在线浏览

最新推荐文章于 2020-06-23 13:21:03 发布

原创最新推荐文章于 2020-06-23 13:21:03 发布 · 337 阅读

CC 4.0 BY-SA版权

本文介绍了一个简单的Android应用示例，该应用能够从网络加载图片并显示在ImageView中。通过使用Handler和线程来实现异步加载，避免了UI阻塞。文章提供了完整的代码示例，包括MainActivity.java、BuildConfig.java、R.java以及activity_main.xml布局文件。

效果图：

MainActivity.java

package com.example.internetimageview;

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

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.TextUtils;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {
    private EditText etImageUrl;
    private ImageView ivImage;
    public static final int SHOWIMAGE=1;
    private Handler handler=new Handler(){
    public void handleMessage(android.os.Message msg) {
      switch (msg.what) {
   case SHOWIMAGE:
    Bitmap bitmap=(Bitmap) msg.obj;
    ivImage.setImageBitmap(bitmap);
    break;

   default:
    break;
   }
    };
    };
@Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  initViews();
}

private void initViews() {
etImageUrl=(EditText) findViewById(R.id.etImageUrl);
ivImage=(ImageView) findViewById(R.id.ivImage);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.main, menu);
  return true;
}

public void viewImage(View view){
  final String imageUrl=etImageUrl.getText().toString();
  if(TextUtils.isEmpty(imageUrl)){
   Toast.makeText(this, "图片路径不能为空", Toast.LENGTH_LONG).show();
  }else{
   new Thread(){

     public void run() {
      try {
       URL url=new URL(imageUrl);
       HttpURLConnection httpURLConnection=(HttpURLConnection) url.openConnection();
          httpURLConnection.setRequestMethod("GET");
          httpURLConnection.setConnectTimeout(5000);
          int responseCode=httpURLConnection.getResponseCode();
          if(responseCode==200){
          InputStream inputStream=httpURLConnection.getInputStream();
          Bitmap bitmap=BitmapFactory.decodeStream(inputStream);
          Message message=new Message();
          message.what=SHOWIMAGE;
          message.obj=bitmap;
          //ivImage.setImageBitmap(bitmap);
          handler.sendMessage(message);
          }else{
          Toast.makeText(MainActivity.this, "显示图片失败", Toast.LENGTH_LONG).show();
          }
      } catch (MalformedURLException e) {
       e.printStackTrace();
      } catch (IOException e) {
       e.printStackTrace();
      }

    }
   }.start();

  }
}

}

BuildConfig.java

/** Automatically generated file. DO NOT MODIFY */
package com.example.internetimageview;

public final class BuildConfig {
public final static boolean DEBUG = true;
}

R.java

/* AUTO-GENERATED FILE. DO NOT MODIFY.
*
* This class was automatically generated by the
* aapt tool from the resource data it found. It
* should not be modified by hand.
*/

package com.example.internetimageview;

public final class R {
    public static final class attr {
    }
    public static final class dimen {
        /** Default screen margins, per the Android Design guidelines.

         Customize dimensions originally defined in res/values/dimens.xml (such as
         screen margins) for sw720dp devices (e.g. 10" tablets) in landscape here.

         */
        public static final int activity_horizontal_margin=0x7f040000;
        public static final int activity_vertical_margin=0x7f040001;
    }
    public static final class drawable {
        public static final int button_bg=0x7f020000;
        public static final int ic_launcher=0x7f020001;
    }
    public static final class id {
        public static final int action_settings=0x7f080003;
        public static final int btnView=0x7f080002;
        public static final int etImageUrl=0x7f080001;
        public static final int ivImage=0x7f080000;
    }
    public static final class layout {
        public static final int activity_main=0x7f030000;
    }
    public static final class menu {
        public static final int main=0x7f070000;
    }
    public static final class string {
        public static final int action_settings=0x7f050001;
        public static final int app_name=0x7f050000;
        public static final int hello_world=0x7f050002;
    }
    public static final class style {
        /**
        Base application theme, dependent on API level. This theme is replaced
        by AppBaseTheme from res/values-vXX/styles.xml on newer devices.

            Theme customizations available in newer API levels can go in
            res/values-vXX/styles.xml, while customizations related to
            backward-compatibility can go here.

        Base application theme for API 11+. This theme completely replaces
        AppBaseTheme from res/values/styles.xml on API 11+ devices.

API 11 theme customizations can go here.

        Base application theme for API 14+. This theme completely replaces
        AppBaseTheme from BOTH res/values/styles.xml and
        res/values-v11/styles.xml on API 14+ devices.

API 14 theme customizations can go here.
         */
        public static final int AppBaseTheme=0x7f060000;
        /** Application theme.
All customizations that are NOT specific to a particular API-level can go here.
         */
        public static final int AppTheme=0x7f060001;
    }
}

activity_main.xml

</LinearLayout>