如何解决NetworkOnMainThreadException错误的Android？ [英] How to solve NetworkOnMainThreadException error in android?
本文介绍了如何解决NetworkOnMainThreadException错误的Android？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我用的JavaMail 来android系统中发送电子邮件。但它抛出异常的 NetworkOnMainThreadException 。如何解决这个例外？
MainActivity
包com.aaa;
进口android.os.Bundle;
进口android.os.NetworkOnMainThreadException;
进口android.app.Activity;
进口android.util.Log;
进口android.view.Menu;
进口android.view.View;
进口android.widget.Toast;公共类MainActivity延伸活动{
私人邮件米;
@覆盖
保护无效的onCreate（捆绑savedInstanceState）{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.activity_main）;
M =新邮件（mail@gmail.com，PWD）;
}
公共无效sendEmail（查看视图）{
的String [] = toArr {samp@gmail.com};
m.setTo（toArr）;
m.setFrom（mail613@gmail.com）;
m.setSubject（主体）;
m.setBody（您的信息放在这里）; 尝试{
//m.addAttachment(\"/sdcard/myPicture.jpg）;
如果（m.send（））{
//成功
Toast.makeText（MainActivity.this，邮件发送成功，Toast.LENGTH_LONG）.show（）;
}其他{
//失败
Toast.makeText（MainActivity.this，电子邮件未发送，Toast.LENGTH_LONG）.show（）;
}
}赶上（例外五）{
//一些其他的问题
//Toast.makeText(MainActivity.this，电子邮件未发送，Toast.LENGTH_LONG）.show（E）;
Toast.makeText（MainActivity.this，+ E +，Toast.LENGTH_LONG）.show（）;
Log.e（的SendMail，e.getMessage（），E）;
} } }
Mail.java
包com.aaa;进口java.util.Date;
进口java.util.Properties;
进口javax.activation.CommandMap;
进口的javax.activation.DataHandler;
进口javax.activation.DataSource;
进口javax.activation.FileDataSource;
进口javax.activation.MailcapCommandMap;
进口javax.mail.BodyPart;
进口javax.mail.Multipart;
进口javax.mail.PasswordAuthentication;
进口javax.mail.Session的;
进口javax.mail.Transport;
进口javax.mail.internet.InternetAddress;
进口javax.mail.internet.MimeBodyPart;
进口的javax.mail.internet.MimeMessage;
进口javax.mail.internet.MimeMultipart;公共类邮件扩展javax.mail.Authenticator {
私人字符串_user;
私人字符串_pass;私有String [] _to;
_from私人字符串;私人字符串_port;
私人字符串_sport;私人字符串_host;私人字符串_subject;
私人字符串_body;私人布尔_auth;私人布尔_debuggable;私人多部分_multipart;
公共邮件（）{
_host =smtp.gmail.com; //默认的SMTP服务器
_port =465; //默认的SMTP端口
_sport =465; //默认的SocketFactory端口 _user =; // 用户名
_pass =; //密码
_from =;从//发送电子邮件
_subject =; // 电子邮件主题
_body =; //邮件正文 _debuggable = FALSE;开启或关闭//调试模式 - 默认关闭
_auth = TRUE; // SMTP认证 - 拖欠 _multipart =新MimeMultipart的（）; //也有一些是错误的MAILCAP，JavaMail的找不到多部分/混合部分的处理程序，所以这一点需要添加。
支持MailcapCommandMap MC =（支持MailcapCommandMap）CommandMap.getDefaultCommandMap（）;
mc.addMailcap（text / html的;;的X Java的内容处理器= com.sun.mail.handlers.text_html）;
mc.addMailcap（文/ XML ;;的X Java的内容处理器= com.sun.mail.handlers.text_xml）;
mc.addMailcap（text / plain的;;的X Java的内容处理器= com.sun.mail.handlers.text_plain）;
mc.addMailcap（多重/ * ;;的X Java的内容处理器= com.sun.mail.handlers.multipart_mixed）;
mc.addMailcap（信息/ RFC822 ;;的X Java的内容处理器= com.sun.mail.handlers.message_rfc822）;
CommandMap.setDefaultCommandMap（MC）;
}公共邮件（用户字符串，字符串传递）{
这个（）; _user =用户;
_pass =传递;
}公共布尔的send（）抛出异常{
属性道具= _setProperties（）; ！如果（_ user.equals（）及与放大器;！_pass.equals（）及与放大器; _to.length大于0＆放大器;＆放大器;！_from.equals（）及与放大器;！_subject .equals（）及与放大器;！_body.equals（））{
会话的会话= Session.getInstance（道具，这一点）; 的MimeMessage味精=新的MimeMessage（会话）; msg.setFrom（新网际地址（_from））; 网际地址[] = addressTo新的网际地址[_to.length]
的for（int i = 0; I＆LT; _to.length;我++）{
addressTo [I] =新的网际地址（_to [I]）;
}
msg.setRecipients（MimeMessage.RecipientType.TO，addressTo）; msg.setSubject（_subject）;
msg.setSentDate（新的Date（））; //设置邮件正文
BodyPart的messageBodyPart =新MimeBodyPart（）;
messageBodyPart.setText（_body）;
_multipart.addBodyPart（messageBodyPart）; 在消息//把部分
msg.setContent（_multipart）; // 发电子邮件
Transport.send（MSG）; 返回true;
}其他{
返回false;
}
}公共无效addAttachment（字符串文件名）抛出异常{
BodyPart的messageBodyPart =新MimeBodyPart（）;
数据源源=新FileDataSource（文件名）;
messageBodyPart.setDataHandler（新的DataHandler（源））;
messageBodyPart.setFileName（文件名）; _multipart.addBodyPart（messageBodyPart）;
}@覆盖
公众的PasswordAuthentication的getPasswordAuthentication（）{
返回新的PasswordAuthentication（_user，_pass）;
}私人性质_setProperties（）{
属性道具=新特性（）; props.put（mail.smtp.host，_host）; 如果（_debuggable）{
props.put（mail.debug为真）;
} 如果（_auth）{
props.put（mail.smtp.auth，真）;
} props.put（mail.smtp.port，_port）;
props.put（mail.smtp.socketFactory.port，_sport）;
props.put（mail.smtp.socketFactory.class，javax.net.ssl.SSLSocketFactory）;
props.put（mail.smtp.socketFactory.fallback，假）; 返回道具;
}// getter和setter
公共字符串getBody（）{
返回_body;
}公共无效setBody（字符串_body）{
this._body = _body;
}公共无效setTo（字符串[] toArr）{
this._to = toArr;
}公共无效setFrom（字符串字符串）{
this._from =串;
}公共无效SETSUBJECT（字符串字符串）{
this._subject =串;
}//更多的getter和setter ... ..
}`
解决方案
您需要使用的 的AsyncTask 做你的所有网络操作。
您的网络操作会占用大量的时间，如果是主UI线程上完成的UI会得到响应。如果你的UI冻结很长一段时间，应用程序可能会得到由OS死亡。
这样的Android 4+使得它强制使用一个后台线程来执行网络操作。
把code里面做网络活动 doInBacground（） 和所有的AsyncTask的使用 的execute（）
下面是你的AsyncTask会是什么样子：
私有类的SendMail扩展的AsyncTask＆LT;字符串，整数，太虚＆GT; {
保护无效doInBackground（）{
发电子邮件（）;
}保护无效onProgressUpdate（）{
//当后台任务使任何进展称为
}在preExecute保护无效（）{
//称为doInBackground（）被启动之前
}
保护无效onPostExecute（）{
//称为doInBackground（）完成后
}
}
你可以在任何地方使用称之为 新的SendMail（）执行（）;
I used javamail to send email in android. But it throws the Exception NetworkOnMainThreadException. How to solve this exception?
MainActivity
package com.aaa;
import android.os.Bundle;
import android.os.NetworkOnMainThreadException;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends Activity {
private Mail m;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
m = new Mail("mail@gmail.com", "pwd");
}
public void sendEmail(View view){
String[] toArr = {"samp@gmail.com"};
m.setTo(toArr);
m.setFrom("mail613@gmail.com");
m.setSubject("subject");
m.setBody("your message goes here");
try {
//m.addAttachment("/sdcard/myPicture.jpg");
if(m.send()) {
// success
Toast.makeText(MainActivity.this, "Email was sent successfully.", Toast.LENGTH_LONG).show();
} else {
// failure
Toast.makeText(MainActivity.this, "Email was not sent.", Toast.LENGTH_LONG).show();
}
} catch(Exception e) {
// some other problem
//Toast.makeText(MainActivity.this, "Email was not sent.", Toast.LENGTH_LONG).show(e);
Toast.makeText(MainActivity.this, ""+e+"", Toast.LENGTH_LONG).show();
Log.e("SendMail",e.getMessage(),e);
}
}
}
Mail.java
package com.aaa;
import java.util.Date;
import java.util.Properties;
import javax.activation.CommandMap;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.activation.MailcapCommandMap;
import javax.mail.BodyPart;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
public class Mail extends javax.mail.Authenticator {
private String _user;
private String _pass;
private String[] _to;
private String _from;
private String _port;
private String _sport;
private String _host;
private String _subject;
private String _body;
private boolean _auth;
private boolean _debuggable;
private Multipart _multipart;
public Mail() {
_host = "smtp.gmail.com"; // default smtp server
_port = "465"; // default smtp port
_sport = "465"; // default socketfactory port
_user = ""; // username
_pass = ""; // password
_from = ""; // email sent from
_subject = ""; // email subject
_body = ""; // email body
_debuggable = false; // debug mode on or off - default off
_auth = true; // smtp authentication - default on
_multipart = new MimeMultipart();
// There is something wrong with MailCap, javamail can not find a handler for the multipart/mixed part, so this bit needs to be added.
MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap();
mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
CommandMap.setDefaultCommandMap(mc);
}
public Mail(String user, String pass) {
this();
_user = user;
_pass = pass;
}
public boolean send() throws Exception {
Properties props = _setProperties();
if(!_user.equals("") && !_pass.equals("") && _to.length > 0 && !_from.equals("") && !_subject.equals("") && !_body.equals("")) {
Session session = Session.getInstance(props, this);
MimeMessage msg = new MimeMessage(session);
msg.setFrom(new InternetAddress(_from));
InternetAddress[] addressTo = new InternetAddress[_to.length];
for (int i = 0; i < _to.length; i++) {
addressTo[i] = new InternetAddress(_to[i]);
}
msg.setRecipients(MimeMessage.RecipientType.TO, addressTo);
msg.setSubject(_subject);
msg.setSentDate(new Date());
// setup message body
BodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setText(_body);
_multipart.addBodyPart(messageBodyPart);
// Put parts in message
msg.setContent(_multipart);
// send email
Transport.send(msg);
return true;
} else {
return false;
}
}
public void addAttachment(String filename) throws Exception {
BodyPart messageBodyPart = new MimeBodyPart();
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
_multipart.addBodyPart(messageBodyPart);
}
@Override
public PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(_user, _pass);
}
private Properties _setProperties() {
Properties props = new Properties();
props.put("mail.smtp.host", _host);
if(_debuggable) {
props.put("mail.debug", "true");
}
if(_auth) {
props.put("mail.smtp.auth", "true");
}
props.put("mail.smtp.port", _port);
props.put("mail.smtp.socketFactory.port", _sport);
props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
props.put("mail.smtp.socketFactory.fallback", "false");
return props;
}
// the getters and setters
public String getBody() {
return _body;
}
public void setBody(String _body) {
this._body = _body;
}
public void setTo(String[] toArr) {
this._to = toArr;
}
public void setFrom(String string) {
this._from = string;
}
public void setSubject(String string) {
this._subject = string;
}
// more of the getters and setters …..
} `
解决方案
You need to use an AsyncTask to do all your network operations.
Your network operation can take a lot of time and the UI would get unresponsive if it is done on the main UI thread. And if your UI freezes for a long time, the app might get killed by the OS.
Thus Android 4+ makes it mandatory to use a background thread to perform network operations.
Put the code to do the network activity inside doInBacground() and all the AsyncTask using execute().
Here is how your AsyncTask would look like :
private class SendMail extends AsyncTask<String, Integer, Void> {
protected void doInBackground() {
sendEmail();
}
protected void onProgressUpdate() {
//called when the background task makes any progress
}
protected void onPreExecute() {
//called before doInBackground() is started
}
protected void onPostExecute() {
//called after doInBackground() has finished
}
}
And you can call it anywhere using new SendMail().execute("");
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