我需要在我的Android应用程序中实现一个水平列表视图。我做了一些研究,遇到了如何在Android中创建一个水平的ListView ?和横向列表视图在Android?然而,这些问题是在Recyclerview发布之前提出的。有没有更好的方法来实现这个现在与Recyclerview?


当前回答

随着RecyclerView库的发布,现在您可以轻松地对齐与文本绑定的图像列表。您可以使用LinearLayoutManager来指定您想要定位列表的方向,可以是垂直的,也可以是水平的,如下所示。

你可以从这篇文章中下载一个完整的工作演示。

其他回答

试试这个:

myrecyclerview.setLayoutManager(
        new LinearLayoutManager(getActivity(),
                                LinearLayoutManager.HORIZONTAL,false));
myrecyclerview.setAdapter(recyclerAdapter);

只是以防你有一个带有碎片的回收视图。

如果你想使用水平回收器视图作为ViewPager,那么现在可以使用线性snaphelper的帮助,它是在支持库24.2.0版本中添加的。

首先添加RecyclerView到你的活动/片段

<android.support.v7.widget.RecyclerView
    android:layout_below="@+id/sign_in_button"
    android:layout_width="match_parent"
    android:orientation="horizontal"
    android:id="@+id/blog_list"
    android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>

在我的情况下,我已经使用了一个CardView在RecyclerView

blog_row.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView

    xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_margin="15dp"
        android:orientation="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            android:orientation="vertical">

            <com.android.volley.toolbox.NetworkImageView
                android:id="@+id/imageBlogPost"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:adjustViewBounds="true"
                android:paddingBottom="15dp"
                android:src="@drawable/common_google_signin_btn_text_light_normal" />

            <TextView
                android:id="@+id/TitleTextView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
               android:layout_marginBottom="20dp"

                android:text="Post Title Here"
                android:textSize="16sp" />

            <TextView
                android:id="@+id/descriptionTextView"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Post Description Here"
                android:paddingBottom="15dp"
                android:textSize="14sp" />
        </LinearLayout>

    </android.support.v7.widget.CardView>

在你的活动/片段中

private RecyclerView mBlogList;

LinearLayoutManager layoutManager =
    new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);

mBlogList = (RecyclerView) findViewById(R.id.blog_list);
mBlogList.setHasFixedSize(true);
mBlogList.setLayoutManager(layoutManager);

LinearSnapHelper snapHelper = new LinearSnapHelper() {
    @Override
    public int findTargetSnapPosition(RecyclerView.LayoutManager lm, int velocityX, int velocityY) {
        View centerView = findSnapView(lm);
        if (centerView == null)
            return RecyclerView.NO_POSITION;

        int position = lm.getPosition(centerView);
        int targetPosition = -1;
        if (lm.canScrollHorizontally()) {
            if (velocityX < 0) {
                targetPosition = position - 1;
            } else {
                targetPosition = position + 1;
            }
        }

        if (lm.canScrollVertically()) {
            if (velocityY < 0) {
                targetPosition = position - 1;
            } else {
                targetPosition = position + 1;
            }
        }

        final int firstItem = 0;
        final int lastItem = lm.getItemCount() - 1;
        targetPosition = Math.min(lastItem, Math.max(targetPosition, firstItem));
        return targetPosition;
    }
};

snapHelper.attachToRecyclerView(mBlogList);

最后一步是将适配器设置为RecyclerView

mBlogList.setAdapter(firebaseRecyclerAdapter);

您可以从布局文件或java/kotlin文件中定义方向和layoutManager

使用XML

<androidx.recyclerview.widget.RecyclerView
        android:id="@+id/my_recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />

在Java中

LinearLayoutManager layoutManager
= new LinearLayoutManager(requireContext(), LinearLayoutManager.HORIZONTAL, false);

RecyclerView rv= (RecyclerView) findViewById(R.id.my_recyclerView);
rv.setLayoutManager(layoutManager);

在Kotlin

val layoutManager
= LinearLayoutManager(requireContext(), LinearLayoutManager.HORIZONTAL, false)
my_recyclerView.layoutManager = layoutManager

随着RecyclerView库的发布,现在您可以轻松地对齐与文本绑定的图像列表。您可以使用LinearLayoutManager来指定您想要定位列表的方向,可以是垂直的,也可以是水平的,如下所示。

你可以从这篇文章中下载一个完整的工作演示。

XML文件

<HorizontalScrollView
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    
    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal"
        android:scrollbars="vertical|horizontal" />

</HorizontalScrollView>

Code

import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.content.ContextWrapper;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;

public class MainActivity extends AppCompatActivity{

    ImageView mImageView1;
    Bitmap bitmap;
    String mSavedInfo;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mImageView1 = (ImageView) findViewById(R.id.image);
    }
    public Bitmap getBitmapFromURL(String src) {
        try {
            java.net.URL url = new java.net.URL(src);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setDoInput(true);
            connection.connect();
            InputStream input = connection.getInputStream();
            Bitmap myBitmap = BitmapFactory.decodeStream(input);
            return myBitmap;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }
    public void button2(View view) {
        new DownloadImageFromTherad().execute();
    }
    private class DownloadImageFromTherad extends AsyncTask<String, Integer, String> {
        @Override
        protected String doInBackground(String... params) {
            bitmap = getBitmapFromURL("https://cdn.pixabay.com/photo/2016/08/08/09/17/avatar-1577909_960_720.png");
            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            File sdCardDirectory = Environment.getExternalStorageDirectory();
            File image = new File(sdCardDirectory, "test.png");
            boolean success = false;
            FileOutputStream outStream;
            mSavedInfo = saveToInternalStorage(bitmap);
            if (success) {
                Toast.makeText(getApplicationContext(), "Image saved with success", Toast.LENGTH_LONG).show();
            } else {
                Toast.makeText(getApplicationContext(), "Error during image saving" + mSavedInfo, Toast.LENGTH_LONG).show();
            }
        }
    }
    private String saveToInternalStorage(Bitmap bitmapImage) {
        ContextWrapper cw = new ContextWrapper(getApplicationContext());
        // path to /data/data/yourapp/app_data/imageDir
        File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
        File mypath = new File(directory, "profile.jpg");
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(mypath);
            bitmapImage.compress(Bitmap.CompressFormat.PNG, 100, fos);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return directory.getAbsolutePath();
    }
    private void loadImageFromStorage(String path) {
        try {
            File f = new File(path, "profile.jpg");
            Bitmap b = BitmapFactory.decodeStream(new FileInputStream(f));
            mImageView1.setImageBitmap(b);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
    public void showImage(View view) {
        loadImageFromStorage(mSavedInfo);
    }
    
}