如何反思性地获取项目中的所有包？我从 Package.getPackages() 开始，但这只获得了与当前包关联的所有包。有没有办法做到这一点？
【问题讨论】：
标签： java unit-testing reflection junit
@PhilippWendler 的评论让我找到了一种完成我需要的方法。我稍微调整了该方法以使其具有递归性。
/**
* Recursively fetches a list of all the classes in a given
* directory (and sub-directories) that have the @UnitTestable
* annotation.
* @param packageName The top level package to search.
* @param loader The class loader to use. May be null; we'll
* just grab the current threads.
* @return The list of all @UnitTestable classes.
*/
public List<Class<?>> getTestableClasses(String packageName, ClassLoader loader) {
// State what package we are exploring
System.out.println("Exploring package: " + packageName);
// Create the list that will hold the testable classes
List<Class<?>> ret = new ArrayList<Class<?>>();
// Create the list of immediately accessible directories
List<File> directories = new ArrayList<File>();
// If we don't have a class loader, get one.
if (loader == null)
loader = Thread.currentThread().getContextClassLoader();
// Convert the package path to file path
String path = packageName.replace('.', '/');
// Try to get all of nested directories.
try {
// Get all of the resources for the given path
Enumeration<URL> res = loader.getResources(path);
// While we have directories to look at, recursively
// get all their classes.
while (res.hasMoreElements()) {
// Get the file path the the directory
String dirPath = URLDecoder.decode(res.nextElement()
.getPath(), "UTF-8");
// Make a file handler for easy managing
File dir = new File(dirPath);
// Check every file in the directory, if it's a
// directory, recursively add its viable files
for (File file : dir.listFiles()) {
if (file.isDirectory())
ret.addAll(getTestableClasses(packageName + '.' + file.getName(), loader));
}
}
} catch (IOException e) {
// We failed to get any nested directories. State
// so and continue; this directory may still have
// some UnitTestable classes.
System.out.println("Failed to load resources for [" + packageName + ']');
}
// We need access to our directory, so we can pull
// all the classes.
URL tmp = loader.getResource(path);
System.out.println(tmp);
if (tmp == null)
return ret;
File currDir = new File(tmp.getPath());
// Now we iterate through all of the classes we find
for (String classFile : currDir.list()) {
// Ensure that we only find class files; can't load gif's!
if (classFile.endsWith(".class")) {
// Attempt to load the class or state the issue
try {
// Try loading the class
Class<?> add = Class.forName(packageName + '.' +
classFile.substring(0, classFile.length() - 6));
// If the class has the correct annotation, add it
if (add.isAnnotationPresent(UnitTestable.class))
ret.add(add);
else
System.out.println(add.getName() + " is not a UnitTestable class");
} catch (NoClassDefFoundError e) {
// The class loader could not load the class
System.out.println("We have found class [" + classFile + "], and couldn't load it.");
} catch (ClassNotFoundException e) {
// We couldn't even find the damn class
System.out.println("We could not find class [" + classFile + ']');
}
}
}
return ret;
}
【讨论】：
这种方法只打印所有包（至少必须先给出根“packageName”）。
它是从上面派生的。
package devTools;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
public class DevToolUtil {
/**
* Method prints all packages (at least a root "packageName" has to be given first).
*
* @see http://stackoverflow.com/questions/9316726/reflectively-get-all-packages-in-a-project
* @since 2016-12-05
* @param packageName
* @param loader
* @return List of classes.
*/
public List<Class<?>> getTestableClasses(final String packageName, ClassLoader loader) {
System.out.println("Exploring package: " + packageName);
final List<Class<?>> ret = new ArrayList<Class<?>>();
if (loader == null) {
loader = Thread.currentThread().getContextClassLoader();
}
final String path = packageName.replace('.', '/');
try {
final Enumeration<URL> res = loader.getResources(path);
while (res.hasMoreElements()) {
final String dirPath = URLDecoder.decode(res.nextElement().getPath(), "UTF-8");
final File dir = new File(dirPath);
if (dir.listFiles() != null) {
for (final File file : dir.listFiles()) {
if (file.isDirectory()) {
final String packageNameAndFile = packageName + '.' + file.getName();
ret.addAll(getTestableClasses(packageNameAndFile, loader));
}
}
}
}
} catch (final IOException e) {
System.out.println("Failed to load resources for [" + packageName + ']');
}
return ret;
}
public static void main(final String[] args) {
new DevToolUtil().getTestableClasses("at", null);
}
}
【讨论】：
可能是题外话（因为它不完全是在java“反射”方面）...... 但是，以下解决方案如何：
Java 包可以被视为文件夹（或 Linux\UNIX 上的目录）。 假设您有一个根包并且它的绝对路径已知，您可以使用以下批处理作为基础递归打印所有具有 *.java 或 *.class 文件的子文件夹：
@echo off
rem List all the subfolders under current dir
FOR /R "." %%G in (.) DO (
Pushd %%G
Echo now in %%G
Popd )
Echo "back home"
您可以将此批处理包装在 java 中，或者如果您在 Linux\Unix 上运行，则在一些 shell 脚本中重写它。
祝你好运！
Aviad。
【讨论】：
这是可能的，但既棘手又昂贵，因为您需要自己走类路径。下面是 TestNG 是怎么做的，你可以自己提取重要的部分：
https://github.com/cbeust/testng/blob/master/src/main/java/org/testng/internal/PackageUtils.java
【讨论】：