Java高性能反射工具包ReflectASM

本是古典何须时尚 2022-01-26 05:17 389阅读 0赞

[ReflectASM][] 使用字节码生成的方式实现了更为高效的反射机制。执行时会生成一个存取类来 set/get 字段，访问方法或创建实例。一看到 ASM 就能领悟到 ReflectASM 会用字节码生成的方式，而不是依赖于 Java 本身的反射机制来实现的，所以它更快，并且避免了访问原始类型因自动装箱而产生的问题。

# **更多关于反射到知识请访问 [www.itkc8.com][]** #

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.jts</groupId>
        <artifactId>t1</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <packaging>jar</packaging>
    
        <properties>
            <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.10</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>com.esotericsoftware</groupId>
                <artifactId>reflectasm</artifactId>
                <version>1.11.0</version>
            </dependency>
        </dependencies>
    </project>

待反射的类：

package com.jts.service;
    
    public class UserService {
        
        public int state;
        
        public void update(int id, String username) {
            
        }
    }

测试类：

package com.jts.test;
    
    import java.lang.reflect.Method;
    
    import org.junit.Test;
    
    import com.esotericsoftware.reflectasm.ConstructorAccess;
    import com.esotericsoftware.reflectasm.FieldAccess;
    import com.esotericsoftware.reflectasm.MethodAccess;
    import com.jts.service.UserService;
    
    public class AppTest {
        
        public static void main(String[] args) throws Exception{
            AppTest test = new AppTest();
            test.testJdkReflect();
            test.testReflectAsm4Name();
            test.testReflectAsm4Index();
        }
        
        /**
         * JDK反射调用方法
         * @throws Exception
         */
        @Test
        public void testJdkReflect() throws Exception {
            UserService target = new UserService();
            long start = System.currentTimeMillis();
            Method method = target.getClass().getMethod("update", int.class, String.class);
            for (int i = 0; i < 100000000; i++) {
                method.invoke(target, 1, "zhangsan");
            }
            long end = System.currentTimeMillis();
            System.out.println("timeout=" + (end - start));//809 753 880 875 816 
        }
    
        /**
         * ReflectAsm反射调用方法
         * 用名称定位反射方法
         */
        @Test
        public void testReflectAsm4Name() {
            UserService target = new UserService();
            MethodAccess access = MethodAccess.get(UserService.class);//生成字节码的方式创建UserServiceMethodAccess
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000000; i++) {
                access.invoke(target, "update", 1, "zhangsan");
            }
            long end = System.currentTimeMillis();
            System.out.println("timeout=" + (end - start));//523 382 415 489 482
        }
    
        /**
         * ReflectAsm反射调用方法
         * 用方法和字段的索引定位反射方法，性能高
         */
        @Test
        public void testReflectAsm4Index() {
            UserService target = new UserService();
            MethodAccess access = MethodAccess.get(UserService.class);
            int index = access.getIndex("update", int.class, String.class);
            long start = System.currentTimeMillis();
            for (int i = 0; i < 100000000; i++) {
                access.invoke(target, index, 1, "zhangsan");
            }
            long end = System.currentTimeMillis();
            System.out.println("timeout=" + (end - start));//12 15 23 14 24
        }
    
        /**
         * ReflectAsm反射来set/get字段值
         */
        @Test
        public void testFieldAccess() {
            UserService target = new UserService();
            FieldAccess fieldAccess = FieldAccess.get(target.getClass());
            fieldAccess.set(target, "state", 1);
            int state = (Integer)fieldAccess.get(target, "state");
            System.out.println(state);
            
        }
    
        /**
         * ReflectAsm反射来调用构造方法
         */
        @Test
        public void testConstructorAccess() {
            ConstructorAccess<UserService> constructorAccess = ConstructorAccess.get(UserService.class);
            UserService userService = constructorAccess.newInstance();
            System.out.println(userService);
        }
    
        /**
         * 查找方法的索引
         */
        @Test
        public void testIndex() {
            UserService target = new UserService();
            MethodAccess methodAccess = MethodAccess.get(target.getClass());
            int index = methodAccess.getIndex("update", int.class, String.class);
            System.out.println(index);
        }
    
    }

[ReflectASM]: http://code.google.com/p/reflectasm/
[www.itkc8.com]: http://www.itkc8.com