Android 使用RecycleView列表实现加载更多

Posted 2021-05-08 ~~~周

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android 使用RecycleView列表实现加载更多

1.界面布局

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#f0f3f5"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".MainActivity">

        <ImageView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:src="@mipmap/logo"/>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp"
            android:orientation="vertical">
            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:gravity="center">

                <TextView
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:layout_height="wrap_content"
                    android:gravity="center"
                    android:text="电影名"/>
                <LinearLayout
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:gravity="center"
                    android:layout_height="wrap_content"
                    android:orientation="horizontal">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="match_parent"
                        android:text="电影评分" />

                </LinearLayout>
                <TextView
                    android:layout_width="0dp"
                    android:layout_weight="1"
                    android:gravity="center"
                    android:layout_height="wrap_content"
                    android:text="电影图片"/>
            </LinearLayout>

        </LinearLayout>
        <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:id="@+id/s1">

            <androidx.recyclerview.widget.RecyclerView
                android:id="@+id/r1"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />


        </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
    </LinearLayout>

</FrameLayout>

列表布局list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="160dp">
    <TextView
        android:id="@+id/t2"
        android:layout_width="0dp"
        android:layout_weight="1.5"
        android:gravity="center"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="我不是药神"/>
    <TextView
        android:id="@+id/t3"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:text="9.0"/>
    <ImageView
        android:id="@+id/i1"
        android:layout_width="0dp"
        android:layout_weight="1.5"
        android:layout_height="150dp"
        android:padding="20dp"
        android:src="@mipmap/ic_launcher"/>
</LinearLayout>

加载更多布局foot_view.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:tools="http://schemas.android.com/tools"
          android:id="@+id/tv_foot"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:padding="10dp"
          android:gravity="center"
          tools:text="下拉刷新"
          android:orientation="vertical"/>

在这里插入图片描述
2.功能实现
(1)添加网络权限

<uses-permission android:name="android.permission.INTERNET"/>

(2)添加使用到的第三方库

    implementation 'com.android.support:design:28.0.0'
    implementation 'com.android.support:support-v4:28.0.0'
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.squareup.okhttp3:okhttp:3.12.1'
    debugImplementation 'com.squareup.okhttp3:logging-interceptor:3.12.1'
    implementation 'com.google.code.gson:gson:2.8.5'
    implementation 'com.github.bumptech.glide:glide:4.9.0'
    annotationProcessor 'com.github.bumptech.glide:compiler:4.9.0'

(3)数据解析
使用GsonFormat插件，快速将json字符串转换成一个Java Bean，免去我们根据json字符串手写对应Java Bean的过程。
定义一个类OneModel.class

public class OneModel implements Serializable {

}

使用快捷键（Alt+s）粘贴全部过去数据，之后一直点击OK
在这里插入图片描述

(4)绑定控件ID

private RecyclerView r1;
private SwipeRefreshLayout s1;
private LinearLayoutManager linearLayoutManager;
private Adapter adapter;

在这里插入图片描述

(5)定义一个Adapter类

package com.example.note4;

import android.content.Context;
import android.graphics.Color;
import android.os.Handler;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.recyclerview.widget.RecyclerView;

import com.bumptech.glide.Glide;

import java.util.List;
public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
    private Context mContext;
    private List<DateModel.SubjectsBean> mData;//数据
    private int max_count = 6;//最大显示数
    private Boolean isFootView = false;//是否添加了FootView
    private String footViewText = "";//FootView的内容

    //两个final int类型表示ViewType的两种类型
    private final int NORMAL_TYPE = 0;
    private final int FOOT_TYPE = 1111;


    public Adapter(Context context, List<DateModel.SubjectsBean> data) {
        this.mContext = context;
        this.mData = data;
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public TextView t3,t2;
        public ImageView i1;
        private TextView tvFootView;

        //初始化viewHolder，此处绑定后在onBindViewHolder中可以直接使用
        public ViewHolder(View itemView, int viewType) {
            super(itemView);
            if (viewType == NORMAL_TYPE) {
                t3 = (TextView) itemView.findViewById(R.id.t3);
                t2 = (TextView) itemView.findViewById(R.id.t2);
                i1=(ImageView)itemView.findViewById(R.id.i1);
            } else if (viewType == FOOT_TYPE) {
                tvFootView = (TextView) itemView.findViewById(R.id.tv_foot);
            }
        }
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View normal_views = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.list, parent, false);
        View foot_view = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.foot_view, parent, false);

        if (viewType == FOOT_TYPE)
            return new ViewHolder(foot_view, FOOT_TYPE);
        return new ViewHolder(normal_views, NORMAL_TYPE);
    }

    @Override
    public int getItemViewType(int position) {
        if (position == max_count - 1) {
            return FOOT_TYPE;
        }
        return NORMAL_TYPE;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        DateModel.SubjectsBean subjectsBean=mData.get(position);
        //如果footview存在，并且当前位置ViewType是FOOT_TYPE
        if (isFootView && (getItemViewType(position) == FOOT_TYPE)) {
            holder.tvFootView.setText(footViewText);
            // 刷新太快 所以使用Hanlder延迟两秒
            Handler handler = new Handler();
            handler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    max_count += 5;
                    notifyDataSetChanged();
                }
            }, 1000);

        } else {
            holder.t2.setText(subjectsBean.getTitle());
            holder.t3.setText(subjectsBean.getRate());
            Glide.with(mContext).load(subjectsBean.getCover()).into(holder.i1);
        }
    }

    @Override
    public int getItemCount() {
        if (mData.size() <= max_count) {
            return mData.size();
        }
        return max_count;
    }

    //创建一个方法来设置footView中的文字
    public void setFootViewText(String footViewText) {
        isFootView = true;
        this.footViewText = footViewText;
    }

}

(6)网络请求

 public void getDate(DateModel dateModel)
    {
        if(dateModel==null||dateModel.getSubjects()==null)
        {
            Toast.makeText(MainActivity.this,"失败",Toast.LENGTH_SHORT).show();
            return;
        }
        Toast.makeText(MainActivity.this,"成功",Toast.LENGTH_SHORT).show();
        adapter=new Adapter(MainActivity.this,dateModel.getSubjects());
        adapter.setFootViewText("加载中...");
        r1.setAdapter(adapter);
        s1.setRefreshing(false);
    }
    public void requestDate() {

        String url = "https://movie.douban.com/j/search_subjects?type=movie&tag=%E8%B1%86%E7%93%A3%E9%AB%98%E5%88%86&sort=recommend&page_limit=200&page_start=0";
        OkHttpClient okHttpClient = new OkHttpClient();
        final Request request = new Request.Builder()
                .url(url)
                .get()
                .build();
        Call call = okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(MainActivity.this, "网络连接失败", Toast.LENGTH_SHORT).show();
                    }
                });
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                String result = response.body().string();
                Gson gson = new Gson();
                final DateModel dateModel = gson.fromJson(result, DateModel.class);
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(MainActivity.this, "网络连接成功", Toast.LENGTH_SHORT).show();
                        getDate(dateModel);
                    }
                });
            }
        });
    }

(7)功能实现
在这里插入图片描述

linearLayoutManager=new LinearLayoutManager(MainActivity.this);
        linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        r1.setLayoutManager(linearLayoutManager);
        requestDate();

        s1.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                new Handler().postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        requestDate();
                    }
                },1000);
            }
        });

(8)源代码
点击下载

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