Android使用PHP在MySQL上进行连接

Question

我试图做我的第一个与MySQL上的连接的android应用程序，我谷歌很多，找到一些教程和类似的东西。 基于它们，我有以下代码：

package com.example.helloworld;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
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.message.BasicNameValuePair;
import org.json.JSONObject;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    String name;
    String id;
    InputStream is=null;
    String result=null;
    String line=null;
    int code;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final EditText e_id=(EditText) findViewById(R.id.editText1);
        final EditText e_name=(EditText) findViewById(R.id.editText2);
        Button insert=(Button) findViewById(R.id.button1);

        insert.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            id = e_id.getText().toString();
            name = e_name.getText().toString();

            insert();
        }
    });
    }

    public void insert()
    {
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();

    nameValuePairs.add(new BasicNameValuePair("id",id));
    nameValuePairs.add(new BasicNameValuePair("name",name));

        try
        {
        HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://localhost/xampp/android_connect/index.php");
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost); 
            HttpEntity entity = response.getEntity();
            is = entity.getContent();
            Log.e("pass 1", "connection success ");
    }
        catch(Exception e)
    {
            Log.e("Fail 1", e.toString());
            Toast.makeText(getApplicationContext(), "Invalid IP Address",
            Toast.LENGTH_LONG).show();
    }     

        try
        {
            BufferedReader reader = new BufferedReader
            (new InputStreamReader(is,"iso-8859-1"),8);
            StringBuilder sb = new StringBuilder();
            while ((line = reader.readLine()) != null)
        {
                sb.append(line + "\n");
            }
            is.close();
            result = sb.toString();
        Log.e("pass 2", "connection success ");
    }
        catch(Exception e)
    {
            Log.e("Fail 2", e.toString());
    }     

    try
    {
            JSONObject json_data = new JSONObject(result);
            code=(json_data.getInt("code"));

            if(code==1)
            {
        Toast.makeText(getBaseContext(), "Inserted Successfully",
            Toast.LENGTH_SHORT).show();
            }
            else
            {
         Toast.makeText(getBaseContext(), "Sorry, Try Again",
            Toast.LENGTH_LONG).show();
            }
    }
    catch(Exception e)
    {
            Log.e("Fail 3", e.toString());
    }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }    
}

我看不到任何错误或任何东西，但是当我尝试加载它时，它说：“无效的IP地址”（这是catch {}的错误消息）。 我尝试研究哪里可能有问题，在LogCat中我发现此错误：

11-16 10:39:10.036: I/ActivityManager(150): Start proc com.example.helloworld for activity com.example.helloworld/.MainActivity: pid=612 uid=10045 gids={3003, 1028}
11-16 10:39:10.386: E/Trace(612): error opening trace file: No such file or directory (2)
11-16 10:39:10.966: D/gralloc_goldfish(612): Emulator without GPU emulation detected.
11-16 10:39:11.016: I/ActivityManager(150): Displayed com.example.helloworld/.MainActivity: +1s32ms
11-16 10:39:11.066: I/Choreographer(150): Skipped 34 frames!  The application may be doing too much work on its main thread.
11-16 10:39:18.945: E/Fail 1(612): android.os.NetworkOnMainThreadException
11-16 10:39:18.975: E/Fail 2(612): java.lang.NullPointerException
11-16 10:39:18.975: E/Fail 3(612): java.lang.NullPointerException
11-16 10:39:19.195: D/dalvikvm(612): GC_CONCURRENT freed 191K, 4% free 6229K/6471K, paused 17ms+65ms, total 206ms
11-16 10:39:20.065: E/Fail 1(612): android.os.NetworkOnMainThreadException
11-16 10:39:20.075: E/Fail 2(612): java.lang.NullPointerException
11-16 10:39:20.075: E/Fail 3(612): java.lang.NullPointerException
11-16 10:39:20.645: E/Fail 1(612): android.os.NetworkOnMainThreadException
11-16 10:39:20.645: E/Fail 2(612): java.lang.NullPointerException
11-16 10:39:20.645: E/Fail 3(612): java.lang.NullPointerException
11-16 10:39:21.055: E/Fail 1(612): android.os.NetworkOnMainThreadException
11-16 10:39:21.065: E/Fail 2(612): java.lang.NullPointerException
11-16 10:39:21.065: E/Fail 3(612): java.lang.NullPointerException
11-16 10:39:21.535: E/Fail 1(612): android.os.NetworkOnMainThreadException
11-16 10:39:21.545: E/Fail 2(612): java.lang.NullPointerException
11-16 10:39:21.545: E/Fail 3(612): java.lang.NullPointerException
11-16 10:39:21.728: E/Fail 1(612): android.os.NetworkOnMainThreadException
11-16 10:39:21.735: E/Fail 2(612): java.lang.NullPointerException
11-16 10:39:21.735: E/Fail 3(612): java.lang.NullPointerException
11-16 10:39:21.925: E/Fail 1(612): android.os.NetworkOnMainThreadException
11-16 10:39:21.925: E/Fail 2(612): java.lang.NullPointerException
11-16 10:39:21.925: E/Fail 3(612): java.lang.NullPointerException
11-16 10:39:22.535: I/Choreographer(612): Skipped 37 frames!  The application may be doing too much work on its main thread.
: E/(): Device disconnected: 1
: E/(): Device disconnected

尤其是我看找不到目录，我尝试在浏览器中打开相同的地址，并且我没有问题地打开它。 有人可以告诉我我在做什么错吗？

谢谢

Answer 1

localhost指向设备本身； 因此，您可以尝试以下操作：

• 如果出于测试目的在自己的网络上运行此程序，请尝试键入本地ip而不是localhost ， 例如 http://192.168.0.123

• 尝试使用http://10.0.2.2而不是localhost ，在设备上的浏览器中键入它，然后查看其是否正确连接。

还要检查这个问题 。

10.0.2.2的参考

---

关于NetworkOnMainThreadException

您正在尝试在应用程序的主线程上进行网络操作，这可能会导致严重的延迟和不可预测的结果 。

您应该始终使用AsyncTask进行网络操作。 请参阅android docs中的这篇文章 。

这是一个示例用法；

您的AsyncTask应该如下所示：

 private class DownloadWebpageTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... urls) {

        // params comes from the execute() call: params[0] is the url.
        try {

            // Initialize your parameters
            ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
            nameValuePairs.add(new BasicNameValuePair("id",urls[1]));
            nameValuePairs.add(new BasicNameValuePair("name",urls[2]));         

            // Make your HTTP Request
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(urls[0]);
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost); 
            HttpEntity entity = response.getEntity();
            is = entity.getContent();

            // Read the response
            BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
            StringBuilder sb = new StringBuilder();
            while ((line = reader.readLine()) != null) {
             sb.append(line + "\n");
            }
            is.close();
            result = sb.toString();

            // Return the response.
            return result;
        } catch (IOException e) {
            return "Unable to retrieve web page. URL may be invalid.";
        }
    }

    // onPostExecute gets the results of the AsyncTask.
    @Override
    protected void onPostExecute(String result) {

        // Read your response into a JSONObject and do stuff...
        JSONObject json_data = new JSONObject(result);
        code=(json_data.getInt("code"));
        if(code==1)
        {
            Toast.makeText(getBaseContext(), "Inserted Successfully", Toast.LENGTH_SHORT).show();
        }
        else
        {
            Toast.makeText(getBaseContext(), "Sorry, Try Again", Toast.LENGTH_LONG).show();
        }
   }
}

您可以像这样使用它：

// Params : url, id, name
new DownloadWebpageTask().execute("http://10.0.2.2/xampp/android_connect/index.php", "12345", "Foo Bar");

这是一个完整的示例，您的代码应如下所示：

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
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.message.BasicNameValuePair;
import org.json.JSONObject;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    String name;
    String id;
    InputStream is=null;
    String result=null;
    String line=null;
    int code;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final EditText e_id=(EditText) findViewById(R.id.editText1);
        final EditText e_name=(EditText) findViewById(R.id.editText2);
        Button insert=(Button) findViewById(R.id.button1);

        insert.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub

                id = e_id.getText().toString();
                name = e_name.getText().toString();

                insert();
            }
        });
    }

    public void insert()
    {
        new DownloadWebpageTask().execute("http://10.0.2.2/xampp/android_connect/index.php", id, name);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    private class DownloadWebpageTask extends AsyncTask<String, Void, String> {
    @Override
    protected String doInBackground(String... urls) {

        // params comes from the execute() call: params[0] is the url.
        try {
            // Initialize your parameters
            ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
            nameValuePairs.add(new BasicNameValuePair("id",urls[1]));
            nameValuePairs.add(new BasicNameValuePair("name",urls[2]));         

            // Make your HTTP Request
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(urls[0]);
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost); 
            HttpEntity entity = response.getEntity();
            is = entity.getContent();

            // Read the response
            BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
            StringBuilder sb = new StringBuilder();
            while ((line = reader.readLine()) != null) {
             sb.append(line + "\n");
            }
            is.close();
            result = sb.toString();

            // Return the response.
            return result;
        } catch (IOException e) {
            return "Unable to retrieve web page. URL may be invalid.";
        }
    }

    // onPostExecute gets the results of the AsyncTask.
    @Override
    protected void onPostExecute(String result) {

        // Read your response into a JSONObject and do stuff...
        JSONObject json_data = new JSONObject(result);
        code=(json_data.getInt("code"));
        if(code==1)
        {
            Toast.makeText(getBaseContext(), "Inserted Successfully", Toast.LENGTH_SHORT).show();
        }
        else
        {
            Toast.makeText(getBaseContext(), "Sorry, Try Again", Toast.LENGTH_LONG).show();
        }
   }
}
}

Answer 2

我认为您有两个问题：

1. 将localhost更改为计算机的IP地址 。
2. 您正在UI线程上进行网络调用，这对性能不利。 您可以改用AsyncTask或使用像Retrofit这样的库！ ;）

Answer 3

你做错了。 尝试10.0.2.2/android_connect/index.php。 10.0.2.2重定向到您的xampp / htdoc /文件夹。