Android Lint简介

英文原文：http://tools.android.com/tips/lint 

参照文章：http://blog.csdn.net/thl789/article/details/8037473

一、简介

Android Lint是SDK Tools 16 (ADT 16)之后才引入的工具，通过它对Android工程源代码进行扫描和检查，可发现潜在的问题，以便程序员及早修正这个问题。Android Lint提供了命令行方式执行，还可与IDE（如Eclipse）集成，并提供了html形式的输出报告。

由于Android Lint在最初设计时就考虑到了independent于IDE,所以它可以很方便的与项目中的其他自动系统（配置/ Build / 测试等）集成.

Android Lint主要用于检查以下这些错误：

1、Missing translations (and unused translations)没有翻译的文本

2、Layout performance problems (all the issues the old layoutopt tool used to find, and more)

3、Unused resources未使用的冗余资源

4、Inconsistent array sizes (when arrays are defined in multiple configurations)在多个配置中的数组大小不一致文件

5、Accessibility and internationalization problems (hardcoded strings, missing contentDescription, etc)

6、Icon problems (like missing densities, duplicate icons, wrong sizes, etc)

7、Usability problems (like not specifying an input type on a text field)

8、Manifest errors

当然Android Lint远远不至检查以上的错误，更多的内容请参考《Android Lint 检查规则列表》

在Eclipse中可以在菜单Window->Preference->“Lint Eerro checking”中设置规则的检查级别，如图1所示。

检查级别可以是:

Default

Fatal

Errro

Waring

Information

Ingore(即不检查)

图1

如果你只是想对lint的检查规则做些简单的定制，请参考《Android Lint 检查规则的定制（基本篇）》或英文官方文档

如果你想对lint的检查规则做些高级的定制，请参考官方文档 Writing New Lint Checks and Writing Custom Lint Rules.

二、命令行中使用Lint

2.1、基本使用

There is a command line tool in the SDK tools/ directory called lint.

If you have the SDK tools/ directory on your path, you can invoke it as “lint”. Just point to a specific Android project directory. You can also point to a random directory, which (if it is not an Android project) will be searched recursively and all projects under that directory will be checked. (And you can also specify multiple projects separated by spaces)

在Android SDK的tools下有个叫lint.bat的文件，它就是lint的命令行工具。

lint命令后可以带一个或多个参数，参数之间用空格隔开，参数表示的是需要使用lint进行扫描的Android项目的目录。

示例1

linux命令行

 lint /src/astrid/Scanning GreenDroid-GoogleAPIs: ..Scanning stream: ...Scanning api: ...........................Scanning GDCatalog: .......................Scanning GreenDroid: ...........................................................Scanning tests: ...Scanning filters: ....Scanning tests: .....Scanning astrid: ....................................................................................................................................................Scanning simple: .......api/res/values-ca: Error: Locale ca is missing translations for: sync_SPr_bgwifi_key, sync_SPr_forget_key, sync_SPr_interval_values, sync_SPr_logged_in_prefix... (2 more) [MissingTranslation]astrid/res/values-ca: Error: Locale ca is missing translations for: DLG_cancel, DLG_dismiss, DLG_ok, EPr_deactivated... (117 more) [MissingTranslation]api/res/values-cs: Error: Locale cs is missing translations for: sync_SPr_bgwifi_key, sync_SPr_forget_key, sync_SPr_interval_values, sync_SPr_logged_in_prefix... (2 more) [MissingTranslation](many lines omitted)43 errors, 466 warnings

示例2

Window命令行

C:\Documents and Settings\Administrator>lint D:\workspace\TestScanning Test: ....................................................................................................................................................................................................................................................Scanning Test (Phase 2): ......res\layout\internet_image_demo.xml:9: Warning: The id "button1" is not referring to any views in this layout [UnknownIdInLayout]        android:layout_alignLeft="@+id/button1"        ^res\layout\internet_image_demo.xml:10: Warning: The id "textView1" is not referring to any views in this layout [UnknownIdInLayout]        android:layout_below="@+id/textView1"        ^AndroidManifest.xml:52: Warning: Exported receiver does not require permission [ExportedReceiver]        <receiver android:name=".AlarmReceiver" >        ^res\menu\activity_main.xml: Warning: The resource R.menu.activity_main appears to be unused [UnusedResources]res\drawable-hdpi\ic_action_search.png: Warning: The resource R.drawable.ic_action_search appears to be unused [UnusedResources]res\values\strings.xml:7: Warning: The resource R.string.hello appears to be unused [UnusedResources]<string name="hello">你好！</string>^res\drawable-mdpi: Warning: Missing the following drawables in drawable-mdpi: icon.png, icon2.png [IconDensities]res\drawable-xhdpi: Warning: Missing the following drawables in drawable-xhdpi: icon.png, icon2.png [IconDensities]res\layout\internet_image_demo.xml:5: Warning: [Accessibility] Missing contentDescription attribute on image [ContentDescription]    <ImageView    ^res\layout\activity_main.xml:17: Warning: [I18N] Hardcoded string "go Hello", should use @string resource [HardcodedText]        android:text="go Hello"        ^res\layout\activity_main.xml:23: Warning: [I18N] Hardcoded string "打印所有任务栈信息", should use @string resource [HardcodedText]        android:text="打印所有任务栈信息"        ^res\layout\activity_main.xml:29: Warning: [I18N] Hardcoded string "打印所有服务信息", should use @string resource [HardcodedText]        android:text="打印所有服务信息"        ^res\layout\activity_main.xml:35: Warning: [I18N] Hardcoded string "打印进程信息", should use @string resource [HardcodedText]        android:text="打印进程信息"        ^res\layout\hello.xml:23: Warning: [I18N] Hardcoded string "please click me", should use @string resource [HardcodedText]        android:text="please click me"        ^0 errors, 14 warnings

2.2、Disabling Checks（--disable）

在执行lint命令时可以通过--disable选项要指定关闭的检查规则项。--disable选项后接要关闭的检查规则项的id（比如示例3中的MissingTranslation）或检查规则项的类别（比如示例3中的Usability:Icons和示例4的Internationalization）。

关于lint检查项的id和类别（Category）等信息请参考《Android Lint 检查规则列表》

示例3

$ lint --disable MissingTranslation,UnusedIds,Usability:Icons /src/astrid/

示例4

C:\Documents and Settings\Administrator>lint --disable Internationalization D:\workspace\TestScanning Test: ....................................................................................................................................................................................................................................................Scanning Test (Phase 2): ......res\layout\internet_image_demo.xml:9: Warning: The id "button1" is not referring to any views in this layout [UnknownIdInLayout]        android:layout_alignLeft="@+id/button1"        ^res\layout\internet_image_demo.xml:10: Warning: The id "textView1" is not referring to any views in this layout [UnknownIdInLayout]        android:layout_below="@+id/textView1"        ^AndroidManifest.xml:52: Warning: Exported receiver does not require permission [ExportedReceiver]        <receiver android:name=".AlarmReceiver" >        ^res\menu\activity_main.xml: Warning: The resource R.menu.activity_main appears to be unused [UnusedResources]res\drawable-hdpi\ic_action_search.png: Warning: The resource R.drawable.ic_action_search appears to be unused [UnusedResources]res\values\strings.xml:7: Warning: The resource R.string.hello appears to be unused [UnusedResources]<string name="hello">你好！</string>^res\drawable-mdpi: Warning: Missing the following drawables in drawable-mdpi: icon.png, icon2.png [IconDensities]res\drawable-xhdpi: Warning: Missing the following drawables in drawable-xhdpi: icon.png, icon2.png [IconDensities]res\layout\internet_image_demo.xml:5: Warning: [Accessibility] Missing contentDescription attribute on image [ContentDescription]    <ImageView    ^0 errors, 9 warnings

2.3、enabling Checks(--enable和--check)

lint的有些检查项默认是关闭的(disable),在执行lint命令时可以通过--enable选项开启它。-enable选项后接要开启的检查规则项的id（比如示例5中的MissingTranslation ）或检查规则项的类别（示例5中的Usability:Icons）

示例5

$ lint --disable MissingTranslation,UnusedIds,Usability:Icons /src/astrid/

在执行lint命令时可以通过--check选项来指定只进行某些检查。-check选项后接要开启的检查规则项的id（比如示例6中的MissingPrefix）

示例6

$ lint --check MissingPrefix /src/astrid/

2.4、检查项类别和检查项id

可以通过lint的--list选项来得到检查项类别和检查项id.

比如：

$ lint --list
Valid issue categories:
Correctness
Security
Performance
Usability
Usability:Icons
Accessibility
Internationalization

Valid issue id‘s:
"ContentDescription": Ensures that image widgets provide a contentDescription
"DuplicateIds": Checks for duplicate ids within a single layout
"StateListReachable": Looks for unreachable states in a <selector>
"InefficientWeight": Looks for inefficient weight declarations in LinearLayouts
"ScrollViewSize": Checks that ScrollViews use wrap_content in scrolling dimension
"MergeRootFrame": Checks whether a root <FrameLayout> can be replaced with a <merge> tag
...

可以通过lint的--show选项后跟检查项id来得到一个检查项的详细说明.

比如：

$ lint --show MissingPrefix
MissingPrefix
-------------
Summary: Detect XML attributes not using the Android namespace

Priority: 8 / 10
Severity: Warning
Category: Correctness

Most Android views have attributes in the Android namespace. When
referencing these attributes you *must* include the namespace prefix,
or your attribute will be interpreted by aapt as just a custom
attribute.

当然你也可以通过《Android Lint 检查规则列表》来查阅检查项的id等详细信息

2.4、html形式的report

在lint中，我们可以通过--html选项接文件路径的形式把代码扫描结果以html文件的形式进行输出。

示例6

C:\Documents and Settings\Administrator>lint --html D:\workspace\Test\report.html D:\workspace\TestScanning Test: ....................................................................................................................................................................................................................................................Scanning Test (Phase 2): ......Wrote HTML report to D:\workspace\Test\report.html

html输出报告如图2所示

图2

By default, links to source files will just use local file:// path resources. You can remap the URLs to a different prefix with the --url option. For example:

$ lint --html /tmp/report.html --url /src/MyProj=http://buildserver/src/MyProj

2.5、命令行帮助

在lint中，你可以使用--help选项来得到lint命令的一些帮助信息。

示例7

lint --help

三、Eclispe中使用Lint

从ADT16开始，lint就集成到了ADT中。该它在lint命令行的基础上新增了以下功能

• Automatic fixes for many warnings自动修正大量警告

• Lint gets run automatically on various editing operations当编辑操作完成后，立即自动运行

• Ability to suppress types of errors as well as specific instances of an error可以suppress(忽略)一种类型的erro，也可以suppress(忽略)特定的一个erro

• Ability to configure issue severities能够配置issue（问题）的severities(严重性)

• Jump directly to the problem source from the lint view通过lint视图能直接跳转到其问题对应的源码处

3.1、Automatic Lint

Lint将在以下情况下自动运行：

• Export an APK. In this case it runs lint in a special mode which only looks for fatal errors (which is faster) and aborts the export if any fatal errors are found. You can turn off this in the Lint Options.在导出APK文件的时候，lint会做快速的扫描，以寻找fatal的错误。如果发现有fatal的错误，导出APK的操作将被迫终止

• Edit and Save and XML file, such as a layout file or a manifest file. In this case, all the file-scope checks that apply to the given file are run and editor markers are added for any issues found.编辑和保存XML文件，lint也会自动扫描这些文件。另外从ADT20开始，对于java源码文件在编辑和保存后，lint也会对他们进行扫描。

• Use the layout editor. After every UI operation, file-scope checks (such as the various layoutopt rules) are run on the layout file and the results are shown in a special lint window (which can be opened from the error marker which shows in the top right corner of the layout editor when errors are found).对于使用layout editor来操作布局文件时，在每个UI操作后,lint也会自动扫描该布局文件。

3.2、Lint Window

在Eclipse中，你可以通过两种方式来手动进行lint的扫描：

一种方式是通过工具栏，双击图3-1中红色箭头指向的按钮，然后出现图3-2所示的下拉框，在该下拉选择要进行lint扫描的工程

图3-1

图3-2

一种方式是选中一个Android工程，单击右键，在下拉菜单中选择“Android tools”->"Run lint:check common erro",如图3-3所示

图3-3

运行lint之后，你将看到如图3-4或图3-5所示的lint 窗口

图3-4

图3-5

默认情况下，同一个类型的issue都是折叠成一块的，图3-4和图3-5是我手动展开的。

lint窗口的工具栏上有一些按钮，如图3-6所示

图3-6

它们的意义分别如下

•  Refresh, which re-runs the current analysis on the same projects

•  Fix, which automatically fixes the issue (this applies to issues where a quickfix is available)

•  Suppress this issue with an attribute or annotation

•  Ignore in this file (saves suppress information in lint.xml)

•  Ignore in this project (ditto)

•  Always ignore

•  Delete this lint marker

•  Delete all lint markers

•  Expand All, 

   Collapse All

•   Configure Columns用于设置在lint Window中对于检查出的issue的哪些项显示哪些项不显示，如图3-7所示

   

•  Edit Options Edit Options 点击该按钮会弹出Lint Preference dialog，如图1或图3-8在里面你可以定制默认/全局的Android Lint的基本检查规则，在其中可以设置所有项目默认的lint检查规则的检查级别，把检查级别(Severity)设为”ignore“,其实就是忽略（suppress）该检查规则

Configure Columns lets you edit which columns are visible. There are several new columns you can display, such as Category, Priority, etc, and you can click on column headers to sort the display by the given column. There‘s also a new "Location" column, shown by default, which incorporates several different pieces of information: the file name, the line number, the parent folder name (useful when looking at translation or configuration issues), and the project name:

Configure Columns用于设置在lint Window中对于检查出的issue的哪些项显示哪些项不显示，如图3-7所示

图3-7

 The Edit Options actions brings up the Lint Preference dialog, which has also been improved.  You can now search through the options by filter:

点击Edit Options按钮会弹出处理Lint Preference dialog，在里面可以定制默认/全局的Android Lint的基本检查规则

图3-8

 3.3、Quick Fixes

Many lint warnings have automatic fixes. For example, the various layoutopt fixes suggest replacements (e.g. replace wrap_content with 0dp). 

• From the lint view（如图3-6所示）, click the lightbulb 
   to invoke a fix.

• From the layout editor warning summary, click the Fix button to fix.

• And from the XML source editor, invoke the Quick Fix (Ctrl-1 or Command-1) and pick the quick fix associated with the warning.

3.4、Suppressing Errors(检查规则的基本定制)

From the editor quick fix menu（如图3-9所示）, you can also choose to

• Ignore the warning in this file only

• Ignore the warning in this project

• Ignore the warning, period.

• Ignore warnings using annotations or attributes, as explained here.

图3-9

(If you do not see the lint fix action in the quickfix list, see the Known Bugs section)

These choices are stored in a file named lint.xml in the project, which is also read by the command line tool. Thus, you can ignore warnings from the UI, and check in thelint.xml file with your source projects, and others running lint will not see warnings you have ignored (presumably because they have been manually verified).

你的选择在被存在Android工程目录下的 lint.xml 文件中