使用Asynctask进行异步任务处理

最新推荐文章于 2024-04-24 10:21:34 发布

原创最新推荐文章于 2024-04-24 10:21:34 发布 · 158 阅读

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本文详细介绍了一个Android应用中如何使用自定义HttpUtils类进行网络数据请求和图片加载的方法。通过AsyncTask实现了异步网络请求，避免了阻塞UI线程，确保了应用的流畅运行。同时，展示了如何解析并显示从网络获取的唐诗数据和图片。

package com.example.util;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;

import javax.net.ssl.HttpsURLConnection;

public class HttpUtils {
    public  static String getNetData(String dataUrl){
       try {
           URL url=new URL(dataUrl);
           HttpsURLConnection connection=(HttpsURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
           int code = connection.getResponseCode();
           if (code==200){
               InputStream inputStream = connection.getInputStream();
               BufferedReader reader=new BufferedReader(new InputStreamReader(inputStream));
               StringBuilder builder=new StringBuilder();
               String str="";
               while ((str=reader.readLine())!=null){
                   builder.append(str);
               }
               return builder.toString();
           }
       }catch (Exception e){
           e.printStackTrace();
       }
        return "";
    }
    public static Bitmap getNetPic(String picUrl){
        try {
            URL url=new URL(picUrl);
            HttpsURLConnection connection=(HttpsURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            int code = connection.getResponseCode();
            if (code==200){
                InputStream inputStream = connection.getInputStream();
                Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
                return bitmap;
            }
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }
}

package com.example.d3_asynctask;

import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ImageView;

import com.example.util.HttpUtils;

/**
 * 使用Asynctask进行异步任务处理
 * 异步请求数据，，，去解析展示
 * 异步请求图片，，，展示到控件
 */
public class MainActivity extends AppCompatActivity {

    private String dataUrl="https://api.apiopen.top/getTangPoetry?page=1&count=20";
    private String picUrl="http://wimg.spriteapp.cn/picture/2018/1209/5c0cb7c74fd49__b.jpg";
    private ImageView img;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        img = findViewById(R.id.img);
        //进行异步请求数据
        MyAsynctask myAsynctask = new MyAsynctask();
        myAsynctask.execute(dataUrl);
        //异步请求图片
        new picAsynctask(img).execute(picUrl);
    }
    /**
     * 创建内部类———请求数据的
     */
    public class MyAsynctask extends AsyncTask<String,Void,String>{
        /**
         *主线程———更新UI
         */
        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            Log.i("aaa","onPostExecute:"+s);
        }

        /**
         *子线程——耗时操作
         */
        @Override
        protected String doInBackground(String... strings) {
            //请求网络数据
            String data = HttpUtils.getNetData(strings[0]);
            return data;
        }
    }
    /**
     * 创建内部类———请求图片的
     */
    public class picAsynctask extends AsyncTask<String,Void,Bitmap>{
        ImageView iv;

        public picAsynctask(ImageView iv) {
            this.iv = iv;
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            super.onPostExecute(bitmap);
            //展示图片
            iv.setImageBitmap(bitmap);
        }

        @Override
        protected Bitmap doInBackground(String... strings) {
            //请求图片
            Bitmap pic = HttpUtils.getNetPic(strings[0]);
            return pic;
        }
    }
}