Android開發之實現水平滾動效果—RecyclerView
阿新 • • 發佈:2019-01-03
ListView由於其強大的功能,在過去的Android開發中有著卓越的貢獻,然而使用ListView,如果不使用一些技巧來提升其效率的話,那麼ListView的效能會很差。
為此,Android提供了一個更加強大的滾動控制元件–RecyclerView。下面來講一下其基本用法。
1.開啟app/build.gradle檔案,在dependencies閉包中新增如下內容:
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
testCompile 'junit:junit:4.12'
**compile 'com.android.support:recyclerview-v7:24.2.1' **
compile 'com.android.support:appcompat-v7:24.2.1'
}
新增完後,要記得Sync Now來進行同步。
然後修改main_activity.xml程式碼:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
tools:context="com.gyq.recyclerviewtest.MainActivity">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView >
</LinearLayout>
2,準備fruit_item.xml佈局,實現左右滑動效果:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:orientation="vertical">
<ImageView
android:id="@+id/iv_item_icon"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_gravity="center_horizontal"
android:src="@drawable/apple"/>
<TextView
android:id="@+id/tv_item_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="10dp"
android:text="apple"
android:textSize="20sp"/>
</LinearLayout>
3,為RecyclerView準備一個介面卡:
package com.gyq.recyclerviewtest.adapter;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import com.gyq.recyclerviewtest.R;
import com.gyq.recyclerviewtest.bean.Fruit;
import java.util.List;
/**
* ${DESC}
* author: gyq
* create at 2016/12/12 18:51
*/
public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {
private List<Fruit> mFruitList;
static class ViewHolder extends RecyclerView.ViewHolder {
// View fruitView;
ImageView fruitImage;
TextView fruitName;
public ViewHolder(View itemView) {
super(itemView);
//fruitView = itemView;
fruitImage = (ImageView)itemView.findViewById(R.id.iv_item_icon);
fruitName = (TextView)itemView.findViewById(R.id.tv_item_name);
}
}
public FruitAdapter(List<Fruit> fruitInfo) {
mFruitList = fruitInfo;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.fruit_item,parent,false);
ViewHolder holder = new ViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Fruit fruit = mFruitList.get(position);
holder.fruitImage.setImageResource(fruit.getImageId());
holder.fruitName.setText(fruit.getName());
}
@Override
public int getItemCount() {
return mFruitList.size();
}
}
解釋一下上面程式碼:首先定義了一個內部類ViewHolder,其繼承RecyclerView.ViewHolder。然後ViewHolder的建構函式中需要傳入一個view引數;
4,介面卡準備好了,接下來我們就來使用RecyclerView:
package com.gyq.recyclerviewtest;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import com.gyq.recyclerviewtest.adapter.FruitAdapter;
import com.gyq.recyclerviewtest.bean.Fruit;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
private List<Fruit> fruitInfo = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initFruit();
RecyclerView recyclerView = (RecyclerView)findViewById(R.id.recycler_view);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
//設定水平滾動
layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
recyclerView.setLayoutManager(layoutManager);
FruitAdapter adapter = new FruitAdapter(fruitInfo);
recyclerView.setAdapter(adapter);
}
private void initFruit() {
for (int i = 0; i < 2;i++) {
Fruit apple = new Fruit("apple",R.drawable.apple);
fruitInfo.add(apple);
Fruit apricot = new Fruit("apricot"),R.drawable.apricot);
fruitInfo.add(apricot);
Fruit banana = new Fruit("banana"),R.drawable.banana);
fruitInfo.add(banana);
Fruit cherry = new Fruit("cherry"),R.drawable.cherry);
fruitInfo.add(cherry);
Fruit kiwi = new Fruit("kiwi"),R.drawable.kiwi);
fruitInfo.add(kiwi);
Fruit lemon = new Fruit("lemon"),R.drawable.lemon);
fruitInfo.add(lemon);
Fruit mango = new Fruit("mango"),R.drawable.mango);
fruitInfo.add(mango);
Fruit orange = new Fruit("orange"),R.drawable.orange);
fruitInfo.add(orange);
Fruit peach = new Fruit("peach"),R.drawable.peach);
fruitInfo.add(peach);
Fruit pear = new Fruit("pear"),R.drawable.pear);
fruitInfo.add(pear);
Fruit strawberry = new Fruit("strawberry"),R.drawable.strawberry);
fruitInfo.add(strawberry);
Fruit tomato = new Fruit("tomato"),R.drawable.tomato);
fruitInfo.add(tomato);
}
}
}
5,還有一個bean類
package com.gyq.recyclerviewtest.bean;
/**
* ${DESC}
* author: gyq
* create at 2016/12/12 17:02
*/
public class Fruit {
private String name;
private int ImageId;
public Fruit(String name, int imageId) {
this.name = name;
this.ImageId = imageId;
}
public String getName() {
return name;
}
public int getImageId() {
return ImageId;
}
}
本篇部落格只是實現了水平滾動的效果;但是沒有設定item中控制元件的點選事件;由於不像listview中有個setOnItemonClick點選事件。下篇部落格,我將給大家帶了一個瀑布流效果,並設定點選事件。