

【问题讨论】：

第 1 行解析错误：{ -KVsGKFs_VfPKYNylmH0 -----^ Expecting 'STRING', '}'

标签： android firebase firebase-realtime-database

【解决方案1】：

以下代码将帮助您从数据库中获取所有键值...这里 BTChild Details 是一个 POJO 类

databaseRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            BTLog.d(TAG, "There are " + snapshot.getChildrenCount() + " blog posts");
for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                BTChildDetails post =postSnapshot.getValue(BTChildDetails.class);
                BTChildDetails btChildDetails = new BTChildDetails(post.getName(), post.getId(), false);
                childList.add(childDetails);
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            BTLog.d(TAG, "The read failed: ");
        }
    });

【讨论】：