在我的Android应用中使用ServerValue.TIMESTAMP [英] Using ServerValue.TIMESTAMP in my Android App

问题描述

我已经阅读了很多与stackoverflow相关的问题

I have read lots of stackoverflow questions related to

ServerValue.TIMESTAMP

但是我不知道如何在我的应用程序中使用它.

but I can't figure out how to use it in my app.

我需要获取创建帖子的时间戳. 应该将timeStamp与帖子的uid，author等添加到同一位置.

I need to get the timeStamp of the creation of a post. The timeStamp should be added to the same place as with uid , author etc. of the post.

编写帖子 firebase数据库的代码段:

Code snippet which writes the post the firebase database:

 private void writeNewPost(String userId, String username, String title, String body) {
    // Create new post at /user-posts/$userid/$postid and at
    // /posts/$postid simultaneously
    String key = mDatabase.child("posts").push().getKey();
    Post post = new Post(userId, username, title, body);
    Map<String, Object> postValues = post.toMap();

    Map<String, Object> childUpdates = new HashMap<>();
    childUpdates.put("/posts/" + key, postValues);
    childUpdates.put("/user-posts/" + userId + "/" + key, postValues);

    mDatabase.updateChildren(childUpdates);
}

我的 Post.java 文件

@IgnoreExtraProperties
public class Post {

public String uid;
public String author;
public String title;
public String body;
public int starCount = 0;
public Map<String, Boolean> stars = new HashMap<>();
public Long timeStamp;

public Post() {
    // Default constructor required for calls to DataSnapshot.getValue(Post.class)
}

public Post(String uid, String author, String title, String body) {
    this.uid = uid;
    this.author = author;
    this.title = title;
    this.body = body;
}

// [START post_to_map]
@Exclude
public Map<String, Object> toMap() {
    HashMap<String, Object> result = new HashMap<>();
    result.put("uid", uid);
    result.put("author", author);
    result.put("title", title);
    result.put("body", body);
    result.put("starCount", starCount);
    result.put("stars", stars);

    return result;
}
// [END post_to_map]

}

我应该如何使用

ServerValue.TIMESTAMP 

在我的代码中获取创建帖子的时间.

in my code to get the time of creation of post.

推荐答案

ServerValue.TIMESTAMP 只是一个占位符值.当Firebase服务器处理更新请求并找到ServerValue.TIMESTAMP作为值时，它将替换为当前服务器时钟.

ServerValue.TIMESTAMP is simply a placeholder value. When the Firebase server processes an update request and finds ServerValue.TIMESTAMP as a value, it replaces it with the current server clock.

在您的writeNewPost()方法中，您可以添加一行以设置创建时间:

In your writeNewPost() method you could add a line to set the creation time:

Map<String, Object> postValues = post.toMap();
postValues.put("timeStamp", ServerValue.TIMESTAMP);

如果仅将Post.toMap()用于创建帖子，而不用于更新，则可以在其中放置类似的语句，而不要放在writeNewPost()中.

If you use Post.toMap() only to create posts, and not for updates, you could put a similar statement there instead of in writeNewPost().

这篇关于在我的Android应用中使用ServerValue.TIMESTAMP的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！