我正在使用 JSON 将数据输入 ListView，但对于第一个级别列表，我使用的是静态代码，简而言之，第一级列表没有使用 JSON，请参见下面的代码用于显示第一级列表。
类别屏幕 （以静态方式显示数据）
产品屏幕 （使用 JSON 获取数据）
类别活动.java：
public class CategoriesActivity extends Activity implements OnItemClickListener {
ListView lview3;
ListViewCustomAdapter adapter;
private ArrayList<Object> itemList;
private ItemBean bean;
ImageButton checkOut;
ImageButton back;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_menus);
prepareArrayLits();
lview3 = (ListView) findViewById(R.id.listView1);
adapter = new ListViewCustomAdapter(this, itemList);
lview3.setAdapter(adapter);
lview3.setOnItemClickListener(this);
}
private static final int Sony = 0;
private static final int Panasonic = 1;
public void onItemClick(AdapterView<?> arg0, View arg1, int position, long id) {
// Set up different intents based on the item clicked:
switch (position)
{
case Sony:
Intent intent1 = new Intent(CategoriesActivity.this, ProductsActivity.class);
intent1.putExtra("category", "Sony");
startActivity(intent1);
break;
case Panasonic:
Intent intent2 = new Intent(CategoriesActivity.this, ProductsActivity.class);
intent2.putExtra("category", "Panasonic");
startActivity(intent2);
break;
default:
break;
}
}
public void prepareArrayLits()
{
itemList = new ArrayList<Object>();
AddObjectToList( "Sony" );
AddObjectToList( "Panasonic" );
}
// Add one item into the Array List
public void AddObjectToList(String title)
{
bean = new ItemBean();
bean.setTitle(title);
itemList.add(bean);
}
}
项目Bean.java：
public class ItemBean
{
String title;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
}
ListViewCustomAdapter.java：
public class ListViewCustomAdapter extends BaseAdapter{
ArrayList<Object> itemList;
public Activity context;
public LayoutInflater inflater;
public ListViewCustomAdapter(Activity context,ArrayList<Object> itemList) {
super();
this.context = context;
this.itemList = itemList;
this.inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount() {
// TODO Auto-generated method stub
return itemList.size();
}
public Object getItem(int position) {
// TODO Auto-generated method stub
return itemList.get(position);
}
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
public static class ViewHolder
{
TextView txtViewTitle;
}
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
ViewHolder holder;
if(convertView==null)
{
holder = new ViewHolder();
convertView = inflater.inflate(R.layout.listrow_categories, null);
holder.txtViewTitle = (TextView) convertView.findViewById(R.id.title);
convertView.setTag(holder);
}
else
holder=(ViewHolder)convertView.getTag();
ItemBean bean = (ItemBean) itemList.get(position);
holder.txtViewTitle.setText(bean.getTitle());
return convertView;
}
}
并使用以下代码将数据放入二级列表（即：产品列表），
ProductsActivity.java:-
public class ProductsActivity extends Activity {
static String URL = "http://10.0.2.2/android/test.json";
static String KEY_CATEGORY = "item";
static final String KEY_TITLE = "ProductName";
ListView list;
LazyAdapter adapter;
/** Called when the activity is first created. */
@SuppressWarnings("deprecation")
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_menus);
final ArrayList<HashMap<String, String>> itemsList = new ArrayList<HashMap<String, String>>();
list = (ListView) findViewById(R.id.listView1);
adapter = new LazyAdapter(this, itemsList);
list.setAdapter(adapter);
if (isNetworkAvailable()) {
new MyAsyncTask().execute();
} else {
AlertDialog alertDialog = new AlertDialog.Builder(ProductsActivity.this).create();
alertDialog.setMessage("The Internet connection appears to be offline.");
alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
});
alertDialog.show();
}
}
private boolean isNetworkAvailable() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
NetworkInfo info = cm.getActiveNetworkInfo();
return (info != null);
}
class MyAsyncTask extends
AsyncTask<String, Integer, ArrayList<HashMap<String, String>>> {
private ProgressDialog progressDialog = new ProgressDialog(
ProductsActivity.this);
@Override
protected void onPreExecute() {
progressDialog.setMessage("Loading, Please wait.....");
progressDialog.show();
}
final ArrayList<HashMap<String, String>> itemsList = new ArrayList<HashMap<String, String>>();
@Override
protected ArrayList<HashMap<String, String>> doInBackground(
String... params) {
HttpClient client = new DefaultHttpClient();
// Perform a GET request for a JSON list
HttpUriRequest request = new HttpGet(URL);
// Get the response that sends back
HttpResponse response = null;
try {
response = client.execute(request);
} catch (ClientProtocolException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
// Convert this response into a readable string
String jsonString = null;
try {
jsonString = StreamUtils.convertToString(response.getEntity()
.getContent());
} catch (IllegalStateException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
// Create a JSON object that we can use from the String
JSONObject json = null;
try {
json = new JSONObject(jsonString);
} catch (JSONException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
JSONArray jsonArray = json.getJSONArray(KEY_CATEGORY);
for (int i = 0; i < jsonArray.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
JSONObject jsonObject = jsonArray.getJSONObject(i);
map.put("KEY", String.valueOf(i));
map.put(KEY_TITLE, jsonObject.getString(KEY_TITLE));
itemsList.add(map);
}
return itemsList;
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
return null;
}
@Override
protected void onPostExecute(ArrayList<HashMap<String, String>> result) {
list = (ListView) findViewById(R.id.listView1);
adapter = new LazyAdapter(ProductsActivity.this, itemsList);
list.setAdapter(adapter);
this.progressDialog.dismiss();
list.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
}
});
}
}
}
LazyAdapter.java：
public class LazyAdapter extends BaseAdapter {
private Activity activity;
private ArrayList<HashMap<String, String>> data;
private static LayoutInflater inflater=null;
public LazyAdapter(Activity a, ArrayList<HashMap<String, String>> d) {
activity = a;
data=d;
inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount() {
return data.size();
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
View vi=convertView;
if(convertView==null)
vi = inflater.inflate(R.layout.listrow_products, null);
TextView title = (TextView)vi.findViewById(R.id.title);
HashMap<String, String> item = new HashMap<String, String>();
item = data.get(position);
// Setting all values in listview
title.setText(item.get(ProductsActivity.KEY_TITLE));
return vi;
}
}
StreamUtils.java:-
public class StreamUtils {
public static String convertToString(InputStream inputStream) throws IOException {
if (inputStream != null) {
Writer writer = new StringWriter();
char[] buffer = new char[1024];
try {
Reader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 1024);
int n;
while ((n = reader.read(buffer)) != -1) {
writer.write(buffer, 0, n);
}
} finally {
inputStream.close();
}
return writer.toString();
} else {
return "";
}
}
}
问题：
如何使用 JSON 获取一级列表，而不是像我在现有程序中编写的那样编写静态代码？
测试.json：
{
"Sony": [{
"ProductID": "1",
"ProductName": "Sony - LED TV"
}, {
"ProductID": "2",
"ProductName": "Sony - Laptop"
}],
"Panasonic": [{
"ProductID": "1",
"ProductName": "Panasonic - LED TV"
}, {
"ProductID": "2",
"ProductName": "Panasonic - Laptop"
}]
}