Java URLDecoder returns?

Question

I have a very basic test which fails on me and I can't figure out why.

Here is my code

System.out.println(URLEncoder.encode("去", "UTF-8")); // result = "%E5%8E%BB"
System.out.println(URLDecoder.decode("%E5%8E%BB", "UTF-8")); result = ?

Why does the second system.out result in a ? I am expecting to see 去 again.

To add to the larger picture, I will be using encodeURIComponent() in javascript to post my data to a servlet in which I want to use the URLDecoder.decode but I can't even get the above example to work. What am I missing?

UPDATE: Just noticed something strange, when I run the code in a servlet I get the result I described but if I just run it in a main method it works. Here is my servlet code

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URLDecoder;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class SaveFile extends BasicServiceServlet {
 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,  IOException {
    //request.setCharacterEncoding("UTF-8"); 
    //response.setContentType("text/html; charset=UTF-8");  
    String DIR = getBaseUrl();

    String project = request.getParameter("project"); 
    String foldername = request.getParameter("foldername"); 
    String filename = request.getParameter("filename");
    String fileContent = (String)request.getParameter("content");
    String ch = (String)request.getParameter("char"); //char = 去
    String pathToFile = DIR + project + "/" + foldername + "/" + filename; 
    System.out.println(URLEncoder.encode("去", "UTF-8")); //reults in %E5%8E%BB
            System.out.println(URLDecoder.decode(ch, "UTF-8")); // results in ?
    System.out.println(URLDecoder.decode("%E5%8E%BB", "UTF-8")); //results in ?
    System.out.println("去".equals(URLDecoder.decode("%E5%8E%BB", "UTF-8"))); //this results in true

    try {
        //writing it to file results in ?
        BufferedWriter out = new BufferedWriter(new FileWriter(pathToFile));
        out.write(URLDecoder.decode(fileContent, "UTF-8"));
        out.close();
        System.out.println("STAT - SaveFile " + filename);
    }catch(IOException e){
        System.out.println("STAT - SaveFile Error");
    }
   }
 }

But running a simple main method works for me

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

 public class test {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    try {
        System.out.println(URLEncoder.encode("去", "UTF-8"));
        System.out.println(URLDecoder.decode("%E5%8E%BB", "UTF-8"));
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}
}

Answer 1

It is only a display issue of your console. The encoding/decoding works fine, as you can see using the following code:

System.out.println("去".equals(URLDecoder.decode("%E5%8E%BB", "UTF-8"))); //displays "true"

--edit--

Your servlet code doesn't work probably because you don't specify the character encoding when constructing the writer, so it uses the default encoding. Use the following instead:

new OutputStreamWriter(new FileOutputStream(pathToFile), "UTF-8");

Answer 2

Firstly The java file must be encoded correctly. Look in the properties for that file, and set the encoding correctly.

In Properties, in the Resources tag set Text File Encoding to UTF-8.

The console output uses the encoding that is defined for the file. Thats the reason you get the ?

Answer 3

Nothing missed in your code, also compiled fine. Just check two thing: 1. If this code into the webpage like JSP then make sure the charset & pageEncoding is UTF-8 2. Check your project properties & make sure that your project encoding is UTF-8, see the attachment image