使用php将数据从mysql检索到android

我创建了一个页面，显示Mysql数据库中存在的数据。我使用PHP进行连接。PHP文件包含select查询，用于显示数据库中的数据。PHP文件由android代码调用。完成JSON解析后，数据应显示在应用程序上。但问题是应用程序无法检索数据

在这里，java代码中没有一个错误。此外，我还执行了php文件localhost，它工作得非常好，在输出中，我得到了JSON数据

唯一的问题是JSON没有在应用程序上检索。请帮帮我。我被困在这里了。为了这个我试了一整天，但什么也没找到。我需要帮助，伙计们！！！如果你发现什么，一定要告诉我

代码：

getIssue.php

<?php 
    //Importing Database Script 
    require_once('dbConfig.php');

    //Creating sql query
    $sql = "SELECT * FROM user_issue";

    //getting result 
    $r = mysqli_query($con,$sql);

    //creating a blank array 
    $result = array();

    //looping through all the records fetched
    while($row = mysqli_fetch_array($r)){

        //Pushing name and id in the blank array created 
        array_push($result,array(
            "id"=>$row['id'],
            "store_name"=>$row['store_name'],
            "issue"=>$row['issue'],
            "describe"=>$row['describ']

        ));
    }

    //Displaying the array in json format 
    echo json_encode(array('result'=>$result));

    mysqli_close($con);

RequestHandler.java
package com.example.mi.mikpiadmin;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

import javax.net.ssl.HttpsURLConnection;

public class RequestHandler {

    //Method to send httpPostRequest
    //This method is taking two arguments
    //First argument is the URL of the script to which we will send the request
    //Other is an HashMap with name value pairs containing the data to be send with the request
    public String sendPostRequest(String requestURL,
                                  HashMap<String, String> postDataParams) {
        //Creating a URL
        URL url;

        //StringBuilder object to store the message retrieved from the server
        StringBuilder sb = new StringBuilder();
        try {
            //Initializing Url
            url = new URL(requestURL);

            //Creating an httmlurl connection
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            //Configuring connection properties
            conn.setReadTimeout(15000);
            conn.setConnectTimeout(15000);
            conn.setRequestMethod("POST");
            conn.setDoInput(true);
            conn.setDoOutput(true);

            //Creating an output stream
            OutputStream os = conn.getOutputStream();

            //Writing parameters to the request
            //We are using a method getPostDataString which is defined below
            BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(os, "UTF-8"));
            writer.write(getPostDataString(postDataParams));

            writer.flush();
            writer.close();
            os.close();
            int responseCode = conn.getResponseCode();

            if (responseCode == HttpsURLConnection.HTTP_OK) {

                BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                sb = new StringBuilder();
                String response;
                //Reading server response
                while ((response = br.readLine()) != null){
                    sb.append(response);
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return sb.toString();
    }

    public String sendGetRequest(String requestURL){
        StringBuilder sb =new StringBuilder();
        try {
            URL url = new URL(requestURL);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));

            String s;
            while((s=bufferedReader.readLine())!=null){
                sb.append(s+"\n");
            }
        }catch(Exception e){
        }
        return sb.toString();
    }

    public String sendGetRequestParam(String requestURL, String id){
        StringBuilder sb =new StringBuilder();
        try {
            URL url = new URL(requestURL+id);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));

            String s;
            while((s=bufferedReader.readLine())!=null){
                sb.append(s+"\n");
            }
        }catch(Exception e){
        }
        return sb.toString();
    }

    private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
        StringBuilder result = new StringBuilder();
        boolean first = true;
        for (Map.Entry<String, String> entry : params.entrySet()) {
            if (first)
                first = false;
            else
                result.append("&");

            result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
            result.append("=");
            result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
        }

        return result.toString();
    }
}

---

RequestHandler是否返回了一些内容？我建议在PostExecute方法上设置一个断点，以查看从后端得到的响应。 另外，我个人更喜欢使用OkHTTP，对于一个简单的get请求，在您的doInBackground上会是这样的：

---

客户端应用程序和远程数据库之间通信的最佳方式是使用RESTfulAPI和著名的HTTP请求GET、PUT、POST和DELETE。当您有一个RESTAPI时，您可以使用同一个数据库创建多个客户端应用程序，如Android、IOS或JAVASCRIPT。它将由一个API_密钥保护，因此只有被授权进行查询或修改的请求才会被接受。 创建RESTAPI有很多方法，因为您是PHP开发人员，我建议您使用它，因为它轻量级且易于使用。

---

使用框架的另一个好处是安全性和sql注入问题，当初学者从头开始编写PHP代码时，会遇到很多问题

你有没有检查你的php代码是否有结果？你需要一步一步走。你确定这不仅仅是打字错误吗？getIssue.php！==见本期。php@jeroen字体对不起，这是打字mistake@PoorviGandhi：是的，我疯了。我检查了所有可能的东西。php文件工作正常。我正在将数据输入本地主机，请查看更新的代码。我还添加了请求处理程序的代码。

<?php 
    //Importing Database Script 
    require_once('dbConfig.php');

    //Creating sql query
    $sql = "SELECT * FROM user_issue";

    //getting result 
    $r = mysqli_query($con,$sql);

    //creating a blank array 
    $result = array();

    //looping through all the records fetched
    while($row = mysqli_fetch_array($r)){

        //Pushing name and id in the blank array created 
        array_push($result,array(
            "id"=>$row['id'],
            "store_name"=>$row['store_name'],
            "issue"=>$row['issue'],
            "describe"=>$row['describ']

        ));
    }

    //Displaying the array in json format 
    echo json_encode(array('result'=>$result));

    mysqli_close($con);

RequestHandler.java
package com.example.mi.mikpiadmin;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;

import javax.net.ssl.HttpsURLConnection;

public class RequestHandler {

    //Method to send httpPostRequest
    //This method is taking two arguments
    //First argument is the URL of the script to which we will send the request
    //Other is an HashMap with name value pairs containing the data to be send with the request
    public String sendPostRequest(String requestURL,
                                  HashMap<String, String> postDataParams) {
        //Creating a URL
        URL url;

        //StringBuilder object to store the message retrieved from the server
        StringBuilder sb = new StringBuilder();
        try {
            //Initializing Url
            url = new URL(requestURL);

            //Creating an httmlurl connection
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            //Configuring connection properties
            conn.setReadTimeout(15000);
            conn.setConnectTimeout(15000);
            conn.setRequestMethod("POST");
            conn.setDoInput(true);
            conn.setDoOutput(true);

            //Creating an output stream
            OutputStream os = conn.getOutputStream();

            //Writing parameters to the request
            //We are using a method getPostDataString which is defined below
            BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(os, "UTF-8"));
            writer.write(getPostDataString(postDataParams));

            writer.flush();
            writer.close();
            os.close();
            int responseCode = conn.getResponseCode();

            if (responseCode == HttpsURLConnection.HTTP_OK) {

                BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                sb = new StringBuilder();
                String response;
                //Reading server response
                while ((response = br.readLine()) != null){
                    sb.append(response);
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return sb.toString();
    }

    public String sendGetRequest(String requestURL){
        StringBuilder sb =new StringBuilder();
        try {
            URL url = new URL(requestURL);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));

            String s;
            while((s=bufferedReader.readLine())!=null){
                sb.append(s+"\n");
            }
        }catch(Exception e){
        }
        return sb.toString();
    }

    public String sendGetRequestParam(String requestURL, String id){
        StringBuilder sb =new StringBuilder();
        try {
            URL url = new URL(requestURL+id);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));

            String s;
            while((s=bufferedReader.readLine())!=null){
                sb.append(s+"\n");
            }
        }catch(Exception e){
        }
        return sb.toString();
    }

    private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
        StringBuilder result = new StringBuilder();
        boolean first = true;
        for (Map.Entry<String, String> entry : params.entrySet()) {
            if (first)
                first = false;
            else
                result.append("&");

            result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
            result.append("=");
            result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
        }

        return result.toString();
    }
}

OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
  .url(Config.URL_GET_ISSUE)
  .build();

Response response = client.newCall(request).execute();
return response.body().string();