android - 如何下载多张图片并像幻灯片一样显示？

Question

嘿，我是 android 世界的新手，正在考虑制作一个小应用程序，它将多个图像(可能从指定的 url)下载到 sdcard 或下载文件夹中，然后这些图像可以被视为幻灯片(有按钮下一个和后面)。另外，在下载过程中应该有一个进度条来显示下载进度。我可以为一张图片做，但不能为多张图片做。这是我的代码:

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;

import android.app.Activity;
import android.app.Dialog;

import android.app.ProgressDialog;

import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;


public class lab1_dhruv extends Activity{
     public static final int DIALOG_DOWNLOAD_PROGRESS = 0;
        private Button startBtn;
        private ProgressDialog mProgressDialog;


        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            startBtn = (Button)findViewById(R.id.startBtn);
            startBtn.setOnClickListener(new OnClickListener(){
                public void onClick(View v) {
                    startDownload();
                }
            });
        }

        private void startDownload() {

            //String url = "http://farm1.static.flickr.com/114/298125983_0e4bf66782_b.jpg";
            //new DownloadFileAsync().execute(url);
            String[] imageList = {"http://farm1.static.flickr.com/114/298125983_0e4bf66782_b.jpg","http://fc03.deviantart.net/fs14/i/2007/086/9/1/Steve_Jobs_portrait_by_tumb.jpg","http://www.buzzreactor.com/sites/default/files/Bill-Gates1.jpg"};

            //String url1 = "http://fc03.deviantart.net/fs14/i/2007/086/9/1/Steve_Jobs_portrait_by_tumb.jpg";
            new DownloadFileAsync().execute(imageList);


        }
        @Override
        protected Dialog onCreateDialog(int id) {
            switch (id) {
            case DIALOG_DOWNLOAD_PROGRESS:
                mProgressDialog = new ProgressDialog(this);
                mProgressDialog.setMessage("Downloading file..");
                mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                mProgressDialog.setCancelable(false);
                mProgressDialog.show();
                return mProgressDialog;
            default:
                return null;
            }
        }

    class DownloadFileAsync extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            showDialog(DIALOG_DOWNLOAD_PROGRESS);
        }

        @Override
        protected String doInBackground(String... aurl) {
            int count;

        try {

        URL url = new URL(aurl[0]);
        URLConnection conexion = url.openConnection();
        conexion.connect();

        int lenghtOfFile = conexion.getContentLength();
        Log.d("ANDRO_ASYNC", "Lenght of file: " + lenghtOfFile);

        InputStream input = new BufferedInputStream(url.openStream());
        OutputStream output = new FileOutputStream("/sdcard/some_photo_from_gdansk_poland.jpg");

        byte data[] = new byte[1024];

        long total = 0;

            while ((count = input.read(data)) != -1) {
                total += count;
                publishProgress(""+(int)((total*100)/lenghtOfFile));
                output.write(data, 0, count);
            }

            output.flush();
            output.close();
            input.close();
        } catch (Exception e) {}
        return null;

        }
        protected void onProgressUpdate(String... progress) {
             Log.d("ANDRO_ASYNC",progress[0]);
             mProgressDialog.setProgress(Integer.parseInt(progress[0]));
        }

        @Override
        protected void onPostExecute(String unused) {
            dismissDialog(DIALOG_DOWNLOAD_PROGRESS);
        }
    }

     public void showDownload(View view) {
         Intent intent = new Intent();  
         intent.setAction(android.content.Intent.ACTION_VIEW);  
         File file = new File("/sdcard/some_photo_from_gdansk_poland.jpg");  
         intent.setDataAndType(Uri.fromFile(file), "image/*");  
         startActivity(intent); 
        }
    }

这里是main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <Button
        android:text="Start the download here"
        android:id="@+id/startBtn"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">
    </Button>

    <Button
        android:text="Show Download Image"
        android:id="@+id/startBtn1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="showDownload">
    </Button>

这里是 androidmanifest.xml:-

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="cmpe235.lab1.dhruv.assignment"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="9" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".lab1_dhruv"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>

是否有任何我可以看到的示例，或者任何人都可以告诉我我应该在我的代码中做什么。我是android的新手，所以不太了解。谢谢

Answer 1

使用画廊小工具。您需要制作一个适配器，为 Gallery-Widget 提供您下载的图像。我确定您可以在此页面或 Google 上找到有关如何实现图库的代码；)

实现画廊后，有几种方法可以在图像之间自动翻转，下面是一个示例:

Using the Android Gallery as an automated slideshow