Mybatis-plus中输出组装好的SQL

    在本地开发调试过程中，有时候需要输出PreparedStatement 的调用的SQL，也就是将每一个SQL调用语句都输出，按照文档的介绍，可以在配置中添加如下日志输出的配置。

# 配置slq打印日志
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

    然而，可以观察日志，知道日志是分别输出若干部分带有"?"参数的SQL语句，也就是需要我们人手去替换"?",这样才可以得到一个完整可以执行的SQL，这个并不是我们要的，我们需要的是一个可以直接输出完整SQL的方法。

    Mybatis-plus 提供了类似于mybatis原生的拦截器一样的拦截器实现，我们只需要模仿官方提供的分页插件，在其之后，添加一个替换完"?"输出SQL的拦截器既可。

import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.autoconfigure.ConfigurationCustomizer;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;


@Configuration
public class MybatisPlusConfig {

    /**
     * 新的分页插件,一缓和二缓遵循mybatis的规则,需要设置 MybatisConfiguration#useDeprecatedExecutor = false 避免缓存出现问题(该属性会在旧插件移除后一同移除)
     */
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        interceptor.addInnerInterceptor(new MyBatisPlusSqlLogInterceptor());
        return interceptor;
    }
    @Bean
    public ConfigurationCustomizer configurationCustomizer() {
        return configuration -> configuration.setUseDeprecatedExecutor(false);
    }
}

//MyBatisPlusSqlLogInterceptor

import com.baomidou.mybatisplus.extension.plugins.inner.InnerInterceptor;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.type.TypeHandlerRegistry;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.SQLException;
import java.text.DateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.regex.Matcher;

/*
 *创建者: LSZ
 *创建时间: 2021-01-19 21:58:10
 *描述: 用于输出格式化好的SQL
 */
public class MyBatisPlusSqlLogInterceptor implements InnerInterceptor {
    private static Logger logger = LoggerFactory.getTraceLogger(MyBatisPlusSqlLogInterceptor.class);
    private static boolean printSQL = false;
    public static void startPrintSQL(){
        printSQL = Boolean.TRUE;
    }

    @Override
    public void beforeQuery(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {
        if(printSQL) {
            MappedStatement mappedStatement = ms;
            String sqlId = mappedStatement.getId();
            Configuration configuration = mappedStatement.getConfiguration();
            String sql = getSql(configuration, boundSql, sqlId);
            logger.info(sql);
        }
    }

    @Override
    public void beforeUpdate(Executor executor, MappedStatement ms, Object parameter) throws SQLException {

        if(printSQL) {
            MappedStatement mappedStatement = ms;
            String sqlId = mappedStatement.getId();
            Configuration configuration = mappedStatement.getConfiguration();
            BoundSql boundSql = mappedStatement.getBoundSql(parameter);
            String sql = getSql(configuration, boundSql, sqlId);
            logger.info(sql);
        }
    }

    public static String getSql(Configuration configuration, BoundSql boundSql, String sqlId ) {
        try {
            String sql = showSql(configuration, boundSql);
            StringBuilder str = new StringBuilder(100);
            str.append(sqlId);
            str.append(" ==> ");
            str.append(sql);
            str.append(";");
            return str.toString();
        } catch(Error e) {
            logger.error("解析 sql 异常", e);
        }
        return "";
    }
    public static String showSql(Configuration configuration, BoundSql boundSql) {
        Object parameterObject = boundSql.getParameterObject();
        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
        String sql = boundSql.getSql().replaceAll("[\\s]+", " ");
        if (parameterMappings != null && parameterMappings.size() > 0 && parameterObject != null) {
            TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
            if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {
                sql = sql.replaceFirst("\\?", Matcher.quoteReplacement(getParameterValue(parameterObject)));
            } else {
                MetaObject metaObject = configuration.newMetaObject(parameterObject);
                for (ParameterMapping parameterMapping : parameterMappings) {
                    String propertyName = parameterMapping.getProperty();
                    if (metaObject.hasGetter(propertyName)) {
                        Object obj = metaObject.getValue(propertyName);
                        sql = sql.replaceFirst("\\?", Matcher.quoteReplacement(getParameterValue(obj)));
                    } else if (boundSql.hasAdditionalParameter(propertyName)) {
                        Object obj = boundSql.getAdditionalParameter(propertyName);
                        sql = sql.replaceFirst("\\?", Matcher.quoteReplacement(getParameterValue(obj)));
                    }
                }
            }
        }
        return sql;
    }

    private static String getParameterValue(Object obj) {
        String value = null;
        if (obj instanceof String) {
            value = "'" + obj.toString() + "'";
        } else if (obj instanceof Date) {
            DateFormat formatter = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.CHINA);
            value = "'" + formatter.format(obj) + "'";
        }else if(obj instanceof LocalDate){
            value = "'" + ((LocalDate) obj).format( DateTimeFormatter.ofPattern("yyyy-MM-dd")) + "'";
        }else if(obj instanceof LocalDateTime){
            value = "'" + ((LocalDateTime) obj).format( DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")) + "'";

        } else {
            if (obj != null) {
                value = obj.toString();
            } else {
                value = "";
            }
        }
        return value;
    }
}

该插件，可以加在测试用例环节或者开发环境中将其打开，以便输出SQL。原理其实就是简单的替换参数并组装成SQL输出而已。