我一直在学习如何在 Android 中使用 php 和 JSON，我正在尝试使用 PHP 将 SQL 数据读入 JSON，然后再读入 Android。我的错误是什么？
PHP
<?php
//PDO is a extension which defines a lightweight, consistent interface for accessing databases in PHP.
$db=new PDO('mysql:dbname=mydb;host=localhost;','root','');
//here prepare the query for analyzing, prepared statements use less resources and thus run faster
$row=$db->prepare('select * from drinks');
$row->execute();//execute the query
$json_data=array();//create the array
foreach($row as $rec)//foreach loop
{
$json_array['drinks_id']=$rec['drinks_id'];
$json_array['drink_name']=$rec['drink_name'];
$json_array['Description']=$rec['Description'];
//here pushing the values in to an array
array_push($json_data,$json_array);
}
//built in PHP function to encode the data in to JSON format
//print_r($json_array);
echo json_encode($json_data);
?>
JSON 输出（示例）
{
"0":{
"drinks_id":"1",
"drink_name":"Uprising Treason West Coast IPA",
"Description":"Beer"
},
"1":{
"drinks_id":"2",
"drink_name":"Flying Dog Snake Dog IPA",
"Description":"Beer"
},
"2":{
"drinks_id":"3",
"drink_name":"Crafty Dan 13 Guns America IPA",
"Description":"Beer"
},
"3":{
"drinks_id":"4",
"drink_name":"Sixpoint Resin Double IPA",
"Description":"Beer"
},
"4":{
"drinks_id":"5",
"drink_name":"Sixpoint Bengali IPA",
"Description":"Beer"
},
"5":{
"drinks_id":"6",
"drink_name":"ShipYard ",
"Description":"Beer"
},
"6":{
"drinks_id":"7",
"drink_name":"Blue Moon Belgian White ",
"Description":"Beer"
},
"7":{
"drinks_id":"8",
"drink_name":"BrewDog Punk IPA ",
"Description":"Beer"
},
"8":{
"drinks_id":"9",
"drink_name":"Lagunitas IPA",
"Description":"Beer"
},
"9":{
"drinks_id":"10",
"drink_name":"Brooklyn Larger ",
"Description":"Larger"
},
"10":{
"drinks_id":"11",
"drink_name":"Hazy Hog Cloudy English Cider ",
"Description":"Cider"
},
"11":{
"drinks_id":"12",
"drink_name":"Angry Orchard ",
"Description":"Cider"
},
"12":{
"drinks_id":"13",
"drink_name":"Aspall Suffolk Cyder ",
"Description":"Cider"
},
"13":{
"drinks_id":"14",
"drink_name":"Devils Backbone ",
"Description":"Cider"
},
"14":{
"drinks_id":"15",
"drink_name":"Carlsburg",
"Description":""
},
"15":{
"drinks_id":"16",
"drink_name":"Foster' s",
"Description":""
},
"16":{
"drinks_id":"17",
"drink_name":"Carling ",
"Description":""
},
"17":{
"drinks_id":"18",
"drink_name":"Coors Light",
"Description":""
},
"18":{
"drinks_id":"19",
"drink_name":"Tuborg ",
"Description":""
},
"19":{
"drinks_id":"20",
"drink_name":"Stella Artois",
"Description":""
},
"20":{
"drinks_id":"21",
"drink_name":"San Miguel ",
"Description":""
},
"21":{
"drinks_id":"22",
"drink_name":"Kronenbourg 1664",
"Description":""
},
"22":{
"drinks_id":"23",
"drink_name":"Heineken",
"Description":""
},
"23":{
"drinks_id":"24",
"drink_name":"Birra Moretti",
"Description":""
},
"24":{
"drinks_id":"25",
"drink_name":"Tsingtao",
"Description":""
},
"25":{
"drinks_id":"26",
"drink_name":"Erdinger",
"Description":""
},
"26":{
"drinks_id":"27",
"drink_name":"Tsyskie Gronie",
"Description":""
},
"27":{
"drinks_id":"28",
"drink_name":"Krombacher Pils",
"Description":""
},
"28":{
"drinks_id":"29",
"drink_name":"Tucher Helles Hefe Weizen",
"Description":""
},
"29":{
"drinks_id":"30",
"drink_name":"Newcastle Brown Ale",
"Description":""
},
"30":{
"drinks_id":"31",
"drink_name":"Efes ",
"Description":""
},
"31":{
"drinks_id":"32",
"drink_name":"Baltika 7",
"Description":""
},
"32":{
"drinks_id":"33",
"drink_name":"Devils Backbone",
"Description":""
},
"33":{
"drinks_id":"34",
"drink_name":"Sharps Doom Bar",
"Description":""
},
"34":{
"drinks_id":"35",
"drink_name":"Green King IPA",
"Description":""
},
"35":{
"drinks_id":"36",
"drink_name":"Abbot Ale",
"Description":""
},
"36":{
"drinks_id":"37",
"drink_name":"John Smiths",
"Description":""
},
"37":{
"drinks_id":"38",
"drink_name":"Guinness",
"Description":""
}
}
主要活动
package northampton.josh.pubapp;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.StrictMode;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.ContextThemeWrapper;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.HashMap;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "Menu";
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "http://192.168.0.11:80/Pub%20crud/GetDrinks4.php";
ArrayList<HashMap<String, String>> drinkList;
@Override
protected void onCreate(Bundle savedInstanceState) {
Log.i(TAG, TAG + ":Menu Started");
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
createMenuButtons();
Log.i(TAG, "Attempting to connect ");
drinkList = new ArrayList<>();
new GetDrinks().execute();
}
//Add buttons to the menu bar to allow navigation between pages
private void createMenuButtons() {
//Get the layout on the left hand side
LinearLayout menu = (LinearLayout) findViewById(R.id.menu);
//Get the style for the buttons
ContextThemeWrapper menuStyle = new ContextThemeWrapper(this, R.style.menuButton);
Button customer = new Button(menuStyle);
customer.setText("Customer");
customer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, Customer.class));
}
});
Button staff = new Button(menuStyle);
staff.setText("Bar");
staff.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, Staff.class));
}
});
Button manager = new Button(menuStyle);
manager.setText("Manager");
manager.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, Manager.class));
}
});
Button settings = new Button(menuStyle);
settings.setText("Settings");
settings.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, Settings.class));
}
});
menu.addView(customer);
menu.addView(staff);
menu.addView(manager);
menu.addView(settings);
}
private class GetDrinks extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray drinks = jsonObj.getJSONArray("0");
// looping through All Contacts
for (int i = 0; i < drinks.length(); i++) {
JSONObject c = drinks.getJSONObject(i);
String drinks_id = c.getString("drinks_id");
String drink_name = c.getString("drink_name");
String Description = c.getString("Description");
// tmp hash map for single contact
HashMap<String, String> drink = new HashMap<>();
// adding each child node to HashMap key => value
drink.put("drinks_id", drinks_id);
drink.put("drink_name", drink_name);
drink.put("Description", Description);
// adding contact to contact list
drinkList.add(drink);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
e.printStackTrace();
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();
}
}
}
HTTP 处理程序
package northampton.josh.pubapp;
import android.util.Log;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
/**
* Created by Josh on 30/01/2017.
*/
public class HttpHandler {
private static final String TAG = "Menu";// HttpHandler.class.getSimpleName();
public String makeServiceCall(String reqUrl) {
String response = null;
try {
URL url = new URL(reqUrl);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
// read the response
InputStream in = new BufferedInputStream(conn.getInputStream());
response = convertStreamToString(in);
} catch (MalformedURLException e) {
Log.e(TAG, "MalformedURLException: " + e.getMessage());
} catch (ProtocolException e) {
Log.e(TAG, "ProtocolException: " + e.getMessage());
} catch (IOException e) {
Log.e(TAG, "IOException: " + e.getMessage());
} catch (Exception e) {
Log.e(TAG, "Exception: " + e.getMessage());
}
return response;
}
private String convertStreamToString(InputStream is) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line;
try {
while ((line = reader.readLine()) != null) {
sb.append(line).append('\n');
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return sb.toString();
}
}