无法将字符串类型的对象转换为位图类型

Question

private void ReadPosts() {
        DatabaseReference reference = FirebaseDatabase.getInstance().getReference("posts");

        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                postsList.clear();

                for (DataSnapshot snapshot1 : snapshot.getChildren()) {
                    Posts post = snapshot1.getValue(Posts.class);
                    for (String id : followingList) {
                        if (post.getPublisher().equals(id)) {
                            postsList.add(post);
                        }
                    }
                }

                postsAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {

            }
        });
    }

public class Posts {

    private Bitmap postImage;
    private String postText;
    private String publisher;
    private String postId;


    public Posts(Bitmap postImage, String postText, String publisher, String postId) {
        this.postImage = postImage;
        this.postText = postText;
        this.publisher = publisher;
        this.postId = postId;
    }


    public Posts() {
    }


    public String getPostId() {
        return postId;
    }

    public void setPostId(String postId) {
        this.postId = postId;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    public Bitmap getPostImage() {
        return postImage;
    }

    public void setPostImage(Bitmap postImage) {
        this.postImage = postImage;
    }


    public String getPostText() {
        return postText;
    }

    public void setPostText(String postText) {
        this.postText = postText;
    }
}

Answer 1

问题是，来自数据库的快照返回带有字符串（可能是图像的链接）的postImage，并且在您的model类中，postImage是用位图声明的。因此，字符串不能直接转换为位图。因此，您必须像这样更改model类：

从专用位图位置；到专用字符串位置；

然后您必须从链接加载图像（可能使用Glide）：

StorageReference ref = storageReference.child(posts.postImage).getDownloadUrl();
Glide.with(this /* context */)
        .using(new FirebaseImageLoader())
        .load(ref)
        .into(imageView);

Glide.with(this /* context */)
        .load(posts.postImage)
        .into(imageView);

implementation 'com.github.bumptech.glide:glide:4.12.0'