Question

我正在使用的应用程序当前包含显示多个图像的画廊视图。这些显示在recycler view中。我最终想要实现的是让用户点击其中一张图像，并在单独的活动中将其作为image view进行打开。我希望我能学到最好的方法。我在搜索中找不到它，请原谅我，我对编码还是很陌生。

画廊活动：

import android.app.ActionBar;
import android.content.Intent;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;

import java.util.ArrayList;

public class GalleryActivity extends AppCompatActivity {



    private final Integer image_ids[] = {
           //all of my image ids from drawable//



    };

    @Override
    public void onBackPressed() {
        Intent returnhome = new Intent(GalleryActivity.this, BleachActivity.class);
        startActivity(returnhome);
        finish();
        return;
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_gallery);
        android.support.v7.app.ActionBar actionBar = getSupportActionBar();
        actionBar.setTitle("//name of app//");


        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.gallery);
        recyclerView.setHasFixedSize(false);

        RecyclerView.LayoutManager layoutManager = new GridLayoutManager(getApplicationContext(), 3);
        recyclerView.setLayoutManager(layoutManager);

        ArrayList<Cell> cells = prepareData();
        MyAdapter adapter = new MyAdapter(getApplicationContext(), cells);
        recyclerView.setAdapter(adapter);


    }

    private ArrayList<Cell> prepareData() {
        ArrayList<Cell> theImage = new ArrayList<>();
        for(int i = 0; i < image_ids.length; i++){
            Cell cell = new Cell();
            cell.setImg(image_ids[i]);
            theImage.add(cell);

    }

    return theImage;

}}

单元Java文件：

public class Cell {

    private Integer img;

    public Integer getImg() {
        return img;
    }

    public void setImg(Integer img) {
        this.img = img;
    }
}

图像适配器Java文件：

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

    private ArrayList<Cell> galleryList;
    private Context context;

    public MyAdapter (Context context, ArrayList<Cell> galleryList){
        this.galleryList = galleryList;
        this.context = context;

    }


    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, final int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.cell, viewGroup, false);
        return new ViewHolder(view);}

    @Override
    public void onBindViewHolder(MyAdapter.ViewHolder viewHolder, final int i){
        viewHolder.img.setScaleType(ImageView.ScaleType.CENTER_CROP);
        viewHolder.img.setImageResource(galleryList.get(i).getImg());
        viewHolder.img.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
            }
        });
    }

    @Override
    public int getItemCount(){
        return galleryList.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder{
        private ImageView img;
        public ViewHolder(View view){
            super(view);

            img = (ImageView) view.findViewById(R.id.img);
        }
    }
}

Answer 1

您首先创建一个新的活动，该活动将保存并显示图像视图，例如ImageViewActivity。然后您有多种选择，我们将审查其中两个。

容易的选择不是很好（不明智的建筑选择）

从适配器开始活动

@Override
public void onBindViewHolder(MyAdapter.ViewHolder viewHolder, final int i){
    viewHolder.img.setScaleType(ImageView.ScaleType.CENTER_CROP);
    viewHolder.img.setImageResource(galleryList.get(i).getImg());
    viewHolder.img.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view) {
            Intent intent = new Intent(context, ImageViewActivity.class);
            context.startActivity(intent);
        }
    });
}

更好的方式

更好的方法是使用委托模式。说明：单击项目不是适配器的责任。因此，为了简单起见，知识应该在其他地方。

MyAdapter

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> { 

    public class Delegate {
        public void onClick(int imageResource);
    }

    private Delegate delegate;

    public MyAdapter (Context context, ArrayList<Cell> galleryList, Delegate delegate){
        this.galleryList = galleryList;
        this.context = context;
        this.delegate = delegate;
    }

    ...

    @Override
    public void onBindViewHolder(MyAdapter.ViewHolder viewHolder, final int i){
        viewHolder.img.setScaleType(ImageView.ScaleType.CENTER_CROP);
        viewHolder.img.setImageResource(galleryList.get(i).getImg());
        viewHolder.img.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                delegate.onClick(galleryList.get(i).getImg());
            }
        });
    }
}

GalleryActivity

public class GalleryActivity extends AppCompatActivity implements MyAdapter.Delegate {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_gallery);

        ...

        MyAdapter adapter = new MyAdapter(getApplicationContext(), cells, this);
        recyclerView.setAdapter(adapter);

        ...
    }

    @Override
    public void onClick() {
        Intent intent = new Intent(this, ImageViewActivity.class);
        context.startActivity(intent);
    }
}

如果您真的对代码的哪个部分感兴趣，可以看一下MVC，MVP，MVVM或Clean Architecture等架构模式（后者应该会取代其余的）。 Google提供了具有不同架构的示例项目： https://github.com/googlesamples/android-architecture

Answer 2

您可以在适配器中创建一种方法，该方法使用所单击的项目信息并将其作为额外的信息传递给活动。

例如：

viewHolder.img.setImageResource(galleryList.get(i).getImg());

您可以使用此行获取图像并将其添加为额外内容。

要获取特定的项目数据，可以在适配器的视图保持器中使用类似的内容：

 view.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    int pos = getAdapterPosition();
                    galleryList.get(pos).getImg());
                }
}

然后通过添加完成作业。

Intent myIntent = new Intent(A.this, B.class);
myIntent.putExtra("extraName", value);
startActivity(myIntent);

如何在单独的活动中从RecyclerView打开图像？

2 个答案: