Android Studio [ImageView/使用第三方库加载图片]

ImageViewActivity.class

package com.xdw.a122;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;

import com.bumptech.glide.Glide;


public class ImageViewActivity extends AppCompatActivity {
    private ImageView mIv4;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_imageview);
        mIv4=findViewById(R.id.iv_2);
        Glide.with(this).load("https://www.baidu.com/img/bd_logo1.png?where=super").into(mIv4);

    }
}

activity_imageview.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ImageViewActivity"
    android:padding="15dp">

    <ImageView
        android:id="@+id/iv_1"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:src="@drawable/back_1"
        android:scaleType="fitCenter"/>
    <ImageView
        android:id="@+id/iv_2"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:scaleType="fitCenter"
        android:background="#000000"
        android:layout_below="@id/iv_1"
        android:layout_marginTop="20dp"/>
</RelativeLayout>

并在build.gradle中添加

repositories {
    mavenCentral()
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
implementation 'com.github.bumptech.glide:glide:4.9.0'
annotationProcessor 'com.github.bumptech.glide:compiler:4.9.0'
}

在AndroidManifest.xml中的<application/>中添加网络权限

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

我学习的：

//导入网络图片

mIv4=findViewById(R.id.iv_2);
Glide.with(this).load("https://www.baidu.com/img/bd_logo1.png?where=super").into(mIv4);

//ImageView块
scaleType=  填充方式
fitCenter   按比例填充直到填满
fitXY       直接填充可能拉伸图片
center crop 按比例填充满，多余切割不显示

<ImageView
　　android:id="@+id/iv_2"
　　android:layout_width="match_parent"
　　android:layout_height="200dp"
　　android:scaleType="fitCenter"
　　android:background="#000000"
　　android:layout_below="@id/iv_1"
　　android:layout_marginTop="20dp"/>