JAVA基础6(代码剖析)

代码摘自善学堂

解析XML的范例：

person.xml:

<?xml version="1.0" encoding="UTF-8" ?>
<persons>
 <person>
  <name>至尊宝</name>
  <age>9000</age>
 </person>
 <person>
  <name>白晶晶</name>
  <age>7000</age>
 </person>
</persons>

Person.java

public class Person {private String name;private int age;public Person() {// TODO Auto-generated constructor stub}public Person(String name, int age) {super();this.name = name;this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}}

PersonHandler.java

package com.bjsxt.xml;import java.util.ArrayList;import java.util.List;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;/** * 存储对象 * @author Administrator * */public class PersonHandler extends DefaultHandler {private List<Person> persons;private Person person;private String tag;//记录标签名@Overridepublic void startDocument() throws SAXException {// TODO Auto-generated method stub//System.out.println("处理文档开始");persons =new ArrayList<Person>();}@Overridepublic void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException {System.out.println("开始一个元素" +qName);if(null!=qName){tag=qName;}if(null!=qName &&qName.equals("person")){person =new Person();}}@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {String str =new String(ch,start,length);if(null!=tag &&tag.equals("name")){//System.out.println(new String(ch,start,length));person.setName(str);}else if(null!=tag &&tag.equals("age")){Integer age = Integer.valueOf(str);person.setAge(age);}}@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {//System.out.println("结束一个元素" +qName);if(qName.equals("person")){this.persons.add(person);}tag =null;}@Overridepublic void endDocument() throws SAXException {System.out.println("文档处理结束");}public List<Person> getPersons() {return persons;}public void setPersons(List<Person> persons) {this.persons = persons;}}

ParseDemo01.java

import java.io.IOException;import java.util.List;import javax.xml.parsers.ParserConfigurationException;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;import org.xml.sax.SAXException;public class ParseDemo01 {/** * @param args * @throws SAXException  * @throws ParserConfigurationException  * @throws IOException  */public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {//1、获取解析工厂SAXParserFactory factory=SAXParserFactory.newInstance();//2、从解析工厂获取解析器SAXParser parse =factory.newSAXParser();//3、加载文档 Document 注册处理器//4、编写处理器PersonHandler handler=new PersonHandler();parse.parse(Thread.currentThread().getContextClassLoader().getResourceAsStream("com/bjsxt/xml/person.xml"),handler );List<Person> persons =handler.getPersons();for(Person p:persons){System.out.println(p.getName()+"-->"+p.getAge());}}}

手写服务器：

Dispatcher.java

import java.io.IOException;import java.net.Socket;import com.bjsxt.util.CloseUtil;/** * 一个请求与响应 就一个此对象 * @author Administrator * */public class Dispatcher implements Runnable{private Socket client;private Request req;private Response rep;private int code=200;Dispatcher(Socket client){this.client=client;try {req =new Request(client.getInputStream());rep =new Response(client.getOutputStream());} catch (IOException e) {//e.printStackTrace();code =500;return ;}}@Overridepublic void run() {try {Servlet serv =WebApp.getServlet(req.getUrl());if(null==serv){this.code=404; //找不到处理}else{serv.service(req, rep);}rep.pushToClient(code); //推送到客户端}catch (Exception e) {e.printStackTrace();this.code=500;}try {rep.pushToClient(500);} catch (IOException e) {e.printStackTrace();}req.close();rep.close();CloseUtil.closeSocket(client);}}

Entity.java

/*   <servlet> <servlet-name>login</servlet-name> <servlet-class>com.bjsxt.server.demo4.LoginServlet</servlet-class> </servlet>  */public class Entity {private String name;private String clz;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getClz() {return clz;}public void setClz(String clz) {this.clz = clz;}}

LoginServlet.java

public class LoginServlet extends Servlet{@Overridepublic void doGet(Request req,Response rep) throws Exception {String name = req.getParameter("uname");String pwd =req.getParameter("pwd");if(login(name,pwd)){rep.println("登录成功");}else{rep.println("登录失败");}}public boolean login(String name,String pwd){return name.equals("bjsxt") && pwd.equals("12346");}@Overridepublic void doPost(Request req,Response rep) throws Exception {}}

Mapping.java

import java.util.ArrayList;import java.util.List;/* <servlet-mapping> <servlet-name>login</servlet-name> <url-pattern>/login</url-pattern>  </servlet-mapping>  <servlet-mapping> <servlet-name>login</servlet-name> <url-pattern>/log</url-pattern>  </servlet-mapping>    */public class Mapping {private String name;private List<String> urlPattern;public Mapping(){urlPattern =new ArrayList<String>();}public String getName() {return name;}public void setName(String name) {this.name = name;}public List<String> getUrlPattern() {return urlPattern;}public void setUrlPattern(List<String> urlPattern) {this.urlPattern = urlPattern;}}

RegisterServlet.java

public class RegisterServlet extends Servlet{@Overridepublic void doGet(Request req,Response rep) throws Exception {}@Overridepublic void doPost(Request req,Response rep) throws Exception {rep.println("<html><head><title>返回注册</title>");rep.println("</head><body>");rep.println("你的用户名为:"+req.getParameter("uname"));rep.println("</body></html>");}}

Request.java

import java.io.InputStream;import java.io.UnsupportedEncodingException;import java.util.ArrayList;import java.util.Arrays;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.StringTokenizer;import com.bjsxt.util.CloseUtil;/** * 封装request * @author Administrator * */public class Request {//请求方式private String method;//请求资源private String url;//请求参数private Map<String,List<String>> parameterMapValues;//内部public static final String CRLF="\r\n";private InputStream is;private String requestInfo;public Request(){method ="";url ="";parameterMapValues=new HashMap<String,List<String>>();requestInfo="";}public Request(InputStream is){this();this.is=is;try {byte[] data = new byte[20480];int len = is.read(data);requestInfo = new String(data, 0, len);} catch (Exception e) {return ;}//分析请求信息parseRequestInfo();}/** * 分析请求信息 */private void parseRequestInfo(){if(null==requestInfo ||(requestInfo=requestInfo.trim()).equals("")){return ;}/** * ===================================== * 从信息的首行分解出 :请求方式    请求路径   请求参数(get可能存在) *   如:GET /index.html?name=123&pwd=5456 HTTP/1.1 *  * 如果为post方式，请求参数可能在 最后正文中 *  * 思路: * 1)请求方式 :找出第一个/  截取即可 * 2)请求资源:找出第一个/   HTTP/  * ===================================== */String paramString =""; //接收请求参数 //1、获取请求方式String firstLine =requestInfo.substring(0,requestInfo.indexOf(CRLF));int idx =requestInfo.indexOf("/"); // /的位置this.method=firstLine.substring(0, idx).trim();String urlStr =firstLine.substring(idx,firstLine.indexOf("HTTP/")).trim();if(this.method.equalsIgnoreCase("post")){this.url=urlStr;paramString=requestInfo.substring(requestInfo.lastIndexOf(CRLF)).trim();}else if(this.method.equalsIgnoreCase("get")){if(urlStr.contains("?")){ //是否存在参数String[] urlArray=urlStr.split("\\?");this.url=urlArray[0];paramString=urlArray[1];//接收请求参数 }else{this.url=urlStr;}}//不存在请求参数if(paramString.equals("")){return ;}//2、将请求参数封装到Map中parseParams(paramString);}private void parseParams(String paramString){//分割 将字符串转成数组StringTokenizer token=new StringTokenizer(paramString,"&");while(token.hasMoreTokens()){String keyValue =token.nextToken();String[] keyValues=keyValue.split("=");if(keyValues.length==1){keyValues =Arrays.copyOf(keyValues, 2);keyValues[1] =null;}String key = keyValues[0].trim();String value = null==keyValues[1]?null:decode(keyValues[1].trim(),"gbk");//转换成Map 分拣if(!parameterMapValues.containsKey(key)){parameterMapValues.put(key,new ArrayList<String>());}List<String> values =parameterMapValues.get(key);values.add(value);}}/** * 解决中文 * @param value * @param code * @return */private String decode(String value,String code){try {return java.net.URLDecoder.decode(value, code);} catch (UnsupportedEncodingException e) {//e.printStackTrace();}return null;}/** * 根据页面的name 获取对应的多个值 * @param args */public String[] getParameterValues(String name){List<String> values=null;if((values=parameterMapValues.get(name))==null){return null;}else{return values.toArray(new String[0]);}}/** * 根据页面的name 获取对应的单个值 * @param args */public String getParameter(String name){String[] values =getParameterValues(name);if(null==values){return null;}return values[0];}public String getUrl() {return url;}public void close(){CloseUtil.closeIO(is);}}

Response.java

import java.io.BufferedWriter;import java.io.IOException;import java.io.OutputStream;import java.io.OutputStreamWriter;import java.net.Socket;import java.util.Date;import com.bjsxt.util.CloseUtil;/** * 封装响应信息 * @author Administrator * */public class Response {//两个常量public static final String CRLF="\r\n";public static final String BLANK=" ";//流private BufferedWriter bw ;//正文private StringBuilder content;//存储头信息private StringBuilder headInfo;//存储正文长度private int len =0;public Response(){headInfo =new StringBuilder();content =new StringBuilder();len =0;}public Response(Socket client){this();try {bw= new BufferedWriter(new OutputStreamWriter(client.getOutputStream()));} catch (IOException e) {headInfo=null;}}public Response(OutputStream os){this();bw= new BufferedWriter(new OutputStreamWriter(os));}/** * 构建正文 */public Response print(String info){content.append(info);len+=info.getBytes().length;return this;}/** * 构建正文+回车 */public Response println(String info){content.append(info).append(CRLF);len+=(info+CRLF).getBytes().length;return this;}/** * 构建响应头 */private void createHeadInfo(int code){//1)  HTTP协议版本、状态代码、描述headInfo.append("HTTP/1.1").append(BLANK).append(code).append(BLANK);switch(code){case 200:headInfo.append("OK");break;case 404:headInfo.append("NOT FOUND");break;case 505:headInfo.append("SEVER ERROR");break;}headInfo.append(CRLF);//2)  响应头(Response Head)headInfo.append("Server:bjsxt Server/0.0.1").append(CRLF);headInfo.append("Date:").append(new Date()).append(CRLF);headInfo.append("Content-type:text/html;charset=GBK").append(CRLF);//正文长度 ：字节长度headInfo.append("Content-Length:").append(len).append(CRLF);headInfo.append(CRLF); //分隔符} //推送到客户端void pushToClient(int code) throws IOException{if(null==headInfo){code =500;}createHeadInfo(code);//头信息+分割符bw.append(headInfo.toString());//正文bw.append(content.toString());bw.flush();}public void close(){CloseUtil.closeIO(bw);}}

Server.java

import java.io.IOException;import java.net.ServerSocket;import com.bjsxt.util.CloseUtil;/** * 创建服务器，并启动 *  * 1、请求 * 2、响应 * @author Administrator * */public class Server {private ServerSocket server;public static final String CRLF="\r\n";public static final String BLANK=" ";private boolean isShutDown= false;/** * @param args */public static void main(String[] args) {Server server = new Server();server.start();}/** * 启动方法 */public void start(){start(8888);}/** * 指定端口的启动方法 */public void start(int port){try {server = new ServerSocket(port);this.receive();} catch (IOException e) {//e.printStackTrace();stop();}}/** * 接收客户端 */private void receive(){try {while(!isShutDown){new Thread(new Dispatcher(server.accept())).start();}} catch (IOException e) {//e.printStackTrace();stop();}}/** * 停止服务器 */public void stop(){isShutDown=true;CloseUtil.closeSocket(server);}}

Servlet.java

/** * 抽象为一个父类 * @author Administrator * */public abstract class Servlet {public void service(Request req,Response rep) throws Exception{this.doGet(req,rep);this.doPost(req,rep);}public abstract void doGet(Request req,Response rep) throws Exception;public abstract void doPost(Request req,Response rep) throws Exception;}

ServletContext.java

import java.util.HashMap;import java.util.Map;/** * 上下文 * @author Administrator * */public class ServletContext {//为每一个servlet取个别名  // login  -->com.bjsxt.server.demo03.LoginServletprivate Map<String,String> servlet ;//url -->login//   /log -->login//   /login -->loginprivate Map<String,String> mapping;ServletContext(){servlet =new HashMap<String,String>();mapping =new HashMap<String,String>();}public Map<String, String> getServlet() {return servlet;}public void setServlet(Map<String, String> servlet) {this.servlet = servlet;}public Map<String, String> getMapping() {return mapping;}public void setMapping(Map<String, String> mapping) {this.mapping = mapping;}}

web.xml

<?xml version="1.0" encoding="UTF-8"?> <web-app> <servlet> <servlet-name>login</servlet-name> <servlet-class>com.bjsxt.server.demo4.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>login</servlet-name> <url-pattern>/login</url-pattern>  <url-pattern>/g</url-pattern>  </servlet-mapping>   <servlet> <servlet-name>reg</servlet-name> <servlet-class>com.bjsxt.server.demo4.RegisterServlet</servlet-class> </servlet>  <servlet-mapping> <servlet-name>reg</servlet-name> <url-pattern>/reg</url-pattern>  </servlet-mapping> </web-app>

WebApp.java

import java.util.List;import java.util.Map;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;public class WebApp {private static ServletContext contxt;static{try {//获取解析工厂SAXParserFactory factory = SAXParserFactory.newInstance();//获取解析器SAXParser sax = factory.newSAXParser();//指定xml+处理器WebHandler web = new WebHandler();sax.parse(Thread.currentThread().getContextClassLoader().getResourceAsStream("com/bjsxt/server/demo4/web.xml"), web);//将list 转成Mapcontxt =new ServletContext();Map<String,String> servlet =contxt.getServlet();//servlet-name  servlet-class for(Entity entity:web.getEntityList()){servlet.put(entity.getName(), entity.getClz());}//url-pattern servlet-nameMap<String,String> mapping =contxt.getMapping();for(Mapping mapp:web.getMappingList()){List<String> urls =mapp.getUrlPattern();for(String url:urls ){mapping.put(url, mapp.getName());}}} catch (Exception e) {}}public static Servlet getServlet(String url) throws InstantiationException, IllegalAccessException, ClassNotFoundException{if((null==url)||(url=url.trim()).equals("")){return null;}//根据字符串(完整路径)创建对象//return contxt.getServlet().get(contxt.getMapping().get(url));String name=contxt.getServlet().get(contxt.getMapping().get(url));return (Servlet)Class.forName(name).newInstance();//确保空构造存在}}

WebHandler.java

import java.io.IOException;import java.util.ArrayList;import java.util.List;import javax.xml.parsers.ParserConfigurationException;import javax.xml.parsers.SAXParser;import javax.xml.parsers.SAXParserFactory;import org.xml.sax.Attributes;import org.xml.sax.SAXException;import org.xml.sax.helpers.DefaultHandler;public class WebHandler extends DefaultHandler{private List<Entity> entityList;private List<Mapping> mappingList;private Entity entity;private Mapping mapping;private String beginTag ;private boolean isMap;  @Overridepublic void startDocument() throws SAXException {//文档解析开始 entityList =new ArrayList<Entity>() ; mappingList =new ArrayList<Mapping>() ; }@Overridepublic void startElement(String uri, String localName, String qName,Attributes attributes) throws SAXException {//开始元素if(null!=qName){beginTag=qName;if(qName.equals("servlet")){isMap=false;entity=new Entity();}else if(qName.equals("servlet-mapping")){isMap=true;mapping=new Mapping();}}}@Overridepublic void characters(char[] ch, int start, int length)throws SAXException {//处理内容if(null!=beginTag){String str =new String(ch,start,length);if(isMap ){if(beginTag.equals("servlet-name")){mapping.setName(str);}else if(beginTag.equals("url-pattern")){mapping.getUrlPattern().add(str);}}else{if(beginTag.equals("servlet-name")){entity.setName(str);}else if(beginTag.equals("servlet-class")){entity.setClz(str);}}}}@Overridepublic void endElement(String uri, String localName, String qName)throws SAXException {//结束元素if(null!=qName){if(qName.equals("servlet")){entityList.add(entity);}else if(qName.equals("servlet-mapping")){mappingList.add(mapping);}}beginTag=null;}@Overridepublic void endDocument() throws SAXException {//文档解析结束}public static void main(String[] args) throws ParserConfigurationException, SAXException, IOException {//获取解析工厂SAXParserFactory factory =SAXParserFactory.newInstance();//获取解析器SAXParser sax =factory.newSAXParser();//指定xml+处理器WebHandler web = new WebHandler();sax.parse(Thread.currentThread().getContextClassLoader().getResourceAsStream("com/bjsxt/server/demo4/web.xml"),web);System.out.println(web.getEntityList());}public List<Entity> getEntityList() {return entityList;}public void setEntityList(List<Entity> entityList) {this.entityList = entityList;}public List<Mapping> getMappingList() {return mappingList;}public void setMappingList(List<Mapping> mappingList) {this.mappingList = mappingList;}}

CloseUtil.java

import java.io.Closeable;import java.net.DatagramSocket;import java.net.ServerSocket;import java.net.Socket;public class CloseUtil {/** * 关闭IO流 *//*public static void closeIO(Closeable... io){for(Closeable temp:io){try {if (null != temp) {temp.close();}} catch (Exception e) {}}}*//** * 使用泛型方法实现关闭IO流 * @param io */public static <T extends Closeable> void closeIO(T... io){for(Closeable temp:io){try {if (null != temp) {temp.close();}} catch (Exception e) {}}}public static  void closeSocket(ServerSocket socket){try {if (null != socket) {socket.close();}} catch (Exception e) {}}public static  void closeSocket(Socket socket){try {if (null != socket) {socket.close();}} catch (Exception e) {}}public static  void closeSocket(DatagramSocket socket){try {if (null != socket) {socket.close();}} catch (Exception e) {}}}