设置minifyEnabled=true进行编译即可，
生成的文件位于build/outputs/mapping/release（或debug）/usage.txt
2、开启R8，生成usage.txt
1、设置minifyEnabled=true
2. 指定生成路径，在proguard-rules.pro文件中添加：
-printusage /usage.txt
3. 编译即可
笔者对比过这两种方式的代码缩减效果，相比之下开启R8后被删掉的代码要比proguard的稍微多一些，但整体相差不大。如下图：左边是proguard，4万1千行，右边是R8，4万4千行
3、基于usage文件内容，我们根据包名进行过滤，可以拿到当前工程中被缩减那部分的代码，文章第三部分实践，可以参考
二、基于shrinkResources结果获取无用资源
获取无用资源相对容易些，将shrinkResources置为true，编译后shrinkResources的结果位于build/outputs/mapping/release（或debug）/resources.txt。内容大概长这样：
除此之外，官方还提供了一个[开启严苛引用检查](()的开关。开启了之后，扫描出的无用资源数量大大增加，但需要注意是否会影响业务
开启严苛检查方法：在res/raw/目录下新增keep.xml文件
三、实践
编译后基于usage.txt 和 resources.txt 的结果，可以通过task来过滤，排序处理。可参考以下：
task codeScan(dependsOn: assembleRelease) {
…
doLast {
if (project.getBuildDir().exists()) {
String basePath = project.getBuildDir().path + “/outputs/mapping/release/”
//无用Class
File uoUseClassRecode = new File(basePath + “usage.txt”)
if (uoUseClassRecode.exists()) {
FileReader fr = new FileReader(uoUseClassRecode)
BufferedReader reader = new BufferedReader(fr)
List classList = new ArrayList<>()
ClassRecorder recorder = null
String packageName = “${project.android.defaultConfig.applicationId}”
if (packageName == null || packageName.size() == 0) {
throw new IllegalArgumentException(
“packageName为空，请检查是否在build.gradle的defaultConfig中配置applicationId属性”)
}
while(reader.ready()){
String line = reader.readLine()
//新的类
if (!line.startsWith(" ")) {
if (isBusinessCode(recorder, packageName)){ //如果是业务代码，记录下来
classList.add(recorder)
}
recorder = new ClassRecorder()
recorder.className = line
} else {
recorder.classMethodList.add(line)
}
}
reader.close()
fr.close()
//读取结束,排序整理
List result = sortByClassName(classList, packageName.size()+1)
//排序完，输出到文件
File outPutFile = new File(basePath + “unusedClass.txt”)
if (outPutFile.exists()) outPutFile.createNewFile()
BufferedWriter bw = new BufferedWriter(new FileWriter(outPutFile))
for (ClassRecorder cr : result) {
bw.writeLine(cr.className)
}
bw.close()
} else {
throw new IllegalArgumentException(“编译产物文件不存在”)
}
boolean checkResPrefix = true
//无用资源
File uoUsedRes = new File(basePath + “resources.txt”)
if (uoUseClassRecode.exists()) {
FileReader fr = new FileReader(uoUsedRes)
BufferedReader reader = new BufferedReader(fr)
List resList = new ArrayList<>()
while(reader.ready()){
String line = reader.readLine()
if (line.startsWith(“Skipped unused resource”)) {
String name = line.split(" ")[3]
name = name.substring(0, name.size()-1)
resList.add(name)
}
}
reader.close()
fr.close()
File outPutFile = new File(basePath + “unusedRes.txt”)
if (outPutFile.exists()) outPutFile.createNewFile()
BufferedWriter bw = new BufferedWriter(new FileWriter(outPutFile))
for (String name : resList) {
bw.writeLine(name)
}
bw.close()
}
}
}
/**
- 是否是业务代码，是否是含有包名
*/
static boolean isBusinessCode(ClassRe 《Android学习笔记总结+最新移动架构视频+大厂安卓面试真题+项目实战源码讲义》无偿开源 徽信搜索公众号【编程进阶路】 corder recorder, String packageName) {
if (recorder == null) return false
return recorder.className.contains(packageName)
recorder, String packageName) {
if (recorder == null) return false
return recorder.className.contains(packageName)
