Question

我是Android开发的新手我正在关注在线教程目前我正在学习线程。

我尝试在以下代码中进行评论和烘烤以找到我的错误我猜错误在newtype行如果我评论这一行和while循环，应用程序运行顺利。

请帮忙。

inputStream = connection.getInputStream();

logcat的：

package com.example.vivzmultithreadingexample;

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.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.Toast;

public class MainActivity extends Activity implements OnItemClickListener {

    private EditText editText;
    private ListView listView;
    private String[] listofImages;
    private ProgressBar progessBar;
    private LinearLayout loadingSection = null;


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

        editText = (EditText) findViewById(R.id.editText1);
        listView = (ListView) findViewById(R.id.urlList);
        listView.setOnItemClickListener(this);
        listofImages = getResources().getStringArray(R.array.imageUrls);
        progessBar = (ProgressBar) findViewById(R.id.downloadProgress);
    }



    public void downloadImage(View v){
        //Toast.makeText(this, "button Clicked", Toast.LENGTH_SHORT).show();
        Thread myThread = new Thread(new DownloadImagesThread());
        myThread.run();
    }

    public boolean downloadImageUsingThread(String url){


        boolean sucessful = false;
        URL downloadUrl = null;
        HttpURLConnection connection= null;
        InputStream inputStream = null;

        try {
            downloadUrl = new URL(url);
            connection =(HttpURLConnection) downloadUrl.openConnection();
            inputStream = connection.getInputStream();
            int read = -1;
            while((read =inputStream.read()) !=-1){
                L.m(""+read);
            }
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            L.m(""+e);

        } catch (IOException e) {
            // TODO Auto-generated catch block
            L.m(""+e);

        }finally{
            if(connection != null){
                connection.disconnect();
            }

            if(inputStream != null){
                try {
                    inputStream.close();
                } catch (IOException e) {
                    L.m(""+e);
                    // TODO Auto-generated catch block
                                    }
            }
        }
        Toast.makeText(this, connection.toString(), Toast.LENGTH_SHORT).show();
        return sucessful;
    }


    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
        editText.setText(listofImages[arg2]);

    }

    public class DownloadImagesThread implements Runnable {
        public void run() {
            downloadImageUsingThread(listofImages[0]);
            editText.setText(listofImages[0]);


        }
    }
}

Answer 1

您正在使用myThread.run()来调用run()方法，这将在调用它的线程中执行run()，在您的情况下，它是MainThread且Android不允许网络访问MainThread。您必须调用myThread.start()来声明执行您的线程。

Answer 2

尝试在此行下使用这些语句

connection =(HttpURLConnection) downloadUrl.openConnection();   
connection.setRequestMethod("GET");
connection.connect();

Answer 3

您正在主线程中调用网络呼叫，为此使用异步任务。使用此代码..

DownLoadImageTask   downloadImageUsingThread =new DownLoadImageTask ();
downloadImageUsingThread.execute(listofImages[0]);

并使用所有代码在doyntask的doInBackground（String ... params）方法中下载图像，并在post方法中设置文本。

   class DownLoadImageTask  extends Asyntask<String,String,String>{

@覆盖

protected String doInBackground(String... params) {

//所有代码都是她的

 }

@Override
protected void onPostExecute(String result1) {

//在此处设置文字

}

enter code here

Answer 4

找到解决方案。刚刚将myThread.run()更改为myThread.start()

应用程序在调用InputStream时崩溃

4 个答案: