20非常有用的Java程序片段 (下)-优快云博客

 
   01. 
        
   02. 
   import java.util.Map;     
  
   03. 
   import org.apache.commons.lang.ArrayUtils;     
  
   04. 
        
   05. 
   public class Main {     
  
   06. 
        
   07. 
      public static void main(String[] args) {     
  
   08. 
        String[][] countries = { {  "United States" ,  "New York" }, {  "United Kingdom" ,  "London" },     
  
   09. 
            {  "Netherland" ,  "Amsterdam" }, {  "Japan" ,  "Tokyo" }, {  "France" ,  "Paris" } };     
  
   10. 
        
   11. 
        Map countryCapitals = ArrayUtils.toMap(countries);     
  
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   13. 
        System.out.println( "Capital of Japan is " + countryCapitals.get( "Japan" ));     
  
   14. 
        System.out.println( "Capital of France is " + countryCapitals.get( "France" ));     
  
   15. 
      }     
  
   16. 
   }

 
   01. 
   import javax.mail.*;     
  
   02. 
   import javax.mail.internet.*;     
  
   03. 
   import java.util.*;     
  
   04. 
        
   05. 
   public void postMail( String recipients[ ], String subject, String message , String from)  throws MessagingException     
  
   06. 
   {     
  
   07. 
        boolean debug =  false ;     
  
   08. 
        
   09. 
         //Set the host smtp address     
  
   10. 
         Properties props =  new Properties();     
  
   11. 
         props.put( "mail.smtp.host" ,  "smtp.example.com" );     
  
   12. 
        
   13. 
        // create some properties and get the default Session     
  
   14. 
        Session session = Session.getDefaultInstance(props,  null );     
  
   15. 
        session.setDebug(debug);     
  
   16. 
        
   17. 
        // create a message     
  
   18. 
        Message msg =  new MimeMessage(session);     
  
   19. 
        
   20. 
        // set the from and to address     
  
   21. 
        InternetAddress addressFrom =  new InternetAddress(from);     
  
   22. 
        msg.setFrom(addressFrom);     
  
   23. 
        
   24. 
        InternetAddress[] addressTo =  new InternetAddress[recipients.length];     
  
   25. 
        for ( int i =  0 ; i < recipients.length; i++)     
  
   26. 
        {     
  
   27. 
            addressTo[i] =  new InternetAddress(recipients[i]);     
  
   28. 
        }     
  
   29. 
        msg.setRecipients(Message.RecipientType.TO, addressTo);     
  
   30. 
        
   31. 
        // Optional : You can also set your custom headers in the Email if you Want     
  
   32. 
        msg.addHeader( "MyHeaderName" ,  "myHeaderValue" );     
  
   33. 
        
   34. 
        // Setting the Subject and Content Type     
  
   35. 
        msg.setSubject(subject);     
  
   36. 
        msg.setContent(message,  "text/plain" );     
  
   37. 
        Transport.send(msg);     
  
   38. 
   }

 
   01. 
        
   02. 
   import java.io.BufferedReader;     
  
   03. 
   import java.io.InputStreamReader;     
  
   04. 
   import java.net.URL;     
  
   05. 
        
   06. 
   public class Main {     
  
   07. 
        public static void main(String[] args)  {     
  
   08. 
            try {     
  
   09. 
                URL my_url =  new URL( "http://cocre.com/ " );     
  
   10. 
                BufferedReader br =  new BufferedReader( new InputStreamReader(my_url.openStream()));     
  
   11. 
                String strTemp =  "" ;     
  
   12. 
                while ( null != (strTemp = br.readLine())){     
  
   13. 
                System.out.println(strTemp);     
  
   14. 
            }     
  
   15. 
            }  catch (Exception ex) {     
  
   16. 
                ex.printStackTrace();     
  
   17. 
            }     
  
   18. 
        }     
  
   19. 
   }

 
   01. 
        
   02. 
   /**    
  
   03. 
   * Reallocates an array with a new size, and copies the contents    
  
   04. 
   * of the old array to the new array.    
  
   05. 
   * @param oldArray  the old array, to be reallocated.    
  
   06. 
   * @param newSize   the new array size.    
  
   07. 
   * @return          A new array with the same contents.    
  
   08. 
   */    
  
   09. 
   private static Object resizeArray (Object oldArray,  int newSize) {     
  
   10. 
       int oldSize = java.lang.reflect.Array.getLength(oldArray);     
  
   11. 
       Class elementType = oldArray.getClass().getComponentType();     
  
   12. 
       Object newArray = java.lang.reflect.Array.newInstance(     
  
   13. 
             elementType,newSize);     
  
   14. 
       int preserveLength = Math.min(oldSize,newSize);     
  
   15. 
       if (preserveLength >  0 )     
  
   16. 
          System.arraycopy (oldArray, 0 ,newArray, 0 ,preserveLength);     
  
   17. 
       return newArray;     
  
   18. 
   }     
  
   19. 
        
   20. 
   // Test routine for resizeArray().     
  
   21. 
   public static void main (String[] args) {     
  
   22. 
       int [] a = { 1 , 2 , 3 };     
  
   23. 
       a = ( int [])resizeArray(a, 5 );     
  
   24. 
       a[ 3 ] =  4 ;     
  
   25. 
       a[ 4 ] =  5 ;     
  
   26. 
       for ( int i= 0 ; i<a.length; i++)     
  
   27. 
          System.out.println (a[i]);     
  
   28. 
   }