我有这段代码来接收聊天消息。但当我试图把它放在AsyncTask时，我感到很困惑。当我将read cannot be resolved放入read.readline()时，我已postexecute发出警告{}。
我想让这段代码在后台工作，检查是否有任何消息来了。我想问，使代码始终在后台运行是使用AsyncTask还是有其他方法可以做到这一点？
有人请帮助我，我很困惑如何做到这一点。谢谢
接收讯息部分
HttpURLConnection connection;
URL url = null;
try{
linkurl = new Koneksi(this);
SERVER_URL = linkurl.getUrl();
SERVER_URL += "/mobile/ChatRoom.php?idu="+param2+"&idch="+param3+"&idcm="+param4;
url = new URL(SERVER_URL);
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestMethod("POST");
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(SERVER_URL);
//ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
//add parameter
//httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpRespose = httpClient.execute(httpPost);
HttpEntity httpEntity = httpRespose.getEntity();
//read content
InputStream in = httpEntity.getContent();
BufferedReader read = new BufferedReader(new InputStreamReader(in));
String msg = "tes";
while(true)
{
try {
msg = read.readLine();
Log.d("","MSGGG: "+ msg);
//msgList.add(msg);
} catch (IOException e) {
// TODO Auto-generated catch block
e.getMessage();
}
if(msg == null)
{
break;
}
else
{
showMessage(msg, false);
}
}}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
我试过的AsyncTask部分 - 更新但在getintent()得到警告，我必须把这些代码放在哪里？
public class ReceivedTask extends AsyncTask<String, String, String> {
Bundle bundle = this.getIntent().getExtras();
final String param2 = bundle.getString("keyUserId");
final String param3 = bundle.getString("keyChatsId");
String param4 = bundle.getString("keyMessagesId");
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
}
@Override
protected String doInBackground(String... arg0) {
// TODO Auto-generated method stub
HttpURLConnection connection;
URL url = null;
try{
linkurl = new Koneksi(ChatRoom.this);
SERVER_URL = linkurl.getUrl();
SERVER_URL += "/mobile/ChatRoom.php?idu="+param2+"&idch="+param3+"&idcm="+param4;
url = new URL(SERVER_URL);
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestMethod("POST");
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(SERVER_URL);
//ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
//add parameter
//httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpRespose = httpClient.execute(httpPost);
HttpEntity httpEntity = httpRespose.getEntity();
//read content
InputStream in = httpEntity.getContent();
BufferedReader read = new BufferedReader(new InputStreamReader(in));
String msg = "tes";
while(true)
{
try {
msg = read.readLine();
Log.d("","MSGGG: "+ msg);
//msgList.add(msg);
} catch (IOException e) {
// TODO Auto-generated catch block
e.getMessage();
}
if(msg == null)
{
break;
}
else
{
showMessage(msg, false);
}
}}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
ChatRoom.java - 我的完整代码
public class ChatRoom extends Activity {
public Koneksi linkurl;
String SERVER_URL;
private EditText messageText;
private TextView meLabel;
private TextView friendLabel;
private ViewGroup messagesContainer;
private ScrollView scrollContainer;
/* private Handler handler = new Handler();*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.chatpage);
messagesContainer = (ViewGroup) findViewById(R.id.messagesContainer);
scrollContainer = (ScrollView) findViewById(R.id.scrollContainer);
Button sendMessageButton = (Button) findViewById(R.id.sendButton);
Bundle bundle = this.getIntent().getExtras();
/*final String paramnama = bundle.getString("nama");*/
messageText = (EditText) findViewById(R.id.messageEdit);
meLabel = (TextView) findViewById(R.id.meLabel);
friendLabel = (TextView) findViewById(R.id.friendLabel);
meLabel.setText("me");
final String param1 = bundle.getString("keyCourseId");
final String param2 = bundle.getString("keyUserId");
final String param3 = bundle.getString("keyChatsId");
String param4 = bundle.getString("keyMessagesId");
sendMessageButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("messages", messageText.getText().toString()));
String response = null;
try {
linkurl = new Koneksi(ChatRoom.this);
SERVER_URL = linkurl.getUrl();
SERVER_URL += "/mobile/ChatKirimTeks.php?idu="+param2+"&idch="+param3;
response = CourseHttpClient.executeHttpPost(SERVER_URL, postParameters);
String res = response.toString();
res = res.trim();
res = res.replaceAll("\\s+","");
if(res.equals("1")){
String messageString = messageText.getText().toString();
showMessage(messageString, true);
messageText.getText().clear();
}else
{
createDialog("Maaf", "Messages Anda Gagal Terkirim");
}
}
catch (Exception e) {
messageText.setText(e.toString());
}
}
});
HttpURLConnection connection;
URL url = null;
try{
linkurl = new Koneksi(this);
SERVER_URL = linkurl.getUrl();
SERVER_URL += "/mobile/ChatRoom.php?idu="+param2+"&idch="+param3+"&idcm="+param4;
url = new URL(SERVER_URL);
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestMethod("POST");
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(SERVER_URL);
//ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
//add parameter
//httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpRespose = httpClient.execute(httpPost);
HttpEntity httpEntity = httpRespose.getEntity();
//read content
InputStream in = httpEntity.getContent();
BufferedReader read = new BufferedReader(new InputStreamReader(in));
String msg = "tes";
while(true)
{
try {
msg = read.readLine();
Log.d("","MSGGG: "+ msg);
//msgList.add(msg);
} catch (IOException e) {
// TODO Auto-generated catch block
e.getMessage();
}
if(msg == null)
{
break;
}
else
{
showMessage(msg, false);
}
}}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public class ReceivedTask extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
}
@Override
protected String doInBackground(String... arg0) {
// TODO Auto-generated method stub
HttpURLConnection connection;
URL url = null;
try{
linkurl = new Koneksi(ChatRoom.this);
SERVER_URL = linkurl.getUrl();
SERVER_URL += "/mobile/ChatRoom.php?idu="+param2+"&idch="+param3+"&idcm="+param4;
url = new URL(SERVER_URL);
connection = (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
connection.setRequestMethod("POST");
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(SERVER_URL);
//ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
//add parameter
//httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpRespose = httpClient.execute(httpPost);
HttpEntity httpEntity = httpRespose.getEntity();
//read content
InputStream in = httpEntity.getContent();
BufferedReader read = new BufferedReader(new InputStreamReader(in));
}
catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return null;
}
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
String msg = "tes";
while(true)
{
try {
msg = read.readLine();
Log.d("","MSGGG: "+ msg);
//msgList.add(msg);
} catch (IOException e) {
// TODO Auto-generated catch block
e.getMessage();
}
if(msg == null)
{
break;
}
else
{
showMessage(msg, false);
}
}
}
}
public void showMessage(String message, boolean leftSide) {
final TextView textView = new TextView(ChatRoom.this);
textView.setTextColor(Color.BLACK);
textView.setText(message);
int bgRes = R.drawable.left_message_bg;
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
if (!leftSide) {
bgRes = R.drawable.right_message_bg;
params.gravity = Gravity.RIGHT;
}
textView.setLayoutParams(params);
textView.setBackgroundResource(bgRes);
runOnUiThread(new Runnable() {
@Override
public void run() {
messagesContainer.addView(textView);
// Scroll to bottom
if (scrollContainer.getChildAt(0) != null) {
scrollContainer.scrollTo(scrollContainer.getScrollX(), scrollContainer.getChildAt(0).getHeight());
}
scrollContainer.fullScroll(View.FOCUS_DOWN);
}
});
}
private void createDialog(String title, String text) {
AlertDialog ad = new AlertDialog.Builder(this)
.setPositiveButton("Ok", null)
.setTitle(title)
.setMessage(text)
.create();
ad.show();
}
}
答案 0 :(得分：1)
您收到错误消息read cannot be resolved，因为Android禁止您从用户界面线程访问互联网。你必须在后台线程中这样做。实际上，使用AsyncTask的目的是使用户界面线程尽可能免费。
每当我使用AsyncTask时，我通常会创建一个类来保存任务的所有参数，并创建另一个类来保存结果。另外，我确保结果类可以表示可能出现的任何错误情况，例如：抛出异常。所以我使用的通用模板看起来像这样（注意：这是在不需要进度报告时）。
public class MyActivity extends Activity {
static class MyAsyncTaskParameters {
// put all the parameters that the task will need here
}
void KickOffAsynctask(...) { // various arguments as required by the task in hand
MyAsyncTaskParameters params = new MyAsyncTaskParameters(...); // package up all the parameters
MyAsyncTask newtask = new MyAsyncTask();
newtask.execute(params);
}
static class MyAsyncTaskResults {
// put all the results that the task can generate here
// NOTE: errors can occur in tasks, also exceptions
// can be thrown in tasks, so make it possible
// for this class to describe all error conditions that can occur
}
static class MyAsyncTask extends AsyncTask<MyAsyncTaskParameters, Void, MyAsyncTaskResults> {
@Override
protected MyAsyncTaskResults doInBackground(MyAsyncTaskParameters... params) {
MyAsyncTaskResults results = new MyAsyncTaskResults();
try {
MyAsyncTaskParameters taskParameters = params[0];
// This method will run in a background thread, so
// do as much as possible of the AsyncTask here.
} catch (Throwable e) {
// Set results object to indicate that an exception occurred.
}
return results;
}
@Override
protected void onPostExecute(MyAsyncTaskResults res) {
// This method will run in the User Interface thread.
// Use it to deal with the results stored in res.
// If an error has occurred, the res object will have it stored
// so take appropriate action, e.g. report to user.
}
}
}
答案 1 :(得分：0)
使用AsyncTask，在doInBackground(...)开展工作。从那里返回您的消息，并在onPostExecute(...)中处理返回的值。
@Override
protected void onPostExecute(String result) {
String msg = "tes"; // Why? You have 'result' String reference one line above.
请勿阅读onPostExecute中的信息流，将其作为后台任务的一部分。否则你将阻止UI线程。
请参阅onPostExecute。