SpringBoot+Mybatis,返回Map的時候,將Map內的Key轉換爲駝峯的命名錶達式

好多查詢都涉及到多表查詢，並且返回的字段又不一樣，也不想寫很多的結果entity，數據庫中對應的是USER_NAME，返回前臺的接口想要得到userName， 所以肯定要做一番處理

百度了相關，參考以下連接

1、比較詳細帶原理分析

https://my.oschina.net/u/2278977/blog/1795969

2、簡單明瞭

https://www.cnblogs.com/wilwei/p/10244726.html

最後選擇了比較簡單的實現方式

只需要兩步：

第一、設置mybatis.configuration.map-underscore-to-camel-case=true

第二、增加mybatis的config配置

/**
 * 
 */
package com.ygjy.authmain.common.config;

import java.util.Map;

import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.wrapper.MapWrapper;
import org.apache.ibatis.reflection.wrapper.ObjectWrapper;
import org.apache.ibatis.reflection.wrapper.ObjectWrapperFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.baomidou.mybatisplus.spring.boot.starter.ConfigurationCustomizer;

/**
 * @Description:TODO(
 * @author Rear
 * @date:   2019年6月10日 下午12:08:40
 */
@Configuration
public class MybatisConfig {
    /**
     * mybatis resultType爲map時下劃線鍵值轉小寫駝峯形式插
     */
    @Bean
    public ConfigurationCustomizer configurationCustomizer() {
        return configuration -> configuration.setObjectWrapperFactory(new MapWrapperFactory());
    }

    
    static class MapWrapperFactory implements ObjectWrapperFactory {
        @Override
        public boolean hasWrapperFor(Object object) {
            return object != null && object instanceof Map;
        }

        @Override
        public ObjectWrapper getWrapperFor(MetaObject metaObject, Object object) {
            return new MyMapWrapper(metaObject, (Map) object);
        }
    }

    static class MyMapWrapper extends MapWrapper {
        MyMapWrapper(MetaObject metaObject, Map<String, Object> map) {
            super(metaObject, map);
        }

        @Override
        public String findProperty(String name, boolean useCamelCaseMapping) {
            if (useCamelCaseMapping
                    && ((name.charAt(0) >= 'A' && name.charAt(0) <= 'Z')
                    || name.contains("_"))) {
                return underlineToCamelhump(name);
            }
            return name;
        }

        /**
         * 將下劃線風格替換爲駝峯風格
         *
         * @param inputString
         * @return
         */
        private String underlineToCamelhump(String inputString) {
            StringBuilder sb = new StringBuilder();

            boolean nextUpperCase = false;
            for (int i = 0; i < inputString.length(); i++) {
                char c = inputString.charAt(i);
                if (c == '_') {
                    if (sb.length() > 0) {
                        nextUpperCase = true;
                    }
                } else {
                    if (nextUpperCase) {
                        sb.append(Character.toUpperCase(c));
                        nextUpperCase = false;
                    } else {
                        sb.append(Character.toLowerCase(c));
                    }
                }
            }
            return sb.toString();
        }
    }
}