GridView实现图片加载

原CSDN博客已弃用，文章会逐渐迁移过来。

一、简单写法

activity_example.xml

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="vertical">  

    <GridView  
        android:id="@+id/gridview"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:columnWidth="90dp"  
        android:numColumns="auto_fit"  
        android:verticalSpacing="10dp"  
        android:horizontalSpacing="10dp"  
        android:stretchMode="columnWidth"  
        android:gravity="center"  
        ></GridView>  

</LinearLayout>  

ExampleActivity.java

package com.administrator.gridviewdemo;  


import android.app.Activity;  
import android.os.Bundle;  
import android.widget.ArrayAdapter;  
import android.widget.GridView;  

import java.util.ArrayList;  
import java.util.List;  

/** 
 * GridView展示文字 
 */  

public class ExampleActivity extends Activity {  

    private GridView gridView;  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_example);  
        gridView= (GridView) findViewById(R.id.gridview);  
        List<String> strList=new ArrayList<String>();  
        for(int i=0;i<9;i++)  
        {  
            strList.add("haha"+i);  
        }  
        //最简单的适配器，数组适配器  
        ArrayAdapter<String>arrayAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_expandable_list_item_1,strList);  
        gridView.setAdapter(arrayAdapter);  
    }  
}  

二、用GridView展示已安装的应用

(一)、首先需要GridView展示的单条条目布局：

item_grid_view.xml

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent">  

    <ImageView  
        android:id="@+id/img_appIcon"  
        android:layout_width="50dp"  
        android:layout_height="50dp"  
        android:scaleType="centerCrop"/>  
    <TextView  
        android:id="@+id/tv_appName"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_marginLeft="5dp"  
        android:text="测试"  
        android:layout_marginTop="5dp"/>  
</LinearLayout>  

(二)、然后需要把在主要引用的页面中，创建GridView用于加载条目的布局位置

activity_example2.xml

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical" android:layout_width="match_parent"  
    android:layout_height="match_parent">  

    <GridView  
        android:id="@+id/gridview"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:columnWidth="90dp"  
        android:numColumns="3"  
        android:verticalSpacing="10dp"  
        android:horizontalSpacing="10dp"  
        android:stretchMode="columnWidth"  
        android:gravity="center"  
        />  

</LinearLayout>  

(三)、需要为GridView增加用于接收数据的实体类

AppInfo.class

package com.administrator.gridviewdemo;  

import android.graphics.drawable.Drawable;  

/** 
 * Created by Administrator on 2018/5/11. 
 */  

public class AppInfo {  
    /** 
     * 应用名称 
     */  
    private String appName;  
    /** 
     * 应用包名 
     */  
    private String pacjageName;  
    /** 
     * 版本名称 
     */  
    private String versionName;  
    /** 
     * 版本号 
     */  
    private int versionCode;  
    /** 
     * 应用图标 
     */  
    private Drawable appIcon;  

    public String getAppName() {  
        return appName;  
    }  

    public void setAppName(String appName) {  
        this.appName = appName;  
    }  

    public String getPacjageName() {  
        return pacjageName;  
    }  

    public void setPacjageName(String pacjageName) {  
        this.pacjageName = pacjageName;  
    }  

    public String getVersionName() {  
        return versionName;  
    }  

    public void setVersionName(String versionName) {  
        this.versionName = versionName;  
    }  

    public int getVersionCode() {  
        return versionCode;  
    }  

    public void setVersionCode(int versionCode) {  
        this.versionCode = versionCode;  
    }  

    public Drawable getAppIcon() {  
        return appIcon;  
    }  

    public void setAppIcon(Drawable appIcon) {  
        this.appIcon = appIcon;  
    }  
}  

(四)、设置GridView的适配器

GridViewAdapter.java

package com.administrator.gridviewdemo;  

import android.content.Context;  
import android.view.View;  
import android.view.ViewGroup;  
import android.widget.BaseAdapter;  
import android.widget.ImageView;  
import android.widget.TextView;  

import java.util.List;  

/** 
 * Created by Administrator on 2018/5/11. 
 */  

public class GridViewAdapter extends BaseAdapter {  

    private Context context;  
    private List<AppInfo>appInfoList;  
    public GridViewAdapter(Context context, List<AppInfo> appInfoList)  
    {  
        this.appInfoList=appInfoList;  
        this.context=context;  
    }  

    @Override  
    public int getCount() {  
        return appInfoList.size();  
    }  

    @Override  
    public Object getItem(int position) {  
        return appInfoList.get(position);  
    }  

    @Override  
    public long getItemId(int position) {  
        return position;  
    }  

    @Override  
    public View getView(int position, View convertView, ViewGroup parent) {  

        ViewHolder holder;  
        if(convertView==null)  
        {  
            convertView=View.inflate(context, R.layout.item_grid_view,null);  
            holder=new ViewHolder();  
            holder.img_appIcon= (ImageView) convertView.findViewById(R.id.img_appIcon);  
            holder.tv_appName= (TextView) convertView.findViewById(R.id.tv_appName);  
            convertView.setTag(holder);  
        } else {  
            holder= (ViewHolder) convertView.getTag();  
        }  

        AppInfo appInfo=appInfoList.get(position);  
        holder.img_appIcon.setImageDrawable(appInfo.getAppIcon());  
        holder.tv_appName.setText(appInfo.getAppName()+" "+appInfo.getVersionName());  

        return convertView;  
    }  

    public class ViewHolder  
    {  
        ImageView img_appIcon;  
        TextView tv_appName;  
    }  
}  

(五)、创建的函数中调用

ExampleActivity2.java

package com.administrator.gridviewdemo;  

import android.content.pm.PackageInfo;  
import android.content.pm.PackageManager;  
import android.support.v7.app.AppCompatActivity;  
import android.os.Bundle;  
import android.widget.GridView;  

import java.util.ArrayList;  
import java.util.List;  

/** 
 * 获取应用列表展示 
 */  
public class ExampleActivity2 extends AppCompatActivity {  

    private GridView gridView;  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_example2);  
        gridView = (GridView)findViewById(R.id.gridview);  
        GridViewAdapter gridViewAdapter = new GridViewAdapter(this,getAppList());  
        gridView.setAdapter(gridViewAdapter);  
    }  
    public List<AppInfo> getAppList() {  
        List<AppInfo> appInfoList = new ArrayList<AppInfo>();  
        PackageManager packageManager = getPackageManager();  
        List<PackageInfo> installedPackages = packageManager.getInstalledPackages(0);  
        for (int i = 0; i < installedPackages.size(); i++) {  
            PackageInfo packageInfo = installedPackages.get(i);  
            AppInfo appInfo = new AppInfo();  
            appInfo.setAppName(packageInfo.applicationInfo.loadLabel(packageManager).toString());  
            appInfo.setAppIcon(packageInfo.applicationInfo.loadIcon(packageManager));  
            appInfo.setPacjageName(packageInfo.packageName);  
            appInfo.setVersionCode(packageInfo.versionCode);  
            appInfo.setVersionName(packageInfo.versionName);  

//            if ((packageInfo.applicationInfo.flags& ApplicationInfo.FLAG_SYSTEM)==0) {//过滤系统应用的判断  
            appInfoList.add(appInfo);  
//            }  
        }  
        return appInfoList;  
    }  
}  

三、用GridView加载网络图片

(一)、添加依赖

build.gradle

dependencies {  
    compile 'com.github.bumptech.glide:glide:3.7.0'  
}  

点击右上角Sync Now

(二)、首先需要GridView展示的单条条目布局：

item_grid_view.xml

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent">  

    <ImageView  
        android:id="@+id/img_appIcon"  
        android:layout_width="50dp"  
        android:layout_height="50dp"  
        android:scaleType="centerCrop"/>  
    <TextView  
        android:id="@+id/tv_appName"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:layout_marginLeft="5dp"  
        android:text="测试"  
        android:layout_marginTop="5dp"/>  
</LinearLayout>  

(三)、然后需要把在主要引用的页面中，创建GridView用于加载条目的布局位置

activity_example.xml

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical" android:layout_width="match_parent"  
    android:layout_height="match_parent">  

    <GridView  
        android:id="@+id/gridview"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:columnWidth="90dp"  
        android:numColumns="3"  
        android:verticalSpacing="10dp"  
        android:horizontalSpacing="10dp"  
        android:stretchMode="columnWidth"  
        android:gravity="center"  
        />  


</LinearLayout>  

(四)、需要为GridView增加用于接收数据的实体类

ImageInfo.java

package com.administrator.gridviewdemo;  

import android.graphics.Bitmap;  

/** 
 * Created by Administrator on 2018/5/11. 
 */  

public class ImageInfo {  
    private String imagePath;  
    private Bitmap bitmap;  
    private String text;  

    public String getText() {  
        return text;  
    }  

    public void setText(String text) {  
        this.text = text;  
    }  

    public String getImagePath() {  
        return imagePath;  
    }  

    public void setImagePath(String imagePath) {  
        this.imagePath = imagePath;  
    }  

    public Bitmap getBitmap() {  
        return bitmap;  
    }  

    public void setBitmap(Bitmap bitmap) {  
        this.bitmap = bitmap;  
    }  
}  

(五)、设置GridView的适配器

GridViewAdapter.java

package com.administrator.gridviewdemo;  

import android.content.Context;  
import android.view.View;  
import android.view.ViewGroup;  
import android.widget.BaseAdapter;  
import android.widget.ImageView;  
import android.widget.TextView;  

import com.bumptech.glide.Glide;  

import java.util.List;  

/** 
 * Created by Administrator on 2018/5/11. 
 */  

public class GridViewAdapter extends BaseAdapter {  

    private Context context;  
    private List<ImageInfo>imageInfoList;  
    public GridViewAdapter(Context context, List<ImageInfo> appImageInfoList)  
    {  
        this.imageInfoList=appImageInfoList;  
        this.context=context;  
    }  

    @Override  
    public int getCount() {  
        return imageInfoList.size();  
    }  

    @Override  
    public Object getItem(int position) {  
        return imageInfoList.get(position);  
    }  

    @Override  
    public long getItemId(int position) {  
        return position;  
    }  

    @Override  
    public View getView(int position, View convertView, ViewGroup parent) {  

        ViewHolder holder;  
        if(convertView==null)  
        {  
            convertView=View.inflate(context, R.layout.item_grid_view,null);  
            holder=new ViewHolder();  
            holder.imageView= (ImageView) convertView.findViewById(R.id.img_appIcon);  
            holder.textView= (TextView) convertView.findViewById(R.id.tv_appName);  
            convertView.setTag(holder);  
        } else {  
            holder= (ViewHolder) convertView.getTag();  
        }  

        ImageInfo imageInfo=imageInfoList.get(position);  

        //placeholder()是图片的占位符，网络还没下载下来的时候占着位置  
        //centerCrop()缓存  
        Glide.with(context).load(imageInfo.getImagePath()).placeholder(R.mipmap.ic_launcher).centerCrop().into(holder.imageView);  

//        /**  
//         * 加载图片  
//         */  
//        if(imageInfo.getBitmap()==null){//如果网络还没下载好  
//            holder.imageView.setImageResource(R.mipmap.ic_launcher);  
//        }else {  
//            holder.imageView.setImageBitmap(imageInfo.getBitmap());  
//        }  
        holder.textView.setText(imageInfo.getText());  

        return convertView;  
    }  

    public class ViewHolder  
    {  
        ImageView imageView;  
        TextView textView;  
    }  
}  

(六)创建的函数中调用

ExampleActivity.java

package com.administrator.gridviewdemo;  

import android.content.Context;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.os.AsyncTask;  
import android.support.v7.app.AppCompatActivity;  
import android.os.Bundle;  
import android.widget.GridView;  

import java.io.IOException;  
import java.io.InputStream;  
import java.net.HttpURLConnection;  
import java.net.MalformedURLException;  
import java.net.URL;  
import java.util.ArrayList;  
import java.util.List;  

public class ExampleActivity extends AppCompatActivity {  

    private GridViewAdapter gridAdpter;  
    private GridView gridView;  
    private List<String> imgList;  
    private List<ImageInfo> imageInfoList;  
    private ImageLoadTask imageLoadTask;  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_example);  
        initUi();  
        initData();  
    }  

    private void initData() {  
        imgList=new ArrayList<String>();  
        imgList.add("http://img5.duitang.com/uploads/item/201406/26/20140626164837_dzKds.jpeg");  
        imgList.add("http://img2.imgtn.bdimg.com/it/u=3980629563,3881837630&fm=21&gp=0.jpg");  
        imgList.add("http://img5q.duitang.com/uploads/item/201505/08/20150508155052_XJaNW.jpeg");  
        imgList.add("http://img4.duitang.com/uploads/item/201407/02/20140702105736_FdN5P.jpeg");  
        imgList.add("http://img2.imgtn.bdimg.com/it/u=2866652161,3841912673&fm=21&gp=0.jpg");  
        imgList.add("http://img4.imgtn.bdimg.com/it/u=883757693,2063816225&fm=21&gp=0.jpg");  
        imgList.add("http://cdn.duitang.com/uploads/item/201309/26/20130926110955_QtUdX.jpeg");  
        imgList.add("http://zjimg.5054399.com/allimg/160815/14_160815161625_9.jpg");  
        imgList.add("http://i-7.vcimg.com/trim/09ce7067d2467c54cf05bbd271ee3ec8430415/trim.jpg");  

        imageInfoList = new ArrayList<ImageInfo>();  
        for(int i = 0;i<9;i++){  
            ImageInfo imageInfo = new ImageInfo();  
            imageInfo.setImagePath(imgList.get(i));  
            imageInfo.setText("图片"+);  
            imageInfoList.add(imageInfo);  
        }  
        gridAdpter = new GridViewAdapter(this,imageInfoList);  
        gridView.setAdapter(gridAdpter);  
//        imageLoadTask = new ImageLoadTask(this,gridAdpter);  
//        imageLoadTask.execute();//启动  
    }  

    private void initUi() {  
        gridView = (GridView)findViewById(R.id.gridview);  
    }  
    public Bitmap getImagefromNetWork(String path){  
        try {  
            URL url = new URL(path);i  
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();  
            urlConnection.setDoInput(true);  
            urlConnection.setConnectTimeout(10*1000);  
            urlConnection.connect();  
            InputStream inputStream = urlConnection.getInputStream();  

            Bitmap bitmap = BitmapFactory.decodeStream(inputStream);  
            inputStream.close();  
            return bitmap;  
        } catch (MalformedURLException e) {  
            e.printStackTrace();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
        return null;  
    }  
    public class ImageLoadTask extends AsyncTask<String,Void,Void>{  

        private GridViewAdapter gridViewAdapter;  
        public ImageLoadTask(Context context,GridViewAdapter gridViewAdapter){  
            this.gridViewAdapter=gridViewAdapter;  
        }  
        @Override  
        protected void onPreExecute() {  
            super.onPreExecute();  
        }  

        @Override  
        protected Void doInBackground(String... strings) {  
            for (int i = 0;i<gridViewAdapter.getCount();i++){  
                ImageInfo imageInfo = (ImageInfo) gridViewAdapter.getItem(i);  
                String imagePath = imageInfo.getImagePath();  
                Bitmap bitmap = getImagefromNetWork(imagePath);  
                imageInfo.setBitmap(bitmap);  
                publishProgress();  
            }  
            return null;  
        }  

        @Override  
        protected void onProgressUpdate(Void... values) {  
            super.onProgressUpdate(values);  
            gridViewAdapter.notifyDataSetChanged();  
        }  

    }  
}