GridView 网格布局使用（可用于图片展示 上）

第一步：引用GridView控件

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

android:columnWidth：指定每列宽度

android:horizontalSpacing="10dp"：水平方向的间距（列间距）

android:verticalSpacing="10dp"：垂直方向的间距（行间距）

android:numColumns="auto_fit"：指定每行有多少列，auto_fit表示根据屏幕自适应，也可以指定具体指，1、2.....

android:stretchMode：剩余空间拉伸模式，有四种选择none、columnWidth、spacingWidth、spacingWidthUniform

                                     none：不拉伸

                                     columnWidth：若有剩余空间，则拉伸列框挤掉空隙

                                     spacingWidth：若有剩余控件，则列宽不变，把空间分配到每列间的空隙

                                     spacingWidthUniform：若有剩余控件，则列宽不变，把空间分配到每列左右的空隙

第二步：读取内置SD卡图片文件夹内容

创建工具类FileUtil ，用来读取照片名称

import java.io.File;
public class FileUtil {
    public static String[] getImageNames(String folderPath) {
        File file01 = new File(folderPath);

        String[] files01 = file01.list();

        int imageFileNums = 0;
        for (int i = 0; i < files01.length; i++) {
            File file02 = new File(folderPath + "/" + files01[i]);

            if (!file02.isDirectory()) {

                if (isImageFile(file02.getName())) {

                    imageFileNums++;
                }
            }
        }

        String[] files02 = new String[imageFileNums];

        int j = 0;
        for (int i = 0; i < files01.length; i++) {
            File file02 = new File(folderPath + "/" + files01[i]);

            if (!file02.isDirectory()) {

                if (isImageFile(file02.getName())) {
                    files02[j] = file02.getName();
                    j++;
                }
            }
        }
        return files02;
    }

    private static boolean isImageFile(String fileName) {
        String fileEnd = fileName.substring(fileName.lastIndexOf(".") + 1,
                fileName.length());
        if (fileEnd.equalsIgnoreCase("jpg")) {
            return true;
        } else if (fileEnd.equalsIgnoreCase("png")) {
            return true;
        } else if (fileEnd.equalsIgnoreCase("bmp")) {
            return true;
        } else {
            return false;
        }
    }

}

//返回SD路径
public class ConfigConstant {
    public static String getSdDir(){
        // 判断是否有内置SD卡
        String sdDir = null;
        boolean isSDcardExist = Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
        if (isSDcardExist) {
            sdDir = Environment.getExternalStorageDirectory().getAbsolutePath();
        } else {
            sdDir = Environment.getRootDirectory().getAbsolutePath();
        }
        return sdDir + "/" ;
    }
}

Activity调用

/**
 * 无人机图片展示页面
 */
public class WuRenJiActivity extends BaseActivity {
    @BindView(R.id.go_back)
    LinearLayout goBack;//返回按钮
    @BindView(R.id.toolbar_title)
    TextView title;//标题设置
    @BindView(R.id.grid_view)
    GridView gridView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_vehicle);
        ButterKnife.bind(this);
        title.setText("图片展示");

        initView();
    }

    public void initView() {
        String dir = ConfigConstant.getSdDir() + "dc/photo/";//照片所放的路径
        String[] titles = FileUtil.getImageNames(dir);
        String[] imagePaths = new String[titles.length];
        for (int i = 0; i < titles.length; i++) {
            imagePaths[i] = dir + titles[i];
        }

        gridView.setAdapter(new PictureAdapter(titles,imagePaths,this));
        gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Log.e("你点击了", "onItemClick: " + position);
            }
        });
    }

    @OnClick(R.id.go_back)
    public void onClik(View v) {
        finish();
    }
}

适配器中图片展示代码调用

//把路径转换为bitmap显示
viewHolder.image.setImageBitmap(BitmapFactory.decodeFile(pictures.get(position).getImages()));

item_photo布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/root"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="5dp"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/image"
        android:layout_width="100dp"
        android:layout_height="150dp"
        android:layout_gravity="center"
        android:padding="4dp"
        android:scaleType="fitXY" />

    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center_horizontal" />
</LinearLayout>