Question

我有一个JSON文件，填充到listview.First，我想知道如何使我的列表视图可点击并导致另一个活动。

第二，我想让列表视图动态化。这意味着，我只需要一个活动来完成我所拥有的列表上的点击操作。填充到Activity的内容（图片，标题，描述）的来源来自网络上的JSON文件。

例如，我在列表中有13个项目，每当我点击其中一个项目时，它转到包含不同图片，标题和描述的一个活动取决于我点击的项目。

我需要有人来改进我在下面提供的代码。

Projects.java

public class Projects {

    public String title;
    public String keyword;
    public String description;
    public String smallImageUrl;
    public String bigImageUrl;
    public int cost;

    @Override
    public String toString()
    {
        return "Title: "+title+ " Keyword: "+keyword+ " Image: "+smallImageUrl;

    }


}

ProjectsAdapter.java

Public class ProjectsAdapter extends ArrayAdapter<Projects> {

    int resource;
    String response;
    Context context;
    //Initialize adapter
    public ProjectsAdapter(Context context, int resource, List<Projects> 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
        Projects 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.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.title);

        return projectView;
    }

}

Main.java

public class Main 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
    ProjectsAdapter arrayAdapter;

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

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

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

        //Instantiate the Web Service Class with he URL of the web service not that you must pass
        WebService webService = new WebService("http://pre.spendino.de/test/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
        {
            //Parse Response into our object
            Type collectionType = new TypeToken<ArrayList<Projects>>(){}.getType();

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

            //Now that we have that list lets add it to the ArrayList which will hold our items.
            for(Projects l : lst)
            {
                prjcts.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();
        }
        catch(Exception e)
        {
            Log.d("Error: ", e.getMessage());
        }


    }

}

WebService.java （我认为我们不需要编辑此内容）

public class WebService{

    DefaultHttpClient httpClient;
    HttpContext localContext;
    private String ret;

    HttpResponse response1 = null;
    HttpPost httpPost = null;
    HttpGet httpGet = null;
    String webServiceUrl;

    //The serviceName should be the name of the Service you are going to be using.
    public WebService(String serviceName){
        HttpParams myParams = new BasicHttpParams();

        HttpConnectionParams.setConnectionTimeout(myParams, 10000);
        HttpConnectionParams.setSoTimeout(myParams, 10000);
        httpClient = new DefaultHttpClient(myParams);
        localContext = new BasicHttpContext();
        webServiceUrl = serviceName;

    }

    //Use this method to do a HttpPost\WebInvoke on a Web Service
    public String webInvoke(String methodName, Map<String, Object> params) {

        JSONObject jsonObject = new JSONObject();

        for (Map.Entry<String, Object> param : params.entrySet()){
            try {
                jsonObject.put(param.getKey(), param.getValue());
            }
            catch (JSONException e) {
                Log.e("Groshie", "JSONException : "+e);
            }
        }
        return webInvoke(methodName,  jsonObject.toString(), "application/json");
    }

    private String webInvoke(String methodName, String data, String contentType) {
        ret = null;

        httpClient.getParams().setParameter(ClientPNames.COOKIE_POLICY, CookiePolicy.RFC_2109);

        httpPost = new HttpPost(webServiceUrl + methodName);
        response1 = null;

        StringEntity tmp = null;       

        //httpPost.setHeader("User-Agent", "SET YOUR USER AGENT STRING HERE");
        httpPost.setHeader("Accept",
"text/html,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5");

        if (contentType != null) {
            httpPost.setHeader("Content-Type", contentType);
        } else {
            httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded");
        }

        try {
            tmp = new StringEntity(data,"UTF-8");
        } catch (UnsupportedEncodingException e) {
            Log.e("Groshie", "HttpUtils : UnsupportedEncodingException : "+e);
        }

        httpPost.setEntity(tmp);

        Log.d("Groshie", webServiceUrl + "?" + data);

        try {
            response1 = httpClient.execute(httpPost,localContext);

            if (response1 != null) {
                ret = EntityUtils.toString(response1.getEntity());
            }
        } catch (Exception e) {
            Log.e("Groshie", "HttpUtils: " + e);
        }

        return ret;
    }

    //Use this method to do a HttpGet/WebGet on the web service
    public String webGet(String methodName, Map<String, String> params) {
        String getUrl = webServiceUrl + methodName;

        int i = 0;
        for (Map.Entry<String, String> param : params.entrySet())
        {
            if(i == 0){
                getUrl += "?";
            }
            else{
                getUrl += "&";
            }

            try {
                getUrl += param.getKey() + "=" + URLEncoder.encode(param.getValue(),"UTF-8");
            } catch (UnsupportedEncodingException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            i++;
        }

        httpGet = new HttpGet(getUrl);
        Log.e("WebGetURL: ",getUrl);

        try {
            response1 = httpClient.execute(httpGet);
        } catch (Exception e) {
            Log.e("Groshie:", e.getMessage());
        }

        // we assume that the response body contains the error message
        try {
            ret = EntityUtils.toString(response1.getEntity());
        } catch (IOException e) {
            Log.e("Groshie:", e.getMessage());
        }

        return ret;
    }

    public static JSONObject Object(Object o){
        try {
            return new JSONObject(new Gson().toJson(o));
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return null;
    }

    public InputStream getHttpStream(String urlString) throws IOException {
        InputStream in = null;
        int response = -1;

        URL url = new URL(urlString);
        URLConnection conn = url.openConnection();

        if (!(conn instanceof HttpURLConnection))
            throw new IOException("Not an HTTP connection");

        try{
            HttpURLConnection httpConn = (HttpURLConnection) conn;
            httpConn.setAllowUserInteraction(false);
            httpConn.setInstanceFollowRedirects(true);
            httpConn.setRequestMethod("GET");
            httpConn.connect();

            response = httpConn.getResponseCode();                

            if (response == HttpURLConnection.HTTP_OK) {
                in = httpConn.getInputStream();
            }
        } catch (Exception e) {
            throw new IOException("Error connecting");
        } // end try-catch

        return in;
    }

    public void clearCookies() {
        httpClient.getCookieStore().clear();
    }

    public void abort() {
        try {
            if (httpClient != null) {
                System.out.println("Abort.");
                httpPost.abort();
            }
        } catch (Exception e) {
            System.out.println("Your App Name Here" + e);
        }
    }


}

这是JSON文件：

[{
    "title": "CARE Deutschland-Luxemburg e.V.",
    "keyword": "CARE",
    "description": "<p><b>Das CARE-Komplett-Paket für Menschen in Not</b",
    "smallImageUrl": "http://cdn.spendino.de/web/img/projects/home/1284113658.jpg",
    "bigImageUrl":"http://cdn.spendino.de/web/img/projects/small/1284113658.jpg",
    "cost": "5"
},
{
    "title": "Brot für die Welt",
    "keyword": "BROT",
    "description": "<p>„Brot für die Welt“ unterstützt unter der Maßgabe 'Helfen, wo die Not am größten ist' ausgewählte Projekte weltweit.",
    "smallImageUrl": "http://cdn.spendino.de/web/img/projects/home/1267454286.jpg",
    "bigImageUrl":"http://cdn.spendino.de/web/img/projects/small/1267454286.jpg",
    "cost": "5"
},
{
    "title": "Deutsche AIDS-Stiftung",
    "keyword": "HIV",
    "description": "<p>Die Deutsche AIDS-Stiftung unterstützt mit ihren finanziellen Mitteln seit mehr als 20 Jahren Betroffene, die an HIV und AIDS erkrankt sind.",
    "smallImageUrl": "http://cdn.spendino.de/web/img/projects/home/1258365722.jpg",
    "bigImageUrl":"http://cdn.spendino.de/web/img/projects/small/1258365722.jpg",
    "cost": "5"
}]

列表视图的屏幕截图： enter image description here

如果不清楚，请告诉我。非常感谢你

Answer 1

使用它来实现点击：

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.
            }
        });

Answer 2

首先，JSON不会为你做这件事。你必须实现你的逻辑将JSON视为一个巨大的数据转储。

以下是你应该如何去做的事情：

拥有JSON
构建一个合适的数据结构（Array，ArrayList，无论你喜欢什么）来保存关于列表视图的关键数据
使用此数据结构作为列表视图的来源
当用户点击任何行时，尝试在列表视图中找到该行的位置，并在源数据结构中的该位置上查找所需的数据。
创建一般处理这些数据的活动
使用用户在步骤4中单击的行的数据打开该活动
在新活动中使用此数据

这样，您可以为活动添加动态，根据单击的行显示数据

Android：使用JSON使列表视图可单击并动态显示

2 个答案: