本文介绍了一个Java网络通信的基础教程，包括如何通过URL获取资源到本地文件，以及使用Java发送带有附件、图片和不同类型的邮件（如纯文本和HTML）。教程还提供了具体的代码示例。
java网络通信例基础入门教程一
文件ExtendString.java
package chapter09.sample9_1;
public class ExtendString {
public ExtendString() {
}
/**
去掉字符串两端的空白字符,并将字符串转化为中国的标准字符gb2312的字符串.
*/
public String CS(String str) { //去掉字符串2端的空白字符
try {
if (str == null)
return "";
str = str.trim();
if (str == null)
return "";
str = new String(str.getBytes("8859_1"), "GBK");
}
catch (Exception e) {
System.out.println(e);
}
return str;
}
}
文件MailSender.java
package chapter09.sample9_1;
import java.io.*;
import java.util.*;
import java.io.File;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Date;
import java.util.Properties;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.Authenticator;
import javax.mail.BodyPart;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.SendFailedException;
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;
import org.htmlparser.Node;
import org.htmlparser.Parser;
import org.htmlparser.tags.ImageTag;
import org.htmlparser.util.ParserException;
public class MailSender {
private String username = null; //邮件发送帐号用户名
private String userpasswd = null; //邮件发送帐号用户口令
protected BodyPart messageBodyPart = null;
protected Multipart multipart = new MimeMultipart("related");
protected MimeMessage mailMessage = null;
protected Session mailSession = null;
protected Properties mailProperties = System.getProperties();
protected InternetAddress mailFromAddress = null;
protected InternetAddress mailToAddress = null;
protected Authenticator authenticator = null;
protected String mailSubject = "";
protected Date mailSendDate = null;
/**
* 构造函数
* @param smtpHost
* @param username
* @param password
*/
protected MailSender(String smtpHost, String username, String password) {
this.username = username;
this.userpasswd = password;
mailProperties.put("mail.smtp.host", smtpHost);
mailProperties.put("mail.smtp.auth", "true"); //设置smtp认证，很关键的一句
mailSession = Session.getDefaultInstance(mailProperties);
mailMessage = new MimeMessage(mailSession);
messageBodyPart = new MimeBodyPart();
}
/**
* 构造一个纯文本邮件发送实例
* @param smtpHost
* @param username
* @param password
* @return
*/
public static MailSender getTextMailSender(String smtpHost, String username, String password) {
return new MailSender(smtpHost,username,password) {
public void setMailContent(String mailContent) throws MessagingException {
messageBodyPart.setText(mailContent);
multipart.addBodyPart(messageBodyPart);
}
};
}
/**
* 构造一个超文本邮件发送实例
* @param smtpHost
* @param username
* @param password
* @return
*/
public static MailSender getHtmlMailSender(String smtpHost, String username, String password) {
return new MailSender(smtpHost,username,password) {
private ArrayList arrayList1 = new ArrayList();
private ArrayList arrayList2 = new ArrayList();
public void setMailContent(String mailContent) throws MessagingException {
String htmlContent = getContent("<img src=", mailContent);
messageBodyPart.setContent(htmlContent, "text/html;charset=GB2312");
multipart.addBodyPart(messageBodyPart);
//调用处理html文件中的图片方法
processHtmlImage(mailContent);
}
//处理html页面上的图片方法如下：
private void processHtmlImage(String mailContent) throws MessagingException {
for (int i = 0; i < arrayList1.size(); i++) {
messageBodyPart = new MimeBodyPart();
DataSource source = new FileDataSource((String) arrayList1.get(i));
messageBodyPart.setDataHandler(new DataHandler(source));
String contentId = "<" + (String) arrayList2.get(i) + ">";
messageBodyPart.setHeader("Content-ID", contentId);
messageBodyPart.setFileName((String) arrayList1.get(i));
multipart.addBodyPart(messageBodyPart);
}
}
//处理要发送的html文件，主要是针对html文件中的图片
private String getContent(String searchString, String mailContent) {
try {
Parser parser = Parser.createParser(new String(mailContent.getBytes(), ISO8859_1));
Node[] images = parser.extractAllNodesThatAre(ImageTag.class);
for(int i=0;i<images.length;i++) {
ImageTag imgTag = (ImageTag) images[i];
if(!imgTag.getImageURL().toLowerCase().startsWith("http://"))
arrayList1.add(imgTag.getImageURL());
}
} catch (UnsupportedEncodingException e1) {
} catch (ParserException e) {}
String afterReplaceStr = mailContent;
//在html文件中用"cid:"+Content-ID来替换原来的图片链接
for (int m = 0; m < arrayList1.size(); m++) {
arrayList2.add(createRandomStr());
String addString = "cid:" + (String) arrayList2.get(m);
afterReplaceStr = mailContent.replaceAll(
(String) arrayList1.get(m), addString);
}
return afterReplaceStr;
}
//产生一个随机字符串，为了给图片设定Content-ID值
private String createRandomStr() {
char[] randomChar = new char[8];
for (int i = 0; i < 8; i++) {
randomChar[i] = (char) (Math.random() * 26 + 'a');
}
String replaceStr = new String(randomChar);
return replaceStr;
}
private final static String ISO8859_1 = "8859_1";
};
}
/**
* 用于实现邮件发送用户验证
* @see javax.mail.Authenticator#getPasswordAuthentication
*/
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(username, userpasswd);
}
/**
* 设置邮件标题
* @param mailSubject
* @throws MessagingException
*/
public void setSubject(String mailSubject) throws MessagingException {
this.mailSubject = mailSubject;
mailMessage.setSubject(mailSubject);
}
/**
* 所有子类都需要实现的抽象方法，为了支持不同的邮件类型
* @param mailContent
* @throws MessagingException
*/
protected void setMailContent(String mailContent) throws MessagingException {
}
/**
* 设置邮件发送日期
* @param sendDate
* @throws MessagingException
*/
public void setSendDate(Date sendDate) throws MessagingException {
this.mailSendDate = sendDate;
mailMessage.setSentDate(sendDate);
}
/**
* 设置邮件发送附件
* @param attachmentName
* @throws MessagingException
*/
public void setAttachments(String attachmentName) throws MessagingException {
messageBodyPart = new MimeBodyPart();
DataSource source = new FileDataSource(attachmentName);
messageBodyPart.setDataHandler(new DataHandler(source));
int index = attachmentName.lastIndexOf(File.separator);
String attachmentRealName = attachmentName.substring(index + 1);
messageBodyPart.setFileName(attachmentRealName);
multipart.addBodyPart(messageBodyPart);
}
/**
* 设置发件人地址
* @param mailFrom
* @throws MessagingException
*/
public void setMailFrom(String mailFrom) throws MessagingException {
mailFromAddress = new InternetAddress(mailFrom);
mailMessage.setFrom(mailFromAddress);
}
/**
* 设置收件人地址，收件人类型为to,cc,bcc(大小写不限)
* @param mailTo 邮件接收者地址
* @param mailType 值为to,cc,bcc
* @author Liudong
*/
public void setMailTo(String[] mailTo, String mailType) throws Exception {
for (int i = 0; i < mailTo.length; i++) {
mailToAddress = new InternetAddress(mailTo[i]);
if (mailType.equalsIgnoreCase("to")) {
mailMessage.addRecipient(Message.RecipientType.TO,mailToAddress);
} else if (mailType.equalsIgnoreCase("cc")) {
mailMessage.addRecipient(Message.RecipientType.CC,mailToAddress);
} else if (mailType.equalsIgnoreCase("bcc")) {
mailMessage.addRecipient(Message.RecipientType.BCC,mailToAddress);
} else {
throw new Exception("Unknown mailType: " + mailType + "!");
}
}
}
/**
* 开始发送邮件
* @throws MessagingException
* @throws SendFailedException
*/
public void sendMail() throws MessagingException, SendFailedException {
if (mailToAddress == null)
throw new MessagingException("请你必须你填写收件人地址！");
mailMessage.setContent(multipart);
Transport.send(mailMessage);
}
/**
* 邮件发送测试
* @param args
*/
public static void main(String args[]) {
String mailHost = "smtp.gmail.com"; //发送邮件服务器地址
String mailUser = "hujie1982"; //发送邮件服务器的用户帐号
String mailPassword = "123456"; //发送邮件服务器的用户密码
String[] toAddress = {"pp1982@gmail.com"};
//使用超文本格式发送邮件
MailSender sendmail = MailSender.getHtmlMailSender(mailHost, mailUser,mailPassword);
//使用纯文本格式发送邮件
//MailSender sendmail = MailSender.getTextMailSender(mailHost, mailUser,mailPassword);
try {
sendmail.setSubject("要发送的标题？");
sendmail.setSendDate(new Date());
String content = "hello world";
//请注意如果是本地图片比如使用斜杠作为目录分隔符,如下所示,不支持中文？？？！！！
// content+="<img src=\"C:/Documents and Settings/Administrator/My Documents/My Pictures/aaa.jpg\"/>";
//sendmail.setMailContent(content); //
//sendmail.setAttachments("E:\\ConList.exe");//文章附件
sendmail.setMailFrom("hujie1982@gmail.com");//显示谁发送的
sendmail.setMailTo(toAddress, "to");//cc抄送，bcc 暗送
//sendmail.setMailTo(toAddress, "cc");//设置抄送给...
//开始发送邮件
System.out.println("正在发送邮件，请稍候.......");
sendmail.sendMail();
System.out.println("恭喜你，邮件已经成功发送!");
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
文件Sample9_1.java
package chapter09.sample9_1;
import java.io.*;
import java.net.*;
public class Sample9_1 {
public static void main(String[] args)
{
try
{
//创建URL对象
URL url=new URL("http://www.sina.com");
//打开指向资源的输入流
InputStream in=url.openStream();
//将输入流由字节流转换为字符流
InputStreamReader isr=new InputStreamReader(in);
//将输入流封装为缓冲输入处理流
BufferedReader br=new BufferedReader(isr);
//创建输出流，并指定目标文件
BufferedWriter bw=new BufferedWriter(new FileWriter("c:/URL.html"));
//对输出流进一步进行封装
PrintWriter pw=new PrintWriter(bw);
//声明临时字符串引用
String temps=null;
//从输入流中获取资源并测试是否读取完毕
while((temps=br.readLine())!=null)
{
//将获取的数据写如目标文件
pw.println(temps);
}
//打印提示信息
System.out.println("恭喜您，资源已经获取完毕，并将其写入了URL.html文件中！！！");
//关闭输入流与输出流
pw.close();
br.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
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