使用Java原生代码实现包扫描

快来打我* 2023-02-25 07:08 14阅读 0赞

package org.example;
    
    import java.io.File;
    import java.io.FileFilter;
    import java.io.IOException;
    import java.net.JarURLConnection;
    import java.net.URL;
    import java.net.URLDecoder;
    import java.util.Enumeration;
    import java.util.LinkedHashSet;
    import java.util.Set;
    import java.util.function.Predicate;
    import java.util.jar.JarEntry;
    import java.util.jar.JarFile;
    
    /** * class 扫描器 * * @author zhangyunan */
    public class ClassScanner { 
    
      private final String basePackage;
      private final boolean recursive;
      private final Predicate<String> packagePredicate;
      private final Predicate<Class> classPredicate;
    
    
      /** * Instantiates a new Class scanner. * * @param basePackage the base package * @param recursive 是否递归扫描 * @param packagePredicate the package predicate * @param classPredicate the class predicate */
      public ClassScanner(String basePackage, boolean recursive, Predicate<String> packagePredicate,
        Predicate<Class> classPredicate) { 
        this.basePackage = basePackage;
        this.recursive = recursive;
        this.packagePredicate = packagePredicate;
        this.classPredicate = classPredicate;
      }
    
      /** * Do scan all classes set. * * @return the set * @throws IOException the io exception * @throws ClassNotFoundException the class not found exception */
      public Set<Class<?>> doScanAllClasses() throws IOException, ClassNotFoundException { 
    
        Set<Class<?>> classes = new LinkedHashSet<Class<?>>();
    
        String packageName = basePackage;
    
        // 如果最后一个字符是“.”，则去掉
        if (packageName.endsWith(".")) { 
          packageName = packageName.substring(0, packageName.lastIndexOf('.'));
        }
    
        // 将包名中的“.”换成系统文件夹的“/”
        String basePackageFilePath = packageName.replace('.', '/');
    
        Enumeration<URL> resources = Thread.currentThread().getContextClassLoader().getResources(basePackageFilePath);
        while (resources.hasMoreElements()) { 
          URL resource = resources.nextElement();
          String protocol = resource.getProtocol();
          if ("file".equals(protocol)) { 
            String filePath = URLDecoder.decode(resource.getFile(), "UTF-8");
            // 扫描文件夹中的包和类
            doScanPackageClassesByFile(classes, packageName, filePath);
          } else if ("jar".equals(protocol)) { 
            doScanPackageClassesByJar(packageName, resource, classes);
          }
        }
    
        return classes;
      }
    
      private void doScanPackageClassesByJar(String basePackage, URL url, Set<Class<?>> classes)
        throws IOException, ClassNotFoundException { 
        // 包名
        String packageName = basePackage;
        // 获取文件路径
        String basePackageFilePath = packageName.replace('.', '/');
        // 转为jar包
        JarFile jar = ((JarURLConnection) url.openConnection()).getJarFile();
        // 遍历jar包中的元素
        Enumeration<JarEntry> entries = jar.entries();
        while (entries.hasMoreElements()) { 
          JarEntry entry = entries.nextElement();
          String name = entry.getName();
          // 如果路径不一致，或者是目录，则继续
          if (!name.startsWith(basePackageFilePath) || entry.isDirectory()) { 
            continue;
          }
          // 判断是否递归搜索子包
          if (!recursive && name.lastIndexOf('/') != basePackageFilePath.length()) { 
            continue;
          }
    
          if (packagePredicate != null) { 
            String jarPackageName = name.substring(0, name.lastIndexOf('/')).replace("/", ".");
            if (!packagePredicate.test(jarPackageName)) { 
              continue;
            }
          }
    
          // 判定是否符合过滤条件
          String className = name.replace('/', '.');
          className = className.substring(0, className.length() - 6);
          // 用当前线程的类加载器加载类
          Class<?> loadClass = Thread.currentThread().getContextClassLoader().loadClass(className);
          if (classPredicate == null || classPredicate.test(loadClass)) { 
            classes.add(loadClass);
          }
    
        }
      }
    
      /** * 在文件夹中扫描包和类 */
      private void doScanPackageClassesByFile(Set<Class<?>> classes, String packageName, String packagePath)
        throws ClassNotFoundException { 
        // 转为文件
        File dir = new File(packagePath);
        if (!dir.exists() || !dir.isDirectory()) { 
          return;
        }
        // 列出文件，进行过滤
        // 自定义文件过滤规则
        File[] dirFiles = dir.listFiles((FileFilter) file -> { 
          String filename = file.getName();
    
          if (file.isDirectory()) { 
            if (!recursive) { 
              return false;
            }
    
            if (packagePredicate != null) { 
              return packagePredicate.test(packageName + "." + filename);
            }
            return true;
          }
    
          return filename.endsWith(".class");
        });
    
        if (null == dirFiles) { 
          return;
        }
    
        for (File file : dirFiles) { 
          if (file.isDirectory()) { 
            // 如果是目录，则递归
            doScanPackageClassesByFile(classes, packageName + "." + file.getName(), file.getAbsolutePath());
          } else { 
            // 用当前类加载器加载 去除 fileName 的 .class 6 位
            String className = file.getName().substring(0, file.getName().length() - 6);
            Class<?> loadClass = Thread.currentThread().getContextClassLoader().loadClass(packageName + '.' + className);
            if (classPredicate == null || classPredicate.test(loadClass)) { 
              classes.add(loadClass);
            }
          }
        }
      }
    }