安卓开发中,对于图片的处理是非常常见的,这里简单介绍gridview加载图片时所使用的的一些技巧。
一、众所周知,加载图片时会消耗很大的内存空间,这里我们使用谷歌推荐的一个库,用于处理图片的加载(官方说明:Glide是一个非常成熟的图片加载库,他可以从多个源加载图片,如:网路,本地,Uri等,更重要的是他内部封装了非常好的缓存机制并且在处理图片的时候能保持一个低的内存消耗。),此外,glide依赖 v4 包;
compile 'com.github.bumptech.glide:glide:3.7.0'
compile 'com.android.support:support-v4:25.1.0'
二、下面介绍GridView的具体使用,首先在布局文件中引入该组件
<?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"
android:background="#000"
>
<GridView
android:id="@+id/grid"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:numColumns="auto_fit"
android:columnWidth="80dp"
android:stretchMode="columnWidth"
></GridView>
</LinearLayout>
GridView属性的含义:
android:numColumns="auto_fit" --------列数设置为自动
android:columnWidth="90dp",----------每列的宽度,也就是Item的宽度
android:stretchMode="columnWidth"------缩放与列宽大小同步
android:verticalSpacing="10dp"----------垂直边距
android:horizontalSpacing="10dp"-------水平边距
三、在activity中
public class MainActivity extends Activity {
private GridView gridView;
private String baseUrl = Environment.getExternalStorageDirectory() + "/下户宝/nextDoorFile/";
private List<String> urls = new ArrayList<>();
private ImageAdapter imageAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
gridView = (GridView) findViewById(R.id.grid);
initData();
}
private void initData() {
getAllFiles(baseUrl);
System.out.println("urls:"+urls.size());
imageAdapter = new ImageAdapter(this,urls);
gridView.setAdapter(imageAdapter);
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Intent intent = new Intent(MainActivity.this,ImageActivity.class);
intent.putExtra("URL",urls.get(i));
startActivity(intent);
}
});
}
private void getAllFiles(String path) {
File file = new File(path);
File files[] = file.listFiles();
if (files!=null){
for(int i = 0;i<files.length;i++){
if (files[i].isDirectory()){
String path1 = files[i].getPath()+"/";
getAllFiles(path1);
}else{
String name[] = files[i].getName().split("\\.");
if (name.length == 2 && (name[1].equals("jpg")||name[1].equals("png"))) {
urls.add(files[i].getPath());
System.out.println("urls1:"+urls.size());
}
}
}
}
}
}
ImageAdapter的代码如下
/** * Created by leven on 2017/3/27. */
public class ImageAdapter extends BaseAdapter {
private Context context;
private List<String> urls = new ArrayList<>();
public ImageAdapter(Context context,List<String> urls) {
this.context = context;
this.urls = urls;
}
public void setUrls(List<String> urls) {
this.urls = urls;
}
@Override
public int getCount() {
return urls.size();
}
@Override
public String getItem(int i) {
return urls.get(i);
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
ViewHolder vh = null;
if(view == null){
view = LayoutInflater.from(context).inflate(R.layout.item_image,null);
vh = new ViewHolder();
vh.imageView = (ImageView) view.findViewById(R.id.image);
vh.checkBox = (CheckBox) view.findViewById(R.id.checkbox);
view.setTag(vh);
}
vh = (ViewHolder) view.getTag();
if(urls!=null && urls.size()>0){
Glide.with(context).load("file://"+urls.get(i)).centerCrop().into(vh.imageView);
}
return view;
}
class ViewHolder{
ImageView imageView;
CheckBox checkBox;
}
}
四、点击每一项进入图片的预览页面,在此引入一个组件,用于图片的显示
compile 'com.commit451:PhotoView:1.2.4'
布局文件如下
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_image" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.leven2.imagegridviewtest.ImageActivity">
<uk.co.senab.photoview.PhotoView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/photoView"/>
</RelativeLayout>
在activity中代码如下
photoView = (PhotoView) findViewById(R.id.photoView);
String url = getIntent().getStringExtra("URL");
photoView.setScaleType(ImageView.ScaleType.FIT_START);
photoView.setImageURI(Uri.parse(url));
文章评论