Fork me on GitHub

黄博文的地盘

我是一个程序员.

CheckStyle, 强制你遵循编码规范

| Comments

如今代码静态检查越来越重要，已经成为构建高质量软件的不可或缺的一个验证步骤。如果你使用的是java语言，那么CheckStyle则是一个利器。 CheckStyle能够帮助程序员检查代码是否符合制定的规范。通过将CheckStyle的检查引入到项目构建中，可以强制让项目中的所有的开发者遵循制定规范，而不是仅仅停留在纸面上。如果发现代码违反了标准，比如类名未以大写开头、单个方法超过了指定行数、甚至单个方法抛出了3个以上的异常等。这些检查由于是基于源码的，所以不需要编译，执行速度快。

CheckStyle有针对不同IDE和构建工具的各种插件，方便开发者随时随地对代码进行静态检查。下面就讲解下如何将CheckStyle引入到maven构建中。

配置CheckStyle插件

在maven中一个名为maven-checkstyle-plugin的插件，用于执行CheckStyle task。下面是一个简单的配置。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-checkstyle-plugin</artifactId>
    <version>2.10</version>
    <executions>
        <execution>
            <id>checkstyle</id>
            <phase>validate</phase>
            <goals>
                <goal>check</goal>
            </goals>
            <configuration>
                <failOnViolation>true</failOnViolation>
            </configuration>
        </execution>
    </executions>
</plugin>

我们定义了在maven lifecycle的validate阶段执行check task，并且如果发现有违反标准的情况就会fail当前的build。

maven-checkstyle-plugin内置了4种规范.

  • config/sun_checks.xml
  • config/maven_checks.xml
  • config/turbine_checks.xml
  • config/avalon_checks.xml

其中sun_checks.xml为默认值。如果想要使用其他三种规范，则只需配置configuration。下面是使用maven_checks.xml的示例。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-checkstyle-plugin</artifactId>
    <version>2.10</version>
    <configuration>
        <configLocation>config/maven_checks.xml</configLocation>
    </configuration>
    <executions>
        <execution>
            <id>checkstyle</id>
            <phase>validate</phase>
            <goals>
                <goal>check</goal>
            </goals>
            <configuration>
                <failOnViolation>true</failOnViolation>
            </configuration>
        </execution>
    </executions>
</plugin>

自定义规范文件

我们可以使用默认的规范未见，当然也支持自定义。下面是google的一个checkstyle规范文件。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<!-- This is a checkstyle configuration file. For descriptions of
what the following rules do, please see the checkstyle configuration
page at http://checkstyle.sourceforge.net/config.html -->

<module name="Checker">


    <module name="RegexpSingleline">
        <!-- Requires a Google copyright notice in each file.
          Code intended to be open-sourced may have a multi-line copyright
          notice, so that this required text appears on the second line:
          <pre>
            /*
             * Copyright 2008 Google Inc.
             *
             * (details of open-source license...)
          </pre>
        -->
        <property name="format"
                  value="^(//| \*) Copyright (\([cC]\) )?[\d]{4}(\-[\d]{4})? (Google Inc\.).*$" />
        <property name="minimum" value="1" />
        <property name="maximum" value="10" />
        <property name="message" value="Google copyright is missing or malformed." />
        <property name="severity" value="error" />
    </module>

    <module name="FileTabCharacter">
        <!-- Checks that there are no tab characters in the file.
        -->
    </module>

    <module name="NewlineAtEndOfFile"/>

    <module name="RegexpSingleline">
        <!-- Checks that FIXME is not used in comments.  TODO is preferred.
        -->
        <property name="format" value="((//.*)|(\*.*))FIXME" />
        <property name="message" value='TODO is preferred to FIXME.  e.g. "TODO(johndoe): Refactor when v2 is released."' />
    </module>

    <module name="RegexpSingleline">
        <!-- Checks that TODOs are named.  (Actually, just that they are followed
             by an open paren.)
        -->
        <property name="format" value="((//.*)|(\*.*))TODO[^(]" />
        <property name="message" value='All TODOs should be named.  e.g. "TODO(johndoe): Refactor when v2 is released."' />
    </module>

    <!-- All Java AST specific tests live under TreeWalker module. -->
    <module name="TreeWalker">

        <!--

        IMPORT CHECKS

        -->

        <module name="RedundantImport">
            <!-- Checks for redundant import statements. -->
            <property name="severity" value="error"/>
        </module>

        <module name="ImportOrder">
            <!-- Checks for out of order import statements. -->

            <property name="severity" value="warning"/>
            <property name="groups" value="com.google,android,junit,net,org,java,javax"/>
            <!-- This ensures that static imports go first. -->
            <property name="option" value="top"/>
            <property name="tokens" value="STATIC_IMPORT, IMPORT"/>
        </module>

        <!--

        JAVADOC CHECKS

        -->

        <!-- Checks for Javadoc comments.                     -->
        <!-- See http://checkstyle.sf.net/config_javadoc.html -->
        <module name="JavadocMethod">
            <property name="scope" value="protected"/>
            <property name="severity" value="warning"/>
            <property name="allowMissingJavadoc" value="true"/>
            <property name="allowMissingParamTags" value="true"/>
            <property name="allowMissingReturnTag" value="true"/>
            <property name="allowMissingThrowsTags" value="true"/>
            <property name="allowThrowsTagsForSubclasses" value="true"/>
            <property name="allowUndeclaredRTE" value="true"/>
        </module>

        <module name="JavadocType">
            <property name="scope" value="protected"/>
            <property name="severity" value="error"/>
        </module>

        <module name="JavadocStyle">
            <property name="severity" value="warning"/>
        </module>

        <!--

        NAMING CHECKS

        -->

        <!-- Item 38 - Adhere to generally accepted naming conventions -->

        <module name="PackageName">
            <!-- Validates identifiers for package names against the
              supplied expression. -->
            <!-- Here the default checkstyle rule restricts package name parts to
              seven characters, this is not in line with common practice at Google.
            -->
            <property name="format" value="^[a-z]+(\.[a-z][a-z0-9]{1,})*$"/>
            <property name="severity" value="warning"/>
        </module>

        <module name="TypeNameCheck">
            <!-- Validates static, final fields against the
            expression "^[A-Z][a-zA-Z0-9]*$". -->
            <metadata name="altname" value="TypeName"/>
            <property name="severity" value="warning"/>
        </module>

        <module name="ConstantNameCheck">
            <!-- Validates non-private, static, final fields against the supplied
            public/package final fields "^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$". -->
            <metadata name="altname" value="ConstantName"/>
            <property name="applyToPublic" value="true"/>
            <property name="applyToProtected" value="true"/>
            <property name="applyToPackage" value="true"/>
            <property name="applyToPrivate" value="false"/>
            <property name="format" value="^([A-Z][A-Z0-9]*(_[A-Z0-9]+)*|FLAG_.*)$"/>
            <message key="name.invalidPattern"
                     value="Variable ''{0}'' should be in ALL_CAPS (if it is a constant) or be private (otherwise)."/>
            <property name="severity" value="warning"/>
        </module>

        <module name="StaticVariableNameCheck">
            <!-- Validates static, non-final fields against the supplied
            expression "^[a-z][a-zA-Z0-9]*_?$". -->
            <metadata name="altname" value="StaticVariableName"/>
            <property name="applyToPublic" value="true"/>
            <property name="applyToProtected" value="true"/>
            <property name="applyToPackage" value="true"/>
            <property name="applyToPrivate" value="true"/>
            <property name="format" value="^[a-z][a-zA-Z0-9]*_?$"/>
            <property name="severity" value="warning"/>
        </module>

        <module name="MemberNameCheck">
            <!-- Validates non-static members against the supplied expression. -->
            <metadata name="altname" value="MemberName"/>
            <property name="applyToPublic" value="true"/>
            <property name="applyToProtected" value="true"/>
            <property name="applyToPackage" value="true"/>
            <property name="applyToPrivate" value="true"/>
            <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
            <property name="severity" value="warning"/>
        </module>

        <module name="MethodNameCheck">
            <!-- Validates identifiers for method names. -->
            <metadata name="altname" value="MethodName"/>
            <property name="format" value="^[a-z][a-zA-Z0-9]*(_[a-zA-Z0-9]+)*$"/>
            <property name="severity" value="warning"/>
        </module>

        <module name="ParameterName">
            <!-- Validates identifiers for method parameters against the
              expression "^[a-z][a-zA-Z0-9]*$". -->
            <property name="severity" value="warning"/>
        </module>

        <module name="LocalFinalVariableName">
            <!-- Validates identifiers for local final variables against the
              expression "^[a-z][a-zA-Z0-9]*$". -->
            <property name="severity" value="warning"/>
        </module>

        <module name="LocalVariableName">
            <!-- Validates identifiers for local variables against the
              expression "^[a-z][a-zA-Z0-9]*$". -->
            <property name="severity" value="warning"/>
        </module>


        <!--

        LENGTH and CODING CHECKS

        -->

        <module name="LineLength">
            <!-- Checks if a line is too long. -->
            <property name="max" value="${com.puppycrawl.tools.checkstyle.checks.sizes.LineLength.max}" default="100"/>
            <property name="severity" value="error"/>

            <!--
              The default ignore pattern exempts the following elements:
                - import statements
                - long URLs inside comments
            -->

            <property name="ignorePattern"
                      value="${com.puppycrawl.tools.checkstyle.checks.sizes.LineLength.ignorePattern}"
                      default="^(package .*;\s*)|(import .*;\s*)|( *\* *https?://.*)$"/>
        </module>

        <module name="LeftCurly">
            <!-- Checks for placement of the left curly brace ('{'). -->
            <property name="severity" value="warning"/>
        </module>

        <module name="RightCurly">
            <!-- Checks right curlies on CATCH, ELSE, and TRY blocks are on
            the same line. e.g., the following example is fine:
            <pre>
              if {
                ...
              } else
            </pre>
            -->
            <!-- This next example is not fine:
            <pre>
              if {
                ...
              }
              else
            </pre>
            -->
            <property name="option" value="same"/>
            <property name="severity" value="warning"/>
        </module>

        <!-- Checks for braces around if and else blocks -->
        <module name="NeedBraces">
            <property name="severity" value="warning"/>
            <property name="tokens" value="LITERAL_IF, LITERAL_ELSE, LITERAL_FOR, LITERAL_WHILE, LITERAL_DO"/>
        </module>

        <module name="UpperEll">
            <!-- Checks that long constants are defined with an upper ell.-->
            <property name="severity" value="error"/>
        </module>

        <module name="FallThrough">
            <!-- Warn about falling through to the next case statement.  Similar to
            javac -Xlint:fallthrough, but the check is suppressed if a single-line comment
            on the last non-blank line preceding the fallen-into case contains 'fall through' (or
            some other variants which we don't publicized to promote consistency).
            -->
            <property name="reliefPattern"
                      value="fall through|Fall through|fallthru|Fallthru|falls through|Falls through|fallthrough|Fallthrough|No break|NO break|no break|continue on"/>
            <property name="severity" value="error"/>
        </module>


        <!--

        MODIFIERS CHECKS

        -->

        <module name="ModifierOrder">
            <!-- Warn if modifier order is inconsistent with JLS3 8.1.1, 8.3.1, and
                 8.4.3.  The prescribed order is:
                 public, protected, private, abstract, static, final, transient, volatile,
                 synchronized, native, strictfp
              -->
        </module>


        <!--

        WHITESPACE CHECKS

        -->

        <module name="WhitespaceAround">
            <!-- Checks that various tokens are surrounded by whitespace.
                 This includes most binary operators and keywords followed
                 by regular or curly braces.
            -->
            <property name="tokens" value="ASSIGN, BAND, BAND_ASSIGN, BOR,
        BOR_ASSIGN, BSR, BSR_ASSIGN, BXOR, BXOR_ASSIGN, COLON, DIV, DIV_ASSIGN,
        EQUAL, GE, GT, LAND, LE, LITERAL_CATCH, LITERAL_DO, LITERAL_ELSE,
        LITERAL_FINALLY, LITERAL_FOR, LITERAL_IF, LITERAL_RETURN,
        LITERAL_SYNCHRONIZED, LITERAL_TRY, LITERAL_WHILE, LOR, LT, MINUS,
        MINUS_ASSIGN, MOD, MOD_ASSIGN, NOT_EQUAL, PLUS, PLUS_ASSIGN, QUESTION,
        SL, SL_ASSIGN, SR_ASSIGN, STAR, STAR_ASSIGN"/>
            <property name="severity" value="error"/>
        </module>

        <module name="WhitespaceAfter">
            <!-- Checks that commas, semicolons and typecasts are followed by
                 whitespace.
            -->
            <property name="tokens" value="COMMA, SEMI, TYPECAST"/>
        </module>

        <module name="NoWhitespaceAfter">
            <!-- Checks that there is no whitespace after various unary operators.
                 Linebreaks are allowed.
            -->
            <property name="tokens" value="BNOT, DEC, DOT, INC, LNOT, UNARY_MINUS,
        UNARY_PLUS"/>
            <property name="allowLineBreaks" value="true"/>
            <property name="severity" value="error"/>
        </module>

        <module name="NoWhitespaceBefore">
            <!-- Checks that there is no whitespace before various unary operators.
                 Linebreaks are allowed.
            -->
            <property name="tokens" value="SEMI, DOT, POST_DEC, POST_INC"/>
            <property name="allowLineBreaks" value="true"/>
            <property name="severity" value="error"/>
        </module>

        <module name="ParenPad">
            <!-- Checks that there is no whitespace before close parens or after
                 open parens.
            -->
            <property name="severity" value="warning"/>
        </module>

    </module>
</module>

如果想启用自定义的规范文件，则依旧是修改configuration，指向你的文件地址。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-checkstyle-plugin</artifactId>
            <version>2.10</version>
            <configuration>
                <configLocation>${basedir}/src/config/custom_checkstyle.xml</configLocation>
            </configuration>
            <executions>
                <execution>
                    <id>checkstyle</id>
                    <phase>validate</phase>
                    <goals>
                        <goal>check</goal>
                    </goals>
                    <configuration>
                        <failOnViolation>true</failOnViolation>
                    </configuration>
                </execution>
            </executions>
        </plugin>

运行checkstyle检查

1

mvn checkstyle:checkstyle

查看checkstyle结果

运行maven命令后可以在console里查看checkstyle运行结果。

1
2
3
4
5
6
7
8
9
10

[INFO]
[INFO] There are 11 checkstyle errors.
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.135s
[INFO] Finished at: Fri Jun 21 13:39:24 CST 2013
[INFO] Final Memory: 6M/81M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:2.10:check (checkstyle) on project SpringMessageSpike: You have 11 Checkstyle violations. -> [Help 1]

checkstye的详细结果信息被存放在target/checkstyle-result.xml中。下面是一个示例。

1
2
3
4
5
6
7
8
9

<?xml version="1.0" encoding="UTF-8"?>
<checkstyle version="5.6">
<file name="/Users/twer/sourcecode/SpringMessageSpike/src/main/java/com/thoughtworks/config/SessionMessageSource.java">
<error line="0" severity="error" message="Google copyright is missing or malformed." source="com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSinglelineCheck"/>
<error line="21" severity="warning" message="Wrong order for &apos;org.slf4j.LoggerFactory.getLogger&apos; import." source="com.puppycrawl.tools.checkstyle.checks.imports.ImportOrderCheck"/>
<error line="27" severity="error" message="Missing a Javadoc comment." source="com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocTypeCheck"/>
<error line="35" severity="error" message="Line is longer than 100 characters (found 115)." source="com.puppycrawl.tools.checkstyle.checks.sizes.LineLengthCheck"/>
</file>
</checkstyle>

跳过对指定文件的某些检查

如果对于指定文件检查出了一些问题，但是你想忽略它，则可以使用suppression。

例如在上述例子中有一个checkstyle error是说某行超过了100字符。如果我们不想修复这个错误怎么办那？可以将其suppress掉。

方法是建立一个checkstyle-suppressions.xml文件。其中加入下述内容

checkstyle-suppressions.xml
1
2
3
4
5
6
7
8
9
10
11

<?xml version="1.0"?>

<!DOCTYPE suppressions PUBLIC
        "-//Puppy Crawl//DTD Suppressions 1.0//EN"
        "http://www.puppycrawl.com/dtds/suppressions_1_0.dtd">

<suppressions>
    <suppress checks="LineLengthCheck"
              files="SessionMessageSource.java"
              />
</suppressions>

然后配置maven-checkstyel-plugin设置suppressionsLocation。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-checkstyle-plugin</artifactId>
    <version>2.10</version>
    <configuration>
        <configLocation>${basedir}/src/config/custom_checkstyle.xml</configLocation>
        <suppressionsLocation>${basedir}/src/config/checkstyle-suppressions.xml</suppressionsLocation>
    </configuration>
    <executions>
        <execution>
            <id>checkstyle</id>
            <phase>validate</phase>
            <goals>
                <goal>check</goal>
            </goals>
            <configuration>
                <failOnViolation>true</failOnViolation>
            </configuration>
        </execution>
    </executions>
</plugin>

Comments