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
17package com.google.clearsilver.jsilver.functions.escape;
18
19import com.google.clearsilver.jsilver.functions.TextFilter;
20
21import java.io.ByteArrayOutputStream;
22import java.io.IOException;
23import java.io.OutputStreamWriter;
24import java.io.UnsupportedEncodingException;
25import 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 */
31public 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