使用springboot的人基本都知道swagger，那么swagger是如何生成swagger-ui.html页面的呢？相信大家都能猜到，就是扫描程序中带有指定注解的类(带有@RestController和 @Controller)和方法(@RequestMapping等)，然后又根据方法上的@ApiOperation和@ApiImplicitParams去生成页面上要显示的一些元素。
实际项目中我们也会有类似需求，例如权限校验，我们需要先扫描程序中有哪些接口(就是找有哪些类有@RestController注解)，然后在根据自定义的一些注解，扫描是否这些controller的方法需要配置权限校验。那么如何来实现？
第一步，
根据basePackage，开始遍历所有的类，然后测试该类是否添加了@RestController注解。
需要注意的是，当我们的类是在jar文件中时，不需要递归，但是在普通的文件中(目录存放文件)需要递归循环。
private List<Class<?>> getClassesWithAnnotationFromPackage(String packageName, Class<? extends Annotation> annotation) {
List<Class<?>> classList = new ArrayList<Class<?>>();
String packageDirName = packageName.replace('.', '/');
Enumeration<URL> dirs = null;
try {
dirs = Thread.currentThread().getContextClassLoader().getResources(packageDirName);
}
catch (IOException e) {
log.error("Failed to get resource", e);
return null;
}
while (dirs.hasMoreElements()) {
URL url = dirs.nextElement();//file:/D:/E/workspaceGitub/springboot/JSONDemo/target/classes/com/yq/controller
String protocol = url.getProtocol();//file
//https://docs.oracle.com/javase/7/docs/api/java/net/URL.html
//http, https, ftp, file, and jar
//本文只需要处理file和jar
if ("file".equals(protocol) ) {
String filePath = null;
try {
filePath = URLDecoder.decode(url.getFile(), "UTF-8");///D:/E/workspaceGitub/springboot/JSONDemo/target/classes/com/yq/controller
}
catch (UnsupportedEncodingException e) {
log.error("Failed to decode class file", e);
}
filePath = filePath.substring(1);
getClassesWithAnnotationFromFilePath(packageName, filePath, classList, annotation);
} else if ("jar".equals(protocol)) {
JarFile jar = null;
try {
jar = ((JarURLConnection) url.openConnection()).getJarFile();
//扫描jar包文件 并添加到集合中
}
catch (Exception e) {
log.error("Failed to decode class jar", e);
}
List<Class<?>> alClassList = new ArrayList<Class<?>>();
findClassesByJar(packageName, jar, alClassList);
getClassesWithAnnotationFromAllClasses(alClassList, annotation, classList);
}
else {
log.warn("can't process the protocol={}", protocol);
}
}
return classList;
}
private static void findClassesByJar(String pkgName, JarFile jar, List<Class<?>> classes) {
String pkgDir = pkgName.replace(".", "/");
Enumeration<JarEntry> entry = jar.entries();
while (entry.hasMoreElements()) {
// 获取jar里的一个实体 可以是目录 和一些jar包里的其他文件 如META-INF等文
JarEntry jarEntry = entry.nextElement();
String name = jarEntry.getName();
// 如果是以/开头的
if (name.charAt(0) == '/') {
// 获取后面的字符串
name = name.substring(1);
}
if (jarEntry.isDirectory() || !name.startsWith(pkgDir) || !name.endsWith(".class")) {
continue;
}
//如果是一个.class文件 而且不是目录
// 去掉后面的".class" 获取真正的类名
String className = name.substring(0, name.length() - 6);
Class<?> tempClass = loadClass(className.replace("/", "."));
// 添加到集合中去
if (tempClass != null) {
classes.add(tempClass);
}
}
}
/**
* 加载类
* @param fullClsName 类全名
* @return
*/
private static Class<?> loadClass(String fullClsName ) {
try {
return Thread.currentThread().getContextClassLoader().loadClass(fullClsName );
} catch (ClassNotFoundException e) {
log.error("PkgClsPath loadClass", e);
}
return null;
}
//filePath is like this 'D:/E/workspaceGitub/springboot/JSONDemo/target/classes/com/yq/controller'
private void getClassesWithAnnotationFromFilePath(String packageName, String filePath, List<Class<?>> classList,
Class<? extends Annotation> annotation) {
Path dir = Paths.get(filePath);//D:\E\workspaceGitub\springboot\JSONDemo\target\classes\com\yq\controller
try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir)) {
for(Path path : stream) {
String fileName = String.valueOf(path.getFileName()); // for current dir , it is 'helloworld'
//如果path是目录的话， 此处需要递归，
boolean isDir = Files.isDirectory(path);
if(isDir) {
getClassesWithAnnotationFromFilePath(packageName + "." + fileName , path.toString(), classList, annotation);
}
else {
String className = fileName.substring(0, fileName.length() - 6);
Class<?> classes = null;
String fullClassPath = packageName + "." + className;
try {
log.info("fullClassPath={}", fullClassPath);
classes = Thread.currentThread().getContextClassLoader().loadClass(fullClassPath);
}
catch (ClassNotFoundException e) {
log.error("Failed to find class={}", fullClassPath, e);
}
if (null != classes && null != classes.getAnnotation(annotation)) {
classList.add(classes);
}
}
}
}
catch (IOException e) {
log.error("Failed to read class file", e);
}
}
private void getClassesWithAnnotationFromAllClasses(List<Class<?>> inClassList,
Class<? extends Annotation> annotation, List<Class<?>> outClassList) {
for(Class<?> myClasss : inClassList) {
if (null != myClasss && null != myClasss.getAnnotation(annotation)) {
outClassList.add(myClasss);
}
}
}
第二步
根据第一步提供的controller，遍历该类的所有方法，检查该方法是否添加MyChecker注解(MyChecker为自定义的注解)
private void geMethodWithAnnotationFromFilePath(String fullClassPath, Map<String, String> checkIdMethodMap,
Class<? extends Annotation> methodAnnotation) {
Class<?> classes = null;
try {
log.info("fullClassPath={}", fullClassPath);
classes = Thread.currentThread().getContextClassLoader().loadClass(fullClassPath);
Method[] methods = classes.getDeclaredMethods();
for (Method method : methods) {
MyChecker myAnnotation = method.getAnnotation(MyChecker.class);
if (null != myAnnotation) {
checkIdMethodMap.put (myAnnotation.id(), method.getName() );
}
}
}
catch (ClassNotFoundException e) {
log.error("Failed to find class={}", fullClassPath, e);
}
}
原文链接：https://blog.csdn.net/russle/article/details/85042351