Android通过PHP访问MySQL数据库_android php查询mysql-优快云博客

本文介绍如何从MySQL数据库读取数据，并在Android应用中使用PHP脚本将其转化为JSON格式，最后通过列表视图展示出来。教程分为三部分：MySQL数据库、PHP Web服务和Android客户端。

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In this post I'm going to describe how we can read data from MySQL database and show them in a Android list view. To fetch data here I used a PHP script which encodes data into json format.
This project has three main parts.
1. MySQL database
2. PHP web service
3.Android web service client

1. MySQL database.

My database has only one table named "emp_info" and it has two columns. "employee name" and "employee no". "employee no" is the primary key.

2.PHP web service
Use following PHP script to fetch data from the database and to encode data in to json format.

<?php
$host = "localhost"; // replace with database hostname
$username = "root"; // replace with database username
$password = ""; // replace with database password
$db_name = "mysqlphp"; // 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 );
?>

3.Android web service client.
This part is bit complected. Android activity is a combination of Async Task json and list view. If you are not familiar with those stuff look following tutorials.

Here is the code for main Android activity.

package com.example.mysqlphp;

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://XXXXXX/employee_details.php";  //XXXXXX为Ip地址
	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;
	}
}

Add Internet permission to AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.mysqlphp"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />
    
    <uses-permission android:name="android.permission.INTERNET" /> 

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.mysqlphp.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Code for main activity layout.

<RelativeLayout 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/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="14dp" >
    </ListView>

</RelativeLayout>

运行结果如图所示：