项目中需要用到包扫描的情况是很多的，一般是在项目初始化的时候，根据一些条件来对某个package下的类进行特殊处理。现在想实现的功能是，在一个filter或interceptor初始化的时候，扫描指定的一些package路径，遍历下面的每个class，找出method上使用了一个特殊注解的所有方法，然后缓存起来，当方法拦截器工作的时候，就不用再挨个判断方法是否需要拦截了
网上有很多自己编码实现scan package功能的例子，但是如果有工具已经帮你实现了，并且经受了普遍的验证，那么，自己造*的必要性就不大了
spring框架中有扫描包的类ClassPathBeanDefinitionScanner 里面的findCandidateComponents方法是我们进行改造的依据
/**
* Scan the class path for candidate components.
* @param basePackage the package to check for annotated classes
* @return a corresponding Set of autodetected bean definitions
*/
public Set<BeanDefinition> findCandidateComponents(String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<BeanDefinition>();
try {
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + "/" + this.resourcePattern;
Resource[] resources = this.resourcePatternResolver.getResources(packageSearchPath);
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
for (Resource resource : resources) {
if (traceEnabled) {
logger.trace("Scanning " + resource);
}
if (resource.isReadable()) {
try {
MetadataReader metadataReader = this.metadataReaderFactory.getMetadataReader(resource);
if (isCandidateComponent(metadataReader)) {
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setResource(resource);
sbd.setSource(resource);
if (isCandidateComponent(sbd)) {
if (debugEnabled) {
logger.debug("Identified candidate component class: " + resource);
}
candidates.add(sbd);
}
else {
if (debugEnabled) {
logger.debug("Ignored because not a concrete top-level class: " + resource);
}
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not matching any filter: " + resource);
}
}
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to read candidate component class: " + resource, ex);
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not readable: " + resource);
}
}
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
改造如下：
方法loadCheckClassMethods的入参是逗号分隔的包路径，如com.xx
利用Spring的
ResourcePatternResolver来寻找包下面的资源Resource，因为我们的扫描pattern是.class文件，所以这里的Resource就是class文件
protected static final String DEFAULT_RESOURCE_PATTERN = "**/*.class";
/**
* 根据扫描包的配置
* 加载需要检查的方法
*/
private void loadCheckClassMethods(String scanPackages) {
String[] scanPackageArr = scanPackages.split(",");
ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory(resourcePatternResolver);
for (String basePackage : scanPackageArr) {
if (StringUtils.isBlank(basePackage)) {
continue;
}
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
ClassUtils.convertClassNameToResourcePath(SystemPropertyUtils.resolvePlaceholders(basePackage)) + "/" + DEFAULT_RESOURCE_PATTERN;
try {
Resource[] resources = resourcePatternResolver.getResources(packageSearchPath);
for (Resource resource : resources) {
//检查resource，这里的resource都是class
loadClassMethod(metadataReaderFactory, resource);
}
} catch (Exception e) {
log.error("初始化SensitiveWordInterceptor失败", e);
} }
}
/**
* 加载资源，判断里面的方法
*
* @param metadataReaderFactory spring中用来读取resource为class的工具
* @param resource 这里的资源就是一个Class
* @throws IOException
*/
private void loadClassMethod(MetadataReaderFactory metadataReaderFactory, Resource resource) throws IOException {
try {
if (resource.isReadable()) {
MetadataReader metadataReader = metadataReaderFactory.getMetadataReader(resource);
if (metadataReader != null) {
String className = metadataReader.getClassMetadata().getClassName();
try {
tryCacheMethod(className);
} catch (ClassNotFoundException e) {
log.error("检查" + className + "是否含有需要信息失败", e);
}
}
}
} catch (Exception e) {
log.error("判断类中的方法实现需要检测xxx失败", e);
}
}
/**
* 把action下面的所有method遍历一次，标记他们是否需要进行xxx验证
* 如果需要，放入cache中
*
* @param fullClassName
*/
private void tryCacheMethod(String fullClassName) throws ClassNotFoundException {
Class<?> clz = Class.forName(fullClassName);
Method[] methods = clz.getDeclaredMethods();
for (Method method : methods) {
if (method.getModifiers() != Modifier.PUBLIC) {
continue;
}
if (CheckXXX.class.isAssignableFrom(CHECK_ANNOTATION)) {
CheckXXX checkXXX = (CheckXXX) method.getAnnotation(CHECK_ANNOTATION);
if (checkXXX != null && checkXXX.check()) {
cache.put(fullClassName + "." + method.getName(), checkXXX);
log.info("检测到需要检查xxx的方法:" + fullClassName + "." + method.getName());
}
}
}
}
tryCacheMethod做的事就是缓存需要处理的public方法
经测试，这种方式可以取到web的class文件和jar包中的class文件
加强版，package父子集合判断
package utils;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.util.SystemPropertyUtils; import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set; /**
* Created by cdliujian1 on 2016/1/13.
* 包工具，根据package路径，加载class
*/
public class PackageUtil { private final static Log log = LogFactory.getLog(PackageUtil.class);
//扫描 scanPackages 下的文件的匹配符
protected static final String DEFAULT_RESOURCE_PATTERN = "**/*.class"; /**
* 结合spring的类扫描方式
* 根据需要扫描的包路径及相应的注解，获取最终测method集合
* 仅返回public方法，如果方法是非public类型的，不会被返回
* 可以扫描工程下的class文件及jar中的class文件
*
* @param scanPackages
* @param annotation
* @return
*/
public static Set<Method> findClassAnnotationMethods(String scanPackages, Class<? extends Annotation> annotation) {
//获取所有的类
Set<String> clazzSet = findPackageClass(scanPackages);
Set<Method> methods = new HashSet<Method>();
//遍历类，查询相应的annotation方法
for (String clazz : clazzSet) {
try {
Set<Method> ms = findAnnotationMethods(clazz, annotation);
if (ms != null) {
methods.addAll(ms);
}
} catch (ClassNotFoundException ignore) {
}
}
return methods;
} /**
* 根据扫描包的,查询下面的所有类
*
* @param scanPackages 扫描的package路径
* @return
*/
public static Set<String> findPackageClass(String scanPackages) {
if (StringUtils.isBlank(scanPackages)) {
return Collections.EMPTY_SET;
}
//验证及排重包路径,避免父子路径多次扫描
Set<String> packages = checkPackage(scanPackages);
ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory(resourcePatternResolver);
Set<String> clazzSet = new HashSet<String>();
for (String basePackage : packages) {
if (StringUtils.isBlank(basePackage)) {
continue;
}
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
org.springframework.util.ClassUtils.convertClassNameToResourcePath(SystemPropertyUtils.resolvePlaceholders(basePackage)) + "/" + DEFAULT_RESOURCE_PATTERN;
try {
Resource[] resources = resourcePatternResolver.getResources(packageSearchPath);
for (Resource resource : resources) {
//检查resource，这里的resource都是class
String clazz = loadClassName(metadataReaderFactory, resource);
clazzSet.add(clazz);
}
} catch (Exception e) {
log.error("获取包下面的类信息失败,package:" + basePackage, e);
} }
return clazzSet;
} /**
* 排重、检测package父子关系，避免多次扫描
*
* @param scanPackages
* @return 返回检查后有效的路径集合
*/
private static Set<String> checkPackage(String scanPackages) {
if (StringUtils.isBlank(scanPackages)) {
return Collections.EMPTY_SET;
}
Set<String> packages = new HashSet<String>();
//排重路径
Collections.addAll(packages, scanPackages.split(","));
for (String pInArr : packages.toArray(new String[packages.size()])) {
if (StringUtils.isBlank(pInArr) || pInArr.equals(".") || pInArr.startsWith(".")) {
continue;
}
if (pInArr.endsWith(".")) {
pInArr = pInArr.substring(0, pInArr.length() - 1);
}
Iterator<String> packageIte = packages.iterator();
boolean needAdd = true;
while (packageIte.hasNext()) {
String pack = packageIte.next();
if (pInArr.startsWith(pack + ".")) {
//如果待加入的路径是已经加入的pack的子集，不加入
needAdd = false;
} else if (pack.startsWith(pInArr + ".")) {
//如果待加入的路径是已经加入的pack的父集，删除已加入的pack
packageIte.remove();
}
}
if (needAdd) {
packages.add(pInArr);
}
}
return packages;
} /**
* 加载资源，根据resource获取className
*
* @param metadataReaderFactory spring中用来读取resource为class的工具
* @param resource 这里的资源就是一个Class
* @throws IOException
*/
private static String loadClassName(MetadataReaderFactory metadataReaderFactory, Resource resource) throws IOException {
try {
if (resource.isReadable()) {
MetadataReader metadataReader = metadataReaderFactory.getMetadataReader(resource);
if (metadataReader != null) {
return metadataReader.getClassMetadata().getClassName();
}
}
} catch (Exception e) {
log.error("根据resource获取类名称失败", e);
}
return null;
} /**
* 把action下面的所有method遍历一次，标记他们是否需要进行敏感词验证
* 如果需要，放入cache中
*
* @param fullClassName
*/
public static Set<Method> findAnnotationMethods(String fullClassName, Class<? extends Annotation> anno) throws ClassNotFoundException {
Set<Method> methodSet = new HashSet<Method>();
Class<?> clz = Class.forName(fullClassName);
Method[] methods = clz.getDeclaredMethods();
for (Method method : methods) {
if (method.getModifiers() != Modifier.PUBLIC) {
continue;
}
Annotation annotation = method.getAnnotation(anno);
if (annotation != null) {
methodSet.add(method);
}
}
return methodSet;
} public static void main(String[] args) {
String packages = "com.a,com.ab,com.c,com.as.t,com.as,com.as.ta,com.at.ja,com.at.jc,com.at.";
System.out.println("检测前的package: " + packages);
System.out.println("检测后的package: " + StringUtils.join(checkPackage(packages), ","));
} }