使用 JSON 将数据从 mysql 显示到 android studio

Question

我想使用 textview 将 mysql 中的数据显示到 android 中，但是当我运行应用程序时，它会自行强制停止， 有人可以帮我解决它，， 任何想法都会很好

dbconfig.php

<?php

//This script is designed by Android-Examples.com
//Define your host here.
$servername = "localhost";
//Define your database username here.
$username = "root";
//Define your database password here.
$password = "";
//Define your database name here.
$dbname = "u727224026_demo";

?>

发送数据.php

<?php
include 'dbconfig.php';


// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 

$sql = "SELECT * FROM TextViewTable";
$result = $conn->query($sql);

if ($result->num_rows > 0) {

    // output data of each row
    while($row[] = $result->fetch_assoc()) {

       $json = json_encode($row);


    }
} else {
    echo "0 results";
}
echo $json;
$conn->close();
?>

MainActivity.java

package flix.yudi.kuesioner2;

import java.io.IOException;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MainActivity extends Activity {

    TextView textview;
    JSONObject json = null;
    String str = "";
    HttpResponse response;
    Context context;
    ProgressBar progressbar;
    Button button;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        progressbar = (ProgressBar)findViewById(R.id.progressBar1);
        textview = (TextView)findViewById(R.id.textView1);
        button = (Button)findViewById(R.id.button1);

        progressbar.setVisibility(View.GONE);

        button.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                progressbar.setVisibility(View.VISIBLE);

                new GetTextViewData(context).execute();

            }
        });
    }


    private class GetTextViewData extends AsyncTask<Void, Void, Void>
    {
        public Context context;


        public GetTextViewData(Context context)
        {
            this.context = context;
        }

        @Override
        protected void onPreExecute()
        {
            super.onPreExecute();
        }

        @Override
        protected Void doInBackground(Void... arg0)
        {

            HttpClient myClient = new DefaultHttpClient();
            HttpPost myConnection = new HttpPost("192.168.1.139/a_test/send-data.php");

            try {
                response = myClient.execute(myConnection);
                str = EntityUtils.toString(response.getEntity(), "UTF-8");

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


            try{
                JSONArray jArray = new JSONArray(str);
                json = jArray.getJSONObject(0);



            } catch ( JSONException e) {
                e.printStackTrace();
            }

            catch (Exception e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return null;
        }
        protected void onPostExecute(Void result)
        {
            try {
                textview.setText(json.getString("ServerData"));

            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            //Hiding progress bar after done loading TextView.
            progressbar.setVisibility(View.GONE);

        }
    }


}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.jsonparsingfromurltextview_android_examples.com.MainActivity" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:text="TextView Static Text Before Load"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:gravity="center"/>

<ProgressBar
    android:id="@+id/progressBar1"
    style="?android:attr/progressBarStyleLarge"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/textView1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="17dp" />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="150dp"
    android:text="Click Here to Load TextView data dynamically from MySQL Database Online Using JSON Parsing" />

logcat 错误提示

10-03 08:35:35.486 1754-2070/flix.yudi.kuesioner2 E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
                                                                Process: flix.yudi.kuesioner2, PID: 1754
                                                                java.lang.RuntimeException: An error occured while executing doInBackground()
                                                                    at android.os.AsyncTask$3.done(AsyncTask.java:300)
                                                                    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
                                                                    at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
                                                                    at java.util.concurrent.FutureTask.run(FutureTask.java:242)
                                                                    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
                                                                    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
                                                                    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
                                                                    at java.lang.Thread.run(Thread.java:841)
                                                                 Caused by: java.lang.IllegalStateException: Target host must not be null, or set in parameters. scheme=null, host=null, path=192.168.1.139/a_test/send-data.php
                                                                    at org.apache.http.impl.client.DefaultRequestDirector.determineRoute(DefaultRequestDirector.java:591)
                                                                    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:293)
                                                                    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
                                                                    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
                                                                    at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
                                                                    at flix.yudi.kuesioner2.MainActivity$GetTextViewData.doInBackground(MainActivity.java:84)
                                                                    at flix.yudi.kuesioner2.MainActivity$GetTextViewData.doInBackground(MainActivity.java:60)
                                                                    at android.os.AsyncTask$2.call(AsyncTask.java:288)
                                                                    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
                                                                    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
                                                                    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
                                                                    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
                                                                    at java.lang.Thread.run(Thread.java:841) 

我试图找到如何解决它，但仍然没有， 请帮帮我，

ADDITIONAL INFO RESPONSE

Answer 1

尝试将http 或https 之类的方案添加到URL：

http://192.168.1.139/a_test/send-data.php

Answer 2

首先在邮递员中尝试你的服务调用......检查你是否从 192.168.1.139/a_test/send-data.php 得到正确的响应

关注her获取邮递员插件

检查下面的代码

 private String makeRESTService(String methodNameWithUrl) throws JSONException {
        final String KEY_USER_NAME = "username";
        final String KEY_PASSWORD = "password";
        System.out.println("url" + methodNameWithUrl);
        String jsonResult = null;
        String jsonObj = null;

        //create a json string
        JSONObject parent = new JSONObject();
        parent.put(KEY_USER_NAME, "manu");
        parent.put(KEY_PASSWORD, "1234");
        Log.e("To json", jsonObj);

        URL url = null;

        HttpURLConnection urlConnection = null;
        try {
            url = new URL("your url"); //place your url
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        try {
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setReadTimeout(10000);
            urlConnection.setConnectTimeout(15000);

            urlConnection.setRequestMethod("POST");
            urlConnection.setRequestProperty("Content-Type", "application/json");
            OutputStream os = urlConnection.getOutputStream();

            BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(os, "UTF-8"));
            writer.write(jsonObj);
            writer.flush();
            writer.close();
            os.close();

            urlConnection.connect();
            InputStream in = new BufferedInputStream(urlConnection.getInputStream());
            jsonResult = inputStreamToString(in)
                    .toString();
            Log.e("jsonResult", jsonResult);

            //   readStream(in);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            urlConnection.disconnect();
        }
        return jsonResult;

    }


    private StringBuilder inputStreamToString(InputStream is) {
        String rLine = "";
        StringBuilder answer = new StringBuilder();
        InputStreamReader isr = new InputStreamReader(is);
        BufferedReader rd = new BufferedReader(isr);
        try {
            while ((rLine = rd.readLine()) != null) {
                answer.append(rLine);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return answer;
    }