java - 如何将 json 代码获取到我的应用程序中

标签 java android json listview

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。

在这里，我只想从选定的项目中获取项目，但我在下一个 Activity SubMenu.java 中从数据库中获取所有项目。就像如果我选择 Pizza，那么在下一个 Activity 中我应该只获取与 Pizza 相关的项目这是我的 TypeMenu.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 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..

<?php 
include ('config.php');

if (isset($_GET["mid"])) 
{
    $type_items = $_GET['mid'];

$sql = mysqli_query($conn,"SELECT * FROM main_menu_items WHERE type_items = '".$type_items."'");                                                          
$arr = array();
$i=0;
while($result = mysqli_fetch_array($sql))
{
$arr[$i]['id']= $result['id'];
$arr[$i]['name']= $result['name'];
$i++;
}
}
echo json_encode($arr);

?>

在这里，当我在浏览器上使用网址时，我没有得到任何内容，只有 null 被写入，如果我在设备上检查它，它会显示这样的错误 “Json 解析错误:org.json.JSONObject$1 类型的值 null 无法转换为 JsonArray”

最佳答案

别做这种傻事

只需添加 Json Libray 从 http://www.java2s.com/Code/Jar/g/Downloadgson222jar.htm 下载 或者

dependencies {
  compile 'com.google.code.gson:gson:2.6.2'
}

就照着做吧 电影是 pojo 类的响应

Gson gson = new GsonBuilder().create();
Movie movie = gson.fromJson(response, Movie.class);

更多详细信息 - https://guides.codepath.com/android/Leveraging-the-Gson-Library和 https://stackoverflow.com/a/22754230/4741746和 https://stackoverflow.com/a/28392599/4741746

创建类，例如

public class Responce implements Serializable {

    @SerializedName("result")
    public ArrayList<Data>  result;

    public class Data implements Serializable {

    @SerializedName("name")
    public String  name;


    }
}

然后在响应中解析它(将这 3 行放在该行 String jsonStr = sh.makeServiceCall(url); 这一行下面)

Gson gson = new GsonBuilder().create();
Responce mResponce = gson.fromJson(jsonStr , Responce .class);
String mName =mResponce.result.name;

关于java - 如何将 json 代码获取到我的应用程序中，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41217629/

上一篇：java - 使用 JPA 和 Hibernate : Persistence. xml 进行 JUnit 测试

下一篇：java - 我们能否将延迟和吞吐量与并行性联系起来

相关文章：

android - 取消所有 AsyncTask？

javascript - 通过名称获取 JSON 对象的属性

php - 从数据库表android中获取行

java - 自动从实体类更新/复制/继承DTO javadoc

java - 使用 JDBC 读取 Oracle DB 中的 XMLType 列

android - listview 每个项目动态改变背景颜色

javascript - 每次使用angularjs调用函数时如何附加web服务json数据

java - 将字符设置为 EOF

java - H2 数据库 Java Servlet 连接路径问题

android - 如何在 Android Q 中拍照并保存？

©2024 IT工具网  联系我们