MyBatis中JNDI数据源的应用

1、JNDI简介：JNDI(Java Naming and Directory Interface)是一个应用程序设计的API，为开发人员提供了查找和访问各种命名和目录服务的通用、统一的接口，类似JDBC都是构建在抽象层上。
2、MyBatis配置JNDI：
MyBatis配置文件：

<?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>
        <package name="Model"></package>
    </typeAliases>

    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <!-- 配置连接数据库的必备信息  type属性表示是否使用数据源（连接池）
                property标签中value属性值java:comp/env/  此为固定写法  ；
                jdbc/mybatis 数据源名称(在META-INF中的配置文件中配置的数据)
            -->
            <dataSource type="JNDI">
                <property name="data_source" value="java:comp/env/jdbc/mybatis"></property>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!--此处使用package标签配置映射需要注意，接口映射文件与SQL映射文件必须是一一对应的，不然编译会出现异常-->
        <package name="myBatis.dao"></package>
        <!--<mapper resource="myBatis/dao/JNDIMapper.xml"></mapper>-->
    </mappers>
</configuration>

**3、**项目配置中需要特别注意的是，在项目目录webapp下需要创建META-INF文件夹，在该文件夹下放置JNDI数据源需要引用的信息：
context.xml:

<?xml version="1.0" encoding="UTF-8"?>
<Context>
<!-- 
<Resource 
name="jdbc/mybatis"						        数据源的名称
type="javax.sql.DataSource"						数据源类型
auth="Container"								数据源提供者
maxActive="20"									最大活动数
maxWait="10000"									最大等待时间
maxIdle="5"										最大空闲数
username="root"									用户名
password="1234"									密码
driverClassName="com.mysql.jdbc.Driver"			驱动类
url="jdbc:mysql://localhost:3306/eesy_mybatis"	连接url字符串
/>
 -->
<Resource 
name="jdbc/mybatis"
type="javax.sql.DataSource"
auth="Container"
maxActive="20"
maxWait="10000"
maxIdle="5"
username="root"
password="root"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/mybatis"
/>
</Context>

4、SQL映射文件：

<?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="myBatis.dao.JNDIMapper">
    <resultMap id="userAccountJNDI" type="userAcountJNDI">
        <id property="id" column="id"></id>
        <result property="username" column="username"></result>
        <result property="address" column="address"></result>
        <result property="sex" column="sex"></result>
        <result property="birthday" column="birthday"></result>
        <collection property="accounts" ofType="account">
            <id property="id" column="aid"></id>
            <result property="uid" column="UID"></result>
            <result property="money" column="MONEY"></result>
        </collection>
    </resultMap>
    <!--账户与用户一一对应的关系：
        此处主要是实现一一对应关系的懒加载(延迟加载)
    -->
    <resultMap id="accountUser" type="accountUsermodel">
        <id property="id" column="id"></id>
        <result property="uid" column="uid"></result>
        <result property="money" column="money"></result>
        <!--此处的column属性必须写，属性的值作为select属性中引用的查询sql的参数-->
        <association property="user" column="uid" javaType="userCRUDmodeltwo" select="myBatis.dao.IUserCRUDDao.queryUserInfoById"></association>
    </resultMap>

    <select id="getAllUserInfo" resultMap="userAccountJNDI">
        SELECT u.*,
               a.id aid,
               a.UID,
               a.MONEY
        FROM user u
        left join account a
        on a.UID = u.id
    </select>

    <select id="getAccountUserByLazy" resultMap="accountUser">
        select * from account
    </select>
</mapper>

5、封装实体类userAcountJNDI.java:

package Model;

import java.util.Date;
import java.util.List;

public class userAcountJNDI {
     
    private Integer id;
    private Date birthday;
    private char sex;
    private String username;
    private String address;

    private List<account> accounts;

    public Integer getId() {
     
        return id;
    }

    public void setId(Integer id) {
     
        this.id = id;
    }

    public Date getBirthday() {
     
        return birthday;
    }

    public void setBirthday(Date birthday) {
     
        this.birthday = birthday;
    }

    public char getSex() {
     
        return sex;
    }

    public void setSex(char sex) {
     
        this.sex = sex;
    }

    public String getUsername() {
     
        return username;
    }

    public void setUsername(String username) {
     
        this.username = username;
    }

    public String getAddress() {
     
        return address;
    }

    public void setAddress(String address) {
     
        this.address = address;
    }

    public List<account> getAccounts() {
     
        return accounts;
    }

    public void setAccounts(List<account> accounts) {
     
        this.accounts = accounts;
    }

    @Override
    public String toString() {
     
        return "userAcountJNDI{" +
                "id=" + id +
                ", birthday=" + birthday +
                ", sex=" + sex +
                ", username='" + username + '\'' +
                ", address='" + address + '\'' +
                ", accounts=" + accounts +
                '}';
    }
}

6、测试此方法需要用到的包：
pom.xml:

  <dependencies>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.30</version>
    </dependency>
    <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.2.2</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
    </dependency>
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>1.2.12</version>
    </dependency>

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.3</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.1</version>
    </dependency>
    <!--此包是在延迟加载配置延迟加载开关后编译报错是缺少该包引入的-->
    <dependency>
      <groupId>cglib</groupId>
      <artifactId>cglib</artifactId>
      <version>3.2.5</version>
    </dependency>
  </dependencies>

7、接口映射文件：

package myBatis.dao;

import Model.accountUserModel;
import Model.userAcountJNDI;

import java.util.List;

public interface JNDIMapper {
     
    /**
     * 查询所有用户及其账户信息
     */
    List<userAcountJNDI> getAllUserInfo();

    /**
     * 账户与人员信息一一对应的 延迟加载 实现
     */
    List<accountUserModel> getAccountUserByLazy();
}

8、jsp文件(index.jsp)

<%@ page import="java.io.InputStream" %>
<%@ page import="org.apache.ibatis.io.Resources" %>
<%@ page import="org.apache.ibatis.session.SqlSessionFactoryBuilder" %>
<%@ page import="org.apache.ibatis.session.SqlSessionFactory" %>
<%@ page import="org.apache.ibatis.session.SqlSession" %>
<%@ page import="java.util.List" %>
<%@ page import="myBatis.dao.JNDIMapper" %>
<%@ page import="Model.userAcountJNDI" %>

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<html>
<body>
<h2>Hello World!</h2>

<%
    //读取mybatis配置文件
    InputStream ins = Resources.getResourceAsStream("MyBatis_JNDI.xml");
    //创建工厂类
    SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
    SqlSessionFactory ssf = builder.build(ins);
    //

    //使用工厂类创建SqlSession对象
    //SqlSession ss = ssf.openSession(true);  //参数true设置自动提交
    SqlSession ss = ssf.openSession();
    //使用SqlSession创建dao层的动态代理类
    JNDIMapper JNDIMap = ss.getMapper(JNDIMapper.class);
    //使用代理对象执行方法
    List<userAcountJNDI> list = JNDIMap.getAllUserInfo();
    for (userAcountJNDI model: list) {
     
        System.out.println(model);
    }
    //释放资源
    ss.close();
    ins.close();
%>
</body>
</html>

9、完成上述步骤之后，将项目的部署在tomcat中，启动tomcat服务器，访问项目，即可测试JNDI数据源得使用。