Question

我正在创建一个具有登录屏幕的Android应用程序。用户必须输入他们的电子邮件地址和密码。当点击登录按钮时，我的代码应该使用post变量将输入的用户名和密码发送到php文件中。 php文件应该使用从应用程序发送的变量来完成select语句，如果有任何匹配，则从服务器上的数据库返回结果。运行应用程序时，从php文件返回的输出是空白的。我不知道post变量是否正确发送到php文件，我在互联网上搜索但似乎无法理解这个概念是如何工作的。

以下是我的代码：

package com.example.csqa;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.*;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import android.os.AsyncTask;
import android.widget.TextView;
import android.widget.Toast;

public class AsyncHttpPost extends AsyncTask<String, String, String> {
    TextView t;
    MainActivity ma;
    List<NameValuePair> nameValuePair = new ArrayList<NameValuePair>();

public AsyncHttpPost(MainActivity m, List<NameValuePair> nvp){
    ma = m;
    nameValuePair = nvp;
}
@Override
protected String doInBackground(String... params) {
    byte[] result = null;
    String str = "";
    HttpClient client = new DefaultHttpClient();
    HttpPost post = new HttpPost(params[0]);// in this case, params[0] is URL

    try {
        post.setEntity(new UrlEncodedFormEntity(nameValuePair));
        HttpResponse response = client.execute(post);
        StatusLine statusLine = response.getStatusLine();
        if(statusLine.getStatusCode() == HttpURLConnection.HTTP_OK){
            result = EntityUtils.toByteArray(response.getEntity());
            str = new String(result, "UTF-8");
        }

    }
    catch (UnsupportedEncodingException e) {

        e.printStackTrace();

    }
    catch (Exception e) {

    }
    return str;
}
@Override
protected void onPostExecute(String output) {
    // do something with the string returned earlier
    Toast.makeText(ma.getApplicationContext(), "Calling validateUser with " + output, Toast.LENGTH_SHORT).show();
    ma.validateUser(output);
}

}

这是PHP脚本

<?php
$con=mysqli_connect("127.0.0.1","S831987","831987",'D831987");
if (mysqli_connect_errno($con))
{
   echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$email = $_POST['email'];
$password = $_POST['password'];
$result = mysqli_query($con,"SELECT * FROM USERS where 
EMAIL='$email' and PASSWORD ='$password'");
$row = mysqli_fetch_array($result);
$data = $row[0];
if($data){
echo $data;
}
mysqli_close($con);
?>

这是当用户按下登录按钮时从主活动执行的代码：

public void btnLoginClicked(View v){
    TextView em = (TextView) findViewById(R.id.tvLogEmail);
    TextView pw = (TextView) findViewById(R.id.tvLogPassword);
    String email = em.getText().toString();
    String password = pw.getText().toString();
    List<NameValuePair> nameValuePair = new ArrayList<NameValuePair>();
    nameValuePair.add(new BasicNameValuePair("email", email));
    nameValuePair.add(new BasicNameValuePair("password", password));
    AsyncHttpPost async = new AsyncHttpPost(this, nameValuePair);
    async.execute("http://lamp.ms.wits.ac.za/~831987/isValidLogin.php");
}

有人可以解决我收到空白回复的原因吗？我按原样测试了sql查询，使用了正确的变量，它可以正常工作。提前谢谢！

Answer 1

为什么不将ServiceHandler与json对象一起使用？这就是它对我有用的方式：

private class AsyncHttpPost extends AsyncTask<String, Void, Void> {

    ProgressDialog progressDialog;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog = ProgressDialog.show(getActivity(), "", "checking email and password...");
    }

    @Override
    protected Void doInBackground(String... arg) {
        String mEmail = arg[0]; // email entered by user
        String mPassword = arg[1] // password entered by user

        // Preparing post params
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("email", mEmail));
        params.add(new BasicNameValuePair("password", mPassword));

        ServiceHandler serviceClient = new ServiceHandler();
        String json = serviceClient.makeServiceCall(YOUR_URL, ServiceHandler.POST, params);

        Log.d("SERVER Request: ", "> " + json);

        if (json != null) {
            try {
                JSONObject jsonObj = new JSONObject(json);
                boolean error = jsonObj.getBoolean("error");
                // checking for error node in json
                if (!error) {
                    // username and password checked successfully
                } else {
                    Log.e("Server Error: ", "> " + jsonObj.getString("message"));
                }

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

        } else {
            Log.e("JSON Data", "JSON data error!");
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);
        progressDialog.dismiss();
    }
}

致谢：

将post变量从java android app传递到php文件以查询数据库

1 个答案: