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      1 /*
      2  * Copyright (C) 2010 Google Inc.
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.clearsilver.jsilver.functions.escape;
     18 
     19 import com.google.clearsilver.jsilver.functions.TextFilter;
     20 
     21 import java.io.ByteArrayOutputStream;
     22 import java.io.IOException;
     23 import java.io.OutputStreamWriter;
     24 import java.io.UnsupportedEncodingException;
     25 import java.net.URLEncoder;
     26 
     27 /**
     28  * This URL encodes the string. This converts characters such as ?, ampersands, and = into their URL
     29  * safe equivilants using the %hh syntax.
     30  */
     31 public class UrlEscapeFunction implements TextFilter {
     32 
     33   private final String encoding;
     34 
     35   public UrlEscapeFunction(String encoding) {
     36     try {
     37       // Sanity check. Fail at construction time rather than render time.
     38       new OutputStreamWriter(new ByteArrayOutputStream(), encoding);
     39     } catch (UnsupportedEncodingException e) {
     40       throw new IllegalArgumentException("Unsupported encoding : " + encoding);
     41     }
     42     this.encoding = encoding;
     43   }
     44 
     45   @Override
     46   public void filter(String in, Appendable out) throws IOException {
     47     try {
     48       out.append(URLEncoder.encode(in, encoding));
     49     } catch (UnsupportedEncodingException e) {
     50       // The sanity check in the constructor should have caught this.
     51       // Things must be really broken for this to happen, so throw an Error.
     52       throw new Error("Unsuported encoding : " + encoding);
     53     }
     54   }
     55 
     56 }
     57