java:基于guava ClassPath工具实现基于包名(package)的类扫描-优快云博客

本文链接：https://blog.youkuaiyun.com/10km/article/details/138128192

google的guava库提供了一个类路径扫描的实用工具ClassPath(参见说明： https://github.com/google/guava/wiki/ReflectionExplained#classpath)工具，适用于非android的Java平台搜索类。基于它可以设计一个过滤包名的搜索工具。

导入依赖库

<dependency>
	<groupId>com.google.guava</groupId>
	<artifactId>guava</artifactId>
	<version>20.0</version>
</dependency>

实现代码：GuavaPackageScanner.java

import java.io.IOException;
import java.util.LinkedHashSet;

import com.google.common.base.Function;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.FluentIterable;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Sets;
import com.google.common.reflect.ClassPath;
import com.google.common.reflect.ClassPath.ClassInfo;

public class GuavaPackageScanner  {
	private final ClassPath classpath ;
	private final ClassLoader classLoader;
	private volatile ImmutableSet<Class<?>> classes;
	public GuavaPackageScanner() {
		try {
			this.classLoader = Thread.currentThread().getContextClassLoader();
			classpath = ClassPath.from(classLoader);
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}
	
	private ImmutableSet<Class<?>> getClasses() {
		if(null == classes) {
			synchronized (this) {
				if(null == classes) {
					classes = FluentIterable.from(classpath.getResources())
							.filter(ClassInfo.class)
							.transform(new ClassInfoClassBuilder())
							.filter(Predicates.notNull())
							.toSet();
					System.out.printf("%d classes loaded\n",classes.size());
				}
			}
		}
		return classes;
	}

	public LinkedHashSet<Class<?>> getClasses(final String packagename) throws IOException {
		return Sets.newLinkedHashSet(
		Iterables.filter(getClasses(), new PackageFilter(packagename)));
	}
	private class ClassInfoClassBuilder implements Function<ClassInfo,Class<?>>{

		@Override
		public Class<?> apply(ClassInfo input) {
			try {
				return Class.forName(input.getName(), false, classLoader);
			} catch (Throwable e) {
				
			}
			return null;
		}};
	private static class PackageFilter implements Predicate<Class<?>>{

		private String packagename;

		public PackageFilter(String packagename) {
			this.packagename = packagename;
		}

		@Override
		public boolean apply(Class<?> input) {
			return input.getPackage().getName().startsWith(packagename);
		}
	}
}

调用示例：
PackageScannerTest.java


import static org.junit.Assert.*;

import java.util.LinkedHashSet;

import org.junit.FixMethodOrder;
import org.junit.Test;
import org.junit.runners.MethodSorters;

@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class PackageScannerTest {
	public static final GuavaPackageScanner GUAVA_PACKAGE_SCANNER = new GuavaPackageScanner();
	@Test
	public void test6GuavaGetClasses() {
		try {
			/** 搜索com.google.common.base包下的所有类输出类名 */ 
			LinkedHashSet<Class<?>> urls = GUAVA_PACKAGE_SCANNER.getClasses("com.google.common.base");
			for(Class<?> url:urls) {
				System.out.printf("class:%s\n",url);
			}
			System.out.printf("class count:%d\n",urls.size());
		} catch (Throwable e) {
			e.printStackTrace();
			fail();
		}
	}

}

输出：

3677 classes loaded
class:class com.google.common.base.Absent
class:class com.google.common.base.AbstractIterator $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . A b s t r a c t I t er a t or$ State
class:class com.google.common.base.AbstractIterator
class:class com.google.common.base.Ascii
class:class com.google.common.base.CaseFormat$1
class:class com.google.common.base.CaseFormat$2
class:class com.google.common.base.CaseFormat$3
class:class com.google.common.base.CaseFormat$4
class:class com.google.common.base.CaseFormat $5 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C a se F or ma t$ StringConverter
class:class com.google.common.base.CaseFormat
class:class com.google.common.base.CharMatcher $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ And
class:class com.google.common.base.CharMatcher $A n yc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ AnyOf
class:class com.google.common.base.CharMatcher $A sc ii c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ BitSetMatcher
class:class com.google.common.base.CharMatcher $B re akin g Whi t es p a cec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ Digit
class:class com.google.common.base.CharMatcher $F a s tM a t c h erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ ForPredicate
class:class com.google.common.base.CharMatcher $I n R an g ec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ Invisible
class:class com.google.common.base.CharMatcher $I sc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ IsEither
class:class com.google.common.base.CharMatcher $I s N o t c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ JavaDigit
class:class com.google.common.base.CharMatcher $J a v a I so C o n t ro l c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ JavaLetter
class:class com.google.common.base.CharMatcher $J a v a L e tt er O rD i g i t c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ JavaLowerCase
class:class com.google.common.base.CharMatcher $J a v a U pp er C a sec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ NamedFastMatcher
class:class com.google.common.base.CharMatcher $N e g a t e d c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ NegatedFastMatcher
class:class com.google.common.base.CharMatcher $N o n ec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ Or
class:class com.google.common.base.CharMatcher $R an g es M a t c h erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C ha r M a t c h er$ SingleWidth
class:class com.google.common.base.CharMatcher$Whitespace
class:class com.google.common.base.CharMatcher
class:class com.google.common.base.Charsets
class:class com.google.common.base.CommonMatcher
class:class com.google.common.base.CommonPattern
class:class com.google.common.base.Converter$1$1
class:class com.google.common.base.Converter $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C o n v er t er$ ConverterComposition
class:class com.google.common.base.Converter $F u n c t i o n B a se d C o n v er t erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C o n v er t er$ IdentityConverter
class:class com.google.common.base.Converter $R e v erse C o n v er t erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . C o n v er t erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . De f a u lt sc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . E n u m s$ StringConverter
class:class com.google.common.base.Enums
class:class com.google.common.base.Equivalence $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . Eq u i v a l e n ce$ Equals
class:class com.google.common.base.Equivalence $Eq u i v a l e n tT o P re d i c a t ec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . Eq u i v a l e n ce$ Identity
class:class com.google.common.base.Equivalence $W r a pp erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . Eq u i v a l e n cec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . E x t r a O bj ec t s M e t h o d s F or W e b c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . F ina l i z ab l e P han t o m R e f ere n cec l a ss : in t er f a ceco m . g oo g l e . co mm o n . ba se . F ina l i z ab l e R e f ere n cec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . F ina l i z ab l e R e f ere n ce Q u e u e$ DecoupledLoader
class:class com.google.common.base.FinalizableReferenceQueue $D i rec t L o a d erc l a ss : in t er f a ceco m . g oo g l e . co mm o n . ba se . F ina l i z ab l e R e f ere n ce Q u e u e$ FinalizerLoader
class:class com.google.common.base.FinalizableReferenceQueue$SystemLoader
class:class com.google.common.base.FinalizableReferenceQueue
class:class com.google.common.base.FinalizableSoftReference
class:class com.google.common.base.FinalizableWeakReference
class:interface com.google.common.base.Function
class:class com.google.common.base.FunctionalEquivalence
class:class com.google.common.base.Functions $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . F u n c t i o n s$ ConstantFunction
class:class com.google.common.base.Functions $F or M a p Wi t h De f a u lt c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . F u n c t i o n s$ FunctionComposition
class:class com.google.common.base.Functions $F u n c t i o n F or M a pN oDe f a u lt c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . F u n c t i o n s$ IdentityFunction
class:class com.google.common.base.Functions $P re d i c a t e F u n c t i o n c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . F u n c t i o n s$ SupplierFunction
class:class com.google.common.base.Functions $T o St r in g F u n c t i o n c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . F u n c t i o n sc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . Jd k P a tt er n$ JdkMatcher
class:class com.google.common.base.JdkPattern
class:class com.google.common.base.Joiner$1
class:class com.google.common.base.Joiner$2
class:class com.google.common.base.Joiner $3 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . J o in er$ MapJoiner
class:class com.google.common.base.Joiner
class:class com.google.common.base.MoreObjects $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . M ore O bj ec t s$ ToStringHelper $Va l u eHo l d erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . M ore O bj ec t s$ ToStringHelper
class:class com.google.common.base.MoreObjects
class:class com.google.common.base.Objects $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . O bj ec t s$ ToStringHelper $Va l u eHo l d erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . O bj ec t s$ ToStringHelper
class:class com.google.common.base.Objects
class:class com.google.common.base.Optional$1$1
class:class com.google.common.base.Optional$1
class:class com.google.common.base.Optional
class:class com.google.common.base.PairwiseEquivalence
class:interface com.google.common.base.PatternCompiler
class:class com.google.common.base.Platform $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . Pl a t f or m$ JdkPatternCompiler
class:class com.google.common.base.Platform
class:class com.google.common.base.Preconditions
class:interface com.google.common.base.Predicate
class:class com.google.common.base.Predicates $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ AndPredicate
class:class com.google.common.base.Predicates $C o m p os i t i o n P re d i c a t ec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ ContainsPatternFromStringPredicate
class:class com.google.common.base.Predicates $C o n t ain s P a tt er n P re d i c a t ec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ InPredicate
class:class com.google.common.base.Predicates $I n s t an ce O f P re d i c a t ec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ IsEqualToPredicate
class:class com.google.common.base.Predicates $N o tP re d i c a t ec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ ObjectPredicate $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ ObjectPredicate $2 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ ObjectPredicate $3 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ ObjectPredicate $4 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ ObjectPredicate
class:class com.google.common.base.Predicates $O r P re d i c a t ec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . P re d i c a t es$ SubtypeOfPredicate
class:class com.google.common.base.Predicates
class:class com.google.common.base.Present
class:class com.google.common.base.SmallCharMatcher
class:class com.google.common.base.Splitter$1$1
class:class com.google.common.base.Splitter$1
class:class com.google.common.base.Splitter$2$1
class:class com.google.common.base.Splitter$2
class:class com.google.common.base.Splitter$3$1
class:class com.google.common.base.Splitter$3
class:class com.google.common.base.Splitter$4$1
class:class com.google.common.base.Splitter$4
class:class com.google.common.base.Splitter $5 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . Spl i tt er$ MapSplitter
class:class com.google.common.base.Splitter $Spl i tt in g I t er a t orc l a ss : in t er f a ceco m . g oo g l e . co mm o n . ba se . Spl i tt er$ Strategy
class:class com.google.common.base.Splitter
class:class com.google.common.base.StandardSystemProperty
class:class com.google.common.base.Stopwatch $1 c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . St o pw a t c h c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . St r in g sc l a ss : in t er f a ceco m . g oo g l e . co mm o n . ba se . S u ppl i erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . S u ppl i ers$ ExpiringMemoizingSupplier
class:class com.google.common.base.Suppliers $M e m o i z in g S u ppl i erc l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . S u ppl i ers$ SupplierComposition
class:interface com.google.common.base.Suppliers $S u ppl i er F u n c t i o n c l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . S u ppl i ers$ SupplierFunctionImpl
class:class com.google.common.base.Suppliers $S u ppl i er O f I n s t an cec l a ss : c l a ssco m . g oo g l e . co mm o n . ba se . S u ppl i ers$ ThreadSafeSupplier
class:class com.google.common.base.Suppliers
class:class com.google.common.base.Throwables$1
class:class com.google.common.base.Throwables
class:class com.google.common.base.Ticker$1
class:class com.google.common.base.Ticker
class:class com.google.common.base.Utf8
class:class com.google.common.base.Verify
class:class com.google.common.base.VerifyException
class:class com.google.common.base.internal.Finalizer
class:interface com.google.common.base.package-info
class count:162