爱码博阁

插件执行流程：

例子：

package com.laoxu.mybatis.executor.plugin;

import org.apache.ibatis.plugin.*;

import java.util.Properties;

public class Test2 {

    public static void main(String[] args) {
        test1();
    }

    private static void test1(){
        MyPlugin myPlugin = new MyPlugin() {
            @Override
            public String sayHi(String name) {
                System.out.println("hello " + name);
                return "hello " + name;
            }
        };
        Interceptor interceptor = null;
        MyPlugin wrap = (MyPlugin) Plugin.wrap(myPlugin, new MyInterceptor());
        wrap.sayHi("程序员");
    }

    public interface MyPlugin{
        String sayHi(String name);
    }

    @Intercepts(
            @Signature(
                    type = MyPlugin.class,
                    method = "sayHi",
                    args = {String.class}
            ))
    public static class MyInterceptor implements Interceptor {

        @Override
        public Object intercept(Invocation invocation) throws Throwable {
            System.out.println("你好");
            return invocation.proceed();
        }

        @Override
        public Object plugin(Object target) {
            return null;
        }

        @Override
        public void setProperties(Properties properties) {

        }
    }

}

执行结果：

你好
hello 程序员

1、根据注解获取 Map<Class<?>, Set<Method>> 这么一个多个类的多个方法map

{
    "com.laoxu.mybatis.executor.plugin.Test2$MyPlugin": [
        {
            "accessible": false,
            "annotatedExceptionTypes": [],
            "annotatedParameterTypes": [
                {
                    "annotations": [],
                    "declaredAnnotations": [],
                    "type": "java.lang.String"
                }
            ],
            "annotatedReceiverType": {
                "annotations": [],
                "declaredAnnotations": [],
                "type": "com.laoxu.mybatis.executor.plugin.Test2$MyPlugin"
            },
            "annotatedReturnType": {
                "annotations": [],
                "declaredAnnotations": [],
                "type": "java.lang.String"
            },
            "annotations": [],
            "bridge": false,
            "declaringClass": "com.laoxu.mybatis.executor.plugin.Test2$MyPlugin",
            "default": false,
            "exceptionTypes": [],
            "genericExceptionTypes": [],
            "genericParameterTypes": [
                "java.lang.String"
            ],
            "genericReturnType": "java.lang.String",
            "modifiers": 1025,
            "name": "sayHi",
            "parameterAnnotations": [
                []
            ],
            "parameterCount": 1,
            "parameterTypes": [
                "java.lang.String"
            ],
            "returnType": "java.lang.String",
            "synthetic": false,
            "typeParameters": [],
            "varArgs": false
        }
    ]
}

2、获取传入的目标类

3、获取该目标类下的所有接口

也就是此例的sayHi接口

4、动态代理执行插件的sayHi方法

调用invoke方法

获取方法集合

[
    {
        "accessible": false,
        "annotatedExceptionTypes": [],
        "annotatedParameterTypes": [
            {
                "annotations": [],
                "declaredAnnotations": [],
                "type": "java.lang.String"
            }
        ],
        "annotatedReceiverType": {
            "annotations": [],
            "declaredAnnotations": [],
            "type": "com.laoxu.mybatis.executor.plugin.Test2$MyPlugin"
        },
        "annotatedReturnType": {
            "annotations": [],
            "declaredAnnotations": [],
            "type": "java.lang.String"
        },
        "annotations": [],
        "bridge": false,
        "declaringClass": "com.laoxu.mybatis.executor.plugin.Test2$MyPlugin",
        "default": false,
        "exceptionTypes": [],
        "genericExceptionTypes": [],
        "genericParameterTypes": [
            "java.lang.String"
        ],
        "genericReturnType": "java.lang.String",
        "modifiers": 1025,
        "name": "sayHi",
        "parameterAnnotations": [
            []
        ],
        "parameterCount": 1,
        "parameterTypes": [
            "java.lang.String"
        ],
        "returnType": "java.lang.String",
        "synthetic": false,
        "typeParameters": [],
        "varArgs": false
    }
]

调用目标插件实现的intercept方法

/**
 *    Copyright 2009-2019 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.apache.ibatis.plugin;

import java.util.Properties;

/**
 * @author Clinton Begin
 */
public interface Interceptor {

  Object intercept(Invocation invocation) throws Throwable;

  default Object plugin(Object target) {
    return Plugin.wrap(target, this);
  }

  default void setProperties(Properties properties) {
    // NOP
  }

}