请教，如何向属性文件test.properties里面写文件？

[qicaihuochai]

请教，如何向属性文件test.properties里面写文件？

如果不用属性文件，也可以，只要能做到：第二次存入的数据不会覆盖前面的数据就好。

我要这个代码，是想用来做JAVA邮件服务器上存储用户名和密码使用。

请各位高手将代码给我，谢谢！！

[OnlyFor_love]

文件操作中都方法是追加到文本最后字符后面的，你查下帮助文档就可以了

[sky_ccy]

用writer类把他打开,用write(String str)写入数据,用newline()换行

[hmsuccess]

若在文件末尾添加，就像FileWriter或FileOutputStream(String name, boolean append)中的append
设为true，若在文件中添加内容，用RandomAccessFile

[hmsuccess]

这里以仅讨论过了：http://topic.csdn.net/u/20080327/23/9b4a61b1-6c80-4a3e-a29f-bd49be3610e7.html

[yibunengjing]

/**
	 * ���ļ�д������
	 * @param fileName 文件名称
	 * @param fromEnd T/F 是否从文本写入��ʼд
	 * @param str 要写入的文本
	 * @throws Exception
	 */
	private static void write(String fileName, boolean fromEnd, StringBuffer str) throws Exception {
		RandomAccessFile raf = new RandomAccessFile(fileName, "rw");
		if(fromEnd){
			raf.seek(raf.length());
			raf.writeBytes(str.toString());
			System.out.println(fileName + " ��!文本插入成功");
		}else{
			File f = new File(fileName);
		    FileOutputStream fos=new FileOutputStream(f);
		    fos.close();
		    raf.writeBytes(str.toString());
		    System.out.println(fileName + " ��д д��ɹ�!重写成功");
		}
	}

[banditgao]

楼上的代码不能写入 还说写入成功

[mayuanfei]

一定要好好看,我写了很长时间的

package com.adm.test2;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
import org.jdom.output.Format;
import org.jdom.output.XMLOutputter;


public class MailServiceTest {
	Document doc = null;
	
	File file = null;
	
	public MailServiceTest() {
		SAXBuilder build = new SAXBuilder();
		try {
			//构建Document.
			file = new File("d:\\mailpassword.xml");
			doc = build.build(this.getClass().getClassLoader().getResource("mailpassword.xml"));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	
	/**
	 * 用于增加一个User的Mail信息
	 */
	public void appendUserMail(User user) throws Exception {
		Element root = doc.getRootElement();
		Element userNode = new Element("user");
		userNode.setAttribute("id", ""+user.getId());
		userNode.setAttribute("name", ""+user.getName());
		Element mailNode = new Element("mail");
		mailNode.setText(user.getMail());
		Element passwordNode = new Element("mail");
		passwordNode.setText(user.getPassword());
		userNode.addContent(mailNode);userNode.addContent(passwordNode);
		root.addContent(userNode);
		
		//输出
        XMLOutputter out = new XMLOutputter();
        Format format = Format.getPrettyFormat();
        out.setFormat(format);
        out.output(doc,new FileOutputStream(file));

		
	}
	
	/**
	 *  获得所有的用户名和密码
	 * @throws Exception 
	 */
	public List<User> getAllUsers() throws Exception{
		List<User> users = new ArrayList<User>();
		Element root = doc.getRootElement();
		List<Element> children = root.getChildren("user");
		for(Element e : children) {
			User user = new User();
			int id = e.getAttribute("id").getIntValue();
			String name = e.getAttributeValue("name").toString();
			String mail = e.getChildText("mail");
			String password = e.getChildText("password");
			user.setId(id);user.setName(name);
			user.setMail(mail);user.setPassword(password);
			users.add(user);
		}
		return users;
	}
	
	/**
	 * 安装用户Id查找一个用户
	 */
	public User findUserById(int id) {
		return null;
	}
	
	/*下面还可以加方法,比如更改一个已经有的用户的用户名密码.等等.*/
	

	public static void main(String[] args) {
		MailServiceTest test = new MailServiceTest();
		try{
			List<User> allUsers = test.getAllUsers();
			for(User user : allUsers) {
				System.out.println(user.getId()+","+user.getName()+","+user.getMail()+","+user.getPassword());
			}
			test.appendUserMail(new User(333,"333","333","3333"));
			List<User> allUsers1 = test.getAllUsers();
			for(User user : allUsers1) {
				System.out.println(user.getId()+","+user.getName()+","+user.getMail()+","+user.getPassword());
			}
		}catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	static class User {
		int id ;
		String name;
		String mail;
		String password;
		
		public User(){
		}
		public User(int id, String name, String mail, String password) {
			this.id = id;
			this.name = name;
			this.mail = mail;
			this.password = password;
		}
		public int getId() {
			return id;
		}
		public void setId(int id) {
			this.id = id;
		}
		public String getName() {
			return name;
		}
		public void setName(String name) {
			this.name = name;
		}
		public String getMail() {
			return mail;
		}
		public void setMail(String mail) {
			this.mail = mail;
		}
		public String getPassword() {
			return password;
		}
		public void setPassword(String password) {
			this.password = password;
		}
		
	}

	public Document getDoc() {
		return doc;
	}

}

[believefym]

		try{
			FileInputStream fis = new FileInputStream("c:\\config.properties");
			Properties pro = new Properties();
			pro.load(fis);
			fis.close();
			pro.setProperty("name", "MyName");
			pro.store(new FileOutputStream("c:\\config.properties"), "comments");
			fis.close();
		}catch(Exception e){
			System.out.println(e.toString());
		}