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我試過這段代碼，它在運行模擬器時沒有顯示任何錯誤。 在點擊事件過程中，我的模擬器不幸中止。無法獲取JSON值工作的http post方法。 Android系統。建議請。
我logcat的
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);
?>
這是MyPhp輸出傳入值之後：
[{"ChildPassportName":"Arun","ChildID":"0"}]
米亞瓦文件
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;
}
}
}