我尝试使用Android应用中的JavaMail API从Gmail检索电子邮件，我已经实现了以下活动，其中包含一个触发检索操作的按钮和一个用于显示结果的textview。
代码在以下行中失败：
store = (GmailSSLStore) session.getStore("gimaps");
返回的store为空。
我在我的电脑上尝试过使用JavaMail的类似代码并且运行良好，我不确定以下是否是在Android中使用JavaMail的正确方法，请提供线索。
我使用的jar文件是从以下链接下载的javax.mail和gimap-1.5.0：
https://java.net/projects/javamail/pages/Home
非常感谢
package com.example.myfirstapp;
import java.io.IOException;
import java.util.Properties;
import javax.mail.FetchProfile;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.Part;
import javax.mail.Session;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.text.Html;
import android.text.Spanned;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import com.sun.mail.gimap.GmailFolder;
import com.sun.mail.gimap.GmailMessage;
import com.sun.mail.gimap.GmailSSLStore;
public class GetMailActivity extends Activity {
final String SENDER_PATTERN_1 = ".*xxxxxx.*";
final String SENDER_PATTERN_2 = ".*yyyyyy.*";
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.activity_get_mail);
// Show the Up button in the action bar.
setupActionBar();
setContentView(R.layout.activity_get_mail);
textView = (TextView) findViewById(R.id.string_bill);
}
/**
* Set up the {@link android.app.ActionBar}, if the API is available.
*/
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private void setupActionBar() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
getActionBar().setDisplayHomeAsUpEnabled(true);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.get_mail, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. Use NavUtils to allow users
// to navigate up one level in the application structure. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
public void getMail(View view){
ConnectivityManager connMgr = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
if(networkInfo != null && networkInfo.isConnected()){
new DownloadMailTask().execute();
}
else{
textView.setText("No network connection available.");
}
}
private class DownloadMailTask extends AsyncTask<String, Void, String>{
protected String doInBackground(String... strings) {
Properties props = new Properties();
props.setProperty("mail.store.protocol", "gimaps");
GmailSSLStore store = null;
GmailFolder folder = null;
String myhtml = "";
try {
Session session = Session.getDefaultInstance(props, null);
store = (GmailSSLStore) session.getStore("gimaps");
store.connect("username", "passwd");
folder = (GmailFolder) store.getFolder("INBOX");
folder.open(Folder.READ_ONLY);
int cnt = folder.getMessageCount();
Message[] ms = folder.getMessages(cnt-5, cnt);
FetchProfile fp = new FetchProfile();
fp.add(GmailFolder.FetchProfileItem.MSGID);
fp.add(GmailFolder.FetchProfileItem.THRID);
fp.add(GmailFolder.FetchProfileItem.LABELS);
folder.fetch(ms, fp);
GmailMessage gm;
for (Message m : ms) {
gm = (GmailMessage) m;
String sender = gm.getSender().toString();
if(/*!sender.matches(SENDER_PATTERN_1) &&*/
!sender.matches(SENDER_PATTERN_2)) {
//System.out.println("not match");
continue;
}
myhtml = dumpPart(gm);
}
} catch (MessagingException ex){
Log.getStackTraceString(ex.getCause().getCause());
return "Unable to retrieve the mails, MessagingException.";
} catch (IOException ie){
return "Unable to retrieve the mails, IOException.";
} catch (Exception ex){
return "Unable to retrieve the mails, Exception.";
}
Spanned result = Html.fromHtml(myhtml);
return result.toString();
}
protected void onPostExecute(String result){
textView.setText(result);
}
private String dumpPart(Part p) throws Exception {
if(p.isMimeType("multipart/*")){
Multipart mp = (Multipart)p.getContent();
for(int i=0; i<mp.getCount(); i++){
dumpPart(mp.getBodyPart(i));
}
}
else{
Object o = p.getContent();
if(o instanceof String){
return ((String)o);
}
}
return null;
}
}
}
LogCat输出：
05-31 03:17:50.336: W/dalvikvm(4585): threadid=8: thread exiting with uncaught exception (group=0xb401a4f0)
05-31 03:17:50.336: E/AndroidRuntime(4585): FATAL EXCEPTION: AsyncTask #1
05-31 03:17:50.336: E/AndroidRuntime(4585): java.lang.RuntimeException: An error occured while executing doInBackground()
05-31 03:17:50.336: E/AndroidRuntime(4585): at android.os.AsyncTask$3.done(AsyncTask.java:200)
05-31 03:17:50.336: E/AndroidRuntime(4585): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
05-31 03:17:50.336: E/AndroidRuntime(4585): at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
05-31 03:17:50.336: E/AndroidRuntime(4585): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
05-31 03:17:50.336: E/AndroidRuntime(4585): at java.util.concurrent.FutureTask.run(FutureTask.java:138)
05-31 03:17:50.336: E/AndroidRuntime(4585): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
05-31 03:17:50.336: E/AndroidRuntime(4585): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
05-31 03:17:50.336: E/AndroidRuntime(4585): at java.lang.Thread.run(Thread.java:1019)
05-31 03:17:50.336: E/AndroidRuntime(4585): Caused by: java.lang.NullPointerException
05-31 03:17:50.336: E/AndroidRuntime(4585): at com.example.myfirstapp.GetMailActivity$DownloadMailTask.doInBackground(GetMailActivity.java:141)
05-31 03:17:50.336: E/AndroidRuntime(4585): at com.example.myfirstapp.GetMailActivity$DownloadMailTask.doInBackground(GetMailActivity.java:1)
05-31 03:17:50.336: E/AndroidRuntime(4585): at android.os.AsyncTask$2.call(AsyncTask.java:185)
05-31 03:17:50.336: E/AndroidRuntime(4585): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
05-31 03:17:50.336: E/AndroidRuntime(4585): ... 4 more