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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"/>

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

(4)绑定控件ID

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

(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

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