java - 在android中的 ListView 上无法从服务器获取数据

Question

我正在处理 json 解析，在我的 TypeMenu java 文件中，我从服务器获取响应，当我单击 ListView 中的项目时，我应该在 ListView 中的下一个 Activity 中获取相关项目..该 ListView 项目也来自服务器...这里我只想从选定的项目中获取项目..但是我在下一个 Activity 中从数据库获取所有项目，即 SubMenu.java...就像如果我选择 Pizza，那么在下一个 Activity 中我应该获得与项目相关的项目只含披萨这是我的 TypeMenu.java 文件 包 com.example.zeba.broccoli;

  import android.app.ProgressDialog;
  import android.content.Intent;
  import android.os.AsyncTask;
  import android.os.Bundle;
  import android.support.v7.app.AppCompatActivity;
  import android.support.v7.widget.Toolbar;
  import android.util.Log;
  import android.view.MenuItem;
  import android.view.View;
  import android.widget.AdapterView;
  import android.widget.ListAdapter;
  import android.widget.ListView;
  import android.widget.SimpleAdapter;
  import android.widget.TextView;
  import android.widget.Toast;

  import org.json.JSONArray;
  import org.json.JSONException;
  import org.json.JSONObject;

  import java.util.ArrayList;
  import java.util.HashMap;



 public class TypeMenu extends AppCompatActivity {

 private String TAG = TypeMenu.class.getSimpleName();
 String bid;

private ProgressDialog pDialog;
private ListView lv;
private static final String TAG_BID = "bid";

// URL to get contacts JSON
private static String url = "http://cloud.granddubai.com/brtemp/index.php";

ArrayList<HashMap<String, String>> contactList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_type_menu);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);




    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    contactList = new ArrayList<>();

    lv = (ListView) findViewById(R.id.list);

    new GetContacts().execute();


    // on seleting single product
    // launching Edit Product Screen
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

            // getting values from selected ListItem

            HashMap<String, String> selected = contactList.get(position);
            String keyId = new ArrayList<>(selected.keySet()).get(0);
            String type_items  = selected.get(keyId);
            Intent in = new Intent(getApplicationContext(), SubMenu.class);
           //  sending pid to next activity
            in.putExtra(TAG_BID ,type_items );
            startActivityForResult(in, 100);
            Toast.makeText(getApplicationContext(),"Toast" +type_items ,Toast.LENGTH_LONG).show();
        }
    });













}

/**
 * Async task class to get json by making HTTP call
 */
private class GetContacts extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(TypeMenu.this);
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);
        pDialog.show();
       // Toast.makeText(getApplicationContext(),"Toast",Toast.LENGTH_LONG).show();

    }

    @Override
    protected Void doInBackground(Void... arg0) {
        HttpHandler sh = new HttpHandler();

        // Making a request to url and getting response
     String jsonStr = sh.makeServiceCall(url);

        Log.e(TAG, "Response from url: " + jsonStr);





        if (jsonStr != null) {
            try {
                JSONArray jsonArry = new JSONArray(jsonStr);

                for (int i = 0; i < jsonArry.length(); i++)
                {

                    JSONObject c = jsonArry.getJSONObject(i);
                    String id = c.getString("id");
                    String type = c.getString("type");
                    HashMap<String, String> contact = new HashMap<>();

                   contact.put("id", id);
                    contact.put("type", type);
                    contactList.add(contact);


                }
            } catch (final JSONException e) {
                Log.e(TAG, "Json parsing error: " + e.getMessage());
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(),
                                "Json parsing error: " + e.getMessage(),
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });

            }
        } else {
            Log.e(TAG, "Couldn't get json from server.");
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(),
                            "Couldn't get json from server. Check LogCat for possible errors!",
                            Toast.LENGTH_LONG)
                            .show();
                }
            });

        }

           return null;
       }



        @Override
             protected void onPostExecute(Void result) {
              super.onPostExecute(result);
            // Dismiss the progress dialog
            if (pDialog.isShowing())
                pDialog.dismiss();
            /**
             * Updating parsed JSON data into ListView
             * */
               ListAdapter adapter = new SimpleAdapter(
                    TypeMenu.this, contactList,
                    R.layout.list_item, new String[]{ "type","id"},
                    new int[]{
                    R.id.type,R.id.id});

            lv.setAdapter(adapter);
        }

}
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                onBackPressed();
                return true;
            default:
                return super.onOptionsItemSelected(item);
            }
          }
          }

这是我的 SubMenu.java 文件

        package com.example.zeba.broccoli;

import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;



public class SubMenu  extends AppCompatActivity {

    private String TAG = SubMenu.class.getSimpleName();
    String type_items ;

    private ProgressDialog pDialog;
    private ListView lv;
    private static final String TAG_BID = "bid";

    // URL to get contacts JSON
    private static String url = "http://cloud.granddubai.com/broccoli/menu_typeitem.php";

    ArrayList<HashMap<String, String>> contactList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_type_menu);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);


        Intent i = getIntent();

        // getting product id (pid) from intent
        type_items = i.getStringExtra(TAG_BID);
        Toast.makeText(getApplicationContext(),"Toast 12" + type_items ,Toast.LENGTH_LONG).show();

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        contactList = new ArrayList<>();

        lv = (ListView) findViewById(R.id.list);

        new GetContacts().execute();


        // on seleting single product
        // launching Edit Product Screen
        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                pDialog = new ProgressDialog(SubMenu.this);
                pDialog.setMessage("Loading book details.");
                pDialog.setIndeterminate(false);
                pDialog.setCancelable(true);
                pDialog.show();
                // getting values from selected ListItem

                HashMap<String, String> selected = contactList.get(position);
                String keyId = new ArrayList<>(selected.keySet()).get(0);
                String type_items = selected.get(keyId);
                //Intent in = new Intent(getApplicationContext(), SubMenu.class);
                // sending pid to next activity
                // in.putExtra(TAG_BID ,text);
                //startActivityForResult(in, 100);
                Toast.makeText(getApplicationContext(),"Toast" + type_items,Toast.LENGTH_LONG).show();
            }
        });













    }

    /**
     * Async task class to get json by making HTTP call
     */
    private class GetContacts extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            // Showing progress dialog
            pDialog = new ProgressDialog(SubMenu.this);
            pDialog.setMessage("Please wait...");
            pDialog.setCancelable(false);
            pDialog.show();
            // Toast.makeText(getApplicationContext(),"Toast",Toast.LENGTH_LONG).show();

        }

        @Override
        protected Void doInBackground(Void... arg0) {
            HttpHandler sh = new HttpHandler();

            // Making a request to url and getting response
            String jsonStr = sh.makeServiceCall(url);

            Log.e(TAG, "Response from url: " + jsonStr);





            if (jsonStr != null) {
                try {
                    JSONArray jsonArry = new JSONArray(jsonStr);

                    for (int i = 0; i < jsonArry.length(); i++)
                    {

                        JSONObject c = jsonArry.getJSONObject(i);
                        String id = c.getString("id");
                        String name = c.getString("name");
                        HashMap<String, String> contact = new HashMap<>();

                        contact.put("id", id);
                        contact.put("name", name);
                        contactList.add(contact);


                    }
                } catch (final JSONException e) {
                    Log.e(TAG, "Json parsing error: " + e.getMessage());
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Toast.makeText(getApplicationContext(),
                                    "Json parsing error: " + e.getMessage(),
                                    Toast.LENGTH_LONG)
                                    .show();
                        }
                    });

                }
            } else {
                Log.e(TAG, "Couldn't get json from server.");
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(),
                                "Couldn't get json from server. Check LogCat for possible errors!",
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });

            }

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            // Dismiss the progress dialog
            if (pDialog.isShowing())
                pDialog.dismiss();
            /**
             * Updating parsed JSON data into ListView
             * */
            ListAdapter adapter = new SimpleAdapter(
                    SubMenu.this, contactList,
                    R.layout.list_item, new String[]{ "name","id"},
                    new int[]{
                            R.id.type});
            lv.setAdapter(adapter);
        }

    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                onBackPressed();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}

这是我的 php 文件..我知道它将显示所有数据..我也尝试了其他代码但不起作用..至少显示了表中的所有数据..但我只想要选定的数据

     <?php 

 if($_SERVER['REQUEST_METHOD']=='GET')
 {


 $id  = $_GET['type_items'];

 require_once('config.php');

 $sql = "SELECT * FROM main_menu_items WHERE type_item='".$id."'";

 $r = mysqli_query($con,$sql);

 $res = mysqli_fetch_array($r);

 $result = array();

 array_push($result,array("name"=>$res['name'],)
 );

 echo json_encode(array("result"=>$result));

 mysqli_close($con);

 }

Answer 1

将 SubMenu.java 类的 GetContacts 的 for 循环替换为以下内容:

  for (int i = 0; i < jsonArry.length(); i++) {

        JSONObject c = jsonArry.getJSONObject(i);
        String id = c.getString("id");
        String name = c.getString("name");
        String type = c.getString("type");
        if (type.equalsIgnoreCase(type_items)) {
            HashMap<String, String> contact = new HashMap<>();
            contact.put("id", id);
            contact.put("name", name);
            contactList.add(contact);
            break;
        }
    }

在子菜单类中，您需要检查所选 ID 是否与 ID 匹配，只需将该数据保存在列表中并中断循环。