说明：
if:判断
• choose (when, otherwise):分支选择；带了break的swtich-case
如果带了id就用id查，如果带了lastName就用lastName查;只会进入其中一个
• trim 字符串截取(where(封装查询条件), set(封装修改条件))
• foreach 遍历集合
目录结构：
主要测试写在各包的DynamicSQL文件中；
一、if & if-where & if-trim：判断；
实例说明：查询员工，携带什么字段查询添加就带上什么字段；
接口文件EmployeeMapper.java：
1 package dao;
2
3 import java.util.List;
4
5 import entity.Employee;
6
7 public interface EmployeeMapperDynamicSQL {
8
9 List<Employee> getList(Employee employee);
10 List<Employee>(Employeeemployee);
11 List<Employee>(Employeeemployee);
12
映射文件EmployeeMapper.xml (if)
- 版本1-if: 给where后面加1=1 以后条件都 and xxx
1 <?xml version="1.0" encoding="UTF-8" ?>
2 <!DOCTYPE mapper
3 PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
4 "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
5 <mapper namespace="dao.EmployeeMapperDynamicSQL">
9 <!-- 查询员工，携带什么字段查询添加就带上什么字段 -->
10 <select id="getList" resultType="entity.Employee">
11 select id as id,
12 last_name as lastName,
13 email as email,
14 gender as gender
15 from tbl_employee
16 where 1=1
17 <!-- test 判断表达式(OGNL) OGNL 参照Apache官方文档 从参数中取值 进行判断 遇见特殊符号应该写转义字符 & ：&
18 也可以写 and ognl 会进行字符串和数字的转换 status==200 即 ”200“ 和 200可以比较 -->
19 <if test="lastName!='' and lastName!=null">
20 and last_name like #{lastName}
21 </if>
22 <if test="email!='' and email!=null">
23 and email like #{email}
24 </if>
25 <if test="gender!='' and gender!=null">
26 and gender like #{gender}
27 </if>
28
29 </select>
30
31 </mapper>
映射文件EmployeeMapper.xml (if-where)
- 版本2-if-where：<where> 标签 给mybatis使用where标签来将所有的查询条件包括在内，mybatis就会将标签中拼装SQL，多出来的and或者or去掉
- where 只会去掉第一个 and 或者 or
1 <!-- 查询员工，携带什么字段查询添加就带上什么字段 <where> -->
2 <select id="getListWhere" resultType="entity.Employee">
3 select id as id,
4 last_name as lastName,
5 email as email,
6 gender as gender
7 from tbl_employee
8 <!-- 查询的时候如果某些条件没带可能sql拼装会有问题 1.给where后面加1=1 以后条件都 and xxx 2.给mybatis使用where标签来将所有的查询条件包括在内，mybatis就会将标签中拼装SQL，多出来的and或者or去掉
9 //where 只会去掉第一个 and 或者 or -->
10 <where>
11 <if test="lastName!='' and lastName!=null">
12 last_name like #{lastName}
13 </if>
14 <if test="email!='' and email!=null">
15 and email like #{email}
16 </if>
17 <if test="gender!='' and gender!=null">
18 and gender like #{gender}
19 </if>
20 </where>
21 </select>
映射文件EmployeeMapper.xml (if-trim)
- 版本3-if-trim：后面多出的and或者or where标签不能解决(推荐)
prefix="":前缀：trim标签体中是整个字符串拼接后的结果 prefix给拼接后的整个字符串加一个前缀
prefixOverdides="": 前缀覆盖：去掉整个字符串前面多余的字符串
suffix=”“： 后缀 suffix给拼接后的整个字符串加一个后缀
suffixOverrides="" 后缀覆盖：去掉整个字符串后面多余的字符串
1 <!-- 查询员工，携带什么字段查询添加就带上什么字段 <where> -->
2 <select id="getListTrim" resultType="entity.Employee">
3 select id as id,
4 last_name as lastName,
5 email as email,
6 gender as gender
7 from tbl_employee
11 <!-- 自定义字符串截取规则 -->
12 <trim prefix="where" suffixOverrides="and">
13 <if test="lastName!='' and lastName!=null">
14 last_name like #{lastName} and
15 </if>
16 <if test="email!='' and email!=null">
17 email like #{email} and
18 </if>
19 <if test="gender!='' and gender!=null">
20 gender like #{gender}
21 </if>
22 </trim>
23 </select>
junit测试类：
1 @Test
2 public void test01() {
3 String resource = "mybatis-config.xml";
4 SqlSession openSession = null;
5 try {
6 InputStream inputStream = Resources.getResourceAsStream(resource);
7 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
8 // 获取openSession 不会自动提交数据
9 openSession = sqlSessionFactory.openSession(true);
10 EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
11 Employee emp = new Employee();
12 emp.setLastName("%x%");
13 List<Employee> testResultType = mapper.getList(emp);
14 List<Employee> testResultTypeWhere = mapper.getListWhere(emp);
15 List<Employee> testResultTypeTrim = mapper.getListTrim(emp);
16 System.out.println("测试 if：" + testResultType);
17 System.out.println("测试 if where：" + testResultTypeWhere);
18 System.out.println("测试 if Trim：" + testResultTypeTrim);
19
20 } catch (Exception e) {
21 // TODO: handle exception
22 } finally {
23 if (openSession != null) {
24 openSession.close();
25 }
26
27 }
28
运行结果：
测试 if：[Employee [id=2, lastName=joy2x22222, email=joy52112225@iclound.com, gender=男]]
测试 if where：[Employee [id=2, lastName=joy2x22222, email=joy52112225@iclound.com, gender=男]]
测试 if Trim：[Employee [id=2, lastName=joy2x22222, email=joy52112225@iclound.com, gender=男]]
二、 choose：只进入一个查询；
接口文件EmployeeMapper.java：
List<Employee> getListChoose(Employee employee);
映射文件EmployeeMapper.xml
1 <select id="getListChoose" resultType="entity.Employee">
2 select id as id,
3 last_name as lastName,
4 email as email,
5 gender as gender
6 from tbl_employee
7 <where>
8 <choose>
9 <when test="id!=null">
10 id = #{id}
11 </when>
12 <when test="lastName!=null">
13 last_name like #{lastName}
14 </when>
15 <when test="email!=null">
16 email like #{email}
17 </when>
18 <otherwise>
19 1=1
20 </otherwise>
21 </choose>
22 </where>
23
24 </select>
junit测试类：
1 @Test
2 public void test02() {
3 String resource = "mybatis-config.xml";
4 SqlSession openSession = null;
5 try {
6 InputStream inputStream = Resources.getResourceAsStream(resource);
7 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
8 // 获取openSession 不会自动提交数据
9 openSession = sqlSessionFactory.openSession(true);
10 EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
11 Employee emp = new Employee();
12 emp.setEmail("%112225%");
13 List<Employee> testResultType = mapper.getListChoose(emp);
14 System.out.println("测试 choose：" + testResultType);
15 } catch (Exception e) {
16 // TODO: handle exception
17 } finally {
18 if (openSession != null) {
19 openSession.close();
20 }
21
22 }
23
运行结果：
测试 choose：[Employee [id=1, lastName=joy33333, email=joy52112225@iclound.com, gender=女], Employee [id=2, lastName=joy2x22222, email=joy52112225@iclound.com, gender=男]]
三、set
更新数据的时候，如果直接写set 很容器出现 “,”多出来的问题；这里直接用trim来解决该问题；
接口文件EmployeeMapper.java：
void
映射文件EmployeeMapper.xml
1 <!-- trim 方式实现更新 -->
2 <update id="updateEmpTrim" parameterType="entity.Employee">
3 update tbl_employee
4 <trim prefix="set" suffixOverrides=",">
5 <if test="lastName!=null">
6 last_name = #{lastName},
7 </if>
8 <if test="email!=null">
9 email=#{email},
10 </if>
11 <if test="gender!=null">
12 gender = #{gender}
13 </if>
14 </trim>
15
16 where id = #{id}
17 </update>
junit测试类：
1 @Test
2 public void test03() {
3 String resource = "mybatis-config.xml";
4 SqlSession openSession = null;
5 try {
6 InputStream inputStream = Resources.getResourceAsStream(resource);
7 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
8 // 获取openSession 不会自动提交数据
9 openSession = sqlSessionFactory.openSession(true);
10 EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
11 Employee emp = new Employee();
12 emp.setEmail("1602211057@qq.com");
13 emp.setId(7);
14 // mapper.updateEmp(emp);
15 mapper.updateEmpTrim(emp);
16 } catch (Exception e) {
17 // TODO: handle exception
18 } finally {
19 if (openSession != null) {
20 openSession.close();
21 }
22
23
四、foreach
foreach的时候最关键的也是最容易出错的就是collection属性，该属性是必须指定的，但是在不同情况 下，该属性的值是不一样的，主要有一下3种情况：
1. 如果传入的是单参数且参数类型是一个List的时候，collection属性值为list;如果User有属性List ids。入参是User对象，那么这个collection = "ids"；如果User有属性Ids ids;其中Ids是个对象，Ids有个属性List id;入参是User对象，那么collection = "ids.id"；
2. 如果传入的是单参数且参数类型是一个array数组的时候，collection的属性值为array；
3. 如果使用Map封装了，collection的属性值为对应的Key；
以下例子以list 的3中情况为实例，array 和 map不做赘述；
情况一：传入的是单参数且参数类型是一个List的时候
接口文件EmployeeMapper.java：
List<Employee> getEmpsByConditionForeach(List<Integer> ids);
映射文件EmployeeMapper.xml
1 <select id="getEmpsByConditionForeach" resultType="entity.Employee" parameterType="java.lang.Integer">
2 select * from tbl_employee where id in
3
4 <!--
5 collection:指定要遍历的集合
6 list类型的参数会封装在map中，map的key就是list
7 itme:将当前遍历出的元素赋值给指定的变量
8 #{变量名}就能取出变量的值也就是当前遍历出的元素
9 separator:元素的分割符
10 open:遍历出所有结果拼接一个开始字符
11 close：遍历出所有结果拼接一个结束字符
12 index:索引。遍历list的时候 index 是索引 item 就是值 遍历map的时候index表示就是map的key,item就是map的值
13 -->
14 <foreach collection="list" item="item_id" separator="," open="(" close=")" index="">
15 #{item_id }
16 </foreach>
17 </select>
junit测试类：
1 @Test
2 public void test04() {
3 String resource = "mybatis-config.xml";
4 SqlSession openSession = null;
5 try {
6 InputStream inputStream = Resources.getResourceAsStream(resource);
7 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
8 // 获取openSession 不会自动提交数据
9 openSession = sqlSessionFactory.openSession(true);
10 EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
11 List<Integer> list = Arrays.asList(1, 2, 3);
12 List<Employee> empList = mapper.getEmpsByConditionForeach(list);
13 System.out.println(empList);
14 } catch (Exception e) {
15 // TODO: handle exception
16 } finally {
17 if (openSession != null) {
18 openSession.close();
19 }
20
21 }
22
运行结果：
[Employee [id=1, lastName=null, email=joy52112225@iclound.com, gender=女], Employee [id=2, lastName=null, email=joy52112225@iclound.com, gender=男]]
情况二：传入的是一个实体且参数类型是一个List
给Employee实体添加了一个List<Integer> ids 私有成员变量； 该情况下，foreach 标签的collection 属性的值必须是ids，否则，就执行失败；
Employee 实体：
1 package entity;
2
3 import java.util.List;
4
5 public class Employee {
6
7 private Integer id;
8 private String lastName;
9 private String email;
10 private String gender;
11 private List<Integer> ids;
12
13 public Integer getId() {
14 return id;
15 }
16
17 public void setId(Integer id) {
18 this.id = id;
19 }
20
21 public String getLastName() {
22 return lastName;
23 }
24
25 public void setLastName(String lastName) {
26 this.lastName = lastName;
27 }
28
29 public String getEmail() {
30 return email;
31 }
32
33 public void setEmail(String email) {
34 this.email = email;
35 }
36
37 public String getGender() {
38 return gender;
39 }
40
41 public void setGender(String gender) {
42 this.gender = gender;
43 }
44
45 public List<Integer> getIds() {
46 return ids;
47 }
48
49 public void setIds(List<Integer> ids) {
50 this.ids = ids;
51 }
52
53 @Override
54 public String toString() {
55 return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email + ", gender=" + gender + "]";
56 }
57
58
View Code
接口文件EmployeeMapper.java：
List<Employee> getEmpsByConditionForeach2(Employee employee);
映射文件EmployeeMapper.xml
1 <select id="getEmpsByConditionForeach2" resultType="entity.Employee" parameterType="entity.Employee">
2 select * from tbl_employee where id in
3 <foreach collection="ids" item="item_id" separator="," open="(" close=")" index="">
4 #{item_id }
5 </foreach>
6 </select>
junit测试类：
1 @Test
2 public void test04() {
3 String resource = "mybatis-config.xml";
4 SqlSession openSession = null;
5 try {
6 InputStream inputStream = Resources.getResourceAsStream(resource);
7 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
8 // 获取openSession 不会自动提交数据
9 openSession = sqlSessionFactory.openSession(true);
10 EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
11 List<Integer> list = Arrays.asList(1, 2, 3);
12 Employee employee = new Employee();
13 employee.setIds(list);
14 List<Employee> empList = mapper.getEmpsByConditionForeach2(employee);
15 System.out.println(empList);
16 } catch (Exception e) {
17 // TODO: handle exception
18 } finally {
19 if (openSession != null) {
20 openSession.close();
21 }
22
23 }
24
运行结果同情况1；
情况三：传入的是一个实体且参数也是一个实体；
该情况下，foreach collection属性就是该实体的list属性值；
也就是说 ids 在 Employee.java实体 的 department成员变量的 ids中;
Employee 实体：
1 package entity;
2
3 public class Employee {
4
5 private Integer id;
6 private String lastName;
7 private String email;
8 private String gender;
9 private Department department;
10
11 public Integer getId() {
12 return id;
13 }
14
15 public void setId(Integer id) {
16 this.id = id;
17 }
18
19 public String getLastName() {
20 return lastName;
21 }
22
23 public void setLastName(String lastName) {
24 this.lastName = lastName;
25 }
26
27 public String getEmail() {
28 return email;
29 }
30
31 public void setEmail(String email) {
32 this.email = email;
33 }
34
35 public String getGender() {
36 return gender;
37 }
38
39 public void setGender(String gender) {
40 this.gender = gender;
41 }
42
43 public Department getDepartment() {
44 return department;
45 }
46
47 public void setDepartment(Department department) {
48 this.department = department;
49 }
50
51 @Override
52 public String toString() {
53 return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email + ", gender=" + gender + "]";
54 }
55
56
View Code
Department实体：
1 package entity;
2
3 import java.util.List;
4
5 public class Department {
6
7 private Integer id;
8 private String departmentName;
9 private List<Employee> empList;
10 private List<Integer> ids;
11
12 public Integer getId() {
13 return id;
14 }
15
16 public void setId(Integer id) {
17 this.id = id;
18 }
19
20 public String getDepartmentName() {
21 return departmentName;
22 }
23
24 public void setDepartmentName(String departmentName) {
25 this.departmentName = departmentName;
26 }
27
28 public List<Employee> getEmpList() {
29 return empList;
30 }
31
32 public void setEmpList(List<Employee> empList) {
33 this.empList = empList;
34 }
35
36 public List<Integer> getIds() {
37 return ids;
38 }
39
40 public void setIds(List<Integer> ids) {
41 this.ids = ids;
42 }
43
44 @Override
45 public String toString() {
46 return "Department [id=" + id + ", departmentName=" + departmentName + "]";
47 }
48
49
View Code
接口文件EmployeeMapper.java：同情况二
映射文件EmployeeMapper.xml：
1 <select id="getEmpsByConditionForeach2" resultType="entity.Employee" parameterType="entity.Employee">
2 select * from tbl_employee where id in
3 <foreach collection="department.ids" item="item_id" separator="," open="(" close=")" index="">
4 #{item_id }
5 </foreach>
6 </select>
junit测试类：同情况二
运行结果同上；
情况四 foreach 循环map的情况
入参设置：
1 @Override
2 public PageInfo<Map<String, Object>> list(Employee employee) {
3 FiledDao f1 = new FiledDao();
4 f1.setColName("TEST_COL1");
5 f1.setFieldName("field1");
6 f1.setFileType("string");
7 FiledDao f2 = new FiledDao();
8 f2.setColName("TEST_COL2");
9 f2.setFieldName("field2");
10 f2.setFileType("list");
11 FiledDao f3 = new FiledDao();
12 f3.setColName("TEST_COL3");
13 f3.setFieldName("field3");
14 f3.setFileType("bool");
15 FiledDao f4 = new FiledDao();
16 f4.setColName("TEST_COL4");
17 f4.setFieldName("field4");
18 f4.setFileType("number");
19 List<FiledDao> list = new ArrayList<>();
20 list.add(f1);
21 list.add(f2);
22 list.add(f3);
23 list.add(f4);
24 employee.setList(list);
25 Map<String, String> map = new HashMap<>();
26 employee.setMap(map);
27 map.put("TEST_COL1", "stringstring");
28 map.put("TEST_COL2", "listlist");
29 map.put("TEST_COL3", "Y");
30 map.put("TEST_COL4", "20");
31 map.put("TEST_COL4", "40");
32 return employeeMapper.list(employee);
33
View Code
入参实体类：
1 package ssm.entity;
2
3 import java.util.List;
4 import java.util.Map;
5
6 public class Employee extends CommonEntity {
7
8 private Integer id;
9 private String lastName;
10 private String email;
11 private String gender;
12
13 private List<FiledDao> list;
14 private Map<String, String> map;
15
16 public Integer getId() {
17 return id;
18 }
19
20 public void setId(Integer id) {
21 this.id = id;
22 }
23
24 public String getLastName() {
25 return lastName;
26 }
27
28 public void setLastName(String lastName) {
29 this.lastName = lastName;
30 }
31
32 public String getEmail() {
33 return email;
34 }
35
36 public void setEmail(String email) {
37 this.email = email;
38 }
39
40 public String getGender() {
41 return gender;
42 }
43
44 public void setGender(String gender) {
45 this.gender = gender;
46 }
47
48 public List<FiledDao> getList() {
49 return list;
50 }
51
52 public void setList(List<FiledDao> list) {
53 this.list = list;
54 }
55
56 public Map<String, String> getMap() {
57 return map;
58 }
59
60 public void setMap(Map<String, String> map) {
61 this.map = map;
62 }
63
64 @Override
65 public String toString() {
66 return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email + ", gender=" + gender + "]";
67 }
68
69
View Code
sql语句：
1 <!-- 查询列表 -->
2 <select id="list" resultType="map">
3 select id,last_name as
4 lastName,email,gender
5 <foreach collection="list" item="item" open="," separator=",">
6 ${item.colName} AS ${item.fieldName}
7 </foreach>
8 from tbl_employee_test
9 where 1=1
10
11 <foreach collection="map" item="value" index="ey" open="" separator="">
12 <foreach collection="list" item="item" open="" separator="">
13 <if test="item.fileType =='string' and key == item.colName">
14 and ${item.colName} like concat("%",#{value,jdbcType=VARCHAR},"%")
15 </if>
16 <if test="item.fileType =='list' and key == item.colName">
17 and ${item.colName} = #{value,jdbcType=VARCHAR}
18 </if>
19 <if test="item.fileType =='bool'and key == item.colName">
20 and ${item.colName} = #{value,jdbcType=VARCHAR}
21 </if>
22 <if test="item.fileType =='number' and key == item.colName">
23 and ${item.colName} = #{value,jdbcType=INTEGER}
24 </if>
25 </foreach>
26 </foreach>
27 </select>
五、批量插入
接口文件EmployeeMapper.java：
void
映射文件EmployeeMapper.xml
MySQL版本：
1 <insert id="insertEmps" parameterType="entity.Employee" useGeneratedKeys="true" keyProperty="id">
2 insert into tbl_employee(last_name,gender,email) values
3 <foreach collection="list" item="item" separator=",">
4 (#{item.lastName},#{item.gender},#{item.email})
5 </foreach>
6 </insert>
Oracle版本方式1：
1 <insert id="insertBatChOracle">
2 <foreach collection="list" item="item" open="begin" close="end">
3 insert into tbl_employee(id,last_name,email)
4 values(employees_seq.nextval,#{item.lastName},#{item.email});_
5 </foreach>
6
7 </insert>
Oracle版本方式2：
1 <insert id="insertBatChOracle">
2 insert into tbl_employee(id,last_name,email)
3 select employees_seq.nextval,lastName,email from(
4 <foreach collection="list" item="item" separator="union">
5 select #{item.lastName},#{item.email} from dual
6 </foreach>
7 )
8 </insert>
junit测试类：
1 @Test
2 public void test05() {
3 String resource = "mybatis-config.xml";
4 SqlSession openSession = null;
5 try {
6 InputStream inputStream = Resources.getResourceAsStream(resource);
7 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
8 // 获取openSession 不会自动提交数据
9 openSession = sqlSessionFactory.openSession(true);
10 EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
11 Employee employee1 = new Employee();
12 employee1.setLastName("zhumama");
13 employee1.setEmail("zhumama@166.com");
14 Employee employee2 = new Employee();
15 employee2.setLastName("zhubaba");
16 employee2.setEmail("zhubaba@166.com");
17 List<Employee> list = new ArrayList<Employee>();
18 list.add(employee1);
19 list.add(employee2);
20 mapper.insertEmps(list);
21 } catch (Exception e) {
22 // TODO: handle exception
23 } finally {
24 if (openSession != null) {
25 openSession.close();
26 }
27
28 }
29
六：内置参数：_parameter、_databaseId
mybatis默认两个内置参数：
1._parameter:代表整个参数
- 单参数：_parameter就是这个参数
- 多个参数：参数会封装为一个map；_parameter就代表整个参数
2._databaseId：如果配置了 DatabaseIdProvider标签 那么 databaseId 就是当前数据库的别名
全局配置文件：
1 <?xml version="1.0" encoding="UTF-8" ?>
2 <!DOCTYPE configuration
3 PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
4 "http://mybatis.org/dtd/mybatis-3-config.dtd">
5 <configuration>
6 <properties resource="dbconfig.properties"></properties>
7
8 <environments default="development">
9 <environment id="development">
10 <transactionManager type="JDBC" />
11 <dataSource type="POOLED">
12 <property name="driver" value="${jdbc.driver}" />
13 <property name="url" value="${jdbc.url}" />
14 <property name="username" value="${jdbc.username}" />
15 <property name="password" value="${jdbc.password}" />
16 </dataSource>
17 </environment>
18 <environment id="development_mysql2">
19 <transactionManager type="JDBC" />
20 <dataSource type="POOLED">
21 <property name="driver" value="${jdbc2.driver}" />
22 <property name="url" value="${jdbc2.url}" />
23 <property name="username" value="${jdbc2.username}" />
24 <property name="password" value="${jdbc2.password}" />
25 </dataSource>
26 </environment>
27 </environments>
28
29 <databaseIdProvider type="DB_VENDOR">
30 <!-- 为不同的数据库厂商取别名 -->
31 <property name="MySQL" value="mysql" />
32 <property name="Oracle" value="oracle" />
33 <property name="SQL Server" value="sqlserver" />
34 </databaseIdProvider>
35 <mappers>
36 <package name="dao" />
37 </mappers>
38 </configuration>
接口文件EmployeeMapper.java：
List<Employee> getEmpsTestInnerParam(Employee employee);
映射文件EmployeeMapper.xml
1 <select id="getEmpsTestInnerParam" parameterType="entity.Employee" resultType="entity.Employee">
2 <!-- bind:可以将ognl 表达式的值绑定到一个变量中，方面后来引用这个变量的值 -->
3
4 <if test="_databaseId=='mysql'">
5 select * from tbl_employee
6 <if test="_parameter!=null">
7 <where>
8 <if test="id!=null">
9 id=#{id}<!-- 也可以这么写 id=#{_parameter.id} -->10 </if>
11 <if test="lastName!=null">
12 <bind name="_lastanme" value="'%'+lastName+'%'"/>
13 and last_name like #{_lastanme}<!-- 也可以这么写 id=#{_parameter.id} -->
14 </if>
15 </where>
16 </if>
17 </if>
18 </select>
junit测试类：
1 @Test
2 public void test06() {
3 String resource = "mybatis-config.xml";
4 SqlSession openSession = null;
5 try {
6 InputStream inputStream = Resources.getResourceAsStream(resource);
7 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
8 // 获取openSession 不会自动提交数据
9 openSession = sqlSessionFactory.openSession(true);
10 EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
11 List<Employee> list = mapper.getEmpsTestInnerParam(null);
12 System.out.println(list);
13 Employee employee = new Employee();
14 // employee.setId(1);
15 employee.setLastName("zhu");
16 List<Employee> list1 = mapper.getEmpsTestInnerParam(employee);
17 System.out.println(list1);// List<Employee> list2 = mapper.getListSqlSegment(null);
18 } catch (Exception e) {
19 // TODO: handle exception
20 } finally {
21 if (openSession != null) {
22 openSession.close();
23 }
24
25 }
26
View Code
运行结果：
[Employee [id=9, lastName=null, email=zhumama@166.com, gender=null], Employee [id=10, lastName=null, email=zhubaba@166.com, gender=null], Employee [id=11, lastName=null, email=zhumama@166.com, gender=null], Employee [id=12, lastName=null, email=zhubaba@166.com, gender=null], Employee [id=13, lastName=null, email=zhumama@166.com, gender=null], Employee [id=14, lastName=null, email=zhubaba@166.com, gender=null], Employee [id=27, lastName=null, email=zhumama@166.com, gender=null], Employee [id=28, lastName=null, email=zhubaba@166.com, gender=null], Employee [id=29, lastName=null, email=zhumama@166.com, gender=null], Employee [id=30, lastName=null, email=zhubaba@166.com, gender=null], Employee [id=31, lastName=null, email=zhumama@166.com, gender=null], Employee [id=32, lastName=null, email=zhubaba@166.com, gender=null]]
七 、sql 片段
抽取可重用的SQL 片段 方便以后引用
sql抽取，经常将要查询的类名，或者插入用的列名抽取出来方便引用
2.include 来引用已经抽取的SQL
3.include 还可以自定义一些property SQL标签内部就能使用自定义属性
include-property：取值的正确方式${prop}
#{不能使用这种方式}
refid="com.common.dao.FunctionDao.SF_GET_LNG_RES_TYPE">
<property name="AI_RES_TYPE_ID" value="a.res_type_id"/>
lng" value="#{lngId}"/>
<property name="female" value="'女'"/>
</include>
应用实例举例：
接口文件EmployeeMapper.java：
List<Employee> getListSqlSegment(Employee employee);
映射文件EmployeeMapper.xml
1 <select id="getListSqlSegment" resultType="entity.Employee">
2 select
3 <!-- 引用外部定义的SQL -->
4 <include refid="searchColumn"></include> 5 from tbl_employee
6 where 1=1
7 <!-- test 判断表达式(OGNL) OGNL 参照Apache官方文档 从参数中取值 进行判断 遇见特殊符号应该写转义字符 & ：&
8 也可以写 and ognl 会进行字符串和数字的转换 status==200 即 ”200“ 和 200可以比较 -->
9 <if test="lastName!='' and lastName!=null">
10 and last_name like #{lastName}
11 </if>
12 <if test="email!='' and email!=null">
13 and email like #{email}
14 </if>
15 <if test="gender!='' and gender!=null">
16 and gender like #{gender}
17 </if>
18
19 </select>
1 <sql id="searchColumn">
2 id as id,
3 last_name as lastName,
4 email as email,
5 gender as gender
6 </sql>
junit测试类：
1 @Test
2 public void test06() {
3 String resource = "mybatis-config.xml";
4 SqlSession openSession = null;
5 try {
6 InputStream inputStream = Resources.getResourceAsStream(resource);
7 SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
8 // 获取openSession 不会自动提交数据
9 openSession = sqlSessionFactory.openSession(true);
10 EmployeeMapperDynamicSQL mapper = openSession.getMapper(EmployeeMapperDynamicSQL.class);
11 List<Employee> list2 = mapper.getListSqlSegment(null);
12 System.out.println(list2);
13 } catch (Exception e) {
14 // TODO: handle exception
15 } finally {
16 if (openSession != null) {
17 openSession.close();
18 }
19
20 }
21
运行结果：
[Employee [id=1, lastName=joy33333, email=joy52112225@iclound.com, gender=女], Employee [id=2, lastName=joy2x22222, email=joy52112225@iclound.com, gender=男], Employee [id=4, lastName=joy, email=joy521125@iclound.com, gender=女], Employee [id=5, lastName=joy, email=joy521125@iclound.com, gender=女], Employee [id=6, lastName=joy, email=joy521125@iclound.com, gender=女], Employee [id=7, lastName=joy, email=1602211057@qq.com, gender=女], Employee [id=8, lastName=joy, email=1602211058@qq.com, gender=女], Employee [id=9, lastName=zhumama, email=zhumama@166.com, gender=null], Employee [id=10, lastName=zhubaba, email=zhubaba@166.com, gender=null], Employee [id=11, lastName=zhumama, email=zhumama@166.com, gender=null], Employee [id=12, lastName=zhubaba, email=zhubaba@166.com, gender=null], Employee [id=13, lastName=zhumama, email=zhumama@166.com, gender=null], Employee [id=14, lastName=zhubaba, email=zhubaba@166.com, gender=null], Employee [id=15, lastName=Tom, email=678@qq.com, gender=男], Employee [id=16, lastName=Tom, email=678@qq.com, gender=男], Employee [id=17, lastName=Tom, email=678@qq.com, gender=男], Employee [id=18, lastName=Tom, email=678@qq.com, gender=男], Employee [id=19, lastName=Tom, email=678@qq.com, gender=男], Employee [id=20, lastName=Tom, email=678@qq.com, gender=男], Employee [id=21, lastName=Tom, email=678@qq.com, gender=男], Employee [id=22, lastName=Tom, email=678@qq.com, gender=男], Employee [id=23, lastName=Tom, email=678@qq.com, gender=男], Employee [id=25, lastName=joy1111, email=joy521125@icloud.com, gender=女], Employee [id=26, lastName=joy222, email=joy521125@icloud.com, gender=女], Employee [id=27, lastName=zhumama, email=zhumama@166.com, gender=null], Employee [id=28, lastName=zhubaba, email=zhubaba@166.com, gender=null], Employee [id=29, lastName=zhumama, email=zhumama@166.com, gender=null], Employee [id=30, lastName=zhubaba, email=zhubaba@166.com, gender=null], Employee [id=31, lastName=zhumama, email=zhumama@166.com, gender=null], Employee [id=32, lastName=zhubaba, email=zhubaba@166.com, gender=null]]
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