java - 通过 JSON 检索 ImageView 中的图像

Question

我创建了一个通过 JSON 数据填充数组列表的 Activity ，当用户单击项目数组时，会显示一个新 Activity ，其中显示与该项目相关的信息。在帮助下，我只能在该页面上显示字符串。

换句话说，在我的单个项目中单击，我能够检索字符串，这很讽刺，因为我能够通过数组列表中的 JSON 填充图像。

在单个项目 Activity 的布局中，我创建了一个水平幻灯片库，其中包含 4 张图片，但希望通过 JSON 数据填充这些图像中的每一个。

下面是填充数组列表并引用单个项目单击 Activity 的 Activity 代码

   public class CasualEventsActivity extends Activity {

        private static final String URL_WEB_SERVICE = "xxxxx";
        private GridView gv;
        private ArrayList<Events_List> container;
        private ArrayList<Events_List> items;
        public Uri list_item_bac;
        public String list_item_name;
        public String list_item_description;
        public String list_item_location;
        public String single_list_item_description;
        public String list_item_price;


        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.events_list_layout);
            gv = (GridView) findViewById(R.id.gridview);
            container = new ArrayList<Events_List>();
            //download JSON
            listDownload();


            GridView s = (GridView) findViewById(R.id.gridview);
            s.setOnItemClickListener(new OnItemClickListener(){

                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    Intent intent = new Intent(CasualEventsActivity.this,CasualEventsSingleItemActivity.class);

                    intent.putExtra("list_item_name", container.get(position).getList_item_title());
                    intent.putExtra("list_item_location", container.get(position).getList_item_location());
                    intent.putExtra("single_list_item_description", container.get(position).getSingle_list_item_description());
                    startActivity(intent); //start Activity
                }
            });
        }
        public void listDownload(){
            RequestQueue volley = Volley.newRequestQueue(this);
            JsonObjectRequest json = new JsonObjectRequest(Method.GET, URL_WEB_SERVICE, null, ResponseListener(), ErrorListener());
            volley.add(json);
        }

        private Response.Listener<JSONObject> ResponseListener() {
            return new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    try {
                        //your JSON Array
                        JSONArray array = response.getJSONArray("list_item");
                        for(int i = 0; i < array.length(); i++){
                            container.add(convertirAnuncio(array.getJSONObject(i)));
                        }
                    } catch (JSONException e) {
                        e.printStackTrace();
                    }
                    gv.setAdapter(new AdapterEvents(getApplicationContext(),container));
                    }
                };
            };


        private Response.ErrorListener ErrorListener() {
            return new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) { }
            };
        }

        //object JSON
        private final Events_List convertirAnuncio(JSONObject obj) throws JSONException {
            long id = obj.getLong("id"); //id 
            String list_item_name = obj.getString("list_item_name"); 
            String list_item_location = obj.getString("list_item_location"); 
            String list_item_description = obj.getString("list_item_description");
            String single_list_item_description = obj.getString("single_list_item_description");
            Uri uri = Uri.parse(obj.getString("list_item_bac"));
            return new Events_List(id, list_item_location, single_list_item_description,list_item_name,list_item_description,list_item_price, uri);
        }
    }

单项 Activity

public class CasualEventsSingleItemActivity extends Activity {

    // Declare Variables
    String list_item_name;
    String list_item_description;
    String list_item_price;
    String list_item_location;

    String single_list_item_description;




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





        Intent i = getIntent();
        list_item_name = i.getStringExtra("list_item_name");
        list_item_location = i.getStringExtra("list_item_location");

       // Uri uri = Uri.parse(obj.getString("list_item_bac"));


        single_list_item_description = i.getStringExtra("single_list_item_description");

        TextView txtname = (TextView) findViewById(R.id.name);
        TextView txtlocation = (TextView) findViewById(R.id.location);
        TextView txtsdescription = (TextView) findViewById(R.id.sdescription);


        ImageView hsvimage1 = (ImageView) findViewById(R.id.hsvimage1);
        ImageView hsvimage2 = (ImageView) findViewById(R.id.hsvimage2);
        ImageView hsvimage3 = (ImageView) findViewById(R.id.hsvimage3);



        // Set results to the TextViews
        txtname.setText(list_item_name);
        txtlocation.setText(list_item_location);
        txtsdescription.setText(single_list_item_description);


        Button mConfirm2 = (Button)findViewById(R.id.bConfirm2);
        mConfirm2.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                ParseUser currentUser = ParseUser.getCurrentUser();

               // Create the class and the columns
                currentUser.saveInBackground();

                currentUser.put("ActivityName", list_item_name); 
                currentUser.saveInBackground(new SaveCallback() {
                    @Override
                    public void done(ParseException e) {
                        setProgressBarIndeterminateVisibility(false);

                        if (e == null) {
                            // Success!
                            Intent intent = new Intent(CasualEventsSingleItemActivity.this, usermatch.class);
                            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
                            startActivity(intent);
                        }
                        else {
                            AlertDialog.Builder builder = new AlertDialog.Builder(CasualEventsSingleItemActivity.this);
                            builder.setMessage(e.getMessage())
                                .setTitle(R.string.signup_error_title)
                                .setPositiveButton(android.R.string.ok, null);
                            AlertDialog dialog = builder.create();
                            dialog.show();
                        }
                   }
               });
                //CasualEventsSingleItemActivity.this.startActivity(new Intent(CasualEventsSingleItemActivity.this, MatchingActivity.class));
            }
        });


    }
}

特别是，下面是我希望 JSON 数据与 ImageView 关联的行

 ImageView hsvimage1 = (ImageView) findViewById(R.id.hsvimage1);
    ImageView hsvimage2 = (ImageView) findViewById(R.id.hsvimage2);
    ImageView hsvimage3 = (ImageView) findViewById(R.id.hsvimage3);

单个项目布局 Activity 代码

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
        android:background="@drawable/blue_bac3"
    android:gravity="center"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginLeft="15dp"
         android:layout_marginTop="10dp"

        android:layout_marginRight="15dp"
        android:alpha="0.9"
        android:paddingBottom="3dp"
        android:shadowColor="#000000"
        android:shadowDx="3"
        android:shadowDy="3"
        android:shadowRadius="0.01"
        android:textColor="#82CAFF"
        android:textSize="24sp" />

    <TextView
        android:id="@+id/location"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/name"
        android:layout_centerHorizontal="true"
        android:layout_marginLeft="15dp"
        android:layout_marginRight="15dp"
        android:alpha="0.8"
        android:paddingBottom="5dp"
        android:shadowColor="#000000"
        android:shadowDx="3"
        android:shadowDy="3"
        android:shadowRadius="0.01"
        android:textAlignment="center"
        android:textColor="#f2f2f2"
        android:textSize="16sp" />

    <ImageView
        android:id="@+id/dividertop"
        android:layout_width="370dp"
        android:layout_centerHorizontal="true"
        android:layout_height="wrap_content"
        android:layout_below="@+id/location"
        android:alpha="0.6"
        android:background="@drawable/divider11"
        android:paddingBottom="3dp" />

    <ImageView
        android:id="@+id/dividerbottom"
        android:layout_width="370dp"
                android:layout_centerHorizontal="true"

        android:layout_height="wrap_content"
        android:layout_below="@+id/vsvdescription"
       android:alpha="0.6"
        android:background="@drawable/divider11"
        android:paddingBottom="3dp" />

    <ImageView
        android:id="@+id/image_head"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:background="#000000"
        android:padding="1dp" />

    <HorizontalScrollView
        android:id="@+id/isgallery"
        android:layout_width="370dp"
        android:layout_height="90dp"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/dividerbottom"
        android:layout_marginTop="8dp"
         >

            <LinearLayout
                android:orientation="horizontal"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" >

               <ImageView
                android:id="@+id/hsvimage1"
                android:layout_width="148dp"
                android:layout_height="90dp"
                android:layout_marginRight="6dp"
                android:layout_alignParentRight="true"
                android:background="#fff"
                android:padding="1dp" />
              <ImageView
                android:id="@+id/hsvimage2"
                android:layout_width="148dp"
                android:layout_height="90dp"
                android:layout_marginRight="6dp"
                android:layout_alignParentRight="true"
                android:background="#000000"
                android:padding="1dp" />
              <ImageView
                android:id="@+id/hsvimage3"
                android:layout_width="148dp"
                android:layout_height="90dp"
                android:layout_marginRight="6dp"
                android:layout_alignParentRight="true"
                android:background="#CCC"
                android:padding="1dp" />
              <ImageView
                android:id="@+id/hsvimage4"
                android:layout_width="148dp"
                android:layout_height="90dp"
                android:layout_alignParentRight="true"
                android:background="#000000"
                android:padding="1dp" />
                        </LinearLayout>

                  </HorizontalScrollView>

    <Button
        android:id="@+id/bConfirm2"
        android:layout_width="90dp"
        android:layout_height="50dp"
        android:layout_below="@+id/isgallery"
        android:layout_centerHorizontal="true"
        android:alpha="0.7"
        android:layout_marginTop="10dp"
        android:background="@drawable/gray_bac"
        android:text="Confirm"
        android:textColor="#2B3856"
        android:textStyle="bold" />

     <ScrollView
        android:id="@+id/vsvdescription"
        android:layout_width="370dp"
        android:layout_height="250dp"
        android:layout_marginTop="7dp"
        android:layout_marginBottom="7dp" 
        android:padding="5dp"       

        android:layout_centerHorizontal="true"
        android:layout_below="@+id/dividertop"
         >

            <RelativeLayout
                android:orientation="vertical"
                android:gravity="center"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" >

    <TextView
        android:id="@+id/sdescription"
        android:layout_width="370dp"
        android:layout_height="250dp"
        android:gravity="center"
        android:alpha="0.65"
        android:textColor="#ffffff"
        android:textSize="18sp" />

    </RelativeLayout>
    </ScrollView>

</RelativeLayout>

管理 JSON 字符串的 Activity 类

public class Events_List {
public long id;
public String list_item_title;
public String list_item_location;
public String list_item_price;
public Uri single_list_item_bac;
public String list_item_description;
public String single_list_item_description;

public Uri url;

public Events_List(long id, String list_item_location, String single_list_item_description, String list_item_title, String list_item_description, String list_item_price, Uri url){
    this.id = id;
    this.list_item_title = list_item_title;
    this.list_item_location = list_item_location;
    this.list_item_description = list_item_description;
    this.single_list_item_description = single_list_item_description;
    this.list_item_price = list_item_price;
    this.url = url;
}

public String getList_item_title()
{
    return this.list_item_title;
}

public String getList_item_location()
{
    return this.list_item_location;
}

public String getList_item_price()
{
    return this.list_item_price;
}

public String getList_item_description()
{
    return this.list_item_description;
}

public String getSingle_list_item_description()
{
    return this.single_list_item_description;
}


} 

如果您需要进一步说明，请告诉我。提前致谢

更新

public class CasualEventsSingleItemActivity extends Activity {

    // Declare Variables
    String list_item_name;
    String list_item_description;
    String list_item_price;
    String list_item_location;

    String single_list_item_description;




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


        RequestQueue mRequestQueue = null;
        ImageLoader mImageLoader = new ImageLoader(mRequestQueue,
                new ImageLoader.ImageCache() {
            private final LruCache<String, Bitmap>
                    cache = new LruCache<String, Bitmap>(20);

            @Override
            public Bitmap getBitmap(String url) {
                return cache.get(url);
            }

            @Override
            public void putBitmap(String url, Bitmap bitmap) {
                cache.put(url, bitmap);
            }
        });


        Intent i = getIntent();
        list_item_name = i.getStringExtra("list_item_name");
        list_item_location = i.getStringExtra("list_item_location");



        single_list_item_description = i.getStringExtra("single_list_item_description");

        TextView txtname = (TextView) findViewById(R.id.name);
        TextView txtlocation = (TextView) findViewById(R.id.location);
        TextView txtsdescription = (TextView) findViewById(R.id.sdescription);


        NetworkImageView hsvimage1 = (NetworkImageView) findViewById(R.id.hsvimage1);
        NetworkImageView hsvimage2 = (NetworkImageView) findViewById(R.id.hsvimage2);
        NetworkImageView hsvimage3 = (NetworkImageView) findViewById(R.id.hsvimage3);

        // Get image URLs from your previous network request...
        // I could not determine where this is stored from code in your question.
        String url1 = "list_item_bac";   // e.g. http://example.com/images/image1.png
        String url2 = "list_item_bac";
        String url3 = "list_item_bac";

        // Set the URL of the image that should be loaded into this view, and
        // specify the ImageLoader that will be used to make the request.
        hsvimage1.setImageUrl(url1, mImageLoader);
        hsvimage2.setImageUrl(url2, mImageLoader);
        hsvimage3.setImageUrl(url3, mImageLoader);


        // Set results to the TextViews
        txtname.setText(list_item_name);
        txtlocation.setText(list_item_location);
        txtsdescription.setText(single_list_item_description);


        Button mConfirm2 = (Button)findViewById(R.id.bConfirm2);
        mConfirm2.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                ParseUser currentUser = ParseUser.getCurrentUser();

               // Create the class and the columns
                currentUser.saveInBackground();

                currentUser.put("ActivityName", list_item_name); 
                currentUser.saveInBackground(new SaveCallback() {
                    @Override
                    public void done(ParseException e) {
                        setProgressBarIndeterminateVisibility(false);

                        if (e == null) {
                            // Success!
                            Intent intent = new Intent(CasualEventsSingleItemActivity.this, usermatch.class);
                            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
                            startActivity(intent);
                        }
                        else {
                            AlertDialog.Builder builder = new AlertDialog.Builder(CasualEventsSingleItemActivity.this);
                            builder.setMessage(e.getMessage())
                                .setTitle(R.string.signup_error_title)
                                .setPositiveButton(android.R.string.ok, null);
                            AlertDialog dialog = builder.create();
                            dialog.show();
                        }
                   }
               });
                //CasualEventsSingleItemActivity.this.startActivity(new Intent(CasualEventsSingleItemActivity.this, MatchingActivity.class));
            }
        });

    }
}

Answer 1

我会使用 Volley 的 NetworkImageView和 ImageLoader这将在后台为您完成所有艰苦的工作。

首先，将所有 ImageView 更改为 NetworkImageView:

           <com.android.volley.toolbox.NetworkImageView
            android:id="@+id/hsvimage1"
            ... />
          <com.android.volley.toolbox.NetworkImageView
            android:id="@+id/hsvimage2"
            ... />
          <com.android.volley.toolbox.NetworkImageView
            android:id="@+id/hsvimage3"
            ... />

接下来，创建一个 ImageLoader。您很可能希望创建一个单例来保存它:

    mImageLoader = new ImageLoader(Volley.newRequestQueue(this),
            new ImageLoader.ImageCache() {
        private final LruCache<String, Bitmap>
                cache = new LruCache<String, Bitmap>(20);

        @Override
        public Bitmap getBitmap(String url) {
            return cache.get(url);
        }

        @Override
        public void putBitmap(String url, Bitmap bitmap) {
            cache.put(url, bitmap);
        }
    });

然后剩下要做的就是为每个 NetworkImageView 设置 URL。

NetworkImageView hsvimage1 = (NetworkImageView) findViewById(R.id.hsvimage1);
NetworkImageView hsvimage2 = (NetworkImageView) findViewById(R.id.hsvimage2);
NetworkImageView hsvimage3 = (NetworkImageView) findViewById(R.id.hsvimage3);

// Get image URLs from your previous network request...
// I could not determine where this is stored from code in your question.
String url1 = ...;   // e.g. http://example.com/images/image1.png
String url2 = ...;
String url3 = ...;

// Set the URL of the image that should be loaded into this view, and
// specify the ImageLoader that will be used to make the request.
hsvimage1.setImageUrl(url1, mImageLoader);
hsvimage2.setImageUrl(url2, mImageLoader);
hsvimage3.setImageUrl(url3, mImageLoader);