BuildConfig是什么？

BuildConfig是android在编译过程中自动生成的一个配置文件。

在不同的编译模式下会生成不同的变量，我们可以利用这些变量来方便不同编译环境下的开发，比如日志的打印（开发环境下可以打印Verbose一级，发布环境下可以打印Warn一级）。

BuildConfig有哪些变量？

没有自己变动过gradle文件的话，自动生成的BuildConfig一般如下文所示。

public final class BuildConfig {  public static final boolean DEBUG = Boolean.parseBoolean("true");  public static final String APPLICATION_ID = "com.xxxx.xxx.xx";  public static final String BUILD_TYPE = "debug";  public static final String FLAVOR = "";  public static final int VERSION_CODE = 1;  public static final String VERSION_NAME = "1.0";}

BuildConfig在哪里？

如图所示

BuildConfig如何使用？

同java常量。

public class MainActivity extends AppCompatActivity {    TextView msgText;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        String lineSep = System.getProperty("line.separator", "\n");        msgText = (TextView) findViewById(R.id.msgText);        String DEBUG = "DEBUG = "                + BuildConfig.DEBUG                + lineSep;        String APPLICATION_ID = "APPLICATION_ID = "                + BuildConfig.APPLICATION_ID                + lineSep;        String BUILD_TYPE = "BUILD_TYPE = "                + BuildConfig.BUILD_TYPE                + lineSep;        String FLAVOR = "FLAVOR = "                + BuildConfig.FLAVOR                + lineSep;        String VERSION_CODE = "VERSION_CODE = "                + BuildConfig.VERSION_CODE                + lineSep;        String VERSION_NAME = "VERSION_NAME = "                + BuildConfig.VERSION_NAME;        String msg = DEBUG                + APPLICATION_ID                + BUILD_TYPE                + FLAVOR                + VERSION_CODE                + VERSION_NAME;        msgText.setText(msg);    }}

BuildConfig可以添加其他变量吗？

可以的。

在app模块的build.gradle中（不是Project的），有个buildTypes节点，我们修改如下。

    buildTypes {        debug {            buildConfigField "int", "myInt", "0"            buildConfigField "String", "myStr", "\"hello\""            buildConfigField "boolean", "myFlag", "true"        }        release {            buildConfigField "int", "myInt", "1"            buildConfigField "String", "myStr", "\"world\""            buildConfigField "boolean", "myFlag", "true"            minifyEnabled false            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'        }    }

其中myInt，myStr，myFlag是我们自己定义的，编译后的BuildConfig为

public final class BuildConfig {  public static final boolean DEBUG = Boolean.parseBoolean("true");  public static final String APPLICATION_ID = "com.qefee.pj.testbuildconfig";  public static final String BUILD_TYPE = "debug";  public static final String FLAVOR = "";  public static final int VERSION_CODE = 1;  public static final String VERSION_NAME = "1.0";  // Fields from build type: debug  public static final boolean myFlag = true;  public static final int myInt = 0;  public static final String myStr = "hello";}

可以看到系统已经为我们生成了.

参考文章

Android BuildConfig.DEBUG的使用
Pro Tip: Android BuildConfig

android的BuildConfig学习