地区选择数据库形式的基础数据转成JSON串

　　在做H5开发过程中，地区选择的基础数据产品经理不知从哪里哪来了一些SQL，而这个数据其实很难会变，存储在后台的DB或者缓存中，好像没有必要，于是得想办法把它转成json串保存到文件中，请求时直接请求这个JSON串文件即可。

基础SQL：

DROP TABLE IF EXISTS Province;
DROP TABLE IF EXISTS City;
DROP TABLE IF EXISTS District;

CREATE TABLE Province (Id int,
	Name varchar(50) ,
	orderid int 
)row_format=dynamic engine=innodb default charset utf8;
insert into Province values('1','北京','0'); 
insert into Province values('2','天津','0');

CREATE TABLE City(
	Id int ,
	ProvinceId int,
	Name varchar(50),
	AreaCode varchar(50)
)row_format=dynamic engine=innodb default charset utf8;

insert into City values('1','1','北京市','010'); 
insert into City values('2','2','天津市','022'); 
insert into City values('3','3','石家庄市','0311'); 
insert into City values('4','3','唐山市','0315'); 

CREATE TABLE District(
	Id int ,
	CityId int ,
	Name varchar(50),
	PostCode varchar(50)
)row_format=dynamic engine=innodb default charset utf8;

insert into District values('1','1','东城区','100010'); 
insert into District values('2','1','西城区','100032'); 
insert into District values('3','1','崇文区','100061'); 
insert into District values('4','1','宣武区','100054'); 
insert into District values('5','1','朝阳区','100020'); 
insert into District values('6','1','丰台区','100071'); 
insert into District values('7','1','石景山区','100043'); 

　　一看，乖乖，这不就是一对多的关系吗？于是想到用MyBatis处理即可。参考myBatis系列之四：关联数据的查询和【Mybatis高级映射】一对一映射、一对多映射、多对多映射很快就写出来了。

Configuration.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>  
    <typeAliases><!-- 别名 -->  
        <typeAlias alias="Province" type="com.bijian.study.dto.Province" />
        <typeAlias alias="City" type="com.bijian.study.dto.City" />
        <typeAlias alias="District" type="com.bijian.study.dto.District" />
    </typeAliases>  
      
    <environments default="development">  
      <environment id="development">  
        <transactionManager type="JDBC"/>  
        <dataSource type="POOLED"><!-- 数据源 -->  
            <property name="driver" value="com.mysql.jdbc.Driver" />  
            <property name="url" value="jdbc:mysql://10.107.96.172:3306/test" />  
            <property name="username" value="test" />  
            <property name="password" value="test" />  
        </dataSource>  
      </environment>  
    </environments>
      
    <mappers><!-- ORM映射文件 -->  
        <mapper resource="com/bijian/study/dto/Province.xml" />
        <mapper resource="com/bijian/study/dto/City.xml" />
        <mapper resource="com/bijian/study/dto/District.xml" />
    </mappers>  
</configuration>

log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>  
<configuration status="OFF">  
  <appenders>  
    <Console name="Console" target="SYSTEM_OUT">  
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>  
    </Console>  
  </appenders>  
  <loggers>  
    <root level="info">  
      <appender-ref ref="Console"/>  
    </root>  
  </loggers>  
</configuration>

ProvinceMapper.java

package com.bijian.study.dao;

import java.util.List;

import com.bijian.study.dto.Province;

public interface ProvinceMapper {
    
    Province getProvinceById(int id);
    List<Province> getProvinceList();
    
    List<Province> getAllProvinceList();
}

Province.java

package com.bijian.study.dto;

import java.util.List;

public class Province {

    private int id;
    private String name;
    private int orderid;
    private List<City> subs;
    
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getOrderid() {
        return orderid;
    }
    public void setOrderid(int orderid) {
        this.orderid = orderid;
    }
    public List<City> getSubs() {
      return subs;
    }
    public void setSubs(List<City> subs) {
      this.subs = subs;
    }
}

Province.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="com.bijian.study.dao.ProvinceMapper">
	
	<resultMap type="Province" id="provinceList1">
		<id column="Id" property="id" />
		<result column="Name" property="name" />
		<result column="orderid" property="orderid" />
	</resultMap>

	<select id="getProvinceById" parameterType="int" resultType="Province">
		select * from Province where Id = #{id}
	</select>

	<select id="getProvinceList" resultMap="provinceList1">
		select * from Province
	</select>
	
	<resultMap type="Province" id="provinceList">
		<result column="p_id" property="id" />
		<result column="p_name" property="name" />
		<!-- Province属性映射到City类 -->
		<collection property="subs" ofType="City">
			<id column="c_id" property="id" />
			<result column="c_provinceId" property="provinceId"/>
			<result column="c_name" property="name" />
			<result column="c_areaCode" property="areaCode" />
			<!-- District属性映射到District类 -->
			<collection property="subs" ofType="District">
				<id column="d_id" property="id" />
				<result column="d_cityId" property="cityId" />
				<result column="d_name" property="name" />
				<result column="d_postCode" property="postCode" />	
			</collection>
		</collection>
	</resultMap>

	<select id="getAllProvinceList" resultMap="provinceList">
		select p.Id p_id, p.Name p_name, c.Id c_id, c.ProvinceId c_provinceId, c.Name c_name, c.AreaCode c_areaCode, d.Id d_id, d.CityId d_cityId, d.Name d_name, d.PostCode d_postCode
		from Province p inner join City c on p.Id=c.ProvinceId
		inner join District d on c.Id=d.CityId
	</select>
</mapper>

Main.java

package com.bijian.study;

import java.io.IOException;
import java.io.Reader;
import java.util.List;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.bijian.study.dao.ProvinceMapper;
import com.bijian.study.dto.Province;
import com.fasterxml.jackson.databind.ObjectMapper;

public class Main {
    
    private static final Logger log = LoggerFactory.getLogger(Main.class);  
    private static SqlSessionFactory sqlSessionFactory;  
  
    private static Reader reader;
    
    public static void main(String[] args) {
        try {
            reader = Resources.getResourceAsReader("Configuration.xml");  
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
            
            SqlSession session = sqlSessionFactory.openSession();
            
            ProvinceMapper mapper = session.getMapper(ProvinceMapper.class);  
            List<Province> provinceList = mapper.getAllProvinceList();
            log.info("{}", provinceList.size());
            
            ObjectMapper objMapper = new ObjectMapper();
            String provinceListStr = objMapper.writeValueAsString(provinceList);
            
            log.info("{}", provinceListStr);
        } catch (IOException e) {  
            log.error("Error thrown while reading the configuration: {}", e);  
        } finally {  
            if (reader != null) {  
                try {  
                    reader.close();  
                } catch (IOException e) {  
                    log.error("Error thrown while closing the reader: {}", e);  
                }  
            }  
        }  
    }
}

运行Main.java，结果如下：

　　当然，由于在实际应用中，根本无需id、cityId等，postCode、areaCode也统一用code，所以修改一下对应的sqlMapper及dto，详见附件工程包《JsonTransfer.rar》，运行Main2.java结果如下所示：