将从LeanCloud下载的图片文件用ImageView显示

1.相关方法

1.1 选择图片

	 private void startChooser() {
        // 启动图片选择器
        imagePicker.startChooser(this, new ImagePicker.Callback() {
            // 选择图片回调
            @Override public void onPickImage(Uri imageUri) {

            }

            // 裁剪图片回调
            @Override public void onCropImage(Uri imageUri) {

                String uri = imageUri.toString();
                Log.d("Uri", imageUri.toString());
                Uri u2 = Uri.parse(uri);


                //  draweeView.setImageURI(imageUri);
                draweeView.setImageURI(u2);
                draweeView.getHierarchy().setRoundingParams(RoundingParams.asCircle());


//                图片上传
                upload(imageUri);
            }

            // 自定义裁剪配置
            @Override public void cropConfig(CropImage.ActivityBuilder builder) {
                builder
                        // 是否启动多点触摸
                        .setMultiTouchEnabled(false)
                        // 设置网格显示模式
                        .setGuidelines(CropImageView.Guidelines.OFF)
                        // 圆形/矩形
                        .setCropShape(CropImageView.CropShape.RECTANGLE)
                        // 调整裁剪后的图片最终大小
                        .setRequestedSize(960, 540)
                        // 宽高比
                        .setAspectRatio(16, 9);
            }

            // 用户拒绝授权回调
            @Override public void onPermissionDenied(int requestCode, String[] permissions,
                                                     int[] grantResults) {
            }
        });
    }

1.1 上传图片

/**
     * 图片上传
     */
    private void upload(@NotNull Uri uri){
        String path = URI.create(uri.toString()).getPath();

        try {
            AVFile file = AVFile.withAbsoluteLocalPath("avatar.jpg", path);
            file.saveInBackground().subscribe(new Observer<AVFile>() {
                @Override
                public void onSubscribe(Disposable d) {
                }

                @Override
                public void onNext(AVFile avFile) {
                    Log.d("avFile and objectId：", avFile.getObjectId());
                    AVUser user = AVUser.getCurrentUser();
                    user.put("headImage", avFile);
                    user.save();

                }

                @Override
                public void onError(Throwable e) {

                }

                @Override
                public void onComplete() {

                }
            });
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }


    }

1.2 将字节数组转换成ImageView可调用的Bitmap对象

 /**
     * 将字节数组转换成ImageView可调用的Bitmap对象
     * @param bytes 字节数组
     * @param opts 设置你换成bitmap的属性（大小 宽 高 编码格式 预览 等），为了防止图片过大可以只获取预览
     * @return
     */
public Bitmap getPicFromBytes(byte[] bytes, BitmapFactory.Options opts) {
        if (bytes != null)
            if (opts != null)
                return BitmapFactory.decodeByteArray(bytes, 0, bytes.length,
                        opts);
            else
                return BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
        return null;
    }

1.3 图片缩放

public Bitmap zoomBitmap(Bitmap bitmap, int w, int h){
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        Matrix matrix = new Matrix();
        float scaleWidth = ((float) w / width);
        float scaleHeight = ((float) h / height);
        matrix.postScale(scaleWidth, scaleHeight);
        Bitmap newBmp = Bitmap.createBitmap(bitmap, 0, 0, width, height,
                matrix, true);
        return newBmp;
    }

2.onCreate()方法中活动中各组件初始化和该活动实现的方法

 	private ImagePicker imagePicker = new ImagePicker();
    private SimpleDraweeView draweeView;

    private Button button;

    private ImageView imageView;

  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_file);
		  // 设置标题
        imagePicker.setTitle("设置头像");
        // 设置是否裁剪图片
        imagePicker.setCropImage(true);

        draweeView = findViewById(R.id.draweeView);
        imageView = findViewById(R.id.image);
//    测试Uri
        String uri = "file:///data/data/com.example.imagepickerapply/cache/cropped994058138.jpg";
        File file = new File(URI.create(uri).getPath());

        if (file.exists()){
//      判断图片是否还存在, 存在的话将头像进行设置
            Log.d("urifile", "存在");
            Uri u2 = Uri.parse(uri);
            draweeView.setImageURI(u2);
            draweeView.getHierarchy().setRoundingParams(RoundingParams.asCircle());
        }else{
            Log.d("urifile", "不存在");
        }

        draweeView.setOnClickListener(this);

        button = findViewById(R.id.button_leancloud);
        button.setOnClickListener(this);
    }

  @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        imagePicker.onActivityResult(this, requestCode, resultCode, data);
    }

    @Override public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                                     @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        imagePicker.onRequestPermissionsResult(this, requestCode, permissions, grantResults);
    }

3.点击事件(从LeanCloud下载图片文件并显示)

 @Override public void onClick(View v) {
   			if (v.getId() == R.id.draweeView) {
            		startChooser();
       		 }else if (v.getId() == R.id.button_leancloud){
       
//            下载图片文件 将字节数组转换成Bitmap对象
            AVUser user = AVUser.getCurrentUser();
            AVFile file = user.getAVFile("headImage");
            file.getDataInBackground().subscribe(new Observer<byte[]>() {
                @Override
                public void onSubscribe(Disposable d) {

                }

                @Override
                public void onNext(byte[] bytes) {
               
					 BitmapFactory.Options opts = new BitmapFactory.Options();
	                 opts.inSampleSize = 2;
	                 //	将opts传入, 获取的bitmap　就是原图的1/4大小
	                 Bitmap bitmap = getPicFromBytes(bytes, opts);

                    Bitmap bitmap = getPicFromBytes(bytes,null);
                	imageView.setImageBitmap(bitmap);
                	draweeView.setImageBitmap(bitmap);
                    draweeView.getHierarchy().setRoundingParams(RoundingParams.asCircle());
                }

                @Override
                public void onError(Throwable e) {

                }

                @Override
                public void onComplete() {

                }
            });

        }
    }

4. 布局文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:fresco="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".FileActivity"
    >

    <com.facebook.drawee.view.SimpleDraweeView
        android:id="@+id/draweeView"
        android:layout_width="130dp"
        android:layout_height="130dp"
        android:layout_centerInParent="true"
        fresco:placeholderImage="@mipmap/click" />

    <Button
        android:id="@+id/button_leancloud"
        android:layout_marginTop="20dp"
        android:layout_below="@+id/draweeView"
        android:layout_alignLeft="@+id/draweeView"
        android:text="button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <ImageView
        android:id="@+id/image"
        android:layout_width="400px"
        android:layout_height="400px"
        android:layout_below="@+id/button_leancloud"
        android:background="@drawable/ic_launcher_background"/>

</RelativeLayout>

5. 运行结果

事件点击前:

事件点击后:

参考文章: https://blog.csdn.net/itheima6/article/details/7516631?utm_medium=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.nonecase&depth_1-utm_source=distribute.pc_relevant_t0.none-task-blog-BlogCommendFromMachineLearnPai2-1.nonecase

本文地址：https://blog.csdn.net/weixin_44086832/article/details/107434509