php - 本地主机不工作，但网站在 Android 中工作

Question

我正在学习Android。我正在尝试从 Android 读取 PHP 输出(通过 JSON )。

如果我给出站点 URL，它就会获取该值。如果您进入该网站，它会显示如下 Json 代码。

http://cpriyankara.coolpage.biz/employee_details.php ”;

{"emp_info":[{"员工姓名":"Adam","员工编号":"101700"},{"员工姓名":"约翰","员工编号":"101701"},{ "员工姓名":"Paul","员工编号":"101702"},{"员工姓名":"马克","员工编号":"101703"},{"员工姓名":"唐纳德","员工编号":"101704"},{"员工姓名":"Brain","员工编号":"101705"},{"员工姓名":"Kevin","员工编号":"101706"}]}

如果我给我的本地主机 PHP 站点，它也会以 Json 格式显示，如上面所示。 (我正在使用 WAMPSERVER 运行 PHP)

{"emp_info":[{"员工姓名":"Adam","员工编号":"101700"},{"员工姓名":"约翰","员工编号":"101701"},{ "员工姓名":"Paul","员工编号":"101702"},{"员工姓名":"马克","员工编号":"101703"},{"员工姓名":"唐纳德","员工编号":"101704"},{"员工姓名":"Brain","员工编号":"101705"},{"员工姓名":"Kevin","员工编号":"101706"}]}

但是在 Android 中，如果我提供站点，它会显示结果，但如果我提供本地主机地址，它会说应用程序意外停止。

请告诉我为什么？？在这种情况下，我如何才能看到错误或异常。

我在下面提供了 PHP 和 Android 代码。

PHP 代码:

<?php
$host=""; //replace with database
$username="root"; //replace with database username 
$password="root"; //replace with database password 
$db_name="and"; //replace with database name

$con=mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");
$sql = "select * from emp_info"; 
$result = mysql_query($sql);
$json = array();

if(mysql_num_rows($result)){
while($row=mysql_fetch_assoc($result)){
$json['emp_info'][]=$row;
}
}
mysql_close($con);
echo json_encode($json); 
?> 

Android Java 代码:

在下面的代码中，我将 URL 更改为本地主机 URL

包com.example.phpmysql;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;

public class MainActivity extends Activity {
 private String jsonResult;
 Private String url = "http://cpriyankara.coolpage.biz/employee_details.php";

 private ListView listView;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  listView = (ListView) findViewById(R.id.listView1);
  accessWebService();
 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.main, menu);
  return true;
 }

 // Async Task to access the web
 private class JsonReadTask extends AsyncTask<String, Void, String> {
  @Override
  protected String doInBackground(String... params) {
   HttpClient httpclient = new DefaultHttpClient();
   HttpPost httppost = new HttpPost(params[0]);
   try {
    HttpResponse response = httpclient.execute(httppost);
    jsonResult = inputStreamToString(
      response.getEntity().getContent()).toString();
   }

   catch (ClientProtocolException e) {
    e.printStackTrace();
   } catch (IOException e) {
    e.printStackTrace();
   }
   return null;
  }

  private StringBuilder inputStreamToString(InputStream is) {
   String rLine = "";
   StringBuilder answer = new StringBuilder();
   BufferedReader rd = new BufferedReader(new InputStreamReader(is));

   try {
    while ((rLine = rd.readLine()) != null) {
     answer.append(rLine);
    }
   }

   catch (IOException e) {
    // e.printStackTrace();
    Toast.makeText(getApplicationContext(),
      "Error..." + e.toString(), Toast.LENGTH_LONG).show();
   }
   return answer;
  }

  @Override
  protected void onPostExecute(String result) {
   ListDrwaer();
  }
 }// end async task

 public void accessWebService() {
  JsonReadTask task = new JsonReadTask();
  // passes values for the urls string array
  task.execute(new String[] { url });
 }

 // build hash set for list view
 public void ListDrwaer() {
  List<Map<String, String>> employeeList = new ArrayList<Map<String, String>>();

  try {
   JSONObject jsonResponse = new JSONObject(jsonResult);
   JSONArray jsonMainNode = jsonResponse.optJSONArray("emp_info");

   for (int i = 0; i < jsonMainNode.length(); i++) {
    JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
    String name = jsonChildNode.optString("employee name");
    String number = jsonChildNode.optString("employee no");
    String outPut = name + "-" + number;
    employeeList.add(createEmployee("employees", outPut));
   }
  } catch (JSONException e) {
   Toast.makeText(getApplicationContext(), "Error" + e.toString(),
     Toast.LENGTH_SHORT).show();
  }

  SimpleAdapter simpleAdapter = new SimpleAdapter(this, employeeList,
    android.R.layout.simple_list_item_1,
    new String[] { "employees" }, new int[] { android.R.id.text1 });
  listView.setAdapter(simpleAdapter);
 }

 private HashMap<String, String> createEmployee(String name, String number) {
  HashMap<String, String> employeeNameNo = new HashMap<String, String>();
  employeeNameNo.put(name, number);
  return employeeNameNo;
 }
}

Answer 1

当本地主机工作时，我假设您是从 http://cpriyankara.coolpage.biz/employee_details.php 的计算机发出请求的。托管地址正确吗？

localhost 的意思是“我现在正在发出请求的这台机器”。

因此，除非您的 Android 机器运行了一个可以使用 localhost 访问名为/employee_details.php 的文件的 Web 服务器，否则该服务器将无法工作。