前几天项目中让扫描出所有使用Restful API的方法。刚开始还想着用python过滤关键字来查找的，后来想想可以使用反射来搞的。主要包含以下三个步骤：
- 根据包名解析包的具体路径
- 查找指定包下指定注解的类
- 在上一步骤中得到的类中，依次扫描包含指定注解的方法
想着写着工具类的形式，代码结构如下：
public class AnnotationScannerUtils {
private static final Logger logger = LoggerFactory.getLogger(AnnotationScannerUtils.class);
private static final String EXT = "class
/**
* 根据包名获取包的URL
* @param pkgName com.demo.controller
* @return
*/
public static String getPkgPath(String pkgName){
String pkgDirName = pkgName.replace('.', File.separatorChar);
URL url = Thread.currentThread().getContextClassLoader().getResource(pkgDirName);
return url == null ? null : url.getFile();
}
/**
* 获取指定包下所有类对象的集合
* @param pkgName 包名(com.demo.controller)
* @param pkgPath 包路径(/Users/xxx/workspace/java/project/out/production/classes/com/demo/controller)
* @param recursive 是否递归遍历子目录
* @return 类集合
*/
public static Set> scanClasses(String pkgName, String pkgPath, final boolean recursive){
Set> classesSet = new HashSet<>();
Collection allClassFile = getAllClassFile(pkgPath, recursive);
for (File curFile : allClassFile){
try {
classesSet.add(getClassObj(curFile, pkgPath, pkgName));
} catch (ClassNotFoundException e) {
logger.error("load class fail", e);
}
}
return classesSet;
}
/**
* 获取指定包下包含指定注解的所有类对象的集合
* @param pkgName 包名(com.demo.controller)
* @param pkgPath 包路径(/Users/xxx/workspace/java/project/out/production/classes/com/demo/controller)
* @param recursive 是否递归遍历子目录
* @param targetAnnotations 指定注解
* @return 以注解和对应类集合构成的键值对
*/
public static Map, Set>> scanClassesByAnnotations(
String pkgName, String pkgPath, final boolean recursive, List> targetAnnotations){
Map, Set>> resultMap = new HashMap<>(16);
Collection allClassFile = getAllClassFile(pkgPath, recursive);
for (File curFile : allClassFile){
try {
Class curClass = getClassObj(curFile, pkgPath, pkgName);
for (Class annotation : targetAnnotations){
if (curClass.isAnnotationPresent(annotation)){
if (!resultMap.containsKey(annotation)){
resultMap.put(annotation, new HashSet>());
}
resultMap.get(annotation).add(curClass);
}
}
} catch (ClassNotFoundException e) {
logger.error("load class fail", e);
}
}
return resultMap;
}
/**
* 加载类
* @param file
* @param pkgPath
* @param pkgName
* @return
* @throws ClassNotFoundException
*/
private static Class getClassObj(File file, String pkgPath, String pkgName) throws ClassNotFoundException{
// 考虑class文件在子目录中的情况
String absPath = file.getAbsolutePath().substring(0, file.getAbsolutePath().length() - EXT.length() - 1);
String className = absPath.substring(pkgPath.length()).replace(File.separatorChar, '.');
className = className.startsWith(".") ? pkgName + className : pkgName + "." + className;
return Thread.currentThread().getContextClassLoader().loadClass(className);
}
/**
* 遍历指定目录下所有扩展名为class的文件
* @param pkgPath 包目录
* @param recursive 是否递归遍历子目录
* @return
*/
private static Collection getAllClassFile(String pkgPath, boolean recursive){
File fPkgDir = new File(pkgPath);
if (!(fPkgDir.exists() && fPkgDir.isDirectory())){
logger.error("the directory to package is empty: {}", pkgPath);
return null;
}
return FileUtils.listFiles(fPkgDir, new String[]{EXT}, recursive);
}
/**
* 查找指定注解的Method
* @param classes 查找范围
* @param targetAnnotations 指定的注解
* @return 以注解和对应Method类集合构成的键值对
*/
public static Map, Set> scanMethodsByAnnotations(Set> classes,
List> targetAnnotations){
Map, Set> resultMap = new HashMap<>(16);
for (Class cls : classes){
Method[] methods = cls.getMethods();
for (Class annotation : targetAnnotations){
for (Method method : methods){
if (method.isAnnotationPresent(annotation)){
if (!resultMap.containsKey(annotation)){
resultMap.put(annotation, new HashSet());
}
resultMap.get(annotation).add(method);
}
}
}
}
return resultMap;
}
}
复制代码 具体使用时，可根据具体情况在原方法上二次开发。如果是直接调用，可以实现扫描包含指定注解的类和方法：
public static void main(String[] args) {
String pkgName = "com.demo.controller";
String pkgPath = getPkgPath(pkgName);
logger.info("pkgPath is {}", pkgName);
// 查找包含RestController和Controller注解的类
Map, Set>> classesMap = scanClassesByAnnotations(pkgName, pkgPath, true,
Arrays.asList(RestController.class, Controller.class));
if (classesMap.size() == 0){
logger.error("Not exists any class in {} with the specified annotation", pkgPath);
return;
}
Set> classSet = new HashSet<>();
classesMap.forEach((k, v) -> {
logger.info("get {} classes with {}", v.size(), k.getSimpleName());
classSet.addAll(v);
});
// 查找包含GetMapping和PostMapping注解的Method
Map, Set> methodMap = scanMethodsByAnnotations(classSet, Arrays.asList(GetMapping.class, PostMapping.class));
if (methodMap.size() == 0){
logger.error("Not exists any method with the specified annotation");
return;
}
methodMap.forEach((k, v) -> {
StringBuilder sb = new StringBuilder();
v.forEach(method -> sb.append(method.getName()+", "));
logger.info(k.getSimpleName() + ": " + sb.toString());
});
}
--------------------------output-------------------------
01-20 15:06:02.293 [ INFO] [ m.i.u.AnnotationScannerUtils: 29] - pkgPath is com.demo.controller
01-20 15:06:02.363 [ INFO] [ m.i.u.AnnotationScannerUtils: 41] - get 5 classes with RestController
01-20 15:06:02.374 [ INFO] [ m.i.u.AnnotationScannerUtils: 41] - get 2 classes with Controller
01-20 15:06:02.388 [ INFO] [ m.i.u.AnnotationScannerUtils: 55] - PostMapping: login, addFavorite, addUser, logout,
01-20 15:06:02.388 [ INFO] [ m.i.u.AnnotationScannerUtils: 55] - GetMapping: webSiteInfo, info, getCategories, favoritesList, getReportByCityId, queryUserById, getReportByCityName, queryBookById,
复制代码