android异步从网上下载图片

最新推荐文章于 2024-08-09 18:00:00 发布

peach0601

最新推荐文章于 2024-08-09 18:00:00 发布

阅读量391

点赞数

分类专栏： Android学习文章标签： android 异步图片

本文链接：https://blog.youkuaiyun.com/peach0601/article/details/49919077

版权

Android学习专栏收录该内容

4 篇文章

订阅专栏

本文介绍了一个使用Android的AsyncTask来从网络加载图片并显示在ImageView中的示例应用。通过HttpClient发起HTTP请求获取图片资源，并在后台线程中将图片转换为Bitmap对象，最后更新UI显示加载完成的图片。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

package com.peach.asynctask;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {

    private Button btn;
    private ImageView img;
    private String image_Path = "图片地址";
    private ProgressDialog dialog;

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

        dialog = new ProgressDialog(this);
        dialog.setTitle("提示信息");
        dialog.setMessage("玩命下载中。。。");
        btn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                new MyTask().execute(image_Path);
            }
        });

    }
    private void initView() {

        btn = (Button) findViewById(R.id.btn);
        img = (ImageView) findViewById(R.id.img);
    }

    class MyTask extends AsyncTask<String,Void,Bitmap>{

        @Override
        protected void onPreExecute() {
            dialog.show();
            super.onPreExecute();
        }

        @Override
        protected Bitmap doInBackground(String... params) {
            HttpClient hc = new DefaultHttpClient();
            HttpGet hg = new HttpGet(params[0]);
            Bitmap bitmap = null;
            HttpResponse hr = httpClient.execute(httpGet);
            byte[] data = EntityUtils.toByteArray(HttpEntity);
            bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
            return bitmap;
        }

    }

    @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;
    }

}

xml

<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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />
    <ImageView 
        android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/btn"
        android:src="@drawable/ic_launcher"/>

</RelativeLayout>