Android：如何从数组中获取随机图像而无需重复使用JSON作为源

Question

我在从数组中获取随机图像（作为按钮）时遇到了麻烦，而没有重复使用Web上的JSON文件作为源。 每个onClick按钮都会根据显示的图像导致一个活动，该活动具有与JSON不同的对象属性。

因此，我将这些图像中的3张放入一个活动中，但不允许它们彼此相同。

有人可以帮我从下面的代码中提供解决方案吗？ 我愿意接受任何一种解决方案。 提前致谢。

这是我的JSON的代码段，我想使用的是'smallImageUrl'属性。

{
  "project_title": "Deutsche Gesellschaft zur Rettung Schiffbrüchiger",
  "organization_title": "Deutsche Gesellschaft zur Rettung Schiffbrüchiger",
  "keyword": "RETTER",
  "short_code":"81190",
  "project_description": "Seit Mitte des 19. Jahrhunderts schenken die Seenotretter Schiffsbrüchigen ein zweites Leben. Die Aufgaben der Organisation umfassen dabei alle Bereiche – vom Abhören der Funkverkehrfrequenzen bis zum sicheren Transport erstversorgter Menschen.  61 Seenotkreuzer und Seenotrettungsboote sind dafür 24 Stunden am Tag, sieben Tage die Woche, bei jedem Wind und Wetter einsatzbereit. Das humanitäre Wirken der Organisation wird dabei nur durch Förderer ermöglicht, denn die DGzRS ist ausschließlich spendenfinanziert. ",
  "smallImageUrl": "http://cdn.spendino.de/web/img/projects/home/1298899521.jpg",
  "bigImageUrl":"http://cdn.spendino.de/web/img/projects/small/1298899521.jpg",
  "price": "5 EUR",
  "country": "Germany"
  },
  {
  "project_title": "CARE Deutschland-Luxemburg e.V.",
  "organization_title": "CARE Deutschland-Luxemburg e.V.",
  "keyword": "CARE",
  "short_code":"81190",
  "project_description": "<p><b>Das CARE-Komplett-Paket für Menschen in Not</b></p><p>Schnell, nachhaltig und durchdacht, das ist das moderne CARE-Paket. CARE ist überzeugt, dass umfassende Hilfe von drei Seiten notwendig ist, um die weltweite Armut Schritt für Schritt zu verringern. Deswegen hat CARE sich seit seiner Gründung 1945 und dem Abwurf der ersten CARE-Pakete über Berlin weiter entwickelt. Heute steckt im CARE-Paket weit mehr als Zucker und Mehl. Heute bietet die Organisation in 70 der ärmsten Länder der Welt ein Komplett-Paket für Menschen in Not.</p><p><b>Das Komplett-Paket für Menschen in Not enthält:</b></p>*sofortige Nothilfe nach Katastrophen<br><br>*langfristige Entwicklungszusammenarbeit<br><br>*Schutz der Menschenrechte<br><br>",
  "smallImageUrl": "http://cdn.spendino.de/web/img/projects/home/1284113658.jpg",
  "bigImageUrl":"http://cdn.spendino.de/web/img/projects/small/1284113658.jpg",
  "price": "5 EUR",
  "country": "Germany"
  },

我从下面的ListActivity调用JSON-parsing方法，但是实际上我现在正在工作的显示随机图像的活动必须作为启动器（在ListActivity之前）：

public class ProjectsList extends Activity {
    /** Called when the activity is first created. */
    //ListView that will hold our items references back to main.xml
    ListView lstTest;
    //Array Adapter that will hold our ArrayList and display the items on the ListView
    ProjectAdapter arrayAdapter;
    ProgressDialog dialog;

    //List that will  host our items and allow us to modify that array adapter
    ArrayList<Project> prjcts=null;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.projects_list);
        //Initialize ListView
        lstTest= (ListView)findViewById(R.id.lstText);

         //Initialize our ArrayList
        prjcts = new ArrayList<Project>();
        //Initialize our array adapter notice how it references the listitems.xml layout
        arrayAdapter = new ProjectAdapter(ProjectsList.this, R.layout.listitems,prjcts);

        //Set the above adapter as the adapter of choice for our list
        lstTest.setAdapter(arrayAdapter);



        WebService webService = new WebService("http://liebenwald.spendino.net/admanager/dev/android/projects.json");

        //Pass the parameters if needed , if not then pass dummy one as follows
        Map<String, String> params = new HashMap<String, String>();
        params.put("var", "");

        //Get JSON response from server the "" are where the method name would normally go if needed example
        // webService.webGet("getMoreAllerts", params);
        String response = webService.webGet("", params);

        try
        {
             dialog = ProgressDialog.show(ProjectsList.this, "", "Fetching Projects...", true);
             dialog.setCancelable(true);
             dialog.setCanceledOnTouchOutside(true);
             dialog.setOnCancelListener(new OnCancelListener() {
                public void onCancel(DialogInterface dialog) {

                }
             });
            //Parse Response into our object
            Type collectionType = new TypeToken<ArrayList<Project>>(){}.getType();

            //JSON expects an list so can't use our ArrayList from the lstart
            List<Project> lst= new Gson().fromJson(response, collectionType);


            //Now that we have that list lets add it to the ArrayList which will hold our items.
            for(Project l : lst)
            {
                prjcts.add(l);
                ConstantData.projectsList.add(l);
            }

            //Since we've modified the arrayList we now need to notify the adapter that
            //its data has changed so that it updates the UI
            arrayAdapter.notifyDataSetChanged();
            dialog.dismiss();
        }
        catch(Exception e)
        {
            Log.d("Error: ", e.getMessage());
        }

        lstTest.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {              
                //@SuppressWarnings("unchecked")
                //Projects p = (Projects ) lstTest.getItemAtPosition(position);     

                //Do your logic and open up a new Activity.
                Intent care = new Intent(ProjectsList.this, ProjectDetail.class);
                care.putExtra("spendino.de.Organization.position",position);
                startActivity(care);
            }
        });

    }
}

这是保存我的JSON索引的类：

public class ConstantData{

   public static String project_title = "project title";
   public static String organization_title = "organization title";
   public static String keyword = "keyword";
   public static String short_code = "short code";
   public static String project_description = "description";
   public static String smallImageUrl = "smallImageUrl";
   public static String bigImageUrl = "bigImageUrl";
   public static String price= "price";
   public static String country= "country";



    public static ArrayList<Project> projectsList = new ArrayList<Project>();
    }

这是随机按钮应导致的活动：

public class ProjectDetail extends Activity implements OnClickListener{


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.project);

        Button weitersagen = (Button) findViewById(R.id.btn_weitersagen);
        weitersagen.setOnClickListener(this);

        Button sms = (Button) findViewById(R.id.btn_sms_spenden);
        sms.setOnClickListener(this);

        int position = getIntent().getExtras().getInt("spendino.de.Organization.position");
        Project project = ConstantData.projectsList.get(position);


      try {
          ImageView projectImage = (ImageView)findViewById(R.id.project_image);
          Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(project.bigImageUrl).getContent());
          projectImage.setImageBitmap(bitmap); 
        } catch (MalformedURLException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        } 

      TextView project_title = (TextView)findViewById(R.id.txt_project_title);
      project_title.setText(project.project_title);

      TextView organization_title = (TextView)findViewById(R.id.txt_organization_title);
      organization_title.setText(Html.fromHtml("von " +project.organization_title));

      TextView project_description = (TextView)findViewById(R.id.txt_project_description);
      project_description.setText(Html.fromHtml(project.project_description));

    }

编辑这是我的ListActivity的ProjectAdapter

公共类ProjectAdapter扩展了ArrayAdapter {

int resource;
String response;
Context context;
//Initialize adapter
public ProjectAdapter(Context context, int resource, List<Project> items) {
    super(context, resource, items);
    this.resource=resource;

}



@Override
public View getView(int position, View convertView, ViewGroup parent)
{
    LinearLayout projectView;
    //Get the current alert object
    Project pro = getItem(position);

    //Inflate the view
    if(convertView==null)
    {
        projectView = new LinearLayout(getContext());
        String inflater = Context.LAYOUT_INFLATER_SERVICE;
        LayoutInflater vi;
        vi = (LayoutInflater)getContext().getSystemService(inflater);
        vi.inflate(resource, projectView, true);
    }
    else
    {
        projectView = (LinearLayout) convertView;
    }

    TextView Title =(TextView)projectView.findViewById(R.id.txt_title);

    try {
          ImageView i = (ImageView)projectView.findViewById(R.id.image);
          Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(pro.smallImageUrl).getContent());
          i.setImageBitmap(bitmap); 
        } catch (MalformedURLException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }


    //Assign the appropriate data from our alert object above
    //Image.setImageDrawable(pro.smallImageUrl);
    Title.setText(pro.project_title);

    return projectView;
}

}

Answer 1

带有说明的好例子：

在Android上的单独线程上通过HTTP加载图像

和示例的用法：

在Android的ListView中加载远程图像

在第一个示例中是ImageThreadLoader，它具有loadImage方法。 该方法从缓存中获取位图，或者如果不存在，则从网络下载。