Question

我必须创建一个显示加速度计的应用程序移动设备上的值并保存到学校的远程SQL数据库项目，所以我试着去做。我的逻辑是：获取传感器值，在Text View中显示它们并调用PHP文件将它们保存在数据库中。尽管语法正确，但应用程序仍被强制执行因某种原因关闭而不显示或做任何事情。我真的很感激一些帮助。

我是新手，我无法理解日志猫在前3个错误中的含义：

Log Cat 06-04 01：35：20.417：W / dalvikvm（11760）：threadid = 1：线程退出时未捕获异常（group = 0x41dba2a0） 06-04 01：35：20.447：E / AndroidRuntime（11760）：致命异常：主要 06-04 01：35：20.447：E / AndroidRuntime（11760）：android.os.NetworkOnMainThreadException

我的MainActivity.java

    package com.example.try1;

    import java.util.ArrayList;
    import java.util.List;
    import org.apache.http.NameValuePair;
    import org.apache.http.message.BasicNameValuePair;
    import org.json.JSONObject;
    import android.app.Activity;
    import android.content.Intent;
    import android.hardware.Sensor;
    import android.hardware.SensorEvent;
    import android.hardware.SensorEventListener;
    import android.hardware.SensorManager;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.TextView;

    public class MainActivity extends Activity implements SensorEventListener {

private static String url_create_product =                 "http://192.168.2.11/android_connect/create_accel_data.php";
 JSONParser jsonParser = new JSONParser();

public void selfDestruct(View view) {
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);

}


    private SensorManager sensorManager;

    TextView xCoor; // declare X axis object
    TextView yCoor; // declare Y axis object
    TextView zCoor; // declare Z axis object

    @Override
    public void onCreate(Bundle savedInstanceState){

super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

xCoor=(TextView)findViewById(R.id.xcoor); // create X axis object
yCoor=(TextView)findViewById(R.id.ycoor); // create Y axis object
zCoor=(TextView)findViewById(R.id.zcoor); // create Z axis object

sensorManager=(SensorManager)getSystemService(SENSOR_SERVICE);
// add listener. The listener will be HelloAndroid (this) class
sensorManager.registerListener(this,
        sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
        SensorManager.SENSOR_DELAY_NORMAL);

/*  More sensor speeds (taken from api docs)
    SENSOR_DELAY_FASTEST get sensor data as fast as possible
    SENSOR_DELAY_GAME   rate suitable for games
    SENSOR_DELAY_NORMAL rate (default) suitable for screen       orientation changes
*/
    }

    public void onAccuracyChanged(Sensor sensor,int accuracy){

    }

    public void onSensorChanged(SensorEvent event){

// check sensor type
if(event.sensor.getType()==Sensor.TYPE_ACCELEROMETER){

    // assign directions
    float x=event.values[0];
    float y=event.values[1];
    float z=event.values[2];

    xCoor.setText("X: "+x);
    yCoor.setText("Y: "+y);
    zCoor.setText("Z: "+z);

 // Building Parameters
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new BasicNameValuePair("x", Float.toString(x)));
    params.add(new BasicNameValuePair("y", Float.toString(y)));
    params.add(new BasicNameValuePair("z", Float.toString(z)));

    // getting JSON Object
    // Note that create product url accepts POST method
    JSONObject json = jsonParser.makeHttpRequest(url_create_product,
            "POST", params);

    Log.d("Create Response", json.toString());
        }
    }
    }

我的JSONParser.java类

    package com.example.try1;

    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.io.UnsupportedEncodingException;
    import java.util.List;
    import org.apache.http.HttpEntity;
    import org.apache.http.HttpResponse;
    import org.apache.http.NameValuePair;
    import org.apache.http.client.ClientProtocolException;
    import org.apache.http.client.entity.UrlEncodedFormEntity;
    import org.apache.http.client.methods.HttpGet;
    import org.apache.http.client.methods.HttpPost;
     import org.apache.http.client.utils.URLEncodedUtils;
    import org.apache.http.impl.client.DefaultHttpClient;
    import org.json.JSONException;
    import org.json.JSONObject;
    import android.util.Log;

public class JSONParser {

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

// constructor
public JSONParser() {

}

// function get json from url
// by making HTTP POST or GET method
public JSONObject makeHttpRequest(String url, String method,
        List<NameValuePair> params) {

    // Making HTTP request
    try {

        // check for request method
        if(method == "POST"){
            // request method is POST
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            httpPost.setEntity(new UrlEncodedFormEntity(params));

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();

        }else if(method == "GET"){
            // request method is GET
            DefaultHttpClient httpClient = new DefaultHttpClient();
            String paramString = URLEncodedUtils.format(params, "utf-8");
            url += "?" + paramString;
            HttpGet httpGet = new HttpGet(url);

            HttpResponse httpResponse = httpClient.execute(httpGet);
            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, "iso-8859-1"), 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;

}
}

我的布局activity_main.xml：

    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
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=".MainActivity" >

<TextView
        android:id="@+id/textView1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:gravity="center"
        android:paddingTop="20dip"
        android:text="pinakas_dedomenwn"
        android:textSize="16sp"
        android:textStyle="bold" />

<TableLayout
    android:id="@+id/tableLayout1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="56dp"
    android:paddingTop="10dip"
    android:stretchColumns="*" >

    <TableRow>

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="14dp"
            android:gravity="center"
            android:text="X-Axis"
            android:textSize="14sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Y-Axis"
            android:textSize="14sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Z-Axis"
            android:textSize="14sp" />
    </TableRow>



    <TableRow>


<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/xcoor"
     android:gravity="center"/>
     <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/ycoor"
    android:gravity="center"/>
    <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/zcoor"
    android:gravity="center"/>
    </TableRow>

</TableLayout>

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="44dp"
    android:onClick="selfDestruct"
    android:text="@string/exit" />

    </RelativeLayout>

我的db_connect_accel.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_accel.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();
}

  }

  ?>

我的db_config_accel.php

     <?php

/*
 * All database connection variables
 */

define('DB_USER', "george1"); // db user
define('DB_PASSWORD', "george1"); // db password (mention your db password here)
define('DB_DATABASE', "db_accelerometer"); // database name
define('DB_SERVER', "localhost"); // db server
?>

最后我的create_accel_data.php应该调用另外两个.php来连接数据库并保存值。

   <?php

/*
 * Following code will create a new product row
 * All product details are read from HTTP Post Request
 */

// array for JSON response
$response = array();

// check for required fields
if (isset($_POST['x']) && isset($_POST['y']) && isset($_POST['z'])) {

$x = $_POST['x'];
$y = $_POST['y'];
$z = $_POST['z'];

// include db connect class
require_once __DIR__ . '/db_connect_accel.php';

// connecting to db
$db = new DB_CONNECT();

// mysql inserting a new row
$result = mysql_query("INSERT INTO accel_data(x, y, z) VALUES('$x', '$y', '$z')");

// check if row inserted or not
if ($result) {
    // successfully inserted into database
    $response["success"] = 1;

} else {
    // failed to insert row
    $response["success"] = 0;

}
} else {
// required field is missing
$response["success"] = 0;

}
?>

有人能看出出了什么问题吗？（我怀疑问题出现在MainActivity中）

Answer 1

诀窍是阅读Exception。 NetworkOnMainThreadException意味着您无法在主线程中打开连接，为此您应该使用新的线程，在Android的情况下，指示使用AsyncTask进行简单请求。

由于某些原因，将传感器上的加速度计值发送到远程数据库是不起作用的

1 个答案: