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Question

我是 Android 初学者，我正在尝试将我的 Android 应用程序连接到一个返回 JSON 对象的简单 php。

每当我运行我的应用程序时，我都会收到错误不幸的是应用程序已在模拟器上停止，并且在ABD LOG中我收到PropertyFetcher:AdbCommandRejectedException正在获取设备的属性emulator-5554:设备离线

 - 

**MainActivity.java**
---------------------


package jsonphp.com.jsonphp;

import android.os.AsyncTask;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

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


public class MainActivity extends ActionBarActivity {

    private TextView responseTextView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        this.responseTextView = (TextView) this.findViewById(R.id.responseTextView);

        new GetAllCustomerTask().execute(new ApiConnector());

    }



    public void setTextToTextView(JSONArray jsonArray)
    {
        String s = "";
        for(int i=0;i<jsonArray.length();i++)
        {
            JSONObject jsonObject = null;
            try {
                jsonObject = jsonArray.getJSONObject(i);
                s = s +
                        "Name : "+jsonObject.getString("name")+"\n"
                        + "Age : "+jsonObject.getString("age")+"\n"
                        + "Address : "+jsonObject.getString("address")+"\n\n";
            }
            catch (JSONException e)
            {
                e.printStackTrace();
            }
        }
        this.responseTextView.setText(s);
    }


    private class GetAllCustomerTask extends AsyncTask<ApiConnector,Long,JSONArray>
    {

        @Override
        protected JSONArray doInBackground(ApiConnector... params) {
            //this execute a bg thread

            return params[0].getAllCustomers();


        }

        protected void onPostExecute(JSONArray jsonArray)
        {
            setTextToTextView(jsonArray);
        }

    }



}

 - 

**ApiConnector.java**
---------------------
package jsonphp.com.jsonphp;

import android.util.Log;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;

import java.io.IOException;

/**
 * Created by SWAPNIL on 20-06-2015.
 */
public class ApiConnector {

    public JSONArray getAllCustomers()
    {
        //URL for getting all customers

        String URL = "http://127.0.0.1/Android/test.php";

        // Get HttpResponse object from URL
        // Get HttpEntity from HTTP Response object
        HttpEntity httpEntity = null;
        try {
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(URL);

            HttpResponse httpResponse = httpClient.execute(httpGet);
            httpEntity = httpResponse.getEntity();
        }
        catch (ClientProtocolException ex)
        {
                    ex.printStackTrace();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }


        //Converting HttpEntity into JSONArray

        JSONArray jsonArray = null;
        if(httpEntity != null)
        {
            try {
                String entityResponse = EntityUtils.toString(httpEntity);
                Log.e("Entity Response : ",entityResponse);
                jsonArray = new JSONArray(entityResponse);
            }
            catch (JSONException ee)
            {
                ee.printStackTrace();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        }
        return  jsonArray;
    }


}

这是我的简单布局。

<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:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New Text"
        android:id="@+id/responseTextView"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="60dp"
        android:textAlignment="center"/>

</RelativeLayout>

还有我的 test.php 文件。

<?php




$con = mysqli_connect("localhost","root","root","My_Database");

if(!$con)
{
    die("Could not connect : ".mysql_error());
}
/*mysqli_select_db("My_Database",$con);*/

$result = mysqli_query($con,"SELECT * From Customer");

while($row=mysqli_fetch_assoc($result))
{
    $output[] = $row;
}

print(json_encode($output));
mysqli_close($con);

?>

我还考虑过一件事 HttpEntity, 默认HttpClient， HttpGet, Http响应， 客户端协议(protocol)异常， 实体实用程序 以上均已弃用

Answer 1

首先你应该检查返回的结果是json数组格式还是json对象格式。 您正在使用的 android 代码用于解析 json 数组。从 php 代码中我得到的是，你返回的 json 不是一个 json 数组。 将其转换为 json 数组，然后在 android 中使用您当前使用的相同代码来解析它。

第二个错误是您使用的是本地主机。 您的设备或模拟器无法与该服务器建立连接。 使用 ip 10.0.0.1 而不是 127.0.0.01 或使其在线