mybatis由浅入深day02_9.3.5使用生成的代码_9.4逆向工程注意事项

　　　　9.3.5 使用生成的代码

需要将生成工程中所生成的代码拷贝到自己的工程中。

拷这4个到我们原来的spring_mybatis1216工程下

ItemsMapper.java

package cn.itcast.ssm.mapper;
 
import cn.itcast.ssm.po.Items;
import cn.itcast.ssm.po.ItemsExample;
 
import java.util.List;
 
import org.apache.ibatis.annotations.Param;
 
public interface ItemsMapper {
    int countByExample(ItemsExample example);
    //删除符合条件的记录
    int deleteByExample(ItemsExample example);
    //根据主键删除
    int deleteByPrimaryKey(Integer id);
    //插入对象所有字段
    int insert(Items record);
    //插入对象不为空的字段
    int insertSelective(Items record);
 
    List<Items> selectByExampleWithBLOBs(ItemsExample example);
    //自定义查询条件查询结果集
    List<Items> selectByExample(ItemsExample example);
    //根据主键查询
    Items selectByPrimaryKey(Integer id);
 
    int updateByExampleSelective(@Param("record") Items record, @Param("example") ItemsExample example);
 
    int updateByExampleWithBLOBs(@Param("record") Items record, @Param("example") ItemsExample example);
 
    int updateByExample(@Param("record") Items record, @Param("example") ItemsExample example);
    //根据主键将对象中不为空的值更新至数据库
    int updateByPrimaryKeySelective(Items record);
 
    int updateByPrimaryKeyWithBLOBs(Items record);
    //根据主键将对象中所有字段的值更新至数据库
    int updateByPrimaryKey(Items record);
}

ItemsMapper.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="cn.itcast.ssm.mapper.ItemsMapper" >
  <resultMap id="BaseResultMap" type="cn.itcast.ssm.po.Items" >
    <id column="id" property="id" jdbcType="INTEGER" />
    <result column="name" property="name" jdbcType="VARCHAR" />
    <result column="price" property="price" jdbcType="REAL" />
    <result column="pic" property="pic" jdbcType="VARCHAR" />
    <result column="createtime" property="createtime" jdbcType="TIMESTAMP" />
  </resultMap>
  <resultMap id="ResultMapWithBLOBs" type="cn.itcast.ssm.po.Items" extends="BaseResultMap" >
    <result column="detail" property="detail" jdbcType="LONGVARCHAR" />
  </resultMap>
  <sql id="Example_Where_Clause" >
    <where >
      <foreach collection="oredCriteria" item="criteria" separator="or" >
        <if test="criteria.valid" >
          <trim prefix="(" suffix=")" prefixOverrides="and" >
            <foreach collection="criteria.criteria" item="criterion" >
              <choose >
                <when test="criterion.noValue" >
                  and ${criterion.condition}
                </when>
                <when test="criterion.singleValue" >
                  and ${criterion.condition} #{criterion.value}
                </when>
                <when test="criterion.betweenValue" >
                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                </when>
                <when test="criterion.listValue" >
                  and ${criterion.condition}
                  <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
                    #{listItem}
                  </foreach>
                </when>
              </choose>
            </foreach>
          </trim>
        </if>
      </foreach>
    </where>
  </sql>
  <sql id="Update_By_Example_Where_Clause" >
    <where >
      <foreach collection="example.oredCriteria" item="criteria" separator="or" >
        <if test="criteria.valid" >
          <trim prefix="(" suffix=")" prefixOverrides="and" >
            <foreach collection="criteria.criteria" item="criterion" >
              <choose >
                <when test="criterion.noValue" >
                  and ${criterion.condition}
                </when>
                <when test="criterion.singleValue" >
                  and ${criterion.condition} #{criterion.value}
                </when>
                <when test="criterion.betweenValue" >
                  and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
                </when>
                <when test="criterion.listValue" >
                  and ${criterion.condition}
                  <foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
                    #{listItem}
                  </foreach>
                </when>
              </choose>
            </foreach>
          </trim>
        </if>
      </foreach>
    </where>
  </sql>
  <sql id="Base_Column_List" >
    id, name, price, pic, createtime
  </sql>
  <sql id="Blob_Column_List" >
    detail
  </sql>
  <select id="selectByExampleWithBLOBs" resultMap="ResultMapWithBLOBs" parameterType="cn.itcast.ssm.po.ItemsExample" >
    select
    <if test="distinct" >
      distinct
    </if>
    <include refid="Base_Column_List" />
    ,
    <include refid="Blob_Column_List" />
    from items
    <if test="_parameter != null" >
      <include refid="Example_Where_Clause" />
    </if>
    <if test="orderByClause != null" >
      order by ${orderByClause}
    </if>
  </select>
  <select id="selectByExample" resultMap="BaseResultMap" parameterType="cn.itcast.ssm.po.ItemsExample" >
    select
    <if test="distinct" >
      distinct
    </if>
    <include refid="Base_Column_List" />
    from items
    <if test="_parameter != null" >
      <include refid="Example_Where_Clause" />
    </if>
    <if test="orderByClause != null" >
      order by ${orderByClause}
    </if>
  </select>
  <select id="selectByPrimaryKey" resultMap="ResultMapWithBLOBs" parameterType="java.lang.Integer" >
    select
    <include refid="Base_Column_List" />
    ,
    <include refid="Blob_Column_List" />
    from items
    where id = #{id,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from items
    where id = #{id,jdbcType=INTEGER}
  </delete>
  <delete id="deleteByExample" parameterType="cn.itcast.ssm.po.ItemsExample" >
    delete from items
    <if test="_parameter != null" >
      <include refid="Example_Where_Clause" />
    </if>
  </delete>
  <insert id="insert" parameterType="cn.itcast.ssm.po.Items" >
    insert into items (id, name, price,
      pic, createtime, detail
      )
    values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR}, #{price,jdbcType=REAL},
      #{pic,jdbcType=VARCHAR}, #{createtime,jdbcType=TIMESTAMP}, #{detail,jdbcType=LONGVARCHAR}
      )
  </insert>
  <insert id="insertSelective" parameterType="cn.itcast.ssm.po.Items" >
    insert into items
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        id,
      </if>
      <if test="name != null" >
        name,
      </if>
      <if test="price != null" >
        price,
      </if>
      <if test="pic != null" >
        pic,
      </if>
      <if test="createtime != null" >
        createtime,
      </if>
      <if test="detail != null" >
        detail,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="id != null" >
        #{id,jdbcType=INTEGER},
      </if>
      <if test="name != null" >
        #{name,jdbcType=VARCHAR},
      </if>
      <if test="price != null" >
        #{price,jdbcType=REAL},
      </if>
      <if test="pic != null" >
        #{pic,jdbcType=VARCHAR},
      </if>
      <if test="createtime != null" >
        #{createtime,jdbcType=TIMESTAMP},
      </if>
      <if test="detail != null" >
        #{detail,jdbcType=LONGVARCHAR},
      </if>
    </trim>
  </insert>
  <select id="countByExample" parameterType="cn.itcast.ssm.po.ItemsExample" resultType="java.lang.Integer" >
    select count(*) from items
    <if test="_parameter != null" >
      <include refid="Example_Where_Clause" />
    </if>
  </select>
  <update id="updateByExampleSelective" parameterType="map" >
    update items
    <set >
      <if test="record.id != null" >
        id = #{record.id,jdbcType=INTEGER},
      </if>
      <if test="record.name != null" >
        name = #{record.name,jdbcType=VARCHAR},
      </if>
      <if test="record.price != null" >
        price = #{record.price,jdbcType=REAL},
      </if>
      <if test="record.pic != null" >
        pic = #{record.pic,jdbcType=VARCHAR},
      </if>
      <if test="record.createtime != null" >
        createtime = #{record.createtime,jdbcType=TIMESTAMP},
      </if>
      <if test="record.detail != null" >
        detail = #{record.detail,jdbcType=LONGVARCHAR},
      </if>
    </set>
    <if test="_parameter != null" >
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateByExampleWithBLOBs" parameterType="map" >
    update items
    set id = #{record.id,jdbcType=INTEGER},
      name = #{record.name,jdbcType=VARCHAR},
      price = #{record.price,jdbcType=REAL},
      pic = #{record.pic,jdbcType=VARCHAR},
      createtime = #{record.createtime,jdbcType=TIMESTAMP},
      detail = #{record.detail,jdbcType=LONGVARCHAR}
    <if test="_parameter != null" >
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateByExample" parameterType="map" >
    update items
    set id = #{record.id,jdbcType=INTEGER},
      name = #{record.name,jdbcType=VARCHAR},
      price = #{record.price,jdbcType=REAL},
      pic = #{record.pic,jdbcType=VARCHAR},
      createtime = #{record.createtime,jdbcType=TIMESTAMP}
    <if test="_parameter != null" >
      <include refid="Update_By_Example_Where_Clause" />
    </if>
  </update>
  <update id="updateByPrimaryKeySelective" parameterType="cn.itcast.ssm.po.Items" >
    update items
    <set >
      <if test="name != null" >
        name = #{name,jdbcType=VARCHAR},
      </if>
      <if test="price != null" >
        price = #{price,jdbcType=REAL},
      </if>
      <if test="pic != null" >
        pic = #{pic,jdbcType=VARCHAR},
      </if>
      <if test="createtime != null" >
        createtime = #{createtime,jdbcType=TIMESTAMP},
      </if>
      <if test="detail != null" >
        detail = #{detail,jdbcType=LONGVARCHAR},
      </if>
    </set>
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKeyWithBLOBs" parameterType="cn.itcast.ssm.po.Items" >
    update items
    set name = #{name,jdbcType=VARCHAR},
      price = #{price,jdbcType=REAL},
      pic = #{pic,jdbcType=VARCHAR},
      createtime = #{createtime,jdbcType=TIMESTAMP},
      detail = #{detail,jdbcType=LONGVARCHAR}
    where id = #{id,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="cn.itcast.ssm.po.Items" >
    update items
    set name = #{name,jdbcType=VARCHAR},
      price = #{price,jdbcType=REAL},
      pic = #{pic,jdbcType=VARCHAR},
      createtime = #{createtime,jdbcType=TIMESTAMP}
    where id = #{id,jdbcType=INTEGER}
  </update>
</mapper>

测试ItemsMapper中的方法

ItemsMapperTest.java

package cn.itcast.ssm.mapper;
 
import java.util.Date;
import java.util.List;
 
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
import cn.itcast.ssm.po.Items;
import cn.itcast.ssm.po.ItemsExample;
 
public class ItemsMapperTest {
 
    private ApplicationContext applicationContext;
 
    private ItemsMapper itemsMapper;
 
    //在setUp()这个方法得到spring容器
    @Before
    public void setUp() throws Exception {
        applicationContext = new ClassPathXmlApplicationContext("classpath:spring/applicationContext.xml");
        itemsMapper = (ItemsMapper) applicationContext.getBean("itemsMapper");
    }
 
    //自定义条件查询
    @Test
    public void testSelectByExample() {
        ItemsExample itemsExample = new ItemsExample();
        //通过criteria构造查询条件
        ItemsExample.Criteria criteria = itemsExample.createCriteria();
        criteria.andNameEqualTo("笔记本");
        //可能返回多条记录
        List<Items> list = itemsMapper.selectByExample(itemsExample);
        System.out.println(list);
    }
 
    //根据主键查询
    @Test
    public void testSelectByPrimaryKey() {
        Items items = itemsMapper.selectByPrimaryKey(1);
        System.out.println(items);
    }
 
    //插入
    @Test
    public void testInsert() {
        //构造items对象
        Items items = new Items();
        items.setName("手机");
        items.setPrice(900f);
        items.setDetail("不错");
        items.setCreatetime(new Date());
        itemsMapper.insert(items);
    }
 
    //根据主键删除
    @Test
    public void testDeleteByPrimaryKey() {
        itemsMapper.deleteByPrimaryKey(4);
    }
 
    //更新数据
    @Test
    public void testUpdateByPrimaryKey() {
        //对所有字段进行更新，需要先查询出来再更新
        Items items = itemsMapper.selectByPrimaryKey(1);
        items.setName("水杯");
 
        itemsMapper.updateByPrimaryKey(items);
        //如果传入字段不空为才更新，在批量更新中使用此方法，不需要先查询再更新
        //itemsMapper.updateByPrimaryKeySelective(record);
    }
}

　　9.4 逆向工程注意事项

　　　　9.4.1 Mapper文件内容不覆盖而是追加

XXXMapper.xml文件已经存在时，如果进行重新生成则mapper.xml文件内容不被覆盖而是进行内容追加，结果导致mybatis解析失败。

解决方法：删除原来已经生成的mapper xml文件再进行生成。

Mybatis自动生成的po及mapper.java文件不是内容而是直接覆盖没有此问题。

　　　　9.4.2 Table schema问题

下边是关于针对oracle数据库表生成代码的schema问题：

Schma即数据库模式，oracle中一个用户对应一个schema，可以理解为用户就是schema。

当Oralce数据库存在多个schema可以访问相同的表名时，使用mybatis生成该表的mapper.xml将会出现mapper.xml内容重复的问题，结果导致mybatis解析错误。

解决方法：在table中填写schema，如下：

<table schema="XXXX" tableName=" " >

XXXX即为一个schema的名称，生成后将mapper.xml的schema前缀批量去掉，如果不去掉当oracle用户变更了sql语句将查询失败。

快捷操作方式：mapper.xml文件中批量替换：“from XXXX.”为空

Oracle查询对象的schema可从dba_objects中查询，如下：

select * from dba_objects