Head First Java Note

//Test Serialization
import java.io.Serializable;
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.lang.Exception;

public class TestS implements Serializable{

    private int width;
    private int height;

    public void setWidth(int width){
         this.width = width;
    }

   

    public int getWidth(){

         return width;

    }

    public void setHeight(int height){
         this.height = height;
    }

 

    public int getHeight(){

         return height;

    }

    public static void main(String[] args){
  
         TestS t = new TestS();
         t.setWidth(99);
         t.setHeight(88); 
         FileOutputStream fos = null;
         ObjectOutputStream oos = null;

         try{
              fos = new FileOutputStream("tests.serializable");
              oos = new ObjectOutputStream(fos);
              oos.writeObject(t);    
         }catch(Exception e){
              e.printStackTrace();
         }finally{
              try{
                   oos.close();
              }catch(Exception es){
                   System.out.println("Exception: oos.close()"); 
              }    
         }
    }

}

//Test FileWriter and FileReader
import java.io.IOException;
import java.io.FileReader;
import java.io.FileWriter;
import java.lang.StringBuilder;
import java.io.BufferedReader;

public class TestFWR{

    public static void main(String[] args){
  
         String file_name = "testfwr.txt"; 
         StringBuilder sb = new StringBuilder();
         sb.append("有些事，不敢去想；有些人，不能忘记。\n");
         sb.append("每个兴奋与失落的时候，我都会触摸那段记忆，但是很多的时候，我又会刻意回避

                        它。\n"); 
         sb.append("什么都不愿想，我怕那些事，更怕那些事中来来往往的那些人；\n");
         sb.append("我怕那些人，更怕那些人勾起曾经的那些事。\n如果生活不够完美，我情愿放弃！");
  
         writeToFile(file_name,sb.toString());
  
         String s = readFromFile(file_name);
         System.out.println("--------------------------------------------");
         System.out.println(sb.toString());
         System.out.println("--------------------------------------------");

    }

    public static void writeToFile(String file_name,String s){
         try{
              FileWriter fr = new FileWriter(file_name);
              fr.write(s);
              fr.close();
         }catch(IOException e){
              e.printStackTrace();
         }
    }

    public static String readFromFile(String file_name){
         StringBuilder sb1 = new StringBuilder();
         try{
              FileReader fr = new FileReader(file_name);
              BufferedReader br = new BufferedReader(fr);
              String line;
              while((line = br.readLine()) != null){
                   System.out.println(line);
                   sb1.append(line + "\n"); 
              }
              fr.close(); 
         }catch(IOException e){
              e.printStackTrace(); 
         }

         return sb1.toString();
    }

}

import java.util.ArrayList;
import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;
import java.lang.Exception;
import java.util.Collections;
import static java.lang.System.out;
import java.util.HashSet;
import java.lang.Comparable;
import java.util.Comparator;

public class UserT{

    ArrayList<User> al = new ArrayList<User>();
  
    void getUserInfo(){
         try{
              BufferedReader br = new BufferedReader(new FileReader(new File("usert.txt")));
              String line= null;
              while((line = br.readLine()) != null){
                   addUser(line);
              }
         }catch(Exception e){ 
              e.printStackTrace();
         }
    }

    void addUser(String user){
         String[] s = user.split("/");
         User u = new User(s[0],s[1],s[2],s[3]);
         al.add(u);
    }

    public void go(){
         getUserInfo();
         System.out.println(al);
         Collections.sort(al);
         System.out.println(al);

         AddrCompare ac = new AddrCompare();
         Collections.sort(al,ac);
         out.println(al);

         HashSet<User> hs = new HashSet<User>();
         hs.addAll(al);
         out.println(hs);
    }

    public static void main(String[] args){
         new UserT().go();
    }

}

 

//Comparator
class AddrCompare implements Comparator<User>{

    public int compare(User u1, User u2){
         return u1.getAddr().compareTo(u2.getAddr());
    }

}

import java.util.ArrayList;

abstract class Animal{
    void eat(){
         System.out.println("animal eating");
    }
}

class Dog extends Animal{
    void bark(){}
}

class Cat extends Animal{
    void meow(){}
}

class Test7{

    public static void main(String[] args){
         new Test8().go();
    }

    public void go(){
         ArrayList<Animal> al = new ArrayList<Animal>();
         al.add(new Dog());
         al.add(new Cat());
         al.add(new Dog());
         go1(al);

         ArrayList<Dog> al1 = new ArrayList<Dog>();
         al1.add(new Dog()); 
         al1.add(new Dog());
         al1.add(new Dog());
         go1(al1);//编译出错
    }

    public void go1(ArrayList<Animal> as){
         for(Animal a:as){
             a.eat(); 
         }
    }

}

<?xml version="1.0" encoding="utf-8"?>

<jnlp spec="0.2.1.0"

       codebase="指定相关文件的起始目录(如：[url]http://127.0.0.1/test[/url])"

       href="相对于codebase的位置路径(myapp.jnlp)">
  
    <information>
         <title>My App</title>
         <vendor>wenlong.meng</vendor>
         <homepage href="index.html"/> 
         <description>Head First java</description>
         <icon href="test.jpg"/> 
         <offline-allowed/>  
    </information>

    <resources>
         <j2ee version="指定java版本(如：1.3+)"/> 
         <jar href="可执行得jar(如：myapp.jar)"/>
    </resources>

    <application-desc main-class="带有main()的类"/>

</jnlp>

//simple example servlet code
import javax.servlet.http.*;
import java.io.*;
import javax.servlet.*;

public class Test7 extends HttpServlet{

    public void doGet(HttpServletRequest req,HttpServletResponse res)

         throws ServletException,IOException{
  
         res.setContentType("text/html");

         PrintWriter pw = new res.getWriter();

         String msg = "if you read this, it worked";

         pw.println("<html>");
         pw.println("<h1>" + msg + "</h1>");
         pw.println("</html>"); 
         pw.close();
    }

 

    public void doPost(HttpServlet req,HttpServletResponse res)

         throws ServletException,IOException{

         doGet();

    }

}