MyBatis
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一、MyBatis简介
MyBatis是支持普通SQL查询,存储过程和高级映射的优秀持久层框架。
MyBatis消除了几乎所有的JDBC代码和参数的手工设置以及对结果集的检索封装。
MyBatis可以使用简单的XML或注解用于配置和原始映射,将接口和Java的POJO(Plain Old Java Objects,普通的Java对象)映射成数据库中的记录.
JDBC -> dbutils(自动封装) -> MyBatis -> Hibernate
mybatis是将sql写在xml中,然后去访问数据库。
二、MyBatis快速入门
2.1.新建java项目
添加mybatis和mysql的驱动jar:mybatis-3.1.1.jar,mysql-connector-java-5.1.7-bin.jar
2.2.新建表
create database mybatis;
use mybatis;
create table users(id int primary key auto_increment, name varchar(20), age int);
insert into users (name,age) values('Tom',12);
insert into users (name, age) values('Jack',11);
2.3.添加mybatis的配置文件conf.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>
<environments
default
=
"development"
>
<environment id=
"development"
>
<transactionManager type=
"JDBC"
/>
<dataSource type=
"POOLED"
>
<property name=
"driver"
value=
"com.mysql.jdbc.Driver"
/>
<property name=
"url"
value=
"jdbc:mysql://localhost:3306/mybatis"
/>
<property name=
"username"
value=
"root"
/>
<property name=
"password"
value=
"root"
/>
</dataSource>
</environment>
</environments>
</configuration>
2.4.定义表对应的实体类
public
class
User {
private
int
id;
private
String name;
private
int
age;
//get,set方法
}
2.5.定义操作users表的sql映射文件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.atguigu.mybatis_test.test1.userMapper"
>
<select id=
"getUser"
parameterType=
"int"
resultType=
"com.atguigu.mybatis_test.test1.User"
>
select * from users where id=#{id}
</select>
</mapper>
2.6.在conf.xml文件中注册userMapper.xml文件
<mappers>
<mapper resource=
"com/atguigu/mybatis_test/test1/userMapper.xml"
/>
</mappers>
2.7.编写测试代码:执行定义的select语句
public
class
Test {
public
static
void
main(String[] args)
throws
IOException {
String resource =
"conf.xml"
;
//加载mybatis的配置文件(它也加载关联的映射文件)
Reader reader = Resources.getResourceAsReader(resource);
//构建sqlSession的工厂
SqlSessionFactory sessionFactory =
new
SqlSessionFactoryBuilder().build(reader);
//创建能执行映射文件中sql的sqlSession
SqlSession session = sessionFactory.openSession();
//映射sql的标识字符串
String statement =
"com.atguigu.mybatis.bean.userMapper"
+
".selectUser"
;
//执行查询返回一个唯一user对象的sql
User user = session.selectOne(statement,
1
);
System.out.println(user);
}
}
三、操作users表的CRUD
3.1.xml的实现
3.1.1.定义sql映射xml文件:
<insert id=
"insertUser"
parameterType=
"com.atguigu.ibatis.bean.User"
>
insert into users(name, age) values(#{name}, #{age});
</insert>
<delete id=
"deleteUser"
parameterType=
"int"
>
delete from users where id=#{id}
</delete>
<update id=
"updateUser"
parameterType=
"com.atguigu.ibatis.bean.User"
>
update users set name=#{name},age=#{age} where id=#{id}
</update>
<select id=
"selectUser"
parameterType=
"int"
resultType=
"com.atguigu.ibatis.bean.User"
>
select * from users where id=#{id}
</select>
<select id=
"selectAllUsers"
resultType=
"com.atguigu.ibatis.bean.User"
>
select * from users
</select>
3.1.2.在config.xml中注册这个映射文件
<mapper resource=
" com/atguigu/ibatis/bean/userMapper.xml"
/>
3.1.3.在dao中调用
public
User getUserById(
int
id) {
SqlSession session = sessionFactory.openSession();
User user = session.selectOne(URI+
".selectUser"
, id);
return
user;
}
3.2.注解的实现
3.2.1.定义sql映射的接口
public
interface
UserMapper {
@Insert
(
"insert into users(name, age) values(#{name}, #{age})"
)
public
int
insertUser(User user);
@Delete
(
"delete from users where id=#{id}"
)
public
int
deleteUserById(
int
id);
@Update
(
"update users set name=#{name},age=#{age} where id=#{id}"
)
public
int
updateUser(User user);
@Select
(
"select * from users where id=#{id}"
)
public
User getUserById(
int
id);
@Select
(
"select * from users"
)
public
List<User> getAllUser();
}
3.2.2.在config中注册这个映射接口
<mapper
class
=
"com.atguigu.ibatis.crud.ano.UserMapper"
/>
3.2.3.在dao中调用
public
User getUserById(
int
id) {
SqlSession session = sessionFactory.openSession();
UserMapper mapper = session.getMapper(UserMapper.
class
);
User user = mapper.getUserById(id);
return
user;
}
四、几个可以优化的地方
4.1.连接数据库的配置可以单独放在一个properties文件中。
## db.properties<br>
<properties resource=
"db.properties"
/>
<property name=
"driver"
value=
"${driver}"
/>
<property name=
"url"
value=
"${url}"
/>
<property name=
"username"
value=
"${username}"
/>
<property name=
"password"
value=
"${password}"
/>
4.2.为实体类定义别名,简化sql映射xml文件中的引用
<typeAliases>
<typeAlias type=
"com.atguigu.ibatis.bean.User"
alias=
"_User"
/>
</typeAliases>
4.3.可以在src下加入log4j的配置文件,打印日志信息
1. 添加jar:
log4j-1.2.16.jar
2.1. log4j.properties(方式一)
log4j.properties,
log4j.rootLogger=DEBUG, Console
#Console
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
log4j.logger.java.sql.ResultSet=INFO
log4j.logger.org.apache=INFO
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG
2.2. log4j.xml(方式二)
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
<appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern"
value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" />
</layout>
</appender>
<logger name="java.sql">
<level value="debug" />
</logger>
<logger name="org.apache.ibatis">
<level value="debug" />
</logger>
<root>
<level value="debug" />
<appender-ref ref="STDOUT" />
</root>
</log4j:configuration>
五、解决字段名与实体类属性名不相同的冲突
5.1.准备表和字段
CREATE TABLE orders(
order_id INT PRIMARY KEY AUTO_INCREMENT,
order_no VARCHAR(
20
),
order_price FLOAT
);
INSERT INTO orders(order_no, order_price) VALUES(
'aaaa'
,
23
);
INSERT INTO orders(order_no, order_price) VALUES(
'bbbb'
,
33
);
INSERT INTO orders(order_no, order_price) VALUES(
'cccc'
,
22
);
5.2.定义实体类
public
class
Order {
private
int
id;
private
String orderNo;
private
float
price;
}
5.3.实现getOrderById(id)的查询:
方式一: 通过在sql语句中定义别名
<select id=
"selectOrder"
parameterType=
"int"
resultType=
"_Order"
>
select order_id id, order_no orderNo,order_price price from orders where order_id=#{id}
</select>
方式二: 通过<resultMap>
<select id=
"selectOrderResultMap"
parameterType=
"int"
resultMap=
"orderResultMap"
>
select * from orders where order_id=#{id}
</select>
<resultMap type=
"_Order"
id=
"orderResultMap"
>
<id property=
"id"
column=
"order_id"
/>
<result property=
"orderNo"
column=
"order_no"
/>
<result property=
"price"
column=
"order_price"
/>
</resultMap>
六、实现关联表查询
6.1.一对一关联
6.1.1.提出需求
根据班级id查询班级信息(带老师的信息)
6.1.2.创建表和数据
CREATE TABLE teacher(
t_id INT PRIMARY KEY AUTO_INCREMENT,
t_name VARCHAR(
20
)
);
CREATE TABLE
class
(
c_id INT PRIMARY KEY AUTO_INCREMENT,
c_name VARCHAR(
20
),
teacher_id INT
);
ALTER TABLE
class
ADD CONSTRAINT fk_teacher_id FOREIGN KEY (teacher_id) REFERENCES teacher(t_id);
INSERT INTO teacher(t_name) VALUES(
'LS1'
);
INSERT INTO teacher(t_name) VALUES(
'LS2'
);
INSERT INTO
class
(c_name, teacher_id) VALUES(
'bj_a'
,
1
);
INSERT INTO
class
(c_name, teacher_id) VALUES(
'bj_b'
,
2
);
6.1.3.定义实体类:
public
class
Teacher {
private
int
id;
private
String name;
}
public
class
Classes {
private
int
id;
private
String name;
private
Teacher teacher;
}
6.1.4.定义sql映射文件ClassMapper.xml
<!--
方式一: 嵌套结果: 使用嵌套结果映射来处理重复的联合结果的子集
SELECT * FROM
class
c, teacher t,student s WHERE c.teacher_id=t.t_id AND c.C_id=s.class_id AND c.c_id=
1
-->
<select id=
"getClass3"
parameterType=
"int"
resultMap=
"ClassResultMap3"
>
select * from
class
c, teacher t,student s where c.teacher_id=t.t_id and c.C_id=s.class_id and c.c_id=#{id}
</select>
<resultMap type=
"_Classes"
id=
"ClassResultMap3"
>
<id property=
"id"
column=
"c_id"
/>
<result property=
"name"
column=
"c_name"
/>
<association property=
"teacher"
column=
"teacher_id"
javaType=
"_Teacher"
>
<id property=
"id"
column=
"t_id"
/>
<result property=
"name"
column=
"t_name"
/>
</association>
<!-- ofType指定students集合中的对象类型 -->
<collection property=
"students"
ofType=
"_Student"
>
<id property=
"id"
column=
"s_id"
/>
<result property=
"name"
column=
"s_name"
/>
</collection>
</resultMap>
<!--
方式二:嵌套查询:通过执行另外一个SQL映射语句来返回预期的复杂类型
SELECT * FROM
class
WHERE c_id=
1
;
SELECT * FROM teacher WHERE t_id=
1
//1 是上一个查询得到的teacher_id的值
SELECT * FROM student WHERE class_id=
1
//1是第一个查询得到的c_id字段的值
-->
<select id=
"getClass4"
parameterType=
"int"
resultMap=
"ClassResultMap4"
>
select * from
class
where c_id=#{id}
</select>
<resultMap type=
"_Classes"
id=
"ClassResultMap4"
>
<id property=
"id"
column=
"c_id"
/>
<result property=
"name"
column=
"c_name"
/>
<association property=
"teacher"
column=
"teacher_id"
javaType=
"_Teacher"
select=
"getTeacher2"
></association>
<collection property=
"students"
ofType=
"_Student"
column=
"c_id"
select=
"getStudent"
></collection>
</resultMap>
<select id=
"getTeacher2"
parameterType=
"int"
resultType=
"_Teacher"
>
SELECT t_id id, t_name name FROM teacher WHERE t_id=#{id}
</select>
<select id=
"getStudent"
parameterType=
"int"
resultType=
"_Student"
>
SELECT s_id id, s_name name FROM student WHERE class_id=#{id}
</select>
6.1.5.测试
@Test
public
void
testOO() {
SqlSession sqlSession = factory.openSession();
Classes c = sqlSession.selectOne(
"com.atguigu.day03_mybatis.test5.OOMapper.getClass"
,
1
);
System.out.println(c);
}
@Test
public
void
testOO2() {
SqlSession sqlSession = factory.openSession();
Classes c = sqlSession.selectOne(
"com.atguigu.day03_mybatis.test5.OOMapper.getClass2"
,
1
);
System.out.println(c);
}
6.2.一对多关联
6.2.1.提出需求
根据classId查询对应的班级信息,包括学生,老师
6.2.2.创建表和数据:
CREATE TABLE student(
s_id INT PRIMARY KEY AUTO_INCREMENT,
s_name VARCHAR(
20
),
class_id INT
);
INSERT INTO student(s_name, class_id) VALUES(
'xs_A'
,
1
);
INSERT INTO student(s_name, class_id) VALUES(
'xs_B'
,
1
);
INSERT INTO student(s_name, class_id) VALUES(
'xs_C'
,
1
);
INSERT INTO student(s_name, class_id) VALUES(
'xs_D'
,
2
);
INSERT INTO student(s_name, class_id) VALUES(
'xs_E'
,
2
);
INSERT INTO student(s_name, class_id) VALUES(
'xs_F'
,
2
);
6.2.3.定义实体类
public
class
Student {
private
int
id;
private
String name;
}
public
class
Classes {
private
int
id;
private
String name;
private
Teacher teacher;
private
List<Student> students;
}
6.2.4.定义sql映射文件ClassMapper.xml
<!--
方式一: 嵌套结果: 使用嵌套结果映射来处理重复的联合结果的子集
SELECT * FROM
class
c, teacher t,student s WHERE c.teacher_id=t.t_id AND c.C_id=s.class_id AND c.c_id=
1
-->
<select id=
"getClass3"
parameterType=
"int"
resultMap=
"ClassResultMap3"
>
select * from
class
c, teacher t,student s where c.teacher_id=t.t_id and c.C_id=s.class_id and c.c_id=#{id}
</select>
<resultMap type=
"_Classes"
id=
"ClassResultMap3"
>
<id property=
"id"
column=
"c_id"
/>
<result property=
"name"
column=
"c_name"
/>
<association property=
"teacher"
column=
"teacher_id"
javaType=
"_Teacher"
>
<id property=
"id"
column=
"t_id"
/>
<result property=
"name"
column=
"t_name"
/>
</association>
<!-- ofType指定students集合中的对象类型 -->
<collection property=
"students"
ofType=
"_Student"
>
<id property=
"id"
column=
"s_id"
/>
<result property=
"name"
column=
"s_name"
/>
</collection>
</resultMap>
<!--
方式二:嵌套查询:通过执行另外一个SQL映射语句来返回预期的复杂类型
SELECT * FROM
class
WHERE c_id=
1
;
SELECT * FROM teacher WHERE t_id=
1
//1 是上一个查询得到的teacher_id的值
SELECT * FROM student WHERE class_id=
1
//1是第一个查询得到的c_id字段的值
-->
<select id=
"getClass4"
parameterType=
"int"
resultMap=
"ClassResultMap4"
>
select * from
class
where c_id=#{id}
</select>
<resultMap type=
"_Classes"
id=
"ClassResultMap4"
>
<id property=
"id"
column=
"c_id"
/>
<result property=
"name"
column=
"c_name"
/>
<association property=
"teacher"
column=
"teacher_id"
javaType=
"_Teacher"
select=
"getTeacher2"
></association>
<collection property=
"students"
ofType=
"_Student"
column=
"c_id"
select=
"getStudent"
></collection>
</resultMap>
<select id=
"getTeacher2"
parameterType=
"int"
resultType=
"_Teacher"
>
SELECT t_id id, t_name name FROM teacher WHERE t_id=#{id}
</select>
<select id=
"getStudent"
parameterType=
"int"
resultType=
"_Student"
>
SELECT s_id id, s_name name FROM student WHERE class_id=#{id}
</select>
6.2.5.测试
@Test
public
void
testOM() {
SqlSession sqlSession = factory.openSession();
Classes c = sqlSession.selectOne(
"com.atguigu.day03_mybatis.test5.OOMapper.getClass3"
,
1
);
System.out.println(c);
}
@Test
public
void
testOM2() {
SqlSession sqlSession = factory.openSession();
Classes c = sqlSession.selectOne(
"com.atguigu.day03_mybatis.test5.OOMapper.getClass4"
,
1
);
System.out.println(c);
}
七、动态sql与模糊查询
7.1.需求
实现多条件查询用户(姓名模糊匹配, 年龄在指定的最小值到最大值之间)。
7.2.准备数据库和表
create table d_user(
id
int
primary key auto_increment,
name varchar(
10
),
age
int
(
3
)
);
insert into d_user(name,age) values(
'Tom'
,
12
);
insert into d_user(name,age) values(
'Bob'
,
13
);
insert into d_user(name,age) values(
'Jack'
,
18
);
7.3.ConditionUser(查询条件实体类)
private String name;
private int minAge;
private int maxAge;
7.4.User表实体类
private
int
id;
private
String name;
private
int
age;
7.5.userMapper.xml(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=
"com.atguigu.day03_mybatis.test6.userMapper"
>
<select id=
"getUser"
parameterType=
"com.atguigu.day03_mybatis.test6.ConditionUser"
resultType=
"com.atguigu.day03_mybatis.test6.User"
>
select * from d_user where age>=#{minAge} and age<=#{maxAge}
<
if
test=
'name!="%null%"'
>and name like #{name}</
if
>
</select>
</mapper>
7.6.UserTest(测试)
public
class
UserTest {
public
static
void
main(String[] args)
throws
IOException {
Reader reader = Resources.getResourceAsReader(
"conf.xml"
);
SqlSessionFactory sessionFactory =
new
SqlSessionFactoryBuilder().build(reader);
SqlSession sqlSession = sessionFactory.openSession();
String statement =
"com.atguigu.day03_mybatis.test6.userMapper.getUser"
;
List<User> list = sqlSession.selectList(statement,
new
ConditionUser(
"%a%"
,
1
,
12
));
System.out.println(list);
}
}
MyBatis中可用的动态SQL标签
八、调用存储过程
8.1.提出需求
查询得到男性或女性的数量, 如果传入的是0就女性否则是男性
8.2.准备数据库表和存储过程:
create table p_user(
id
int
primary key auto_increment,
name varchar(
10
),
sex
char
(
2
)
);
insert into p_user(name,sex) values(
'A'
,
"男"
);
insert into p_user(name,sex) values(
'B'
,
"女"
);
insert into p_user(name,sex) values(
'C'
,
"男"
);
#创建存储过程(查询得到男性或女性的数量, 如果传入的是
0
就女性否则是男性)
DELIMITER $
CREATE PROCEDURE mybatis.ges_user_count(IN sex_id INT, OUT user_count INT)
BEGIN
IF sex_id=
0
THEN
SELECT COUNT(*) FROM mybatis.p_user WHERE p_user.sex=
'女'
INTO user_count;
ELSE
SELECT COUNT(*) FROM mybatis.p_user WHERE p_user.sex=
'男'
INTO user_count;
END IF;
END
$
#调用存储过程
DELIMITER ;
SET
@user_count
=
0
;
CALL mybatis.ges_user_count(
1
,
@user_count
);
SELECT
@user_count
;
8.3.创建表的实体类
public
class
User {
private
String id;
private
String name;
private
String sex;
}
8.4.userMapper.xml
<mapper namespace=
"com.atguigu.mybatis.test7.userMapper"
>
<!--
查询得到男性或女性的数量, 如果传入的是
0
就女性否则是男性
CALL mybatis.get_user_count(
1
,
@user_count
);
-->
<select id=
"getCount"
statementType=
"CALLABLE"
parameterMap=
"getCountMap"
>
call mybatis.get_user_count(?,?)
</select>
<parameterMap type=
"java.util.Map"
id=
"getCountMap"
>
<parameter property=
"sex_id"
mode=
"IN"
jdbcType=
"INTEGER"
/>
<parameter property=
"user_count"
mode=
"OUT"
jdbcType=
"INTEGER"
/>
</parameterMap>
</mapper>
8.5.测试
Map<String, Integer> paramMap =
new
HashMap<>();
paramMap.put(
"sex_id"
,
0
);
session.selectOne(statement, paramMap);
Integer userCount = paramMap.get(
"user_count"
);
System.out.println(userCount);
九、MyBatis缓存
9.1.理解mybatis缓存
正如大多数持久层框架一样,MyBatis 同样提供了一级缓存和二级缓存的支持
1.一级缓存: 基于PerpetualCache 的 HashMap本地缓存,其存储作用域为 Session,当 Session flush 或 close 之后,该Session中的所有 Cache 就将清空。
2. 二级缓存与一级缓存其机制相同,默认也是采用 PerpetualCache,HashMap存储,不同在于其存储作用域为 Mapper(Namespace),并且可自定义存储源,如 Ehcache。
3. 对于缓存数据更新机制,当某一个作用域(一级缓存Session/二级缓存Namespaces)的进行了 C/U/D 操作后,默认该作用域下所有 select 中的缓存将被clear。
9.2.mybatis一级缓存
9.2.1.根据任务查询
根据id查询对应的用户记录对象。
9.2.2.准备数据库表和数据
CREATE TABLE c_user(
id INT PRIMARY KEY AUTO_INCREMENT,
NAME VARCHAR(
20
),
age INT
);
INSERT INTO c_user(NAME, age) VALUES(
'Tom'
,
12
);
INSERT INTO c_user(NAME, age) VALUES(
'Jack'
,
11
);
9.2.3.创建表的实体类
public
class
User
implements
Serializable{
private
int
id;
private
String name;
private
int
age;
9.2.4.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.atguigu.mybatis.test8.userMapper"
>
<select id=
"getUser"
parameterType=
"int"
resultType=
"_CUser"
>
select * from c_user where id=#{id}
</select>
<update id=
"updateUser"
parameterType=
"_CUser"
>
update c_user set
name=#{name}, age=#{age} where id=#{id}
</update>
</mapper>
9.2.5.测试
/*
* 一级缓存: 也就Session级的缓存(默认开启)
*/
@Test
public
void
testCache1() {
SqlSession session = MybatisUtils.getSession();
String statement =
"com.atguigu.mybatis.test8.userMapper.getUser"
;
User user = session.selectOne(statement,
1
);
System.out.println(user);
/*
* 一级缓存默认就会被使用
*/
/*
user = session.selectOne(statement, 1);
System.out.println(user);
*/
/*
1. 必须是同一个Session,如果session对象已经close()过了就不可能用了
*/
/*
session = MybatisUtils.getSession();
user = session.selectOne(statement, 1);
System.out.println(user);
*/
/*
2. 查询条件是一样的
*/
/*
user = session.selectOne(statement, 2);
System.out.println(user);
*/
/*
3. 没有执行过session.clearCache()清理缓存
*/
/*
session.clearCache();
user = session.selectOne(statement, 2);
System.out.println(user);
*/
/*
4. 没有执行过增删改的操作(这些操作都会清理缓存)
*/
/*
session.update("com.atguigu.mybatis.test8.userMapper.updateUser",
new User(2, "user", 23));
user = session.selectOne(statement, 2);
System.out.println(user);
*/
}
9.3.MyBatis二级缓存
9.3.1.添加一个<cache>在userMapper.xml中
<mapper namespace=
"com.atguigu.mybatis.test8.userMapper"
>
<cache/>
9.3.2.测试
/*
* 测试二级缓存
*/
@Test
public
void
testCache2() {
String statement =
"com.atguigu.mybatis.test8.userMapper.getUser"
;
SqlSession session = MybatisUtils.getSession();
User user = session.selectOne(statement,
1
);
session.commit();
System.out.println(
"user="
+user);
SqlSession session2 = MybatisUtils.getSession();
user = session2.selectOne(statement,
1
);
session.commit();
System.out.println(
"user2="
+user);
}
9.3.3.补充说明
1
. 映射语句文件中的所有select语句将会被缓存。
2
. 映射语句文件中的所有insert,update和delete语句会刷新缓存。
3
. 缓存会使用Least Recently Used(LRU,最近最少使用的)算法来收回。
4
. 缓存会根据指定的时间间隔来刷新。
5
. 缓存会存储
1024
个对象
<cache
eviction=
"FIFO"
//回收策略为先进先出
flushInterval=
"60000"
//自动刷新时间60s
size=
"512"
//最多缓存512个引用对象
readOnly=
"true"
/>
//只读
十、Spring集成MyBatis
10.1.添加jar
【mybatis】
mybatis-
3.2
.
0
.jar
mybatis-spring-
1.1
.
1
.jar
log4j-
1.2
.
17
.jar
【spring】
spring-aop-
3.2
.
0
.RELEASE.jar
spring-beans-
3.2
.
0
.RELEASE.jar
spring-context-
3.2
.
0
.RELEASE.jar
spring-core-
3.2
.
0
.RELEASE.jar
spring-expression-
3.2
.
0
.RELEASE.jar
spring-jdbc-
3.2
.
0
.RELEASE.jar
spring-test-
3.2
.
4
.RELEASE.jar
spring-tx-
3.2
.
0
.RELEASE.jar
aopalliance-
1.0
.jar
cglib-nodep-
2.2
.
3
.jar
commons-logging-
1.1
.
1
.jar
【MYSQL驱动包】
mysql-connector-java-
5.0
.
4
-bin.jar
10.2.数据库表
CREATE TABLE s_user(
user_id INT AUTO_INCREMENT PRIMARY KEY,
user_name VARCHAR(
30
),
user_birthday DATE,
user_salary DOUBLE
)
10.3.实体类:User
public
class
User {
private
int
id;
private
String name;
private
Date birthday;
private
double
salary;
//set,get方法
}
10.4.DAO接口: UserMapper (XXXMapper)
public
interface
UserMapper {
void
save(User user);
void
update(User user);
void
delete(
int
id);
User findById(
int
id);
List<User> findAll();
}
10.5.SQL映射文件: userMapper.xml(与接口忽略大小写同名)
<?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.atguigu.mybatis.test9.UserMapper"
>
<resultMap type=
"User"
id=
"userResult"
>
<result column=
"user_id"
property=
"id"
/>
<result column=
"user_name"
property=
"name"
/>
<result column=
"user_birthday"
property=
"birthday"
/>
<result column=
"user_salary"
property=
"salary"
/>
</resultMap>
<!-- 取得插入数据后的id -->
<insert id=
"save"
keyColumn=
"user_id"
keyProperty=
"id"
useGeneratedKeys=
"true"
>
insert into s_user(user_name,user_birthday,user_salary)
values(#{name},#{birthday},#{salary})
</insert>
<update id=
"update"
>
update s_user
set user_name = #{name},
user_birthday = #{birthday},
user_salary = #{salary}
where user_id = #{id}
</update>
<delete id=
"delete"
>
delete from s_user
where user_id = #{id}
</delete>
<select id=
"findById"
resultMap=
"userResult"
>
select *
from s_user
where user_id = #{id}
</select>
<select id=
"findAll"
resultMap=
"userResult"
>
select *
from s_user
</select>
</mapper>
10.6.spring的配置文件: beans.xml
<?xml version=
"1.0"
encoding=
"UTF-8"
?>
<beans xmlns=
"http://www.springframework.org/schema/beans"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
xmlns:p=
"http://www.springframework.org/schema/p"
xmlns:context=
"http://www.springframework.org/schema/context"
xmlns:tx=
"http://www.springframework.org/schema/tx"
xsi:schemaLocation="
http:
//www.springframework.org/schema/beans
http:
//www.springframework.org/schema/beans/spring-beans-3.2.xsd
http:
//www.springframework.org/schema/context
http:
//www.springframework.org/schema/context/spring-context-3.2.xsd
http:
//www.springframework.org/schema/tx
http:
//www.springframework.org/schema/tx/spring-tx-3.2.xsd">
<!--
1
. 数据源 : DriverManagerDataSource -->
<bean id=
"dataSource"
class
=
"org.springframework.jdbc.datasource.DriverManagerDataSource"
>
<property name=
"driverClassName"
value=
"com.mysql.jdbc.Driver"
/>
<property name=
"url"
value=
"jdbc:mysql://localhost:3306/mybatis"
/>
<property name=
"username"
value=
"root"
/>
<property name=
"password"
value=
"root"
/>
</bean>
<!--
2
. mybatis的SqlSession的工厂: SqlSessionFactoryBean
dataSource / typeAliasesPackage
-->
<bean id=
"sqlSessionFactory"
class
=
"org.mybatis.spring.SqlSessionFactoryBean"
>
<property name=
"dataSource"
ref=
"dataSource"
/>
<property name=
"typeAliasesPackage"
value=
"com.atuigu.spring_mybatis2.domain"
/>
</bean>
<!--
3
. mybatis自动扫描加载Sql映射文件 : MapperScannerConfigurer
sqlSessionFactory / basePackage
-->
<bean
class
=
"org.mybatis.spring.mapper.MapperScannerConfigurer"
>
<property name=
"basePackage"
value=
"com.atuigu.spring_mybatis2.mapper"
/>
<property name=
"sqlSessionFactory"
ref=
"sqlSessionFactory"
/>
</bean>
<!--
4
. 事务管理 : DataSourceTransactionManager -->
<bean id=
"txManager"
class
=
"org.springframework.jdbc.datasource.DataSourceTransactionManager"
>
<property name=
"dataSource"
ref=
"dataSource"
/>
</bean>
<!--
5
. 使用声明式事务 -->
<tx:annotation-driven transaction-manager=
"txManager"
/>
</beans>
10.7.mybatis的配置文件: mybatis-config.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>
<!-- Spring整合myBatis后,这个配置文件基本可以不要了-->
<!-- 设置外部配置文件 -->
<!-- 设置类别名 -->
<!-- 设置数据库连接环境 -->
<!-- 映射文件 -->
</configuration>
10.8.测试
@RunWith
(SpringJUnit4ClassRunner.
class
)
//使用Springtest测试框架
@ContextConfiguration
(
"/beans.xml"
)
//加载配置
public
class
SMTest {
@Autowired
//注入
private
UserMapper userMapper;
@Test
public
void
save() {
User user =
new
User();
user.setBirthday(
new
Date());
user.setName(
"marry"
);
user.setSalary(
300
);
userMapper.save(user);
System.out.println(user.getId());
}
@Test
public
void
update() {
User user = userMapper.findById(
2
);
user.setSalary(
2000
);
userMapper.update(user);
}
@Test
public
void
delete() {
userMapper.delete(
3
);
}
@Test
public
void
findById() {
User user = userMapper.findById(
1
);
System.out.println(user);
}
@Test
public
void
findAll() {
List<User> users = userMapper.findAll();
System.out.println(users);
}
}
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