在执行php文件之前检索数据

时间：2017-07-21 18:36:30

标签： php android

如何在android中检索textView文本，以便.php文件将其读作＆＃39; $ _ id＆＃39;的ID。在预执行php文件之前？因为在我的php文件中，我需要在执行json数组之前从我的android工作室检索一个ID（这是我认为至少在错误中我想到的）

我是编程新手所以请解释一下，当你还是编程的新手时

这是我的php代码：

<?php
$host='localhost';
$user='root';
$password='';
$db='employee101';
$_id = $_POST['id'];

$sql = "select * from employee_comments where id = $_id;";

$con = mysqli_connect($host,$user,$password,$db);

$result = mysqli_query($con, $sql);

$response = array();

while($row = mysqli_fetch_array($result)){

    array_push($response,array("id"=>$row[0],"comment"=>$row[1],"rating"=>$row[2]));

}

echo json_encode(array("server_respo"=>$response));

mysqli_close($con);




?>

以下是我在android studio中的代码     包rjj.tutorial_jsonandlistview; 

import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.w3c.dom.Text;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;

public class MainActivity extends AppCompatActivity {

    String Json_STRING;
    TextView textView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new BackgroundTask().execute();
         //new line


    }




    /*public void getJSON(View view) {

        new BackgroundTask().execute();

    }*/


    class BackgroundTask extends AsyncTask<Void, Void, String> {

        String json_url;
        String JSON_STRING;

        @Override
        protected void onPreExecute() {

            json_url = "http://10.0.2.2/json_comments.php";
        }

        @Override
        protected String doInBackground(Void... params) {
            try {
                URL url = new URL(json_url);
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                InputStream inputStream = httpURLConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                StringBuilder stringBuilder = new StringBuilder();
                while ((JSON_STRING = bufferedReader.readLine()) != null) {

                    stringBuilder.append(JSON_STRING + "\n");
                }

                bufferedReader.close();
                inputStream.close();
                httpURLConnection.disconnect();
                return stringBuilder.toString().trim();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            super.onProgressUpdate(values);
        }

        @Override
        protected void onPostExecute(String result) {
            TextView textView = (TextView)findViewById(R.id.textView2);
            textView.setText(result);
            Json_STRING = result;
        }

    }

编辑： php文件

<?php
$host='localhost';
$user='root';
$password='';
$db='employee101';

if (!empty($_POST['id'])) {
$_id = $_POST['id'];

$sql = "select * from employee_comments where id = $_id;";

$con = mysqli_connect($host,$user,$password,$db);

$result = mysqli_query($con, $sql);

$response = array();

while($row = mysqli_fetch_array($result)){

    array_push($response,array("id"=>$row[0],"comment"=>$row[1],"rating"=>$row[2]));

}
}

echo json_encode(array("server_respo"=>$response));

mysqli_close($con);




?>

在预执行中添加了一行以检索ID，但我认为它无效

protected void onPreExecute() {
            textView = (TextView) findViewById(R.id.textView3);
            String password = textView.getText().toString();


            json_url = "http://10.0.2.2/json_comments.php";
        }

PHP中的错误：

  

注意：未定义的索引：在C：\ wamp64 \ www \ json_comments.php中的id在线   6注意：未定义的变量：响应中   第25行的C：\ wamp64 \ www \ json_comments.php注意：未定义   变量：第27行的C：\ wamp64 \ www \ json_comments.php中的con警告：   mysqli_close（）期望参数1为mysqli，null为null   第27行的C：\ wamp64 \ www \ json_comments.php

3 个答案:

答案 0 :(得分：0)

你需要将你的代码包装在条件

中 
if (!empty($_POST['id'])) {
  # place your code here
}

修改 

<?php 
$host='localhost';
$user='root';
$password='';
$db='employee101';

if (!empty($_POST['id'])) {
    $_id = $_POST['id'];

    $sql = "select * from employee_comments where id = $_id;";

    $con = mysqli_connect($host,$user,$password,$db);

    $result = mysqli_query($con, $sql);

    $response = array();

    while($row = mysqli_fetch_array($result)){

        array_push($response,array("id"=>$row[0],"comment"=>$row[1],"rating"=>$row[2]));

    }

echo json_encode(array("server_respo"=>$response));

mysqli_close($con);

}
?>

答案 1 :(得分：0)

在php文件中，您从 $ _ POST ['id'] 获取ID。那么，在Java文件中， HttpURLConnection httpURLConnection 你需要使用方法POST，并将数据发送到php文件。

import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.w3c.dom.Text;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;

public class MainActivity extends AppCompatActivity {

    String Json_STRING;
    TextView textView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new BackgroundTask().execute();
        //new line


    }




    /*public void getJSON(View view) {

        new BackgroundTask().execute();

    }*/


    class BackgroundTask extends AsyncTask<Void, Void, String> {

        String json_url;
        String JSON_STRING;

        @Override
        protected void onPreExecute() {

            json_url = "http://10.0.2.2/json_comments.php";
        }

        @Override
        protected String doInBackground(Void... params) {
            try {

                String urlParameters  = "id=your_id";
                byte[] postData       = urlParameters.getBytes( StandardCharsets.UTF_8 );
                int    postDataLength = postData.length;
                String request        = json_url;;
                URL    url            = new URL( request );
                HttpURLConnection conn= (HttpURLConnection) url.openConnection();
                conn.setDoOutput( true );
                conn.setInstanceFollowRedirects( false );
                conn.setRequestMethod( "POST" );
                conn.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded");
                conn.setRequestProperty( "charset", "utf-8");
                conn.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
                conn.setUseCaches( false );
                try( DataOutputStream wr = new DataOutputStream( conn.getOutputStream())) {
                    wr.write( postData );
                }

                if(conn.getResponseCode() == HttpURLConnection.HTTP_OK){
                    is = urlConn.getInputStream();
                    BufferedReader in = new BufferedReader(new InputStreamReader(is));
                    StringBuilder stringBuilder = new StringBuilder();
                    while ((inputLine = in.readLine()) != null)
                        stringBuilder.append(inputLine + "\n");
                    in.close();
                    return stringBuilder.toString().trim();



                    //Your code read data return here ...

                } else {
                    is = urlConn.getErrorStream();
                }

                return null;


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

            return null;
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            super.onProgressUpdate(values);
        }

        @Override
        protected void onPostExecute(String result) {
            TextView textView = (TextView)findViewById(R.id.textView2);
            textView.setText(result);
            Json_STRING = result;
        }

    }

答案 2 :(得分：-1)

首先你不能在asynctask里面的textview中设置值，因为所有ui相关的操作只能在ui线程上完成，见下文

如果您想在代码中读取和写入文本，可以执行以下操作：

public class MainActivity extends AppCompatActivity {

String Json_STRING;
TextView textView;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    textView=findViewById(R.id.text_view_id);
    String text=textview.getText();
    new BackgroundTask().execute(text);
     //new line


}




/*public void getJSON(View view) {

    new BackgroundTask().execute();

}*/

// change first param of asynctask to String to accept array of string params

class BackgroundTask extends AsyncTask<String, Void, String> {

    String json_url;
    String JSON_STRING;

    @Override
    protected void onPreExecute() {

        json_url = "http://10.0.2.2/json_comments.php";
    }

    @Override
    protected String doInBackground(String... params) {
        try {
String param=params[0]; // you can access text of textview from here and pass it to your url like "json_url?id=param"
            URL url = new URL(json_url);
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            InputStream inputStream = httpURLConnection.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            StringBuilder stringBuilder = new StringBuilder();
            while ((JSON_STRING = bufferedReader.readLine()) != null) {

                stringBuilder.append(JSON_STRING + "\n");
            }

            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return stringBuilder.toString().trim();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }

    @Override
    protected void onPostExecute(String result) {
        runOnUiThread(new Runnable() {
           @Override
           public void run() {
              textView.setText(result);       
           }
        });
    }

}

php android

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