代码

//一.Document对象相关
 //1.读取XML文件,获得document对象.
 SAXReader reader = new SAXReader();
Document document = reader.read(new File("input.xml"));
 //2.解析XML形式的文本,得到document对象.
 String text = "<members></members>";
Document document = DocumentHelper.parseText(text);
 //3.主动创建document对象.
 Document document = DocumentHelper.createDocument();
Element root = document.addElement("members");// 创建根节点
 //二.节点相关
 //1.获取文档的根节点.
Element rootElm = document.getRootElement();
//2.取得某节点的单个子节点.
Element memberElm=root.element("member");// "member"是节点名
//3.取得节点的文字
String text=memberElm.getText();
//也可以用:
String text=root.elementText("name");这个是取得根节点下的name字节点的文字.
//4.取得某节点下名为"member"的所有字节点并进行遍历.
List nodes = rootElm.elements("member");
for (Iterator it = nodes.iterator(); it.hasNext();) {
Element elm = (Element) it.next();
// do something
}
//5.对某节点下的所有子节点进行遍历.
for(Iterator it=root.elementIterator();it.hasNext();){
Element element = (Element) it.next();
// do something
}
//6.在某节点下添加子节点.
Element ageElm = newMemberElm.addElement("age");
//7.设置节点文字.
ageElm.setText("29");
//8.删除某节点.
parentElm.remove(childElm);// childElm是待删除的节点,parentElm是其父节点
//三.属性相关.
//1.取得某节点下的某属性
Element root=document.getRootElement();
Attribute attribute=root.attribute("size");// 属性名name
//2.取得属性的文字
String text=attribute.getText();
//也可以用:
String text2=root.element("name").attributeValue("firstname");这个是取得根节点下name字节点的属性firstname的值.
//3.遍历某节点的所有属性
Element root=document.getRootElement();
for(Iterator it=root.attributeIterator();it.hasNext();){
Attribute attribute = (Attribute) it.next();
String text=attribute.getText();
System.out.println(text);
}
//4.设置某节点的属性和文字.
newMemberElm.addAttribute("name", "sitinspring");
//5.设置属性的文字
Attribute attribute=root.attribute("name");
attribute.setText("sitinspring");
//6.删除某属性
Attribute attribute=root.attribute("size");// 属性名name
root.remove(attribute);
//四.将文档写入XML文件.
//1.文档中全为英文,不设置编码,直接写入的形式.
XMLWriter writer = new XMLWriter(new FileWriter("output.xml"));
writer.write(document);
writer.close();
//2.文档中含有中文,设置编码格式写入的形式.
OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("GBK"); // 指定XML编码
XMLWriter writer = new XMLWriter(new FileWriter("output.xml"),format);
writer.write(document);
writer.close();
//五.字符串与XML的转换
//1.将字符串转化为XML
String text = "<members> <member>sitinspring</member> </members>";
Document document = DocumentHelper.parseText(text);
//2.将文档或节点的XML转化为字符串.
SAXReader reader = new SAXReader();
Document document = reader.read(new File("input.xml"));
Element root=document.getRootElement();
String docXmlText=document.asXML();
String rootXmlText=root.asXML();
Element memberElm=root.element("member");
String memberXmlText=memberElm.asXML();
//六.使用XPath快速找到节点.
//读取的XML文档示例
//<?xml version="1.0" encoding="UTF-8"?>
//<projectDescription>
//<name>MemberManagement</name>
//<comment></comment>
//<projects>
//<project>PRJ1</project>
//<project>PRJ2</project>
//<project>PRJ3</project>
//<project>PRJ4</project>
//</projects>
//<buildSpec>
//<buildCommand>
//<name>org.eclipse.jdt.core.javabuilder</name>
//<arguments>
//</arguments>
//</buildCommand>
//</buildSpec>
//<natures>
//<nature>org.eclipse.jdt.core.javanature</nature>
//</natures>
//</projectDescription>
//使用XPath快速找到节点project.
public static void main(String[] args){
    SAXReader reader = new SAXReader();
    try{
        Document doc = reader.read(new File("sample.xml"));
        List projects = doc.selectNodes("/projectDescription/projects/project");
        Iterator it=projects.iterator();
        while(it.hasNext()){
            Element elm=(Element)it.next();
            System.out.println(elm.getText());
        }
}
    catch(Exception ex){
        ex.printStackTrace();
    }
}

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.Properties;

public class TestMain {

//根据key读取value
public static String readValue(String filePath,String key) {
Properties props = new Properties();
try {
    InputStream in = new BufferedInputStream (new    FileInputStream(filePath));
props.load(in);
String value = props.getProperty (key);
System.out.println(key+value);
return value;
} catch (Exception e) {
e.printStackTrace();
 return null;
 }
 }

 //读取properties的全部信息
 public static void readProperties(String filePath) {
 Properties props = new Properties();
 try {
 InputStream in = new BufferedInputStream (new FileInputStream(filePath));
 props.load(in);
 Enumeration en = props.propertyNames();
 while (en.hasMoreElements()) {
 String key = (String) en.nextElement();
 String Property = props.getProperty (key);
 System.out.println(key+Property);
 }
 } catch (Exception e) {
 e.printStackTrace();
 }
 }

 //写入properties信息
 public static void writeProperties(String filePath,String parameterName,String parameterValue) {
 Properties prop = new Properties();
 try {
 InputStream fis = new FileInputStream(filePath);
 //从输入流中读取属性列表（键和元素对）
 prop.load(fis);
 //调用 Hashtable 的方法 put。使用 getProperty 方法提供并行性。
 //强制要求为属性的键和值使用字符串。返回值是 Hashtable 调用 put 的结果。
 OutputStream fos = new FileOutputStream(filePath);
 prop.setProperty(parameterName, parameterValue);
 //以适合使用 load 方法加载到 Properties 表中的格式，
 //将此 Properties 表中的属性列表（键和元素对）写入输出流
 prop.store(fos, "Update '" + parameterName + "' value");
 } catch (IOException e) {
 System.err.println("Visit "+filePath+" for updating "+parameterName+" value error");
 }
 }

 public static void main(String[] args) {
 readValue("info.properties","url");
 writeProperties("info.properties","age","21");
 readProperties("info.properties" );
 System.out.println("OK");
 }
}

package com.banding.web.servlet;


import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ImageServlet extends HttpServlet{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        //设置Content-type响应头
        resp.setContentType("image/jpeg");
        
        //设置http头，不允许客户端缓存验证码图片(单个是指针对某一个浏览器生效)
        resp.setHeader("pragma", "No-cache");
        resp.setHeader("Cache-Control", "No-cache");
        resp.setDateHeader("Expires", 0);
        
        //向客户端输出二进制数据
        OutputStream out = resp.getOutputStream();
        
        //以下代码用来生成验证码图片
        int width = 56;
        int height = 17;
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
        Graphics g = image.getGraphics();
        g.fillRect(0, 0, width, height);
        g.setFont(new Font("Times New Roman",Font.ITALIC,18));
        
        String checkCode= "";
        Random random = new Random();
        for(int i = 0; i < 4; i++){
            String rand = String.valueOf(random.nextInt(10));
            checkCode += rand;
            //随即设置数字颜色，增加识别验证码的难度，防止识别软件盗用使用
            g.setColor(new Color(20+random.nextInt(110),
                    20+random.nextInt(110),
                    20+random.nextInt(110)));
            
            g.drawString(rand, i * 10 + 8, 16);
        }
        g.dispose();    //生成图片完毕
        
        //将产生的验证码存Session中
        
        req.getSession().setAttribute("checkCode",checkCode);
        
        ImageIO.write(image,"JPEG",out);
    }
}