java架构师 | SpringAOP那些无处不在的动态代理-百知教育IT培训学校

环境配置

代码结构

pom.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<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.gupaoedu</groupId>
	<artifactId>gupaoedu-springaop</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>gupaoedu-springaop</name>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<version>1.16.10</version>
		</dependency>

		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>1.7.25</version>
		</dependency>

		<dependency>
			<groupId>ch.qos.logback</groupId>
			<artifactId>logback-classic</artifactId>
			<version>1.2.3</version>
		</dependency>

	</dependencies>

</project>

application.properties文件

#多切面配置可以在key前面加前缀
#例如 aspect.logAspect.
#切面表达式,expression#
pointCut=public .* com.gupaoedu.springaop.demo.service..*Service..*(.*)
#切面类#
aspectClass=com.gupaoedu.springaop.demo.aspect.LogAspect
#切面前置通知#
aspectBefore=before
#切面后置通知#
aspectAfter=after
#切面异常通知#
aspectAfterThrow=afterThrowing
#切面异常类型#
aspectAfterThrowingName=java.lang.Exception

业务代码

Member实体类

package com.gupaoedu.springaop.demo.model;

public class Member {

}

IMermverServer接口

package com.gupaoedu.springaop.demo.service;

import com.gupaoedu.springaop.demo.model.Member;

/**
 * 注解版业务操作类
 * @author Tom
 */

public interface IMemberService {
	
	public Member get(String id);

	public Member get();
	
	public void save(Member member);
	
	public Boolean delete(String id) throws Exception;
	
}

MemberService业务实现类

package com.gupaoedu.springaop.demo.service.impl;

import com.gupaoedu.springaop.demo.model.Member;
import com.gupaoedu.springaop.demo.service.IMemberService;
import lombok.extern.slf4j.Slf4j;

/**
 * 注解版业务操作类
 * @author Tom
 */
@Slf4j
public class MemberService implements IMemberService{
	
	public Member get(String id){
		log.info("getMemberById method . . .");
		return new Member();
	}
	
	public Member get(){
		log.info("getMember method . . .");
		return new Member();
	}
	
	public void save(Member member){
		log.info("save member method . . .");
	}
	
	public Boolean delete(String id) throws Exception{
		log.info("delete method . . .");
		throw new Exception("spring aop ThrowAdvice演示");
	}
}

LogAspect切面增强类

package com.gupaoedu.springaop.demo.aspect;

import lombok.extern.slf4j.Slf4j;

/**
 * Created by Tom.
 */
@Slf4j
public class LogAspect {

    //在调用一个方法之前，执行before方法
    public void before(){
        //这个方法中的逻辑，是由我们自己写的
        log.info("Invoker Before Method!!!");
    }
    //在调用一个方法之后，执行after方法
    public void after(){
        log.info("Invoker After Method!!!");
    }

    public void afterThrowing(){
        log.info("出现异常");
    }
}

仿写JDK动态代理

GPInvocationHandler JDK动态代理接口

package com.gupaoedu.springaop.framework.proxy;

import java.lang.reflect.Method;

/**
 * Created by Tom.
 */
public interface GPInvocationHandler {
    Object invoke(Object proxy, Method method, Object[] args) throws Throwable;
}

GPClassLoader自定义类加载器

package com.gupaoedu.springaop.framework.proxy;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;

/**
 * Created by Tom.
 */
public class GPClassLoader extends ClassLoader {

    private File classPathFile;
    public GPClassLoader(){
        String classPath = GPClassLoader.class.getResource("").getPath();
        this.classPathFile = new File(classPath);
    }

    @Override
    protected Class<?> findClass(String name) throws ClassNotFoundException {

        String className = GPClassLoader.class.getPackage().getName() + "." + name;
        if(classPathFile  != null){
            File classFile = new File(classPathFile,name.replaceAll("\\.","/") + ".class");
            if(classFile.exists()){
                FileInputStream in = null;
                ByteArrayOutputStream out = null;
                try{
                    in = new FileInputStream(classFile);
                    out = new ByteArrayOutputStream();
                    byte [] buff = new byte[1024];
                    int len;
                    while ((len = in.read(buff)) != -1){
                        out.write(buff,0,len);
                    }
                    return defineClass(className,out.toByteArray(),0,out.size());
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
        }
        return null;
    }
}

GPProxy 动态生成代理类

package com.gupaoedu.springaop.framework.proxy;

import javax.tools.JavaCompiler;
import javax.tools.StandardJavaFileManager;
import javax.tools.ToolProvider;
import java.io.File;
import java.io.FileWriter;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

/**
 * 用来生成源代码的工具类
 * Created by Tom.
 */
public class GPProxy {

    public static final String ln = "\r\n";

    public static Object newProxyInstance(GPClassLoader classLoader, Class<?> [] interfaces, GPInvocationHandler h){
       try {
           //1、动态生成源代码.java文件
           String src = generateSrc(interfaces);

           //2、Java文件输出磁盘
           String filePath = GPProxy.class.getResource("").getPath();
//           System.out.println(filePath);
           File f = new File(filePath + "$Proxy0.java");
           FileWriter fw = new FileWriter(f);
           fw.write(src);
           fw.flush();
           fw.close();

           //3、把生成的.java文件编译成.class文件
           JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
           StandardJavaFileManager manage = compiler.getStandardFileManager(null,null,null);
           Iterable iterable = manage.getJavaFileObjects(f);

           JavaCompiler.CompilationTask task = compiler.getTask(null,manage,null,null,null,iterable);
           task.call();
           manage.close();

           //4、编译生成的.class文件加载到JVM中来
           Class proxyClass =  classLoader.findClass("$Proxy0");
           Constructor c = proxyClass.getConstructor(GPInvocationHandler.class);
           f.delete();

            //5、返回字节码重组以后的新的代理对象
            return c.newInstance(h);
       }catch (Exception e){
           e.printStackTrace();
       }
        return null;
    }

    private static String generateSrc(Class<?>[] interfaces){
            StringBuffer sb = new StringBuffer();
            sb.append("package com.gupaoedu.springaop.framework.proxy;" + ln);
            sb.append("import java.lang.reflect.*;" + ln);
            sb.append("public class $Proxy0 implements " + interfaces[0].getName() + "{" + ln);
                sb.append("GPInvocationHandler h;" + ln);
                sb.append("public $Proxy0(GPInvocationHandler h) { " + ln);
                    sb.append("this.h = h;");
                sb.append("}" + ln);
                for (Method m : interfaces[0].getMethods()){
                    Class<?>[] params = m.getParameterTypes();

                    StringBuffer paramNames = new StringBuffer();
                    StringBuffer paramValues = new StringBuffer();
                    StringBuffer paramTypes = new StringBuffer();

                    for (int i = 0; i < params.length; i++) {
                        Class clazz = params[i];
                        String type = clazz.getName();
                        String paramName = toLowerFirstCase(clazz.getSimpleName());
                        paramNames.append(type + " " +  paramName);
                        paramValues.append(paramName);
                        paramTypes.append(clazz.getName() + ".class");
                        if(i > 0 && i < params.length-1){
                            paramNames.append(",");
                            paramTypes.append(",");
                            paramValues.append(",");
                        }
                    }

                    sb.append("public " + m.getReturnType().getName() + " " + m.getName() + "(" + paramNames.toString() + ") {" + ln);
                        sb.append("try{" + ln);
                            sb.append("Method m = " + interfaces[0].getName() + ".class.getMethod(\"" + m.getName() + "\",new Class[]{" + paramTypes.toString() + "});" + ln);
                            sb.append((hasReturnValue(m.getReturnType()) ? "return (" + m.getReturnType().getName() + ")" : "") + getCaseCode("this.h.invoke(this,m,new Object[]{" + paramValues + "})",m.getReturnType()) + ";" + ln);
                        sb.append("}catch(Error _ex) { }");
                        sb.append("catch(Throwable e){" + ln);
                        sb.append("throw new UndeclaredThrowableException(e);" + ln);
                        sb.append("}");
                        sb.append(getReturnEmptyCode(m.getReturnType()));
                    sb.append("}");
                }
            sb.append("}" + ln);
            return sb.toString();
    }


    private static Map<Class,Class> mappings = new HashMap<Class, Class>();
    static {
        mappings.put(int.class,Integer.class);
    }

    private static String getReturnEmptyCode(Class<?> returnClass){
        if(mappings.containsKey(returnClass)){
            return "return 0;";
        }else if(returnClass == void.class){
            return "";
        }else {
            return "return null;";
        }
    }

    private static String getCaseCode(String code,Class<?> returnClass){
        if(mappings.containsKey(returnClass)){
            return "((" + mappings.get(returnClass).getName() +  ")" + code + ")." + returnClass.getSimpleName() + "Value()";
        }
        return code;
    }

    private static boolean hasReturnValue(Class<?> clazz){
        return clazz != void.class;
    }

    private static String toLowerFirstCase(String src){
        char [] chars = src.toCharArray();
        chars[0] += 32;
        return String.valueOf(chars);
    }

}

手写Spring AOP

GPAopConfig 保存配置信息

package com.gupaoedu.springaop.framework.config;

import lombok.Data;

/**
 * Created by Tom.
 */
@Data
public class GPAopConfig {

    private String pointCut;
    private String aspectBefore;
    private String aspectAfter;
    private String aspectClass;
    private String aspectAfterThrow;
    private String aspectAfterThrowingName;

}

GPAdvice通知接口

package com.gupaoedu.springaop.framework.aspect;

import java.lang.reflect.Method;

/**
 * 用于通知回调
 */
public class GPAdvice {
    private Object aspect;
    private Method adviceMethod;
    private String throwName;

    public GPAdvice(Object aspect, Method adviceMethod) {
        this.aspect = aspect;
        this.adviceMethod = adviceMethod;
    }

    public Object getAspect() {
        return aspect;
    }

    public Method getAdviceMethod() {
        return adviceMethod;
    }

    public void setThrowName(String throwName) {
        this.throwName = throwName;
    }

    public String getThrowName() {
        return throwName;
    }
}

GPJoinPoint切点

package com.gupaoedu.springaop.framework.aspect;

import java.lang.reflect.Method;


public interface GPJoinPoint {

    Object getThis();

    Object[] getArguments();

    Method getMethod();

    void setUserAttribute(String key, Object value);

    Object getUserAttribute(String key);
}

GPAdvisedSupport 解析切面配置

package com.gupaoedu.springaop.framework.aop;

import com.gupaoedu.springaop.framework.aspect.GPAdvice;
import com.gupaoedu.springaop.framework.config.GPAopConfig;
import com.gupaoedu.springaop.framework.proxy.GPClassLoader;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Created by Tom.
 */
public class GPAdvisedSupport {

    private GPClassLoader classLoader;

    private Class<?> targetClass;

    private Object target;

    private GPAopConfig config;

    private Pattern pointCutClassPattern;

    private transient Map<Method, Map<String,GPAdvice>> methodCache;

    public GPAdvisedSupport(GPAopConfig config) {
        this.config = config;
        this.classLoader = new GPClassLoader();
    }

    public Class<?> getTargetClass(){
        return this.targetClass;
    }

    public Object getTarget(){
        return this.target;
    }

    public Map<String,GPAdvice> getInterceptorsAndDynamicInterceptionAdvice(Method method, Class<?> targetClass) throws Exception{
        Map<String,GPAdvice> cached = methodCache.get(method);
        if(cached == null){
            Method m = targetClass.getMethod(method.getName(),method.getParameterTypes());

            cached = methodCache.get(m);

            //底层逻辑，对代理方法进行一个兼容处理
            this.methodCache.put(m,cached);
        }

        return cached;
    }

    public void setTargetClass(Class<?> targetClass) {
        this.targetClass = targetClass;
        parse();
    }

    private void parse() {
        String pointCut = config.getPointCut()
                .replaceAll("\\.","\\\\.")
                .replaceAll("\\\\.\\*",".*")
                .replaceAll("\\(","\\\\(")
                .replaceAll("\\)","\\\\)");
        //pointCut=public .* com.gupaoedu.vip.spring.demo.service..*Service..*(.*)
        //玩正则
        String pointCutForClassRegex = pointCut.substring(0,pointCut.lastIndexOf("\\(") - 4);
        pointCutClassPattern = Pattern.compile("class " + pointCutForClassRegex.substring(
                pointCutForClassRegex.lastIndexOf(" ") + 1));

        try {

            methodCache = new HashMap<Method, Map<String,GPAdvice>>();
            Pattern pattern = Pattern.compile(pointCut);


            Class aspectClass = Class.forName(this.config.getAspectClass());
            Map<String,Method> aspectMethods = new HashMap<String,Method>();
            for (Method m : aspectClass.getMethods()) {
                aspectMethods.put(m.getName(),m);
            }

            for (Method m : this.targetClass.getMethods()) {
                String methodString = m.toString();
                if (methodString.contains("throws")) {
                    methodString = methodString.substring(0, methodString.lastIndexOf("throws")).trim();
                }

                Matcher matcher = pattern.matcher(methodString);
                if(matcher.matches()){
                    //执行器链
                    Map<String,GPAdvice> advices = new HashMap<String, GPAdvice>();
                    //把每一个方法包装成 MethodIterceptor
                    //before
                    if(!(null == config.getAspectBefore() || "".equals(config.getAspectBefore()))) {
                        //创建一个Advivce
                        advices.put("before",new GPAdvice(aspectClass.newInstance(),aspectMethods.get(config.getAspectBefore())));
                    }
                    //after
                    if(!(null == config.getAspectAfter() || "".equals(config.getAspectAfter()))) {
                        //创建一个Advivce
                        advices.put("after",new GPAdvice(aspectClass.newInstance(),aspectMethods.get(config.getAspectAfter())));
                    }
                    //afterThrowing
                    if(!(null == config.getAspectAfterThrow() || "".equals(config.getAspectAfterThrow()))) {
                        //创建一个Advivce
                        GPAdvice throwingAdvice = new GPAdvice(aspectClass.newInstance(),aspectMethods.get(config.getAspectAfterThrow()));
                        throwingAdvice.setThrowName(config.getAspectAfterThrowingName());
                        advices.put("afterThrow",throwingAdvice);
                    }
                    methodCache.put(m,advices);
                }

            }
        }catch (Exception e){
            e.printStackTrace();
        }


    }

    public void setTarget(Object target) {
        this.target = target;
    }

    public boolean pointCutMatch() {
        return pointCutClassPattern.matcher(this.targetClass.toString()).matches();
    }

    public GPClassLoader getClassLoader() { return classLoader; }
}

GPJdkDynamicAopProxy实现动态代理

package com.gupaoedu.springaop.framework.aop;

import com.gupaoedu.springaop.framework.aspect.GPAdvice;
import com.gupaoedu.springaop.framework.proxy.GPClassLoader;
import com.gupaoedu.springaop.framework.proxy.GPInvocationHandler;
import com.gupaoedu.springaop.framework.proxy.GPProxy;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import java.util.Map;

/**
 * Created by Tom.
 */
public class GPJdkDynamicAopProxy implements GPInvocationHandler {

    private GPAdvisedSupport advised;

    public GPJdkDynamicAopProxy(GPAdvisedSupport config){
        this.advised = config;
    }

    public Object getProxy() {
        return getProxy(this.advised.getClassLoader());
    }


    public Object getProxy(GPClassLoader classLoader) {
        return GPProxy.newProxyInstance(classLoader,this.advised.getTargetClass().getInterfaces(),this);
    }


    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Map<String,GPAdvice> advices = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method,this.advised.getTargetClass());
        invokeAdvice(advices.get("before"));
        Object returnValue = null;
        try {
            returnValue = method.invoke(this.advised.getTarget(), args);
        }catch (Exception e){
            invokeAdvice(advices.get("afterThrow"));
        }
        invokeAdvice(advices.get("after"));
        return returnValue;
    }

    private void invokeAdvice(GPAdvice advice){
        try {
            advice.getAdviceMethod().invoke(advice.getAspect());
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
    }
}

测试代码

MemberServiceTest测试用例

package com.gupaoedu.springaop.service;

import com.gupaoedu.springaop.demo.service.IMemberService;
import com.gupaoedu.springaop.framework.GPApplicationContext;

public class MemberServiceTest {
    
    public static void main(String[] args) {
        GPApplicationContext applicationContext = new GPApplicationContext();
        IMemberService memberService = (IMemberService)applicationContext.getBean("memberService");
        try {
            memberService.delete("1");
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

运行结果

java培训班

java培训班：http://www.baizhiedu.com/java2019

java架构师 | SpringAOP那些无处不在的动态代理

发布百知教育 来源：学习课程 2019-11-29

pom.xml文件

application.properties文件

业务代码

Member实体类

IMermverServer接口

MemberService业务实现类

LogAspect切面增强类

仿写JDK动态代理

GPInvocationHandler JDK动态代理接口

GPClassLoader自定义类加载器

GPProxy 动态生成代理类

手写Spring AOP

GPAopConfig 保存配置信息

GPAdvice通知接口

GPJoinPoint切点

GPAdvisedSupport 解析切面配置

GPJdkDynamicAopProxy实现动态代理

测试代码

MemberServiceTest测试用例

运行结果

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发布百知教育来源：学习课程 2019-11-29