When you start a new Spring roo project, the default page will be “index.jspx”, what if we want to implement a controller to it?

First of all, locate the webmvc-config.xml in your project folder. Find and remove the following line
<mvc:view-controller path="/index"/>

Then, create a Java class file in the source folder, in my case, will be the web folder. Let’s call it IndexController

package com.justthor.web;

import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@RequestMapping("/")
@Controller
public class IndexController {
  @RequestMapping(value = "/index", method = RequestMethod.GET)
  public String index(ModelMap modelMap) {
          /* Implement logic here...*/
          return "index";
  }
}

Happy coding

Happy coding

This is normally how we read files in Java.First we open a reading stream, then read the content and process it,and at last we close the stream.

package com.justthor;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class SampleFileReader {

  /**
   * @param args
   */
  public static void main(String[] args) {
    BufferedReader in; 
    try {
      // Open file
      in = new BufferedReader(new FileReader("test.txt"));
          String str;
       
          // Start reading
          while ((str = in.readLine()) != null) {
        // Print the content
        System.out.println(str);
          }
          
          // Close the stream
          in.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
  }
}

With some third party libraries, such as Apache Common Io, we can simplify the code to something like this.

package com.justthor;

import java.io.File;
import java.io.IOException;
import java.util.List;

import org.apache.commons.io.FileUtils;

public class SampleFileReader {

  /**
   * @param args
   */
  @SuppressWarnings("unchecked")
  public static void main(String[] args) {
    try {
      List<String> contents = FileUtils.readLines(new File("test.txt"));
      for ( String content : contents ) {
        System.out.println(content);
      }
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
}

Well, it does look a bit simple now compare to the previous version. But we only manage to type 1 or 2 lines less than the previous version. This is due to we are force to handle the checked IOException. What if we try to achieve the same thing using Scala?

package com.justthor

import scala.io.Source

object SampleFileReader {
 def main(args : Array[String]) = {
  Source fromFile("test.txt") getLines foreach { println }
 }
}

Its much simple, right? Scala provides an util for IO named Source. This util read the file and get the contents by calling getLines method. This getLines method returns a Iterator[String]. And from there we can process the content by looping the returned iterator. We can use Source util to do more than reading files. I will provide more examples in the next few posts.

Happy coding.

For instance,we want to store a PHP array in database and later to be processed by Java,we can do something like

$aValue = array("key1"=>"value1","key2"=>"value2");
$sEncodedValue = json_encode($aValue)
//we will get something like {"key1":"value1","key2":"value2"}
//and then, we store the value to db

On the other hand,we use Java to read it and decode it.

//read from db and got the resultset,assuming we are using JDBC
while (rs.next()){
String rawValue = rs.getString("encodedValue");
// since we encoded an associative array,it will be translated to a Java Map object instance.
// we are using JSON-lib for JSON parsing the following example
JSONObject json = JSONObject.fromObject(jsonString);
Map decodedValue = (Map) JSONObject.toBean(json, Map.class);
String value1 = decodedValue.get("key1");
}

What if we are trying to store unicode value using JSON format in PHP?
For example,

$aValue = array("key1"=>"你好吗","key2"=>"value2");
$sEncodedValue = json_encode($aValue);
//This is what we get after encoded
//{"key1":"\u4f60\u597d\u5417","key2":"value2"}

If you decoded it back to Java,key1 value will return “u4f60u597du5417″ instead.This is so wrong.

How to solve it?
We can use mb_convert_encoding function in PHP.
Let’s make some changes to our code.

$aValue = array("key1"=>mb_convert_encoding("你好吗", "UTF-8"),"key2"=>"value2");
$sEncodedValue = json_encode($aValue);

By doing so,values are stored in database in unicode format,and you can decode it back in Java.

Happy coding.

This is how we do in Java.

public class Hello {
 public static void main(String[] args) {
  System.out.println("Hello world");
 }
}

object Hello {
 def main(args : Array[String]) = println("Hello world")
}

Java style

public class HelloArgument {
 public static void main(String[] args) {
  for (String arg : args) {
   System.out.println("Hello, " + arg);
  }
 }
}

Scala style

object HelloArgument {
 def main(args : Array[String]) = args.foreach(arg => println("Hello, " + arg))
}

Pretty impressive,huh?Comparing Java,we are actually writing less and more readable code in Scala,and the results are the same.

Happy coding.