Android笔记之强大的buildConfigField

在进行项目开发或维护时，经常会遇到调试和发布所用到的参数值不一致的情况

例如，服务器会分测试和正式，为了能方便地更改（自动更换）服务器地址，buildConfigField就派上用场了

以前都是手动更改的，极易出错T_T

buildConfigField语法如下

buildConfigField "TypeName", "FieldName", "FieldValue"

示例

build.gradle (Module: app)

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.bu_ish.debug_release_test"
        minSdkVersion 19
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
            buildConfigField "String", "TextToShow", "\"当前处于发布模式\""
        }
        debug {
            buildConfigField "String", "TextToShow", "\"当前处于调试模式\""
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

Gradle会自动生成BuildConfig.java

BuildConfig中包含了字段TextToShow

生成的Debug版BuildConfig如下

/**
 * Automatically generated file. DO NOT MODIFY
 */
package com.bu_ish.debug_release_test;

public final class BuildConfig {
  public static final boolean DEBUG = Boolean.parseBoolean("true");
  public static final String APPLICATION_ID = "com.bu_ish.debug_release_test";
  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 String TextToShow = "当前处于调试模式";
}

在使用BuildConfig.TextToShow时，Gradle就帮我们自动地完成了调试值"当前处于调试模式"和发布值"当前处于发布模式"的切换