mybatis 一二事（2） - 动态代理

db.properties 单独提取出来的数据库配置，方便以后维护管理

 jdbc.driver=com.mysql.jdbc.Driver
 jdbc.url=jdbc:mysql://localhost:3306/mybatis
 jdbc.username=root
 jdbc.password=root

SqlMapConfig.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>
     <!-- 加载数据库连接参数配置文件 -->
     <properties resource="db.properties" />

     <!--
         全局配置参数
         比如 二级缓存 延迟加载...等
         此全局参数会影响mybatis运行的性能，要谨慎配置
      -->
 <!--     <settings> -->
 <!--     <setting name="" value=""/> -->
 <!--     </settings> -->

     <!-- 定义别名 -->
     <typeAliases>
         <!-- 单个别名定义
         type：pojo的路径
         alias：别名的名称
         -->
         <!-- <typeAlias type="cn.itcast.mybatis.po.User" alias="user"/> -->
         <!-- 批量别名定义
         name：指定包名，将包下边的所有pojo定义别名 ，别名为类名（首字母大写或小写都行）
          -->
         <package name="com.mybatis.bean"/>
     </typeAliases>

     <!-- 和spring整合后 environments配置将废除 -->
     <environments default="development">
         <environment id="development">
             <transactionManager type="JDBC" />
             <dataSource type="POOLED">
                 <property name="driver" value="${jdbc.driver}"/>
                 <property name="url" value="${jdbc.url}"/>
                 <property name="username" value="${jdbc.username}"/>
                 <property name="password" value="${jdbc.password}"/>
             </dataSource>
         </environment>
     </environments>

     <!-- 配置mapper映射文件 -->
     <mappers>
         <!-- resource方式
         在UserMapper.xml，定义namespace为mapper接口的地址，映射文件通过namespace找到对应的mapper接口文件
          -->
         <!-- <mapper resource="sqlmap/UserMapper.xml" /> -->
         <!-- class方式
         class：指定 mapper接口的地址
         遵循规则：将mapper.xml和mapper.java文件放在一个目录 且文件名相同
          -->
         <!-- <mapper class="cn.itcast.mybatis.mapper.UserMapper"/> -->

         <!--
             批量mapper扫描
             遵循规则：将mapper.xml和mapper.java文件放在一个目录 且文件名相同
             主要以这样的方式为主来加载mapper
           -->
         <package name="com.mybatis.mapper"/>

     </mappers>
 </configuration>

UserMapper.java

 package com.mybatis.mapper;

 import java.util.List;
 import java.util.Map;

 import com.mybatis.bean.QueryVo;
 import com.mybatis.bean.User;

 public interface UserMapper {

     public User findUserById(int id) throws Exception;

     public List<User> findUserList(String name) throws Exception;

     public Integer insertUser(User user) throws Exception;

     public void deleteUser(int id) throws Exception;

     public void updateUser(User user) throws Exception;

     public List<User> findUserByBean(User user) throws Exception;

     public List<User> findUserByMap(Map<String, Object> map) throws Exception;

     public List<User> findUserByCustom(QueryVo queryVo) throws Exception;

 //    public Map findUserMapByCustom(QueryVo queryVo) throws Exception;

     public void updateUserSet(User user) throws Exception;

 }

UserMapper.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.mybatis.mapper.UserMapper" >

     <!--
         sql 片段，可以供其他的sql一起使用
         建议以单表抽取查询条件
      -->
      <sql id="query_for_user">
         <if test=" user != null ">
             <if test=" user.name != null and user.name != '' ">
                 and name like '%${user.name}%'
             </if>
             <if test=" user.sex != null and user.sex != '' ">
                 and sex = #{user.sex}
             </if>
         </if>

         <if test="ids != null">
              <foreach collection="ids" separator="or" item="item" open="and (" close=")">
                  id = #{item}
              </foreach>
          </if>
      </sql>

     <select id="findUserById" parameterType="int" resultType="com.mybatis.bean.User">
         SELECT * FROM USER WHERE id = #{id}
     </select>

     <!--
         #{} 表示占位符，#{}可以使用value或者其他字符，可以防止sql注入，使用时无需考虑参数的类型
         ${} 表示sql拼接，把原始的内容不加修饰的放入sql中，${}只能使用value，不可以防止sql注入，必须考虑参数的类型
         一般在没有特殊情况下使用#{}为主
         有些情况必须使用${}，比如
             动态拼接表名：select * from ${tablename}, 如果使用了#{}则会在传入的表名上加单引号 ''
             动态拼接排序字段：select * from user order by ${username}

         举个栗子：
         查询日期的区别：
             select * from user where birthday >= #{date}
             select * from user where birthday >= to_date('${date}', 'yyyy-MM-dd')
      -->

     <select id="findUserList" parameterType="java.lang.String" resultType="com.mybatis.bean.User" >
         select * from user where name like '%${value}%'
     </select>

     <insert id="insertUser" parameterType="com.mybatis.bean.User">
         <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer">
             select LAST_INSERT_ID()
         </selectKey>
         insert into user(name,age,sex) values(#{name},#{age},#{sex})
     </insert>

     <delete id="deleteUser" parameterType="int">
        delete from user where id=#{id}
     </delete>

     <update id="updateUser" parameterType="com.mybatis.bean.User">
        update user set name=#{name},age=#{age},sex=#{sex}  where id=#{id}
     </update>

     <select id="findUserByBean" parameterType="User" resultType="User">
         select * from user where name like '%${name}%' and sex = #{sex}
     </select>

     <select id="findUserByMap" parameterType="hashmap" resultType="User">
         select * from user where name like '%${name}%' and age >= #{age}
     </select>

     <!--
         parameterMap 已经过期不建议使用, 官方已经废除
         resultMap 不建议使用，太复杂
      -->
     <select id="findUserByCustom" parameterType="QueryVo" resultType="User">
         select * from user 

         <!--
             where标签自动将 where后的第一个and去掉，比where 1=1 and 要好很多
             where name like '%${user.name}%' and sex = #{user.sex}
          -->
 <!--         <where> -->
 <!--             <if test=" user != null "> -->
 <!--                 <if test=" user.name != null and user.name != '' "> -->
 <!--                     and name like '%${user.name}%' -->
 <!--                 </if> -->
 <!--                 <if test=" user.sex != null and user.sex != '' "> -->
 <!--                     and sex = #{user.sex} -->
 <!--                 </if> -->
 <!--             </if> -->
 <!--         </where> -->

         <where>
             <include refid="query_for_user"></include>
         </where>

     </select>

     <!--
         不建议使用map作为返回值，因为在代码中需要对key进行硬编码
      -->
 <!--     <select id="findUserMapByCustom" parameterType="QueryVo"  resultType="hashmap"> -->
 <!--         select * from user where name like '%${user.name}%' and sex >= #{user.sex} -->
 <!--     </select> -->

     <update id="updateUserSet" parameterType="User">
         update user
         <set>
             <if test="name != null and name != '' ">
                 name = #{name},
             </if>
             <if test="age != null and age != '' and age != 0 ">
                 age = #{age},
             </if>
             <if test="sex != null and sex != '' ">
                 sex = #{sex},
             </if>
         </set>
         where id = #{id};
     </update>     

 </mapper>

QueryVo.java

 package com.mybatis.bean;

 import java.util.List;

 /**
  * 查询的封装类
  *
  * @author leechenxiang
  * @date 2016年3月5日
  *
  */
 public class QueryVo {

     private User user;

     private UserCustom uc;

     private List<Integer> ids;

     public UserCustom getUc() {
         return uc;
     }

     public void setUc(UserCustom uc) {
         this.uc = uc;
     }

     public User getUser() {
         return user;
     }

     public void setUser(User user) {
         this.user = user;
     }

     public List<Integer> getIds() {
         return ids;
     }

     public void setIds(List<Integer> ids) {
         this.ids = ids;
     }

 }

User.java

 package com.mybatis.bean;

 public class User {

     private int id;
     private String name;
     private int age;
     private String sex;

     public User() {
         super();
     }

     public User(String name, int age, String sex) {
         super();
         this.name = name;
         this.age = age;
         this.sex = sex;
     }

     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 getAge() {
         return age;
     }
     public void setAge(int age) {
         this.age = age;
     }
     public String getSex() {
         return sex;
     }
     public void setSex(String sex) {
         this.sex = sex;
     }

     @Override
     public String toString() {
         return "User [id=" + id + ", name=" + name + ", age=" + age + ", sex="
                 + sex + "]";
     }

 }

UserCustom.java

 package com.mybatis.bean;

 /**
  * 扩展User的自定义类
  * 扩展对象以'XxxxCustom'的格式命名
  *
  * @author leechenxiang
  * @date 2016年3月5日
  *
  */
 public class UserCustom extends User {

     private String youngOrOld;

     public String getYoungOrOld() {
         return youngOrOld;
     }

     public void setYoungOrOld(String youngOrOld) {
         this.youngOrOld = youngOrOld;
     }

 }

最后附上github地址：https://github.com/leechenxiang/mybatis002-dynamic-proxy