Android+PHP uses HttpClient to submit POST requests and uses JSON to parse the response.

 Here’s an introduction to how to make your Android program have networking capabilities. Of course, you must first have a server. If you are just testing, you can use a LAN instead (mobile phone connected to computer wifi).

Requires the computer to be configured with Apache+PHP environment.

The following is a simple Android program. I believe that as long as you have a certain Java foundation, you can roughly "guess" its meaning. (The program may not be well written enough)

Android program

layout file

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/<strong>Activity</strong>_vertical_margin"
    android:paddingLeft="@dimen/<strong>Activity</strong>_horizontal_margin"
    android:paddingRight="@dimen/<strong>Activity</strong>_horizontal_margin"
    android:paddingTop="@dimen/<strong>Activity</strong>_vertical_margin"
    tools:c
    android:orientation="vertical" >

    <TextView 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:<strong>gravity</strong>="center"
        android:text="使用JSON解析"
        android:textSize="30sp"/>
    
    <LinearLayout 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:<strong>gravity</strong>="center">
        
        <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="账号"
        android:textSize="20sp"
        android:layout_marginRight="20dp" />
        
        <EditText 
            android:id="@+id/et_id"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>
    
	<LinearLayout 
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:<strong>gravity</strong>="center">
        
        <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="密码"
        android:textSize="20sp"
        android:layout_marginRight="20dp" />
        
        <EditText 
            android:id="@+id/et_psw"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"/>
    </LinearLayout>    
    
	<Button 
	    android:id="@+id/btn_login"
	    android:layout_width="match_parent"
	    android:layout_height="wrap_content"
	    android:text="登录"/>
</LinearLayout>

MainActivity.java

package com.example.jsontest;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import org.<strong>Apache</strong>.http.HttpEntity;
import org.<strong>Apache</strong>.http.HttpResponse;
import org.<strong>Apache</strong>.http.NameValuePair;
import org.<strong>Apache</strong>.http.client.HttpClient;
import org.<strong>Apache</strong>.http.client.entity.UrlEncodedFormEntity;
import org.<strong>Apache</strong>.http.client.methods.HttpPost;
import org.<strong>Apache</strong>.http.impl.client.DefaultHttpClient;
import org.<strong>Apache</strong>.http.message.BasicNameValuePair;
import org.<strong>Apache</strong>.http.protocol.HTTP;
import org.json.JSONArray;
import org.json.JSONObject;

import android.os.Bundle;
import android.os.Looper;
import android.support.v7.app.ActionBar<strong>Activity</strong>;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;


public class Main<strong>Activity</strong> extends ActionBar<strong>Activity</strong> {
	EditText et_id;
	EditText et_psw;
	Button btn_login;
	
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.<strong>Activity</strong>_main);
        
        initView();
    }
    
    private boolean check(String id, String psw) {
    	if("".equals(id) || "".equals(psw))
    		return false;
    	return true;
    }
    
    private void initView() {
    	et_id = (EditText)findViewById(R.id.et_id);
    	et_psw = (EditText)findViewById(R.id.et_psw);
    	btn_login = (Button)findViewById(R.id.btn_login);
    	
    	btn_login.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				//获取用户输入的用户名和密码
				final String id = et_id.getText().toString().trim();
				final String psw = et_psw.getText().toString().trim();
				
				if(check(id, psw)) {
					new Thread() {
						public void run() {
							try {
								HttpPost post = new HttpPost("这里要改成服务器文件所在URL地址");
								//如果传递参数个数比较多，可以对传递的参数进行封装
								List<NameValuePair> params = new ArrayList<NameValuePair>();
								params.add(new BasicNameValuePair("id", id));
								params.add(new BasicNameValuePair("psw", psw));
								//设置请求参数
								post.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
								
								HttpClient httpClient = new DefaultHttpClient();
								//发送POST请求
								HttpResponse response = httpClient.execute(post);
								//如果服务器成功地返回响应
								if(response.getStatusLine().getStatusCode() == 200) {
									//String msg = EntityUtils.toString(response.getEntity());
									HttpEntity entity = response.getEntity();
									InputStream is = entity.getContent();
									
									BufferedReader reader = new BufferedReader(new InputStreamReader(is, "utf-8"), 8);
									StringBuilder sb = new StringBuilder();
									sb.append(reader.readLine() + "\n"); // 这里 “ + "\n" ”加不加似乎对结果没有什么影响
									
									String line = "0";
									while((line = reader.readLine()) != null) {
										sb.append(line + "\n"); // 这里 “ + "\n" ”加不加似乎对结果没有什么影响
									}
									is.close();
									
									//获取请求响应结果
									String result = sb.toString();
									System.out.println(result);
									
									//打包成JSON进行解析
									JSONArray jsonArray = new JSONArray(result);
									JSONObject jsonData = null;
									//返回用户ID，用户密码
									String userId = "";
									String userPsw = "";
									//使用List进行存储
									List<String> data = new ArrayList<String>();
									for(int i = 0; i < jsonArray.length(); i++) {
										jsonData = jsonArray.getJSONObject(i);
										userId = jsonData.getString("userId"); //userId是来源于服务器端php程序响应结果res的<strong>索引</strong>，根据<strong>索引</strong>获取值
										userPsw = jsonData.getString("userPsw"); //userPsw是来源于服务器端php程序响应结果res的<strong>索引</strong>，根据<strong>索引</strong>获取值
										data.add("用户ID：" + userId + "，用户密码：" + userPsw); //保存返回的值，可进行相应的操作，这里只进行显示
									}
									
									Looper.prepare();
									Toast.makeText(Main<strong>Activity</strong>.this, data.toString(), Toast.LENGTH_LONG).show();
									Looper.loop();
								}
								else {
									Looper.prepare();
									Toast.makeText(Main<strong>Activity</strong>.this, "登录失败", Toast.LENGTH_LONG).show();
									Looper.loop();
								}
							}
							catch(<strong>Exception</strong> e) {
								e.printStackTrace();
							}
						}
					}.start();
				}
			}
		});
    }


    @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;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent <strong>Activity</strong> in <strong>AndroidManifest.xml</strong>.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

And the following is a server-side php file (within the file For operations that have not connected to the database, if you want, you can connect to the database and obtain dynamic data. People who know PHP can easily change it to connect to the databaseto obtain data)

checkId. php

<?php
	//获取客户端发送过来的ID和密码
	$id=$_POST[&#39;id&#39;];
	$psw=$_POST[&#39;psw&#39;];

	if($id == "admin" && $psw == "123") {
		$res=array(array());
		$res[0][&#39;userId&#39;]=$id;
		$res[0][&#39;userPsw&#39;]=$psw;

		$res[1][&#39;userId&#39;]="testId1";
		$res[1][&#39;userPsw&#39;]="testPsw1";

		$res[2][&#39;userId&#39;]="testId2";
		$res[2][&#39;userPsw&#39;]="testPsw2";
	}

	echo json_encode($res);
?>

The above introduces Android+PHP using HttpClient to submit POST requests and using JSON to parse the response, including gravity, Apache, Exception, index, and database connection. I hope it will be helpful to friends who are interested in PHP tutorials.