android studio 讀取網絡圖片

activity_main

界面代碼如下

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"

    tools:context=".MainActivity">
    <LinearLayout
        android:id="@+id/ll_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="5dp"
        android:layout_marginTop="10dp"
        android:orientation="horizontal">
        <EditText
            android:id="@+id/et_path"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginRight="3dp"
            android:layout_weight="1"
            android:background="#EBEBEB"
            android:hint="請輸入圖片路徑"
            android:inputType="textUri"
            android:paddingLeft="3dp"
            android:textColor="#696969"
            android:textSize="20sp" />
        <Button
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="4"
            android:background="#EBEBEB"
            android:onClick="click"
            android:text="瀏覽"
            android:textColor="#696969"
            android:textSize="20sp" />
    </LinearLayout>

    <ImageView
        android:id="@+id/iv_pic"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/ll_text"
        android:scaleType="fitCenter" />
</RelativeLayout>

MainActivity

代碼如下

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.text.TextUtils;
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 {
    protected static final int CHANGE_UI = 1;
    protected static final int ERROR = 2;
    private EditText et_path;
    private ImageView ivPic;
    // 主線程創建消息處理器
    private Handler handler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            if (msg.what == CHANGE_UI) {
                Bitmap bitmap = (Bitmap) msg.obj;
                ivPic.setImageBitmap(bitmap);
            } else if (msg.what == ERROR) {
                Toast.makeText(MainActivity.this, "顯示圖片錯誤",
                        Toast.LENGTH_SHORT).show();
            }
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        et_path = (EditText) findViewById(R.id.et_path);
        ivPic = (ImageView) findViewById(R.id.iv_pic);
    }
    public void click(View view) {
        final String path = et_path.getText().toString().trim();
        if (TextUtils.isEmpty(path)) {
            Toast.makeText(this, "圖片路徑不能爲空", Toast.LENGTH_SHORT).show();
        } else {
            //子線程請求網絡,Android4.0以後訪問網絡不能放在主線程中
            new Thread() {
                private HttpURLConnection conn;
                private Bitmap bitmap;
                public void run() {
                    // 連接服務器 get 請求 獲取圖片
                    try {
                        //創建URL對象
                        URL url = new URL(path);
                        // 根據url 發送 http的請求
                        conn = (HttpURLConnection) url.openConnection();
                        // 設置請求的方式
                        conn.setRequestMethod("GET");
                        //設置超時時間
                        conn.setConnectTimeout(5000);
                        // 得到服務器返回的響應碼
                        int code = conn.getResponseCode();
                        //請求網絡成功後返回碼是200
                        if (code == 200) {
                            //獲取輸入流
                            InputStream is = conn.getInputStream();
                            //將流轉換成Bitmap對象
                            bitmap = BitmapFactory.decodeStream(is);
                            //將更改主界面的消息發送給主線程
                            Message msg = new Message();
                            msg.what = CHANGE_UI;
                            msg.obj = bitmap;
                            handler.sendMessage(msg);
                        } else {
                            //返回碼不等於200 請求服務器失敗
                            Message msg = new Message();
                            msg.what = ERROR;
                            handler.sendMessage(msg);
                        }
                    } catch (Exception e) {
                        e.printStackTrace();
                        Message msg = new Message();
                        msg.what = ERROR;
                        handler.sendMessage(msg);
                    }
                    //關閉連接
                    conn.disconnect();
                }
            }.start();
        }
    }
}

最後記得給 AndroidManifest中 加上 訪問網絡的權限

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

最後打開虛擬機

輸入圖片地址
https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1576162426696&di=d84e2f38070db06a909401060b047222&imgtype=0&src=http%3A%2F%2Fpic1.zhimg.com%2F50%2Fv2-fe41e8f50ce5a9d096f29585551d02c8_hd.jpg

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