Android GridLayoutManager示例
时间：2020-02-23 14:28:58 来源:igfitidea点击:
Android GridLayoutManager是RecyclerView.LayoutManager的实现，用于对网格中的项目进行布局。
在本教程中，我们将创建一个应用程序，该应用程序以GridLayout的形式在RecyclerView内显示CardViews。
另外，我们将实现一个接口，使RecyclerView项目单击类似于ListView itemClickListener。
Android GridLayoutManager
我们在这里使用LinearLayoutManager实现了RecyclerView。
现在，让我们使用" GridLayoutManager"将RecyclerView布局为网格。
以下是GridLayoutManager的构造函数。
GridLayoutManager (Context context,
int spanCount,
int orientation,
boolean reverseLayout)
reverseLayout如果设置为true，则从头到尾布局项目。
要设置每个项目的跨度大小，我们在GridLayoutManager上调用方法setSpanSizeLookup
让我们在新的Android Studio项目中使用GridLayoutManager实现RecyclerView。
Android GridLayoutManager示例项目结构
该项目由单个Activity：MainActivity.java，适配器类RecyclerViewAdapter.java，DataModel.java类和自定义GridLayoutManager类AutoFitGridLayoutManager.java组成。
MainActivity.java类的xml布局在文件" activity_main.xml"中定义为
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="https://schemas.android.com/apk/res/android"
xmlns:tools="https://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="https://schemas.android.com/apk/res-auto"
android:fitsSystemWindows="true"
tools:context=".MainActivity">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
</RelativeLayout>
</android.support.design.widget.CoordinatorLayout>
注意：不要忘记在build.gradle文件中为Material Design小部件和CardView添加以下依赖项。
compile 'com.android.support:cardview-v7:25.1.1' compile 'com.android.support:design:25.1.1'
下面给出了DataModel.java类：package com.theitroad.recyclerviewgridlayoutmanager;
public class DataModel {
public String text;
public int drawable;
public String color;
public DataModel(String t, int d, String c )
{
text=t;
drawable=d;
color=c;
}
}
DataModel类将保存每个项目单元格的文本，可绘制图标和背景颜色。
RecyclerViewAdapter.java类如下所示：
package com.theitroad.recyclerviewgridlayoutmanager;
import android.content.Context;
import android.graphics.Color;
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.RelativeLayout;
import android.widget.TextView;
import java.util.ArrayList;
public class RecyclerViewAdapter extends RecyclerView.Adapter {
ArrayList mValues;
Context mContext;
protected ItemListener mListener;
public RecyclerViewAdapter(Context context, ArrayList values, ItemListener itemListener) {
mValues = values;
mContext = context;
mListener=itemListener;
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView textView;
public ImageView imageView;
public RelativeLayout relativeLayout;
DataModel item;
public ViewHolder(View v) {
super(v);
v.setOnClickListener(this);
textView = (TextView) v.findViewById(R.id.textView);
imageView = (ImageView) v.findViewById(R.id.imageView);
relativeLayout = (RelativeLayout) v.findViewById(R.id.relativeLayout);
}
public void setData(DataModel item) {
this.item = item;
textView.setText(item.text);
imageView.setImageResource(item.drawable);
relativeLayout.setBackgroundColor(Color.parseColor(item.color));
}
@Override
public void onClick(View view) {
if (mListener != null) {
mListener.onItemClick(item);
}
}
}
@Override
public RecyclerViewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(mContext).inflate(R.layout.recycler_view_item, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder Vholder, int position) {
Vholder.setData(mValues.get(position));
}
@Override
public int getItemCount() {
return mValues.size();
}
public interface ItemListener {
void onItemClick(DataModel item);
}
}
在上面的代码中，我们定义了一个ItemListener接口，该接口将在MainActivity.java类中实现。
每个RecyclerView项的xml布局如下。recycler_view_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
xmlns:card_view="https://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:id="@+id/cardView"
android:layout_width="match_parent"
android:layout_height="150dp"
card_view:cardCornerRadius="0dp"
card_view:cardElevation="@dimen/margin10"
card_view:cardMaxElevation="@dimen/margin10"
card_view:contentPadding="@dimen/margin10">
<RelativeLayout
android:id="@+id/relativeLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_gravity="center">
<ImageView
android:id="@+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:tint="@android:color/white"
android:padding="5dp"
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:textColor="@android:color/white"
android:layout_below="@+id/imageView"
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
下面给出了AutoFitGridLayoutManager.java类：
package com.theitroad.recyclerviewgridlayoutmanager;
import android.content.Context;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
public class AutoFitGridLayoutManager extends GridLayoutManager {
private int columnWidth;
private boolean columnWidthChanged = true;
public AutoFitGridLayoutManager(Context context, int columnWidth) {
super(context, 1);
setColumnWidth(columnWidth);
}
public void setColumnWidth(int newColumnWidth) {
if (newColumnWidth > 0 && newColumnWidth != columnWidth) {
columnWidth = newColumnWidth;
columnWidthChanged = true;
}
}
@Override
public void onLayoutChildren(RecyclerView.Recycler recycler, RecyclerView.State state) {
if (columnWidthChanged && columnWidth > 0) {
int totalSpace;
if (getOrientation() == VERTICAL) {
totalSpace = getWidth() - getPaddingRight() - getPaddingLeft();
} else {
totalSpace = getHeight() - getPaddingTop() - getPaddingBottom();
}
int spanCount = Math.max(1, totalSpace/columnWidth);
setSpanCount(spanCount);
columnWidthChanged = false;
}
super.onLayoutChildren(recycler, state);
}
}
跨度计数是根据可用的方向，宽度和高度动态计算的。
MainActivity.java类如下：
package com.theitroad.recyclerviewgridlayoutmanager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity implements RecyclerViewAdapter.ItemListener {
RecyclerView recyclerView;
ArrayList arrayList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
arrayList = new ArrayList();
arrayList.add(new DataModel("Item 1", R.drawable.battle, "#09A9FF"));
arrayList.add(new DataModel("Item 2", R.drawable.beer, "#3E51B1"));
arrayList.add(new DataModel("Item 3", R.drawable.ferrari, "#673BB7"));
arrayList.add(new DataModel("Item 4", R.drawable.jetpack_joyride, "#4BAA50"));
arrayList.add(new DataModel("Item 5", R.drawable.three_d, "#F94336"));
arrayList.add(new DataModel("Item 6", R.drawable.terraria, "#0A9B88"));
RecyclerViewAdapter adapter = new RecyclerViewAdapter(this, arrayList, this);
recyclerView.setAdapter(adapter);
/**
AutoFitGridLayoutManager that auto fits the cells by the column width defined.
**/
/*AutoFitGridLayoutManager layoutManager = new AutoFitGridLayoutManager(this, 500);
recyclerView.setLayoutManager(layoutManager);*/
/**
Simple GridLayoutManager that spans two columns
**/
GridLayoutManager manager = new GridLayoutManager(this, 2, GridLayoutManager.VERTICAL, false);
recyclerView.setLayoutManager(manager);
}
@Override
public void onItemClick(DataModel item) {
Toast.makeText(getApplicationContext(), item.text + " is clicked", Toast.LENGTH_SHORT).show();
}
}
- 上面的类实现了接口RecyclerViewAdapter.ItemListener，并覆盖了适配器类中定义的方法onItemClick。
通过这样做，我们在Activity中实现了RecyclerView Click Listener而不是Adapter类(类似于为ListView定义的标准onItemClickListener) - DataModel类保存每个RecyclerView项的详细信息
- 可以通过实例化列宽度设置为500的AutoFitGridLayoutManager类或者通过调用GridLayoutManager类对象并将列数设置为2来定义RecyclerView的LayoutManager。
让我们看看带有标准GridLayoutManager代码的应用程序的输出。
如您所见，每一行都有两个在两个方向上都跨越列宽的项目。
现在注释掉简单GridLayoutManager的代码，并运行AutoFitGridLayoutManager的代码
AutoFitGridLayoutManager layoutManager = new AutoFitGridLayoutManager(this, 500); recyclerView.setLayoutManager(layoutManager);
实际应用程序的输出如下。
从上面的输出中可以看到，当方向更改为横向时，每行都有三项，从而动态调整项目的大小以自动适应列宽。
