从url读取json（Android）
[英]Read json from url(Android)
问题描述
Sorry for my English. 
对不起我的英语不好。 I can not in any way to display data that are taken from the json link. 我无法以任何方式显示从json链接获取的数据。 Like a lot of examples on the internet, but I can not seem to understand what is the error. 就像互联网上的许多示例一样，但我似乎无法理解什么是错误。 I think that is not correct php files, although it can be. 我认为这是不正确的php文件，尽管可以。 I ask you, programmers help to understand why the application does not work. 我请您，程序员帮助您了解为什么该应用程序无法正常工作。 Below I have brought all the files: Working json link from which I am trying to read data http://ksupulse.tk/get_all.php 下面，我带来了所有文件：正在尝试从中读取数据的json链接http://ksupulse.tk/get_all.php
db_config.php db_config.php
<?php
define('DB_USER', "login");
define('DB_PASSWORD', "pass");
define('DB_DATABASE', "database");
define('DB_SERVER', "server");
?>
db_connect.php db_connect.php
<?php
/**
* A class file to connect to database
*/
class DB_CONNECT {
// constructor
function __construct() {
// connecting to database
$this->connect();
}
// destructor
function __destruct() {
// closing db connection
$this->close();
}
/**
* Function to connect with database
*/
function connect() {
// import database connection variables
require_once __DIR__ . '/db_config.php';
// Connecting to mysql database
$con = mysql_connect(DB_SERVER, DB_USER, DB_PASSWORD) or die(mysql_error());
// Selecing database
$db = mysql_select_db(DB_DATABASE) or die(mysql_error()) or die(mysql_error());
// returing connection cursor
return $con;
}
/**
* Function to close db connection
*/
function close() {
// closing db connection
mysql_close();
}
}
?>
get_all.php get_all.php
<?php
header('Content-Type: application/json; charset=utf-8');
$response = array();
require 'db_connect.php';
$db = new DB_CONNECT();
$result = mysql_query("SELECT * FROM demo") or die(mysql_error());
if (mysql_num_rows($result) > 0) {
$response["demo"] = array();
while ($row = mysql_fetch_array($result)) {
$product = array();
$product["id"] = $row["id"];
$product["name"] = $row["name"];
$product["detaly"] = $row["detaly"];
array_push($response["demo"], $product);
}
$response["success"] = 1;
echo json_encode($response);
} else {
$response["success"] = 0;
$response["message"] = "No products found";
echo json_encode($response);
}
?>
Android files: Android档案：
MainActivity 主要活动
public class MainActivity extends Activity {
//URL to get JSON Array
private static String url = "http://ksupulse.tk/get_all.php";
//JSON Node Names
private static final String TAG_USER = "detaly";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
JSONArray user = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Creating new JSON Parser
JSONParser jParser = new JSONParser();
// Getting JSON from URL
JSONObject json = jParser.getJSONFromUrl(url);
try {
// Getting JSON Array
user = json.getJSONArray(TAG_USER);
JSONObject c = user.getJSONObject(0);
// Storing JSON item in a Variable
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String email = c.getString(TAG_EMAIL);
//Importing TextView
final TextView uid = (TextView)findViewById(R.id.uid);
final TextView name1 = (TextView)findViewById(R.id.name);
final TextView email1 = (TextView)findViewById(R.id.email);
//Set JSON Data in TextView
uid.setText(id);
name1.setText(name);
email1.setText(email);
} catch (JSONException e) {
e.printStackTrace();
}
}
JSONParser JSONParser
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "utf-8"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
This is something that I am concerned in error: 这是我担心的错误：
11-22 18:37:57.448: E/JSON Parser(1850): Error parsing data org.json.JSONException: Value of type java.lang.String cannot be converted to JSONObject
All errors: 所有错误：
11-22 18:37:54.748: E/Trace(1850): error opening trace file: No such file or directory (2) 11-22 18:37:57.448: E/JSON Parser(1850): Error parsing data org.json.JSONException: Value of type java.lang.String cannot be converted to JSONObject 11-22 18:37:57.448: D/AndroidRuntime(1850): Shutting down VM 11-22 18:37:57.460: W/dalvikvm(1850): threadid=1: thread exiting with uncaught exception (group=0xa6265288) 11-22 18:37:57.468: E/AndroidRuntime(1850): FATAL EXCEPTION: main 11-22 18:37:57.468: E/AndroidRuntime(1850): java.lang.RuntimeException: Unable to start activity ComponentInfo{learn2crack.jsonparsing/learn2crack.jsonparsing.MainActivity}: java.lang.NullPointerException 11-22 18:37:57.468: E/AndroidRuntime(1850): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059) 11-22 18:37:57.468: E/AndroidRuntime(1850): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 11-22 18:37:57.468: E/AndroidRuntime(1850): at android.app.ActivityThread.acc
1 个解决方案
解决方案1
0 已采纳 2014-11-22 20:28:23
- http://ksupulse.tk/get_all.php doesn't work and the stack trace shows 'No such file' so make sure you're passing the correct link. http://ksupulse.tk/get_all.php无法正常工作，并且堆栈跟踪显示“无此类文件”，因此请确保您传递的链接正确。
- Use a website such as http://www.jsoneditoronline.org/ to see exactly what's coming back. 使用诸如http://www.jsoneditoronline.org/的网站来确切了解返回的内容。 The error is in your MainActivity class when you're parsing the JSON. 解析JSON时，该错误位于MainActivity类中。 "Error parsing data org.json.JSONException: Value of type java.lang.String cannot be converted to JSONObject". “解析数据org.json.JSONException时出错：java.lang.String类型的值不能转换为JSONObject”。 Your line JSONObject c = user.getJSONObject(0); 您的行JSONObject c = user.getJSONObject（0）; needs a string passed in instead of "0." 需要传入一个字符串而不是“ 0”。
Side comment: It's not good practice to make networking calls on the main thread in Android. 旁注：在Android的主线程上进行网络调用不是一个好习惯。 Use AsyncTask. 使用AsyncTask。
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