将 Firebase 数据导入 android class
Import Firebase data into android class
我正在尝试查询 Firebase 数据并将其存储到下面示例 link 中的 Dinosaur class 中。我在直接从 Firebase 导入 Dinosaur Facts class 时遇到问题。它能够创建查询并进入 "onChildAdded" 方法。然后它转到 Dinosaur 构造函数 class 但在那之后立即崩溃。
DinosaurFacts facts = snapshot.getValue(DinosaurFacts.class); //CRASHES HERE
https://www.firebase.com/docs/android/guide/retrieving-data.html
这是 DinosaurFacts class
package jobsme.com.firebasequery;
import android.util.Log;
public class DinosaurFacts {
long height;
double length;
long weight;
public DinosaurFacts() {
Log.i("MyActivity", "FIIIIIIIIIIIIIIIIIINDMEEEE2");
// empty default constructor, necessary for Firebase to be able to deserialize blog posts
}
public long getHeight() {
Log.i("MyActivity", "FIIIIIIIIIIIIIIIIIINDMEEEE3");
return height;
}
public double getLength() {
return length;
}
public long getWeight() {
return weight;
}
}
这里是MainAcitivity中的onCreate方法
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Firebase.setAndroidContext(this);
Firebase ref = new Firebase("https://dinosaur-facts.firebaseio.com/dinosaurs");
Query queryRef = ref.orderByChild("height");
queryRef.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot snapshot, String previousChild) {
Log.i("MyActivity", "onChildAdded");
DinosaurFacts facts = snapshot.getValue(DinosaurFacts.class);
Log.i("MyActivity", snapshot.getKey() + " was " + facts.getHeight() + " meters tall");
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
// ....
});
Log.i("MyActivity", "FIIIIIIIIIIIIIIIIIINDMEEEE");
}
查询成功，导入失败。希望这意味着我正确设置了一切？
这是日志输出：
12-11 16:48:37.793 5581-5581/jobsme.com.firebasequery E/AndroidRuntime: FATAL EXCEPTION: main
Process: jobsme.com.firebasequery, PID: 5581
com.firebase.client.FirebaseException: Failed to bounce to type
at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:196)
at jobsme.com.firebasequery.MainActivity.onChildAdded(MainActivity.java:45)
at com.firebase.client.core.ChildEventRegistration.run(ChildEventRegistration.java:50)
at com.firebase.client.core.view.EventRaiser.run(EventRaiser.java:37)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "vanished" (class jobsme.com.firebasequery.DinosaurFacts), not marked as ignorable (3 known properties: , "weight", "length", "height"])
at [Source: java.io.StringReader@52851428; line: 1, column: 33] (through reference chain: jobsme.com.firebasequery.DinosaurFacts["vanished"])
at com.fasterxml.jackson.databind.DeserializationContext.reportUnknownProperty(DeserializationContext.java:555)
at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:708)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:1160)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:315)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2034)
at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:192)
at jobsme.com.firebasequery.MainActivity.onChildAdded(MainActivity.java:45)
at com.firebase.client.core.ChildEventRegistration.run(ChildEventRegistration.java:50)
at com.firebase.client.core.view.EventRaiser.run(EventRaiser.java:37)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
这是该数据库中一种恐龙的 JSON：
"bruhathkayosaurus": {
"appeared": -70000000,
"height": 25,
"length": 44,
"order": "saurischia",
"vanished": -70000000,
"weight": 135000
},
您正在使用的 DinosaurFacts class 只有这些属性的字段+getter：height、length、weight。因此，当 Firebase 尝试将 JSON 反序列化为 DinosaurFacts 对象时，它会抱怨未映射的属性。
消除错误的最简单方法是告诉 Jackson（Firebase 在内部使用它在 JSON 和 Java 之间进行映射）忽略它在 [=45] 中遇到的任何未映射的属性=]:
@JsonIgnoreProperties(ignoreUnknown = true)
public static class DinosaurFacts {
但是注意这个。如果您现在 将 一个 DinosaurFacts 对象写回数据库，它将只有 height、length 和 weight 属性。它不会有：appeared、order 或 vanished。事实上：即使属性did之前存在于数据库中，写回这个对象也会删除它们。
所以正确的解决方案是将 JSON 结构中的所有属性映射到 Java class:
public static class DinosaurFacts {
long appeared, vanished;
double height, length, weight;
String order;
public long getAppeared() {
return appeared;
}
public long getVanished() {
return vanished;
}
public double getHeight() {
return height;
}
public double getLength() {
return length;
}
public double getWeight() {
return weight;
}
public String getOrder() {
return order;
}
}
我正在尝试查询 Firebase 数据并将其存储到下面示例 link 中的 Dinosaur class 中。我在直接从 Firebase 导入 Dinosaur Facts class 时遇到问题。它能够创建查询并进入 "onChildAdded" 方法。然后它转到 Dinosaur 构造函数 class 但在那之后立即崩溃。
DinosaurFacts facts = snapshot.getValue(DinosaurFacts.class); //CRASHES HERE
https://www.firebase.com/docs/android/guide/retrieving-data.html
这是 DinosaurFacts class
package jobsme.com.firebasequery;
import android.util.Log;
public class DinosaurFacts {
long height;
double length;
long weight;
public DinosaurFacts() {
Log.i("MyActivity", "FIIIIIIIIIIIIIIIIIINDMEEEE2");
// empty default constructor, necessary for Firebase to be able to deserialize blog posts
}
public long getHeight() {
Log.i("MyActivity", "FIIIIIIIIIIIIIIIIIINDMEEEE3");
return height;
}
public double getLength() {
return length;
}
public long getWeight() {
return weight;
}
}
这里是MainAcitivity中的onCreate方法
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Firebase.setAndroidContext(this);
Firebase ref = new Firebase("https://dinosaur-facts.firebaseio.com/dinosaurs");
Query queryRef = ref.orderByChild("height");
queryRef.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot snapshot, String previousChild) {
Log.i("MyActivity", "onChildAdded");
DinosaurFacts facts = snapshot.getValue(DinosaurFacts.class);
Log.i("MyActivity", snapshot.getKey() + " was " + facts.getHeight() + " meters tall");
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(FirebaseError firebaseError) {
}
// ....
});
Log.i("MyActivity", "FIIIIIIIIIIIIIIIIIINDMEEEE");
}
查询成功，导入失败。希望这意味着我正确设置了一切？
这是日志输出：
12-11 16:48:37.793 5581-5581/jobsme.com.firebasequery E/AndroidRuntime: FATAL EXCEPTION: main
Process: jobsme.com.firebasequery, PID: 5581
com.firebase.client.FirebaseException: Failed to bounce to type
at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:196)
at jobsme.com.firebasequery.MainActivity.onChildAdded(MainActivity.java:45)
at com.firebase.client.core.ChildEventRegistration.run(ChildEventRegistration.java:50)
at com.firebase.client.core.view.EventRaiser.run(EventRaiser.java:37)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "vanished" (class jobsme.com.firebasequery.DinosaurFacts), not marked as ignorable (3 known properties: , "weight", "length", "height"])
at [Source: java.io.StringReader@52851428; line: 1, column: 33] (through reference chain: jobsme.com.firebasequery.DinosaurFacts["vanished"])
at com.fasterxml.jackson.databind.DeserializationContext.reportUnknownProperty(DeserializationContext.java:555)
at com.fasterxml.jackson.databind.deser.std.StdDeserializer.handleUnknownProperty(StdDeserializer.java:708)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.handleUnknownProperty(BeanDeserializerBase.java:1160)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:315)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:121)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2888)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2034)
at com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:192)
at jobsme.com.firebasequery.MainActivity.onChildAdded(MainActivity.java:45)
at com.firebase.client.core.ChildEventRegistration.run(ChildEventRegistration.java:50)
at com.firebase.client.core.view.EventRaiser.run(EventRaiser.java:37)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
这是该数据库中一种恐龙的 JSON：
"bruhathkayosaurus": {
"appeared": -70000000,
"height": 25,
"length": 44,
"order": "saurischia",
"vanished": -70000000,
"weight": 135000
},
您正在使用的 DinosaurFacts class 只有这些属性的字段+getter：height、length、weight。因此，当 Firebase 尝试将 JSON 反序列化为 DinosaurFacts 对象时，它会抱怨未映射的属性。
消除错误的最简单方法是告诉 Jackson（Firebase 在内部使用它在 JSON 和 Java 之间进行映射）忽略它在 [=45] 中遇到的任何未映射的属性=]:
@JsonIgnoreProperties(ignoreUnknown = true)
public static class DinosaurFacts {
但是注意这个。如果您现在 将 一个 DinosaurFacts 对象写回数据库，它将只有 height、length 和 weight 属性。它不会有：appeared、order 或 vanished。事实上：即使属性did之前存在于数据库中，写回这个对象也会删除它们。
所以正确的解决方案是将 JSON 结构中的所有属性映射到 Java class:
public static class DinosaurFacts {
long appeared, vanished;
double height, length, weight;
String order;
public long getAppeared() {
return appeared;
}
public long getVanished() {
return vanished;
}
public double getHeight() {
return height;
}
public double getLength() {
return length;
}
public double getWeight() {
return weight;
}
public String getOrder() {
return order;
}
}