php - 滚动期间的Android json listview loadmore

Question

首先我需要加载前 10 个内容，如果我滚动列表视图然后加载另外 10 个内容。

private String jsonResult;
public static final int DIALOG_DOWNLOAD_JSON_PROGRESS = 0;
private String url = "http://192.1.1.1/xxxx/myphp.php";
String urll = url;
private ListView listView;
private static final String HTTP_REQUEST_FAILED = null;
int[] flags;
String strImageName;
int n = 10000;
String[] mySecondStringArray = new String[n];
String[] strArray;
private ProgressDialog mProgressDialog;
HashMap<String, String> hm;
List<HashMap<String, String>> aList;
boolean flag_loading = true;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    Button b = (Button) findViewById(R.id.button1);
    listView = (ListView) findViewById(R.id.listview);
    try {
        accessWebService();
    } catch (Exception e) {
        Toast.makeText(getApplicationContext(),
                "Check ur network connection", 10000).show();
    }
    b.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            additem();
        }
    });
    listView.setOnScrollListener(new OnScrollListener() {

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {

        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {

            // what is the bottom iten that is visible

            // int lastInScreen = firstVisibleItem + visibleItemCount;
            if (firstVisibleItem + visibleItemCount == totalItemCount
                    && totalItemCount != 0) {
                if (flag_loading == false) {
                    flag_loading = true;
                    Toast.makeText(getApplicationContext(), "fh", 1000)
                            .show();

                    additem();
                }
            }
        }
    });
}

@Override
protected Dialog onCreateDialog(int id) {
    switch (id) {
    case DIALOG_DOWNLOAD_JSON_PROGRESS:
        mProgressDialog = new ProgressDialog(this);
        mProgressDialog.setMessage("Please wait.....");
        mProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        mProgressDialog.setCancelable(true);
        mProgressDialog.show();
        return mProgressDialog;

    default:
        return null;
    }
}

// Async Task to access the web
private class JsonReadTask extends AsyncTask<String, Void, String> {
    protected void onPreExecute() {
        super.onPreExecute();
        showDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
    }

    @Override
    protected String doInBackground(String... params) {
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(params[0]);
        try {
            HttpResponse response = httpclient.execute(httppost);
            jsonResult = inputStreamToString(
                    response.getEntity().getContent()).toString();
        }

        catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    private StringBuilder inputStreamToString(InputStream is) {
        String rLine = "";
        StringBuilder answer = new StringBuilder();
        BufferedReader rd = new BufferedReader(new InputStreamReader(is));

        try {
            while ((rLine = rd.readLine()) != null) {
                answer.append(rLine);
            }
        }

        catch (IOException e) {
            // e.printStackTrace();
            Toast.makeText(getApplicationContext(),
                    "Error..." + e.toString(), Toast.LENGTH_LONG).show();
        }
        return answer;
    }

    @Override
    protected void onPostExecute(String result) {

        ListDrwaer();

        dismissDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);

    }
}

public void accessWebService() {
    JsonReadTask task = new JsonReadTask();
    // passes values for the urls string array
    task.execute(new String[] { url });
}

public void ListDrwaer() {
    flag_loading = false;
    try {
        JSONObject jsonResponse = new JSONObject(jsonResult);
        JSONArray jsonMainNode = jsonResponse.optJSONArray("products");

        aList = new ArrayList<HashMap<String, String>>();
        for (int i = 0; i < jsonMainNode.length(); i++) {
            JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
            String name = jsonChildNode.optString("name");

            hm = new HashMap<String, String>();
            hm.put("txt", name);
            // hm.put("cur", number);

            aList.add(hm);

        }
    } catch (JSONException e) {
        Toast.makeText(getApplicationContext(), "Error" + e.toString(),
                Toast.LENGTH_SHORT).show();
    }
    String[] from = { "flag", "txt" };
    int[] to = { R.id.flag, R.id.txt };
    SimpleAdapter adapter = new SimpleAdapter(getBaseContext(), aList,
            R.layout.news, from, to);
    listView.setAdapter(adapter);

}

public void additem() {

    try {
        JSONObject jsonResponse = new JSONObject(jsonResult);
        JSONArray jsonMainNode = jsonResponse.optJSONArray("tablename");

        aList = new ArrayList<HashMap<String, String>>();

        for (int i = 0; i < jsonMainNode.length(); i++) {
            JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
            String name = jsonChildNode.optString("fieldname");

            hm = new HashMap<String, String>();
            hm.put("txt", name);
            // hm.put("cur", number);

            aList.add(hm);

        }
    } catch (JSONException e) {
        Toast.makeText(getApplicationContext(), "Error" + e.toString(),
                Toast.LENGTH_SHORT).show();
    }
    String[] from = { "flag", "txt" };
    int[] to = { R.id.flag, R.id.txt };
    SimpleAdapter adapter = new SimpleAdapter(getBaseContext(), aList,
            R.layout.news, from, to);

    listView.setAdapter(adapter);
    adapter.notifyDataSetChanged();

    flag_loading = true;

}

}

我的 php 文件

<?php
$host="localhost"; //replace with database hostname 
$username="root"; //replace with database username 
$password=""; //replace with database password 
$db_name="databasename"; //replace with database name

$con=mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");




$sql = "SELECT * FROM tablename LIMIT 10"; 

$result1 = mysql_query($sql);

$json = array();

if(mysql_num_rows($result1)){
while($row=mysql_fetch_assoc($result1)){
$json['tablename'][]=$row;
}
}


mysql_close($con);
echo json_encode($json); 

?> 

我使用此代码并进行了很多搜索，但我找不到解决方案。如果有人知道尽快发布您的答案。