自定义SmartImageView实现（案例）

需求： 模仿smartImageView自己封装功能类似的 MySmartImageView.

步骤

• 定义一个 MySmartImageView 类，并继承 ImageView
• 在该类中实现 想要实现的功能，例如 setImageUrl

具体代码

• MySmartImageView.java

package com.example.www.mysmartimageview;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class MySmartImageView extends android.support.v7.widget.AppCompatImageView {

    private Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            Bitmap bitmap = (Bitmap)msg.obj;
            MySmartImageView.this.setImageBitmap(bitmap);
        }
    };

    public MySmartImageView(Context context) {
        super(context);
    }

    public MySmartImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public MySmartImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    //设置显示图片的方法
    public void setImageUrl(final String path) {
        new Thread() {
            @Override
            public void run() {
                try {
                    URL url = new URL(path);
                    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                    conn.setRequestMethod("GET");
                    conn.setConnectTimeout(5000);
                    int responseCode = conn.getResponseCode();
                    if (responseCode == 200) {
                        InputStream is = conn.getInputStream();
                        Bitmap bitmap = BitmapFactory.decodeStream(is);
                        Message msg = Message.obtain();
                        msg.obj = bitmap;
                        mHandler.sendMessage(msg);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }.start();

    }

}

使用示例

• activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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=".MainActivity">

    <com.example.www.mysmartimageview.MySmartImageView
        android:id="@+id/mysmartview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</android.support.constraint.ConstraintLayout>

• MainActivity.java

package com.example.www.mysmartimageview;

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

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        MySmartImageView mySmartImageView = (MySmartImageView) findViewById(R.id.mysmartview);
        mySmartImageView.setImageUrl("http://192.168.80.85:8080/img/1.png");
    }
}

• 配置权限 AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.www.mysmartimageview">

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

效果展示：