项目短视频

操作示范如下（时长25：10）

【例6-6】用GridView展示相册示例

GridView可以把一个空间组织成一个二维的网格，然后放入一批图片。加载的若干图片被统一进行大小限制和加边框处理。GridView是实现九宫格图的首选。

布局文件grid_view.xml的源代码

<?xml version="1.0" encoding="utf-8"?>

<GridView xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:id="@+id/grid_view"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:columnWidth="90dp"

    android:horizontalSpacing="5dp"

    android:numColumns="auto_fit"

    android:verticalSpacing="10dp"

    tools:context=".GridViewActivity">

</GridView>

控制文件GridViewActivity.java的源代码如下：

package com.example.chap06;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;

import android.os.Bundle;

import android.view.View;

import android.view.ViewGroup;

import android.widget.Adapter;

import android.widget.AdapterView;

import android.widget.BaseAdapter;

import android.widget.GridView;

import android.widget.ImageView;

import android.widget.Toast;

public class GridViewActivity extends AppCompatActivity

        implements AdapterView.OnItemClickListener {

    GridView grid_view;

    Integer[] mThumbIds={

            R.drawable.grid_view_01,R.drawable.grid_view_02,R.drawable.grid_view_03,

            R.drawable.grid_view_04,R.drawable.grid_view_05,R.drawable.grid_view_06,

            R.drawable.grid_view_07,R.drawable.grid_view_08,R.drawable.grid_view_09,

            R.drawable.grid_view_10,R.drawable.grid_view_11,R.drawable.grid_view_12,

            R.drawable.grid_view_13,R.drawable.grid_view_14,R.drawable.grid_view_15};

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.grid_view);

        grid_view = (GridView)findViewById(R.id.grid_view);

        grid_view.setAdapter(new ImageAdapter(this));

        grid_view.setOnItemClickListener(this);

    }

    @Override

    public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {

        Toast.makeText(this,"你选中图片序号:"+Integer.toString(position),Toast.LENGTH_SHORT).show();

    }

    class ImageAdapter extends BaseAdapter{

        Context mContext;

        public ImageAdapter(Context c){

            mContext = c;

        }

        @Override

        public int getCount() {

            return mThumbIds.length;

        }

        @Override

        public Object getItem(int i) {

            return null;

        }

        @Override

        public long getItemId(int i) {

            return 0;

        }

        @Override

        public View getView(int position, View view, ViewGroup viewGroup) {

            ImageView imageView;

            if(view==null) {

                imageView = new ImageView(mContext);

                imageView.setLayoutParams(new GridView.LayoutParams(385, 385));

                imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);

                //imageView.setPadding(8, 8, 8, 8);  

                imageView.setImageResource(mThumbIds[position]);

            }else{

                imageView=(ImageView)view;

            }

            return imageView;

        }

    }

}

打开项目配置文件AndroidManifest.xml，确保工程要启动的Activity类名为 GridViewActivity。