14 Разработка игрового веб-сервера на Java. Пример работы с рефлексией и сериализацией (XML, SAX)

test.xml

<class type='main.SerializationObject'>
    <name>Malcolm</name>
    <age>45</age>
</class>

reflection

src/reflection/ReflectionHelper.java

package reflection;

import java.lang.reflect.Field;

public class ReflectionHelper {
    public static Object createIntance(String className){
        try {
            return Class.forName(className).newInstance();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }
    
    public static void setFieldValue(Object object, 
            String fieldName, 
            String value){
        
        try {
            Field field = object.getClass().getDeclaredField(fieldName);
            field.setAccessible(true);
            
            if(field.getType().equals(String.class)){
                field.set(object, value);
            } else if (field.getType().equals(int.class)){
                field.set(object, Integer.decode(value));
            }           
            
            field.setAccessible(false);
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }
}

sax

src/sax/ReadXMLFileSAX.java

package sax;

import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.helpers.DefaultHandler;

public class ReadXMLFileSAX { 
    public static Object readXML(String xmlFile) {   
        try {    
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParser saxParser = factory.newSAXParser();
         
            //SaxHandler handler = new SaxHandler();    
            SaxEmptyHandler handler = new SaxEmptyHandler();    
            saxParser.parse(xmlFile, handler);
            
            return handler.getObject();
     
         } catch (Exception e) {
           e.printStackTrace();
         }
        return null;
     
       }
     
    
}

src/sax/SaxEmptyHandler.java

package sax;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

public class SaxEmptyHandler extends DefaultHandler {
    private static String CLASSNAME = "class"; 
    
    private boolean inElement = false;
    
    public void startDocument() throws SAXException {
        System.out.println("Start document");
    }
 
    public void endDocument() throws SAXException {
        System.out.println("End document ");
    }
    
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        System.out.println("Start element: " + qName);
        if(qName != CLASSNAME)
            inElement = true;
        else
            System.out.println("Class name: " + attributes.getValue(0));
        
    }
 
    public void endElement(String uri, String localName, String qName) throws SAXException {
        System.out.println("End element: " + qName);
        inElement = false;
    }
 
    public void characters(char ch[], int start, int length) throws SAXException {
        if(inElement)
            System.out.println("Process : " + new String(ch, start, length));
    }
    
    public Object getObject(){
        return null;
    }
}

src/sax/SaxHandler.java

package sax;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import reflection.ReflectionHelper;

public class SaxHandler extends DefaultHandler {
    private static String CLASSNAME = "class";  
    private String element = null; 
    private Object object = null;
    
    public void startDocument() throws SAXException {
        System.out.println("Start document");
    }
 
    public void endDocument() throws SAXException {
        System.out.println("End document ");
    }
    
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        if(qName != CLASSNAME){
            element = qName;
        }
        else{
            String className = attributes.getValue(0);
            System.out.println("Class name: " + className);
            object = ReflectionHelper.createIntance(className);
        }   
    }
 
    public void endElement(String uri, String localName, String qName) throws SAXException {
        element = null;
    }
 
    public void characters(char ch[], int start, int length) throws SAXException {
        if(element != null){
            String value = new String(ch, start, length);
            System.out.println(element + " = " + value);
            ReflectionHelper.setFieldValue(object, element, value);
        }
    }
    
    public Object getObject(){
        return object;
    }
}

main

src/main/SerializationObject.java

package main;

import java.io.Serializable;

public class SerializationObject extends Object implements Serializable {
    private static final long serialVersionUID = -3895203507200457732L;
    private String name;
    private int age;
    
    private Object test = new Object();
    
    //private ObjectFactory test2 = new ObjectFactory();
    
    public SerializationObject(){
        this.name = "Nobody";
        this.age = 0;
    }
    
    public SerializationObject(String name, int age){
        this.setAge(age);
        this.setName(name);
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    
    
    public String toString(){
        return "Name: " + name + " age: " + age;
    }
}

src/main/ObjectFactory.java

package main;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;

public class ObjectFactory {
    public static Object readObject(String path) {      
        try{
             FileInputStream fileOut = new FileInputStream(path);
             ObjectInputStream in = new ObjectInputStream(fileOut);
             Object object = in.readObject();
             in.close();
             return object;
        }catch(IOException i){
             i.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }
}

src/main/Main.java

package main;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import reflection.ReflectionHelper;
import sax.ReadXMLFileSAX;

public class Main {
    
    public static void main(String[] args){
        writeToBinFile();
        //readFromBinFile();
        //workWithReflection();
        //workWithFactory();
        //workWithSAX();
    }

    private static void workWithSAX() {
        SerializationObject object = (SerializationObject) ReadXMLFileSAX.readXML("test.xml");
        if(object != null)
            System.out.append(object.toString() + '\n');
    }

    private static void workWithFactory() {
        SerializationObject object = (SerializationObject) ObjectFactory.readObject("test.bin");
        System.out.append(object.toString() + '\n');
    }

    private static void workWithReflection() {
        SerializationObject object = (SerializationObject)ReflectionHelper.createIntance("main.SerializationObject");
        System.out.append(object.toString() + '\n');
        
        ReflectionHelper.setFieldValue(object, "name", "Kaylee");
        ReflectionHelper.setFieldValue(object, "age", "25");
        System.out.append(object.toString() + '\n');
    }

    private static void readFromBinFile() {
        System.out.append("Read from bin file\n");
        try{
             FileInputStream fileOut = new FileInputStream("test.bin");
             ObjectInputStream in = new ObjectInputStream(fileOut);
             SerializationObject object = (SerializationObject) in.readObject();
             System.out.append(object.toString() + '\n');
             in.close();
        }catch(IOException i){
             i.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    private static void writeToBinFile() {
        System.out.append("Write to bin file\n");
        try{
             SerializationObject object = new SerializationObject("Zoe", 31);
             FileOutputStream fileOut = new FileOutputStream("test.bin");
             ObjectOutputStream out = new ObjectOutputStream(fileOut);
             out.writeObject(object);
             out.close();
        }catch(IOException i){
             i.printStackTrace();
        }       
    }
}

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https://github.com/vitaly-chibrikov/tp_java_2013_02/tree/master/lecture7