1 /*
2 * Copyright 2011-2013 smartics, Kronseder & Reiner GmbH
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 package de.smartics.pmd.rules.strings;
17
18 import java.nio.ByteBuffer;
19 import java.nio.CharBuffer;
20 import java.nio.charset.CharacterCodingException;
21 import java.nio.charset.Charset;
22 import java.nio.charset.CharsetDecoder;
23
24 import net.sourceforge.pmd.AbstractJavaRule;
25 import net.sourceforge.pmd.PropertyDescriptor;
26 import net.sourceforge.pmd.ast.ASTLiteral;
27 import net.sourceforge.pmd.properties.StringProperty;
28
29 /**
30 * Rule to detect usage of characters of disallowed encoding in String literals.
31 */
32 public class StringLiteralEncodingRule extends AbstractJavaRule
33 {
34 // ********************************* Fields *********************************
35
36 // --- constants ------------------------------------------------------------
37
38 /**
39 * The descriptor to the {@link #encoding} property of this rule.
40 */
41 private static final PropertyDescriptor ENCODING_DESCRIPTOR =
42 new StringProperty("encoding",
43 "The name of the allowed encoding for string literals.", "US-ASCII",
44 1.0f);
45
46 // --- members --------------------------------------------------------------
47
48 /**
49 * The allowed encoding.
50 */
51 private String encoding;
52
53 /**
54 * The decoder dependent on the {@link #encoding}.
55 */
56 private CharsetDecoder decoder;
57
58 // ****************************** Initializer *******************************
59
60 // ****************************** Constructors ******************************
61
62 // ****************************** Inner Classes *****************************
63
64 // ********************************* Methods ********************************
65
66 // --- init -----------------------------------------------------------------
67
68 // --- get&set --------------------------------------------------------------
69
70 // --- business -------------------------------------------------------------
71
72 /**
73 * Checks that there are disallowed encoded characters in String literals.
74 * {@inheritDoc}
75 *
76 * @see net.sourceforge.pmd.AbstractJavaRule#visit(net.sourceforge.pmd.ast.ASTLiteral,
77 * java.lang.Object)
78 */
79 @Override
80 public Object visit(final ASTLiteral node, final Object data)
81 {
82 provideRuleProperties();
83
84 if (node.isStringLiteral())
85 {
86 final String literal = node.getImage();
87 if (!isProperlyEncoded(literal))
88 {
89 final String message = createMessage(literal);
90 addViolationWithMessage(data, node, message);
91 }
92 }
93
94 return super.visit(node, data);
95 }
96
97 private String createMessage(final String literal)
98 {
99 return "String literal '" + literal + "' is not encoded with '" + encoding
100 + "'.";
101 }
102
103 private void provideRuleProperties()
104 {
105 if (encoding == null)
106 {
107 encoding = getStringProperty(ENCODING_DESCRIPTOR);
108 decoder = Charset.forName(encoding).newDecoder();
109 }
110 }
111
112 /**
113 * Inspired by <a href=
114 * "http://stackoverflow.com/questions/3585053/in-java-is-it-possible-to-check-if-a-string-is-only-ascii"
115 * >In Java, is it possible to check if a String is only ASCII?</a>.
116 */
117 private boolean isProperlyEncoded(final String string)
118 {
119 final byte[] stringBytes = string.getBytes();
120
121 try
122 {
123 final CharBuffer buffer = decoder.decode(ByteBuffer.wrap(stringBytes));
124 buffer.toString();
125 }
126 catch (final CharacterCodingException e)
127 {
128 return false;
129 }
130
131 return true;
132 }
133
134 // --- object basics --------------------------------------------------------
135
136 /**
137 * Returns the string representation of the class for debugging.
138 *
139 * @return the string representation of the class for debugging.
140 */
141 @Override
142 public String toString()
143 {
144 return "StringLiteralEncodingRule with encoding '" + encoding + "'.";
145 }
146 }