Android加载网络图片并保存到系统相册

加载网络图片并点击保存图片到系统相册
1.首先在清单文件上加入相关权限

     <uses-permission android:name="android.permission.INTERNET" />        <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2.定义一个ImageUtils工具类

import android.content.Context;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.net.Uri;import android.os.Environment;import android.provider.MediaStore;import android.util.Log;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;public class ImageUtils {    private static File mPhotoFile = null;    public static void setPhotoFile(File photoFile){        mPhotoFile = photoFile;    }    public static File getPhotoFile(){        return mPhotoFile;    }    /**     * 保存图片到图库     * @param bmp     */    public static void saveImageToGallery(Bitmap bmp, String bitName ) {        // 首先保存图片        File appDir = new File(Environment.getExternalStorageDirectory(),                "picture");        if (!appDir.exists()) {            appDir.mkdir();        }        String fileName = bitName + ".png";        File file = new File(appDir, fileName);        Log.v("Photo",fileName);        try {            FileOutputStream fos = new FileOutputStream(file);            bmp.compress(Bitmap.CompressFormat.PNG, 100, fos);            fos.flush();            fos.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        setPhotoFile(file);    }    /**     * @param bmp 获取的bitmap数据     * @param picName 自定义的图片名     */    public static void saveBmp2Gallery(Context context, Bitmap bmp, String picName) {        saveImageToGallery(bmp,picName);        String fileName = null;        //系统相册目录        String galleryPath = Environment.getExternalStorageDirectory()                + File.separator + Environment.DIRECTORY_DCIM                + File.separator + "Camera" + File.separator;        // 声明文件对象        File file = null;        // 声明输出流        FileOutputStream outStream = null;        try {            // 如果有目标文件，直接获得文件对象，否则创建一个以filename为名称的文件            file = new File(galleryPath, picName + ".png");            // 获得文件相对路径            fileName = file.toString();            // 获得输出流，如果文件中有内容，追加内容            outStream = new FileOutputStream(fileName);            if (outStream!=null) {                bmp.compress(Bitmap.CompressFormat.PNG, 90, outStream);            }        }catch (Exception e) {            e.getStackTrace();        } finally {            try {                if (outStream != null) {                //关闭输出流                    outStream.close();                }            } catch (IOException e) {                e.printStackTrace();            }        }//添加图片到系统相册并更新通知        MediaStore.Images.Media.insertImage(context.getContentResolver(),bmp,fileName,null);        Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);        Uri uri = Uri.fromFile(file);        intent.setData(uri);        context.sendBroadcast(intent);    }    /**     * 将URL转化成bitmap形式     * @param url     * @return bitmap type     */    public final static Bitmap returnBitMap(String url) {        URL myFileUrl;        Bitmap bitmap = null;        try {            myFileUrl = new URL(url);            HttpURLConnection conn;            conn = (HttpURLConnection) myFileUrl.openConnection();            conn.setDoInput(true);            conn.connect();            InputStream is = conn.getInputStream();            bitmap = BitmapFactory.decodeStream(is);        } catch (MalformedURLException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        return bitmap;    }}

Notes:这里Bitmap.compress(Bitmap.CompressFormat.PNG, 90, outStream);解压缩是PNG格式的图片
推荐阅读：BitmapFactory.decodeResource为null的处理方法之一

3.使用Glide加载图片

3.1添加依赖

//glide加载图片implementation 'com.github.bumptech.glide:glide:4.6.1'annotationProcessor 'com.github.bumptech.glide:compiler:4.6.1'

3.2加载图片

   String imgUrl;//设置全局变量   imgURl=mData.get(0).url;//通过下标获得第一张图片       GlideApp.with(BaseApplication.getContext()).load(imgURl).apply(options).into(mImage);

4.开启子线程获取网络图片，更新UI

//保存图片必须在子线程中操作，是耗时操作                new Thread(new Runnable() {                    @Override                    public void run() {                        Bitmap bp = ImageUtils.returnBitMap(imgURl);                        if (EmptyUtils.isNotEmpty(bp))                        ImageUtils.saveBmp2Gallery(BaseApplication.getContext(), bp, "picName");                    }                }).start();

Notes:保存图片之前先一层判断，判断Bitmap对象是否为空，否则程序容易出现空指针异常错误。一旦出现空指针异常的错误，一定要去找哪一个引用没有指向实际存在的对象，导致为null

Attempt to invoke virtual method 'boolean android.graphics.Bitmap.compress(android.graphics.Bitmap$CompressFormat, int, java.io.OutputStream)' on a null object reference

5.用到的EmptyUtils工具类

import android.os.Build;import android.util.SparseArray;import android.util.SparseBooleanArray;import android.util.SparseIntArray;import android.util.SparseLongArray;import java.lang.reflect.Array;import java.util.Collection;import java.util.Map;public final class EmptyUtils {    private EmptyUtils() {        throw new UnsupportedOperationException("u can't instantiate me...");    }    /**     * 判断对象是否为空     *     * @param obj 对象     * @return {@code true}: 为空
{@code false}: 不为空     */    public static boolean isEmpty(Object obj) {        if (obj == null) {            return true;        }        if (obj instanceof String && obj.toString().length() == 0) {            return true;        }        if (obj.getClass().isArray() && Array.getLength(obj) == 0) {            return true;        }        if (obj instanceof Collection && ((Collection) obj).isEmpty()) {            return true;        }        if (obj instanceof Map && ((Map) obj).isEmpty()) {            return true;        }        if (obj instanceof SparseArray && ((SparseArray) obj).size() == 0) {            return true;        }        if (obj instanceof SparseBooleanArray && ((SparseBooleanArray) obj).size() == 0) {            return true;        }        if (obj instanceof SparseIntArray && ((SparseIntArray) obj).size() == 0) {            return true;        }        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {            if (obj instanceof SparseLongArray && ((SparseLongArray) obj).size() == 0) {                return true;            }        }        return false;    }    /**     * 判断对象是否非空     *     * @param obj 对象     * @return {@code true}: 非空
{@code false}: 空     */    public static boolean isNotEmpty(Object obj) {        return !isEmpty(obj);    }}

感谢查看！

更多相关文章

随机推荐