1 在接口中书写方法

public interface EmployeeMapperDynamicSQL {

public List<Employee> getEmpsTestInnerParameter(Employee employee);

}

2在映射中进行配置

 

<!-- 查询员工，要求，携带了哪个字段查询条件就带上这个字段的值 -->

<!-- public List<Employee> getEmpsByConditionIf(Employee employee); -->

<select id="getEmpsByConditionIf" resultType="com.atguigu.mybatis.bean.Employee">

select * from tbl_employee

<!-- where -->

<where>

<!-- test：判断表达式（OGNL）

OGNL参照PPT或者官方文档。

c:if test

从参数中取值进行判断

遇见特殊符号应该去写转义字符：

&&：

-->

<if test="id!=null">

id=#{id}

</if><!-- &amp;为& &quot;为“ -->

<if test="lastName!=null &amp;&amp; lastName!=&quot;&quot;">

and last_name like #{lastName}

</if>

<if test="email!=null and email.trim()!=&quot;&quot;">

and email=#{email}

</if>

<!-- ognl会进行字符串与数字的转换判断 "0"==0 -->

<if test="gender==0 or gender==1">

and gender=#{gender}

</if>

</where>

</select>

3进行测试

public SqlSessionFactory getSqlSessionFactory() throws IOException {

String resource = "mybatis-config.xml";

InputStream inputStream = Resources.getResourceAsStream(resource);

return new SqlSessionFactoryBuilder().build(inputStream);

}

@Test

public void testDynamicSql() throws IOException{

SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();

SqlSession openSession = sqlSessionFactory.openSession();

try{

EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);

//select * from tbl_employee where id=? and last_name like ?

//测试if\where

Employee employee = new Employee(null, "jerry2", null, null);

List<Employee> emps = mapper.getEmpsByConditionIf(employee );

for (Employee emp : emps) {

System.out.println(emp);

}

}finally{

openSession.close();

}

}