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);
}
}