Android RecyclerView使用详解（含通过网络请求得到数据）
RecyclerView概述RecyclerView是Android中非常受接待的控件，RecyclerView是官方在Android5.0之后新添加的控件，推出用来替换传统的ListView和GridView列表控件，以是如果你还在使用ListView的话可以替换为RecyclerView了。
对于RecyclerView的使用根据现实项目进行说明，一些功能大概是你现在正在做的，对你有帮助也说不定。
一、RecyclerView底子使用
第一步：在build.gradle中添加依靠
implementation ("androidx.recyclerview:recyclerview:1.1.0")//可横向滚动
第二步：添加RecyclerView
点开一个结构文件，找到RecyclerView控件，拖动到要添加的位置即可添加RecyclerView。https://i-blog.csdnimg.cn/blog_migrate/4640b0f2e8547ff6956db4b640562b57.gif
xml代码如下：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraintLayout"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginTop="1dp"
android:background="#6750A4"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="实例"
android:textColor="#FFFFFF"
android:textSize="16sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="409dp"
android:layout_height="688dp"
android:layout_marginTop="1dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/constraintLayout">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycleview"
android:layout_width="409dp"
android:layout_height="688dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout> 第三步：再添加一个news_item_layout.xml的结构文件,用于显示一条数据https://i-blog.csdnimg.cn/blog_migrate/f554ebab361f9cba6351c83087942b62.png
在根结构上面设置好每条显示的数据的长宽，并添加内容到根结构内里。
代码如下：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="90dp">
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:text="title"
android:textColor="#000000"
android:textSize="18sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="5dp"
android:text="content"
android:textColor="#707070"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView2" />
</androidx.constraintlayout.widget.ConstraintLayout>
第四步：添加逻辑代码
界说一个实体类:
https://i-blog.csdnimg.cn/blog_migrate/43e3ec7f668e1e27d11248d1ebd6a496.png
实体类代码如下：
public class News {
public String title; // 标题
public String content; //内容
} 然后在MainActivity中界说内部类 ViewHolder类、 MyAdapter类以及设置RecyclerView相关逻辑
首先是内部类 MyViewHolder类：用于初始化控件
class MyViewHoder extends RecyclerView.ViewHolder {
TextView title;
TextView content;
public MyViewHoder(@NonNull View itemView) {
super(itemView);
title = itemView.findViewById(R.id.textView2);
content = itemView.findViewById(R.id.textView3);
}
} 再就是内部类 MyAdapter类：将添加到的数据与item进行绑定
class MyAdapter extends RecyclerView.Adapter<MyViewHoder> {
//绑定item布局
@NonNull
@Override
public MyViewHoder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = View.inflate(MainActivity.this, R.layout.news_item_layout, null);
MyViewHoder myViewHoder = new MyViewHoder(view);
return myViewHoder;
}
//给item添加数据
@Override
public void onBindViewHolder(@NonNull MyViewHoder holder, int position) {
News news = newsList.get(position);
holder.title.setText(news.title);
holder.content.setText(news.content);
}
//设置item条数
@Override
public int getItemCount() {
return newsList.size();
}
} 最后就是构造数据：
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRecyclerView = findViewById(R.id.recycleview);
// 构造一些数据
for (int i = 0; i < 100; i++) {
News news = new News();
news.title = "标题" + i;
news.content = "内容" + i;
newsList.add(news);
}
mMyAdapter = new MyAdapter();
mRecyclerView.setAdapter(mMyAdapter);
LinearLayoutManager layoutManager = new LinearLayoutManager(MainActivity.this);
mRecyclerView.setLayoutManager(layoutManager);
} 完备 MainActivity.java 代码：
package com.example.retrofit;import androidx.annotation.NonNull;import androidx.appcompat.app.AppCompatActivity;import androidx.recyclerview.widget.LinearLayoutManager;import androidx.recyclerview.widget.RecyclerView;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity { RecyclerView mRecyclerView; MyAdapter mMyAdapter ; List<News> newsList = new ArrayList<>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mRecyclerView = findViewById(R.id.recycleview); // 构造一些数据 for (int i = 0; i < 50; i++) { News news = new News(); news.title = "标题" + i; news.content = "内容" + i; newsList.add(news); } mMyAdapter = new MyAdapter(); mRecyclerView.setAdapter(mMyAdapter); LinearLayoutManager layoutManager = new LinearLayoutManager(MainActivity.this); mRecyclerView.setLayoutManager(layoutManager); } class MyAdapter extends RecyclerView.Adapter<MyViewHoder> {
//绑定item布局
@NonNull
@Override
public MyViewHoder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = View.inflate(MainActivity.this, R.layout.news_item_layout, null);
MyViewHoder myViewHoder = new MyViewHoder(view);
return myViewHoder;
}
//给item添加数据
@Override
public void onBindViewHolder(@NonNull MyViewHoder holder, int position) {
News news = newsList.get(position);
holder.title.setText(news.title);
holder.content.setText(news.content);
}
//设置item条数
@Override
public int getItemCount() {
return newsList.size();
}
} class MyViewHoder extends RecyclerView.ViewHolder {
TextView title;
TextView content;
public MyViewHoder(@NonNull View itemView) {
super(itemView);
title = itemView.findViewById(R.id.textView2);
content = itemView.findViewById(R.id.textView3);
}
}}
若要实现横向滑动：在 MainActivity.java 添加一句如下代码
layoutManager.setOrientation(RecyclerView.HORIZONTAL);
https://i-blog.csdnimg.cn/blog_migrate/a82ed399ead81e8e21a6c2de71688ba0.png
若要每行显示多条数据，可对代码做如下修改：
mRecyclerView.setLayoutManager(new GridLayoutManager(MainActivity.this,3));//每行三个
https://i-blog.csdnimg.cn/blog_migrate/93704bb3350cc5e34f44f6e00aa3143a.png
运行结果如下：https://i-blog.csdnimg.cn/blog_migrate/f9e2a90db55e48f1b8464ae7ce961488.gifhttps://i-blog.csdnimg.cn/blog_migrate/af9fe87c463be7fa7c5a5829372b8421.gifhttps://i-blog.csdnimg.cn/blog_migrate/2f27641ac771e6863eca1698b8006730.gif
二、RecyclerView进阶使用：通过网络请求得到数据
前期预备：添加依靠包：
implementation("com.squareup.okhttp3:okhttp:4.11.0")
implementation ("com.squareup.retrofit2:retrofit:2.9.0")
implementation ("com.squareup.retrofit2:converter-gson:2.9.0")
implementation ("io.github.youth5201314:banner:2.2.3")
implementation ("com.github.bumptech.glide:glide:4.15.1")
implementation ("com.google.code.gson:gson:2.10.1") 添加网络请求权限：
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
android:allowBackup="true" https://i-blog.csdnimg.cn/blog_migrate/2fdb45cd0211dd87dfed77af50deefe8.png
添加一些数据到mock中去（useMock 免费在线Mock平台 Api数据模拟助手）
重新构造实体类：https://i-blog.csdnimg.cn/blog_migrate/6b3e42e3f2f96066a4c8e04dcdf4de77.png
获取网络数据，将网络数据赋值给newsDTOList数组
// 构造一些数据
Request request = new Request.Builder()
.url("https://detail.usemock.com/shiyan")
.get().build();
OkHttpClient okHttpClient = new OkHttpClient();
Call call = okHttpClient.newCall(request);
//构造item数据
call.enqueue(new Callback() {
@Override
public void onFailure(@NonNull Call call, @NonNull IOException e) {
}
@Override
public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
String result = response.body().string();
MainActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
try {
Gson gson = new Gson();
News news = gson.fromJson(result,News.class);
newsDTOList.addAll(news.news);
mMyAdapter.notifyDataSetChanged();
}catch (Exception e){
throw new RuntimeException(e);
}
}
});
}
}); 再对MainActivity中界说内部类 ViewHolder类、 MyAdapter类以及设置RecyclerView相关逻辑的修改。具体操纵很简朴，这里省略，下面是完备的代码,供参考：
MainActivity.java代码：
import androidx.annotation.NonNull;import androidx.appcompat.app.AppCompatActivity;import androidx.recyclerview.widget.DividerItemDecoration;import androidx.recyclerview.widget.GridLayoutManager;import androidx.recyclerview.widget.LinearLayoutManager;import androidx.recyclerview.widget.RecyclerView;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.TextView;import com.bumptech.glide.Glide;import com.google.gson.Gson;import java.io.IOException;import java.util.ArrayList;import java.util.List;import okhttp3.Call;import okhttp3.Callback;import okhttp3.OkHttpClient;import okhttp3.Request;import okhttp3.Response;public class MainActivity extends AppCompatActivity { RecyclerView mRecyclerView; MyAdapter mMyAdapter ; List<News.NewsDTO> newsDTOList = new ArrayList<>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mRecyclerView = findViewById(R.id.recycleview); DividerItemDecoration mDivider = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL); mRecyclerView.addItemDecoration(mDivider); // 构造一些数据
Request request = new Request.Builder()
.url("https://detail.usemock.com/shiyan")
.get().build();
OkHttpClient okHttpClient = new OkHttpClient();
Call call = okHttpClient.newCall(request);
//构造item数据
call.enqueue(new Callback() {
@Override
public void onFailure(@NonNull Call call, @NonNull IOException e) {
}
@Override
public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {
String result = response.body().string();
MainActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
try {
Gson gson = new Gson();
News news = gson.fromJson(result,News.class);
newsDTOList.addAll(news.news);
mMyAdapter.notifyDataSetChanged();
}catch (Exception e){
throw new RuntimeException(e);
}
}
});
}
}); mMyAdapter = new MyAdapter(); mRecyclerView.setAdapter(mMyAdapter); //mRecyclerView.setLayoutManager(new GridLayoutManager(MainActivity.this,3));//每行三个
LinearLayoutManager layoutManager = new LinearLayoutManager(MainActivity.this); //layoutManager.setOrientation(RecyclerView.HORIZONTAL);
mRecyclerView.setLayoutManager(layoutManager); } class MyAdapter extends RecyclerView.Adapter<MyViewHoder> { //绑定item结构 @NonNull @Override public MyViewHoder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) { View view = View.inflate(MainActivity.this, R.layout.news_item_layout, null); MyViewHoder myViewHoder = new MyViewHoder(view); return myViewHoder; } //给item添加数据 @Override public void onBindViewHolder(@NonNull MyViewHoder holder, int position) { News.NewsDTO newsDTO = newsDTOList.get(position); holder.title.setText(newsDTO.title); Glide.with(MainActivity.this).load(newsDTO.content).into(holder.content); } //设置item条数 @Override public int getItemCount() { return newsDTOList.size(); } } class MyViewHoder extends RecyclerView.ViewHolder { TextView title; ImageView content; public MyViewHoder(@NonNull View itemView) { super(itemView); title = itemView.findViewById(R.id.textView2); content = itemView.findViewById(R.id.imageView); } }} activity_main.xml代码：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraintLayout"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginTop="1dp"
android:background="#6750A4"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="实例"
android:textColor="#FFFFFF"
android:textSize="16sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="409dp"
android:layout_height="688dp"
android:layout_marginTop="1dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/constraintLayout">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recycleview"
android:layout_width="409dp"
android:layout_height="688dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout> News.java代码：
import java.util.List;
public class News {
@com.google.gson.annotations.SerializedName("news")
public List<NewsDTO> news;
public static class NewsDTO {
@com.google.gson.annotations.SerializedName("title")
public String title;
@com.google.gson.annotations.SerializedName("content")
public String content;
}
} news_item_layout.xml代码:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="200dp"
android:layout_height="150dp">
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:text="title"
android:textColor="#000000"
android:textSize="18sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="@+id/imageView"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_marginStart="16dp"
android:layout_marginTop="8dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView2"
app:srcCompat="@drawable/ic_launcher_background" />
</androidx.constraintlayout.widget.ConstraintLayout> 运行结果:https://i-blog.csdnimg.cn/blog_migrate/26a03d84a54006680070da8c28e533db.gif
如有不清楚，或者本文章中有错误的地方，本人客气接受指正。
下一期:Android Studio动画结果的使用详解
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