android查看网络图片（案例）

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需求描述： 输入一个 图片地址，下载到本地 展示

效果展示

代码清单

• MainActivity.java

package com.example.www.checkimage;

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

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

public class MainActivity extends AppCompatActivity {

    private EditText mPt_url;
    private ImageView mIv_show;
    private Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            if(msg.what == 1){
                Bitmap bitmap = (Bitmap) msg.obj;
                mIv_show.setImageBitmap(bitmap);
                Toast.makeText(getApplicationContext(), "图片展示成功", Toast.LENGTH_LONG).show();
            }
        }
    };

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

        mPt_url = (EditText) findViewById(R.id.pt_url);
        mIv_show = (ImageView) findViewById(R.id.imageCon);
    }

    public void checkImage(View v) {
        new Thread(){
            @Override
            public void run() {

                try {
                    String path = mPt_url.getText().toString().trim();
                    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(); // 创建 消息
                        msg.obj = bitmap;
                        msg.what = 1;


                        mHandler.sendMessage(msg);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }

            }
        }.start();
    }
}

• activiity_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">

    <EditText
        android:id="@+id/pt_url"
        android:layout_width="368dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:ems="10"
        android:hint="请输入与图片地址"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:text="Button"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        android:onClick="checkImage"
        app:layout_constraintTop_toBottomOf="@+id/pt_url" />

    <ImageView
        android:id="@+id/imageCon"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button"
        app:srcCompat="@mipmap/ic_launcher" />
</android.support.constraint.ConstraintLayout>

• AndroidManifest.xml

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

    <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>