题目：基于TCP/IP用DOM4j修改XML

（1）使用dom4j将信息存入xml中

（2）读取信息，并打印控制台

（3）添加一个city节点与子节点

（4）使用socket TCP协议编写服务端与客户端，

客户端输入城市ID，服务器响应相应城市信息

（5）使用socket TCP协议编写服务端与客户端，客户端要求用户输入city对象，服务端接收并使用dom4j保存至XML文件

xml文件：

1.
<?xml version="1.0" encoding="GBK"?>
<citys><city id='010'><cityname>北京</cityname><cityarea>华北</cityarea><population>2114.8万人</population></city><city id='021'><cityname>上海</cityname><cityarea>华东</cityarea><population>2,500万人</population></city><city id='020'><cityname>广州</cityname><cityarea>华南</cityarea><population>1292.68万人</population></city><city id='028'><cityname>成都</cityname><cityarea>华西</cityarea><population>1417万人</population></city>
</citys>

第一题：

public class Save {public static void main(String[] args) {try {Document document = DocumentHelper.createDocument();Element root = document.addElement("citys");//添加根节点Element element1 = root.addElement("city");element1.addAttribute("id","010");element1.addElement("cityname").setText("洛阳");element1.addElement("cityarea").setText("华中");element1.addElement("population").setText("1000");Element element2 = root.addElement("city");element2.addAttribute("id","011");element2.addElement("cityname").setText("北京");element2.addElement("cityarea").setText("华北");element2.addElement("population").setText("9000");//写入XMLWriter xmlWriter = new XMLWriter(new FileWriter("D:\\idea-workspace\\Book03\\ch010\\src\\QuestionText\\city.xml"));xmlWriter.write(document);xmlWriter.close();} catch (Exception e) {e.printStackTrace();}}}

第二题：

package QuestionText.SecondQuestion;import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;import java.util.List;public class ReadElement {public static void main(String[] args) {//  这些是读入try {SAXReader saxReader = new SAXReader();Document document = saxReader.read("D:\\idea-workspace\\Book03\\ch010\\src\\QuestionText\\city.xml");//获取根节点Element rootElement = document.getRootElement();//根节点下的所有子节点List<Element> firstElementList = rootElement.elements();for (Element element1 :firstElementList){String id = element1.attributeValue("id");String cityname = element1.elementText("cityname");String cityarea = element1.elementText("cityarea");String population = element1.elementText("population");System.out.println("id:"+id+"  cityname:"+cityname+"  cityarea:"+cityarea+"  population:"+population);}} catch (Exception e) {e.printStackTrace();}}
}

第三题：

public class AddOne {public static void main(String[] args) {try {SAXReader saxReader = new SAXReader();Document document = saxReader.read("D:\\idea-workspace\\Book03\\ch010\\src\\QuestionText\\city.xml");Element rootElement = document.getRootElement();Element element = rootElement.addElement("city");element.addAttribute("id","022");element.addElement("cityname").setText("上海");element.addElement("cityarea").setText("华西");element.addElement("population").setText("980");//写入XMLWriter xmlWriter = new XMLWriter(new FileWriter("D:\\idea-workspace\\Book03\\ch010\\src\\QuestionText\\city.xml"));xmlWriter.write(document);xmlWriter.close();} catch (Exception e) {e.printStackTrace();}}
}

第四题：

服务端：

public class Tcp {//使用socket TCP协议编写服务端与客户端，//客户端输入城市ID，服务器响应相应城市信息//服务端public static void main(String[] args) {System.out.println("服务端——————————————————————");try {ServerSocket serverSocket = new ServerSocket(8888);Socket socket = serverSocket.accept();//获取输出流InputStream inputStream = socket.getInputStream();byte b[] = new byte[100];inputStream.read(b);String id = new String(b).trim();System.out.println(id);String cityString = selectById(id);//返回信息OutputStream outputStream = socket.getOutputStream();outputStream.write(cityString.getBytes());} catch (Exception e) {e.printStackTrace();}}public static String selectById(String id) {//接收到输入的以后在XML文件中寻找
//try {SAXReader saxReader = new SAXReader();Document document = null;document = saxReader.read("D:\\idea-workspace\\Book03\\ch010\\src\\QuestionText\\city.xml");Element rootElement = document.getRootElement();List<Element> elements = rootElement.elements();String msg = null;for (Element element : elements) {String cityid = element.attributeValue("id");if (id.equals(cityid)) {msg += "id" + cityid;msg += ",cityname" + element.elementText("cityname");msg += ",cityarea" + element.elementText("cityarea");msg += ",population" + element.elementText("population");}}return msg;}catch(Exception e){e.printStackTrace();}return  null;}}

客户端：

public class TCPclient {public static void main(String[] args) {System.out.println("客户端——————————————————————");Scanner sc = new Scanner(System.in);System.out.println("请输入城市id");String id = sc.next();try {Socket socket = new Socket("127.0.0.1",8888);OutputStream os = socket.getOutputStream();os.write(id.getBytes());//结束Outputsocket.shutdownOutput();//接收InputStream inputStream =  socket.getInputStream();byte b[] = new byte[1000];inputStream.read(b);String msg = new String(b).trim();System.out.println(msg);} catch (IOException e) {e.printStackTrace();}}
}

第五题：

客户端：

public class TcpClient {public static void main(String[] args) {System.out.println("客户端——————————————");try {Scanner sc = new Scanner(System.in);Socket socket = new Socket("127.0.0.1",8888);OutputStream os = socket.getOutputStream();City city = new City();System.out.println("请输入id：");city.setId(sc.next());System.out.println("请输入城市名：");city.setCityname(sc.next());System.out.println("请输入地区：");city.setCityarea(sc.next());System.out.println("请输入人口数量(万人)：");city.setPopulation(sc.next()+"万人");//序列化输出流ObjectOutputStream oos = new ObjectOutputStream(os);oos.writeObject(city);} catch (IOException e) {throw new RuntimeException(e);}}
}

服务端：

public class TCP {public static void main(String[] args) {try {System.out.println("服务端");ServerSocket serverSocket = new ServerSocket(8888);Socket socket = serverSocket.accept();ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());City city = (City)ois.readObject();//插入XMLString msg = editXml(city);System.out.println(msg);} catch (Exception e) {e.printStackTrace();}}public static String editXml(City city){try {SAXReader saxReader = new SAXReader();Document document = saxReader.read("D:\\idea-workspace\\Book03\\ch010\\src\\QuestionText\\city.xml");Element rootElement = document.getRootElement();Element element = rootElement.addElement("city");element.addAttribute("id",city.getId());element.addElement("cityname").setText(city.getCityname());element.addElement("cityarea").setText(city.getCityarea());element.addElement("population").setText(city.getPopulation());//写入XMLWriter xmlWriter = new XMLWriter(new FileWriter("D:\\idea-workspace\\Book03\\ch010\\src\\QuestionText\\city.xml"));xmlWriter.write(document);xmlWriter.close();return "新增成功";} catch (Exception e) {e.printStackTrace();}return "新增失败";}
}

city对象：

import java.io.Serializable;public class City implements Serializable {private String id;private String cityname;private String cityarea;private String population;public String getId() {return id;}public void setId(String id) {this.id = id;}public String getCityname() {return cityname;}public void setCityname(String cityname) {this.cityname = cityname;}public String getCityarea() {return cityarea;}public void setCityarea(String cityarea) {this.cityarea = cityarea;}public String getPopulation() {return population;}public void setPopulation(String population) {this.population = population;}public City(String id, String cityname, String cityarea, String population) {this.id = id;this.cityname = cityname;this.cityarea = cityarea;this.population = population;}public City() {}
}