【Mybatis】获取sql

最近项目遇到springboot共享数据库连接池问题，解决方案是连接池单独做一个服务，其他服务通过Feign把sql传过去执行调用。

这样想要对项目改动最小的就是用mybatis获取sql

1、首先去掉mybatis启动的maven配置，只要mybatis原生的就可以了

<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.4.6</version>
</dependency>

pom.xml

<?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</groupId>
    <artifactId>mybatis</artifactId>
    <version>1.0</version>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>

        <!-- 集成lombok 框架 -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
            <scope>provided</scope>
            <version>1.18.12</version>
        </dependency>
    </dependencies>

</project>

2、mapper.xml，这里测试是User.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="UserMapper">
    <select id="findUserById" parameterType="com.mybatis.entity.User" resultType="com.mybatis.entity.User">
        SELECT * FROM USER WHERE id = #{id}
    </select>

    <select id="findUserByUsername" parameterType="com.mybatis.entity.User" resultType="com.mybatis.entity.User">
        SELECT * FROM USER WHERE username = #{username}
    </select>

    <insert id="insertUser" parameterType="com.mybatis.entity.User">
        insert into user (id, username, password) values (#{id}, #{username}, #{password})
    </insert>


    <update id="updateUserUsernamePassword" parameterType="com.mybatis.entity.User">
        update user set username=#{username}, password=#{password}  where id=#{id}
    </update>

</mapper>

3、mybatis.xml读取User.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <mappers>
        <mapper resource="mapper/User.xml" />
    </mappers>
</configuration>

4、User类

package com.mybatis.entity;

import lombok.Data;

@Data
public class User {
    private int id;
    private String username;
    private String password;
}

5、测试

package com.mybatis.test;

import com.mybatis.entity.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ParameterMapping;
import org.apache.ibatis.mapping.ParameterMode;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.property.PropertyTokenizer;
import org.apache.ibatis.scripting.xmltags.ForEachSqlNode;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.lang.reflect.Field;
import java.util.List;
import java.util.Map;

public class Mytest {

    public static void main(String[] args) throws IOException {
        // 创建SqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis.xml"));

        User user = new User();
        user.setId(1);
        user.setUsername("zhangsan");
        user.setPassword("33333");
        String sql = getMyBatisSql("UserMapper.insertUser", user, sqlSessionFactory);
        System.out.println(sql);

    }

    /**
     * 运行期获取MyBatis执行的SQL及参数
     *
     * @param id Mapper xml 文件里的select Id
     * @param obj      参数
     * @param sqlSessionFactory
     * @return
     */
    public static String getMyBatisSql(String id, Object obj, SqlSessionFactory sqlSessionFactory) {
        MappedStatement ms = sqlSessionFactory.getConfiguration().getMappedStatement(id);
        BoundSql boundSql = ms.getBoundSql(obj);
        String sql = boundSql.getSql();
        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
        if (parameterMappings != null) {
            Object[] parameterArray = new Object[parameterMappings.size()];
            ParameterMapping parameterMapping = null;
            Object value = null;
            Object parameterObject = null;
            MetaObject metaObject = null;
            PropertyTokenizer prop = null;
            String propertyName = null;
            String[] names = null;
            for (int i = 0; i < parameterMappings.size(); i++) {
                parameterMapping = parameterMappings.get(i);
                if (parameterMapping.getMode() != ParameterMode.OUT) {
                    propertyName = parameterMapping.getProperty();
                    names = propertyName.split("\.");
                    if (propertyName.indexOf(".") != -1 && names.length == 2) {
                        parameterObject = boundSql.getAdditionalParameter(names[0]);
                        propertyName = names[1];
                    } else if (propertyName.indexOf(".") != -1 && names.length == 3) {
                        parameterObject = boundSql.getAdditionalParameter(names[0]); // map
                        if (parameterObject instanceof Map) {
                            parameterObject = ((Map) parameterObject).get(names[1]);
                        }
                        propertyName = names[2];
                    } else {
                        parameterObject = boundSql.getAdditionalParameter(propertyName);
                    }
                    if (null == parameterObject) {
                        parameterObject = getFieldValueByFieldName(propertyName, obj);
                    }
                    prop = new PropertyTokenizer(propertyName);
                    if (parameterObject == null) {
                        value = null;
                    } else if (ms.getConfiguration().getTypeHandlerRegistry().hasTypeHandler(parameterObject.getClass())) {
                        value = parameterObject;
                    } else if (boundSql.hasAdditionalParameter(propertyName)) {
                        value = boundSql.getAdditionalParameter(propertyName);
                    } else if (propertyName.startsWith(ForEachSqlNode.ITEM_PREFIX) && boundSql.hasAdditionalParameter(prop.getName())) {
                        value = boundSql.getAdditionalParameter(prop.getName());
                    } else {
                        value = metaObject == null ? null : metaObject.getValue(propertyName);
                    }
                    parameterArray[i] = value;
                }
                parameterObject = null;
            }
            int i = 0;
            while (sql.indexOf("?") != -1) {
                if (null == parameterArray[i]) {
                    throw new RuntimeException("mybatis获取sql异常");
                }
                if (parameterArray[i] instanceof String) {
                    sql = sql.replaceFirst("\?", "'" + parameterArray[i].toString() + "'");
                } else {
                    sql = sql.replaceFirst("\?", parameterArray[i].toString());
                }
                i++;
            }
            int index;
            StringBuilder sb = new StringBuilder();
            for (String s : sql.split("
")) {
                index = s.indexOf("--");
                if (-1 == index) {
                    index = s.length();
                }
                sb.append(s.substring(0, index).replace("	", " ").trim()).append(" ");
            }
            return sb.toString().replaceAll("(
?
(\s*
?
)+)", " ").replaceAll("
", " ").replaceAll("
", " ").replaceAll("    ", " ").replaceAll("   ", " ").replaceAll("  ", " ");

        }
        return sql;
    }

    /**
     * 根据属性名获取属性值
     *
     * @param fieldName
     * @param object
     * @return
     */
    public static Object getFieldValueByFieldName(String fieldName, Object object) {
        try {
            Field field = object.getClass().getDeclaredField(fieldName);
            //设置对象的访问权限，保证对private的属性的访问
            field.setAccessible(true);
            return  field.get(object);
        } catch (Exception e) {
            new RuntimeException(e);
            return null;
        }
    }

}

 

项目结构