database

Usually im using javabean as both parameter and return values for MyBatis. But actually, MyBatis also able to use HashMaps as both parameter and return values. Here is the example,

First is a simple pom file to load all the libraries needed,

<?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.edw</groupId>
    <artifactId>MyBatisSelectMap</artifactId>
    <version>1.0</version>
    <packaging>jar</packaging>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.7</maven.compiler.source>
        <maven.compiler.target>1.7</maven.compiler.target>
    </properties>
    
    <dependencies>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.2.2</version>
        </dependency>
    </dependencies>
</project>

And my configuration.xml file, to hold my MyBatis’ configuration

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="UNPOOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost/test"/>
                <property name="username" value="root"/>
                <property name="password" value="password"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/edw/mybatisselectmap/sqlmap/SelectMapper.xml" />
    </mappers>
</configuration>

An xml file, to hold all my queries, i named it SelectMapper.xml.
Please note the difference between using #{} and ${}. Hashtags sign means a prepared statement variables, while dollar sign means a simple string replace.

<?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.edw.mybatisselectmap.mapper.SelectMapper" >    
    <select resultType="java.util.Map"  parameterType="java.util.Map" id="select" >
        SELECT
                *
        FROM
                testing 
        WERE  
                name LIKE #{myname}
        ORDER BY ${orderBy} 
    </select>    
</mapper>

A simple java file to map my xml queries,

package com.edw.mybatisselectmap.mapper;

import java.util.HashMap;
import java.util.List;

public interface SelectMapper {
    List<HashMap<Object, Object>> select(HashMap<Object, Object> hashMap);
}

and my java configuration file, to load all my MyBatis’ configurations

package com.edw.mybatisselectmap.config;

import java.io.IOException;
import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MyBatisSqlSessionFactory {

    private static final SqlSessionFactory FACTORY;

    static {
        try {
            Reader reader = Resources.getResourceAsReader("com/edw/mybatisselectmap/sqlmap/Configuration.xml");
            FACTORY = new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            throw new RuntimeException("Fatal Error. Cause: " + e, e);
        }
    }

    public static SqlSessionFactory getSqlSessionFactory() {
        return FACTORY;
    }
}

And finally my main java file,

package com.edw.mybatisselectmap;

import com.edw.mybatisselectmap.config.MyBatisSqlSessionFactory;
import com.edw.mybatisselectmap.mapper.SelectMapper;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;

public class Main {

    private static Logger logger = Logger.getLogger(Main.class);

    public static void main(String[] args) {
        SqlSession sqlSession = null;
        try {
            
            HashMap<Object, Object> hashMapParameter = new HashMap<Object, Object>();
            hashMapParameter.put("orderBy", "id");
            hashMapParameter.put("myname", "%edw%");
            
            sqlSession = MyBatisSqlSessionFactory.getSqlSessionFactory().openSession(true);
            SelectMapper mapper = sqlSession.getMapper(SelectMapper.class);
            
            List<HashMap<Object, Object>> hashMapResults = mapper.select(hashMapParameter);
            
            for (HashMap<Object, Object> hashMapResult : hashMapResults) {
                logger.debug(hashMapResult);
            }
        } catch (Exception e) {
            logger.error(e, e);
        } finally {
            if (sqlSession != null) {
                sqlSession.close();
            }
        }
    }
}

You can find this post’s sourcecode at my github page here, https://github.com/edwinkun/MyBatisSelectMap.