Android 下载图片并显示在ImageViewzu

 

MainActivity.java
package com.example.test4_downloadimage;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;

public class MainActivity extends AppCompatActivity {
    private EditText editText;
    private Button button;
    private ImageView imageView;

    private Bitmap bitmap;
    myHandle myhandle = new myHandle();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        editText = (EditText) findViewById(R.id.imagePath);
        button = (Button) findViewById(R.id.upload);
        imageView = (ImageView) findViewById(R.id.imageView);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Upload upload = new Upload();
                upload.start();
            }
        });
    }

    /*在主线程中更新UI的Handler*/
    private class myHandle extends Handler {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            if (msg.what == 111) {
                imageView.setImageBitmap(bitmap);
            }
        }
    }

    private class Upload extends Thread {
        @Override
        public void run() {
            super.run();
            //图片地址
            String iPath = editText.getText().toString();
            try {
                //对资源链接
                URL url = new URL(iPath);
                //打开输入流
                InputStream inputStream = url.openStream();
                //对网上资源进行下载并转换为位图图片
                bitmap = BitmapFactory.decodeStream(inputStream);
                myhandle.sendEmptyMessage(111);
                inputStream.close();
                //再打开一次
                inputStream = url.openStream();
                File file = new File(Environment.getExternalStorageDirectory() + "/newImage.png");
                FileOutputStream fileOutputStream = new FileOutputStream(file);
                int hasRead = 0;
                while ((hasRead = inputStream.read()) != -1) {
                    fileOutputStream.write(hasRead);
                }
                fileOutputStream.close();
                inputStream.close();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.test4_downloadimage">

    <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>

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

Avtivity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/imagePath"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="http://img4.imgtn.bdimg.com/it/u=2146046871,2611785107&amp;fm=26&amp;gp=0.jpg" />

    <Button
        android:id="@+id/upload"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Upload" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="300dp"
        android:background="#11d6ae" />
</LinearLayout>