无法获取获取 JSON 值工作的 http post 方法.人造人.请提出建议

Question

我尝试过这段代码，它在运行模拟器时没有显示任何错误。在单击事件期间，我的模拟器不幸停止了。

我的洛格猫

03-04 08:46:17.633: E/AndroidRuntime(1391): FATAL EXCEPTION: AsyncTask #1
03-04 08:46:17.633: E/AndroidRuntime(1391): Process: com.example.childprofile, PID: 1391
03-04 08:46:17.633: E/AndroidRuntime(1391): java.lang.RuntimeException: An error occured while executing doInBackground()
03-04 08:46:17.633: E/AndroidRuntime(1391):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at java.lang.Thread.run(Thread.java:841)
03-04 08:46:17.633: E/AndroidRuntime(1391): Caused by: java.lang.NullPointerException
03-04 08:46:17.633: E/AndroidRuntime(1391):     at com.example.childprofile.ChildProfile$sendPostData.doInBackground(ChildProfile.java:123)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at com.example.childprofile.ChildProfile$sendPostData.doInBackground(ChildProfile.java:1)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
03-04 08:46:17.633: E/AndroidRuntime(1391):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
03-04 08:46:17.633: E/AndroidRuntime(1391):     ... 4 more
03-04 08:46:20.123: I/Choreographer(1391): Skipped 59 frames!  The application may be doing too much work on its main thread.

PHP文件

<?php
$con=mysql_connect("localhost","arun","sachin11");
$rows = array();
$db_select = mysql_select_db('Schoolapp', $con);
$username = $_GET['username'];
$password = $_GET['password'];
$result = mysql_query("SELECT ChildPassportName,ChildID FROM SchoolDB where Username='$username' and Password='$password'",$con);
while($r = mysql_fetch_assoc($result)) {
    $rows[] = $r;
}
print json_encode($rows);
mysql_close($con);
?>

这是传入值后的MyPhp输出：

[{"ChildPassportName":"Arun","ChildID":"0"}]

我的爪哇文件

package com.example.childprofile;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;
import org.apache.http.client.ClientProtocolException;
import org.json.JSONException;
import org.json.JSONObject;
import android.os.AsyncTask; 
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class ChildProfile extends Activity {
    private TextView childname,childid;
    private Button get;
    private EditText username,password;
    private JSONObject jObj;
    private static String user,pass,json,child,id;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.child_profile);
        username=(EditText) findViewById(R.id.profile_username);
        password=(EditText) findViewById(R.id.profile_password);
        childname=(TextView) findViewById(R.id.profile_email);
        childid=(TextView) findViewById(R.id.profile_childid);
        get=(Button) findViewById(R.id.profile_button1);
        get.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                new sendPostData().execute();
            }
        });
    }
    private class sendPostData extends AsyncTask<String, Void, String>
    {
           @Override
           protected void onPostExecute(String result) { 
               //View your result here.
                  try {
                    jObj = new JSONObject(result);
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                  try {
                    child=jObj.getString("ChildPassportName");
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                  try {
                    id=jObj.getString("ChildID");
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                  childname.setText(child);
                  childid.setText(id);
               }
        @Override
        protected String doInBackground(String... params) {
            // TODO Auto-generated method stub
            StringBuilder sb = null;
            try
            {
            user=username.getText().toString();
            pass=password.getText().toString();
            String link="http://192.168.1.22:81/arun.php?";
            String data  = URLEncoder.encode("username", "UTF-8") 
            + "=" + URLEncoder.encode(user, "UTF-8");
            data += "&" + URLEncoder.encode("password", "UTF-8") 
            + "=" + URLEncoder.encode(pass, "UTF-8");
            URL url = new URL(link);
            URLConnection conn = url.openConnection(); 
            conn.setDoOutput(true); 
            OutputStreamWriter wr = new OutputStreamWriter
            (conn.getOutputStream()); 
            wr.write( data ); 
            wr.flush(); 
            BufferedReader reader = new BufferedReader
            (new InputStreamReader(conn.getInputStream())); 
            sb = new StringBuilder();
            String line = null;
            // Read Server Response
            while((line = reader.readLine()) != null)
            {
               sb.append(line);
               break;
            }

            }
            catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            json=sb.toString();

            return json;
        }
     }
    }

Answer 1

这应该可以解决你的问题。我已经简化了某些部分的代码。

private class SendPostData extends AsyncTask<String, Void, String>
{
    private String user = null;
    private String pass = null;
    @Override
    protected void onPreExecute()
    {
        this.user = username.getText().toString();
        this.pass = password.getText().toString();
    }
    @Override
    protected String doInBackground(String... params)
    {
        StringBuilder sb = new StringBuilder();
        try
        {
            String link="http://192.168.1.22:81/arun.php?";
            link += URLEncoder.encode("username", "UTF-8") + "=" + URLEncoder.encode(user, "UTF-8");
            link += "&" + URLEncoder.encode("password", "UTF-8")  + "=" + URLEncoder.encode(pass, "UTF-8");
            URL url = new URL(link);
            URLConnection conn = url.openConnection(); 
            conn.setDoOutput(false); 
            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); 
            String line = null;
            // Read Server Response
            while((line = reader.readLine()) != null)
            {
                sb.append(line);
                break;
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        return sb.toString();
    }
    @Override
    protected void onPostExecute(String result)
    {
        try
        {
            ChildProfile.this.json = result;
            JSONObject jObj = new JSONObject(result);
            if (jObj.has("ChildPassportName"))
            {
                String child = jObj.getString("ChildPassportName");
                ChildProfile.this.childname.setText(child);
            }
            if (jObj.has("ChildID"))
            {
                String id = jObj.getString("ChildID");
                ChildProfile.this.childid.setText(id);
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}