mybatis学习系列五--插件及类型处理器
2 插件编写（80-81）
单个插件编写
2.1实现interceptor接口(ibatis）
invocation.proceed()方法执行必须要有，否则不会无法实现拦截作用
2.2 使用@intercepts注解完成插件签名
2.3 将插件注册到全局配置文件中<plugins>标签
全局配置文件注册plugin时报错：
The content of element type "configuration" must match
"(properties?,settings?,typeAliases?,typeHandlers?,objectFactory?,objectWrapperFactory?,reflectorFactory?,plugins?,environments?,databaseIdProvider?,mappers?)".
原因：configuration 中的元素不仅有类型限制，还有顺序限制
https://blog.csdn.net/u011199063/article/details/78971527
按照提示的顺序即可
多个插件
插件动态代理时，按插件配置顺序配置层层代理对象，执行目标方法时，按逆向顺序执行
配置的插件顺序
<!-- 自定义插件 -->
<plugins>
<plugin interceptor="com.mybatis.bean.MyPlugin">
<!-- 配置插件属性，在插件setProperties方法中使用 -->
<property name="username1" value="root1"/>
<property name="password1" value="1"/>
</plugin>
<plugin interceptor="com.mybatis.bean.MySecondPlugin">
<property name="username2" value="root2"/>
<property name="password2" value="2"/>
</plugin>
</plugins>
执行打印日志：
22:29:05,207 INFO Class:50 - myfirstplugin plugin:org.apache.ibatis.executor.SimpleExecutor@24b1d79b
22:29:05,208 INFO Class:50 - mysecondplugin plugin:org.apache.ibatis.executor.SimpleExecutor@24b1d79b
22:29:05,239 INFO Class:50 - myfirstplugin plugin:org.apache.ibatis.scripting.defaults.DefaultParameterHandler@70beb599
22:29:05,239 INFO Class:50 - mysecondplugin plugin:org.apache.ibatis.scripting.defaults.DefaultParameterHandler@70beb599
22:29:05,242 INFO Class:50 - myfirstplugin plugin:org.apache.ibatis.executor.resultset.DefaultResultSetHandler@365c30cc
22:29:05,242 INFO Class:50 - mysecondplugin plugin:org.apache.ibatis.executor.resultset.DefaultResultSetHandler@365c30cc
22:29:05,243 INFO Class:50 - myfirstplugin plugin:org.apache.ibatis.executor.statement.RoutingStatementHandler@4148db48
22:29:05,243 INFO Class:50 - mysecondplugin plugin:org.apache.ibatis.executor.statement.RoutingStatementHandler@4148db48
显示包装顺序按配置顺序
再看执行intercept方法执行顺序：
22:29:05,272 INFO Class:40 - myfirstplugin intercept:null
22:29:05,272 INFO Class:40 - mysecondplugin intercept:null
也是按顺序执行，并不是如图所示的包装按正序，执行按逆序
3 插件开发（82）
只有再插件类中intercept方法中调用invocation.proceed()方法才能执行拦截的目标方法
简单开发：修改sql参数
//获取拦截的对象
Object target=invocation.getTarget();
log.info(target);
//获取target的元数据
MetaObject metaObject=SystemMetaObject.forObject(target);
Object value=metaObject.getValue("parameterHandler.parameterObject");
System.out.println("sql语句的参数："+value);
//修改sql语句参数
metaObject.setValue("parameterHandler.parameterObject", 3);
//执行目标方法
Object proceed = invocation.proceed();
log.info("myfirstplugin intercept:"+proceed);
执行后打印信息：
sql语句的参数：2
22:00:27,942 DEBUG getMyDeptById:145 - ==> Parameters: 3(Integer)
可见，sql参数从2修改为3了
4 pagehelper分页插件（83）
引入：
1pom配置
<!-- pagehelper分页插件 -->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>4.1.4</version>
</dependency>
2全局配置文件中配置
mybatis-config.xml
<plugins>
<!-- 分页插件 -->
<plugin interceptor="com.github.pagehelper.PageHelper">
<property name="dialect" value="mysql"/>
<property name="offsetAsPageNum" value="false"/>
<property name="rowBoundsWithCount" value="false"/>
<property name="pageSizeZero" value="true"/>
<property name="reasonable" value="false"/>
<property name="supportMethodsArguments" value="false"/>
<property name="returnPageInfo" value="none"/>
</plugin>
</plugins>
3 测试类
EmployeeMapper mapper=session.getMapper(EmployeeMapper.class);
//获取页码信息方式1 (startPage方式)
Page<Object> startPage = PageHelper.startPage(3, 3);
List<Employee> emps=mapper.selectEmployeeByInnerParameter(null);
// System.out.println("当前页码:"+startPage.getPageNum());
// System.out.println("总记录数:"+startPage.getTotal());
// System.out.println("每页记录数:"+startPage.getPageSize());
// System.out.println("总页码:"+startPage.getPages());
// System.out.println("分页后当前页码数据条数:"+emps.size());
//获取页码信息方式2 (pageInfo信息更丰富)
// PageInfo<Employee> pageInfo = new PageInfo<>(emps);
//2个参数，后面参数表示分页导航，连续显示多少页码（即每次显示5页，如2，3，4，5，6）
PageInfo<Employee> pageInfo = new PageInfo<>(emps,2);
System.out.println("当前页码:"+pageInfo.getPageNum());
System.out.println("总记录数:"+pageInfo.getTotal());
System.out.println("每页记录数:"+pageInfo.getPageSize());
System.out.println("总页码:"+pageInfo.getPages());
System.out.println("分页后当前页码数据条数:"+emps.size());
System.out.println("是否第一页:"+pageInfo.isIsFirstPage());
System.out.println("连续显示页码:"+pageInfo.getNavigatePages());
int[] navigatepageNums = pageInfo.getNavigatepageNums();
for ( int i=0;i<navigatepageNums.length;i++) {
System.out.println(navigatepageNums[i]);
}
输出结果：
当前页码:3
总记录数:11
每页记录数:3
总页码:4
分页后当前页码数据条数:3
是否第一页:false
连续显示页码:2
2
3
5 mybatis批量操作（84）
1采用batch方式进行批量插入操作：
//batch类型的session
SqlSession session = sqlSessionFactory.openSession(ExecutorType.BATCH);
try {
EmployeeMapper mapper=session.getMapper(EmployeeMapper.class);
long start=System.currentTimeMillis();
for(int i=0;i<1000;i++) {
mapper.addEmp(new Employee(null,"name_"+i, "email_"+i+"@com.cn", (i%2)+"", (i%2)));
}
session.commit();
long end=System.currentTimeMillis();
System.out.println("执行时间："+(end-start));
} finally {
session.close();
}
执行效果：
21:49:06,354 DEBUG addEmp:145 - ==> Parameters: name_304(String), email_304@com.cn(String), 0(String), 0(Integer)
21:49:06,355 DEBUG addEmp:145 - ==> Parameters: name_305(String), email_305@com.cn(String), 1(String), 1(Integer)
21:49:06,355 DEBUG addEmp:145 - ==> Parameters: name_306(String), email_306@com.cn(String), 0(String), 0(Integer)
21:49:06,355 DEBUG addEmp:145 - ==> Parameters: name_307(String), email_307@com.cn(String), 1(String), 1(Integer)
21:49:06,356 DEBUG addEmp:145 - ==> Parameters: name_308(String), email_308@com.cn(String), 0(String), 0(Integer)
执行时间：
21:49:07,208 DEBUG JdbcTransaction:69 - Committing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@6ebc05a6]
执行时间：1198
2非batch方式批量操作：
//非batch批量操作session
SqlSession session = sqlSessionFactory.openSession();
try {
EmployeeMapper mapper=session.getMapper(EmployeeMapper.class);
long start=System.currentTimeMillis();
for(int i=0;i<1000;i++) {
mapper.addEmp(new Employee(null,"name_"+i, "email_"+i+"@com.cn", (i%2)+"", (i%2)));
}
session.commit();
long end=System.currentTimeMillis();
System.out.println("执行时间："+(end-start));
} finally {
session.close();
}
执行情况：
21:52:44,356 DEBUG addEmp:145 - ==> Parameters: name_987(String), email_987@com.cn(String), 1(String), 1(Integer)
21:52:44,356 DEBUG addEmp:145 - <== Updates: 1
21:52:44,356 DEBUG addEmp:145 - ==> Preparing: insert into myemployeee(last_name,email,gender,dept_id) values (?,?, ?,?)
21:52:44,356 DEBUG addEmp:145 - ==> Parameters: name_988(String), email_988@com.cn(String), 0(String), 0(Integer)
21:52:44,357 DEBUG addEmp:145 - <== Updates: 1
执行时间：
执行时间：1376
原因：
批量batch方式：（预编译sql一次==》设置参数==》1000次==）
非批量：（预编译sql==》设置参数==》执行）==》1000次
|
执行次数 |
非批量执行时间(ms) |
批量执行时间(ms) |
|
1000 |
1376 |
1198 |
|
10000 |
11649 |
3607 |
|
50000 |
37831 |
10593 |
|
100000 |
62868 |
20195 |
性能在3倍左右
spring整合时，如果获取bath的sqlsession
配置带batch的sqlsession并使用
使用时引入：
6mybatis存储过程（85-86）
可以理解为sql集合，复杂sql情况下
Oracle中分页借助伪列(rowid)
先<=end，再>=start (注意如果先>=start再<=end会导致数据不确定而错误)
1创建分页类：
/**
* 分页类
* @author admin
*
*/
public class Page {
private int start;
private int end;
private int count;
private List<Employee> emps;
public int getStart() {
return start;
}
分页查询：先查询总记录数，再进行分页查询
2/**创建oracle存储过程*/
create or replace procedure
hello_test(//存储过程名
p_start in int,//p_start-->参数开始行;in-->表示输入;int表示参数类型
p_end in int,//p_end-->参数结束行;in-->表示输入;int表示参数类型
p_count out int,//输出
p_emps out sys_refcursor//输出，游标
) as
begin
select count(*) into p_count from employee;//将查询的总记录数交给p_count
open p_emps for //打开游标
select * from
(select rownum rn,e.* from employee e where rownum<=p_end)
where rn>=p_start;
end hello_test;
3使用存储过程：
3.1Select * from user_source;
查看存储过程
3.2mybatis调用存储过程
1）定义查询接口
//调用存储过程分页(参数为定义的page）
void getPageByProcedure(Page page);
2）mapper中定义查询存储过程的sql
<!-- statementType="CALLABLE" 表示调用存储过程 -->
<select id="getPageByProcedure" statementType="CALLABLE" databaseId="oracle">
<!-- 固定用法 { call 存储过程名(参数1，参数2,...) } -->
{call
hello_test(
#{start,mode=IN,jdbcType=INTEGER},
#{end,mode=IN,jdbcType=INTEGER},
#{end,mode=IN,jdbcType=INTEGER},
#{count,mode=OUT,jdbcType=INTEGER},
#{emps,mode=OUT,jdbcType=CURSOR,javaType=ResultSet,resultMap=resultMap}
<!-- 游标处理,使用ResultSet封装结果集 -->
) }
</select>
3）调用测试
//存储过程查询
EmployeeMapper mapper=session.getMapper(EmployeeMapper.class);
Page page = new Page();
page.setStart(1);
page.setEnd(10);
mapper.getPageByProcedure(page);
System.out.println("总记录数："+page.getCount());
System.out.println("查出的数据："+page.getEmps().size());
7 mybatis存自定义类型处理器（87）
自定义typehandler处理枚举类型
设置参数和处理结果时调用typehandler处理参数，将java类型和数据库类型映射。
查看typehandler接口：
public interface TypeHandler<T> {
void setParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException;
T getResult(ResultSet rs, String columnName) throws SQLException;
T getResult(ResultSet rs, int columnIndex) throws SQLException;
T getResult(CallableStatement cs, int columnIndex) throws SQLException;
}
初步使用枚举
/**
* 枚举工具类
* @author admin
*
*/
public class EnumUtils {
//雇员状态
public enum EmployeeStaus{
LOGIN,//登陆
LONGOUT,//推出
REMOVE//移除
}
//枚举测试
public static void main(String[] args) {
EmployeeStaus status=EmployeeStaus.LOGIN;
System.out.println("枚举的索引:"+status.ordinal());
System.out.println("枚举的名字："+status.name());
}
}
输出：
枚举的索引:0
枚举的名字：LOGIN
即枚举有索引和名字，接下来测试mybatis默认存放的是什么
1）表myemployeee新增字段status
-- 新增状态字段
alter table myemployeee add column status varchar(11);
2) bean对象添加对应属性
private EmployeeStaus status=EmployeeStaus.LONGOUT;//状态枚举类型,默认退出状态
并提供构造方法：
public Employee(String lastName, String email, String gender, Integer deptId, MyDept myDept,
EmployeeStaus status) {
super();
this.lastName = lastName;
this.email = email;
this.gender = gender;
this.deptId = deptId;
this.myDept = myDept;
this.status = status;
}
3)mapper新增插入字段
<insert id="addEmp" parameterType="com.mybatis.bean.Employee">
insert into myemployeee(last_name,email,gender,dept_id,status)
values (#{lastName,jdbcType=VARCHAR},#{email,jdbcType=VARCHAR},
#{gender,jdbcType=VARCHAR},#{deptId,jdbcType=INTEGER},#{status})
</insert>
4）测试插入：
EmployeeMapper mapper=session.getMapper(EmployeeMapper.class);
mapper.addEmp(new Employee("test11", "test11@com.cn",
1+"", 1, null, EmployeeStaus.LONGOUT));
5）查看数据库存入数据
select t.* from myemployeee t order by t.id desc limit 1;
可以看到默认存储的是枚举的名字
原因：
默认使用enumTypehandler处理（包含EnumTypeHandler和EnumOrdinalTypeHandler共2种类型）
设置参数时代码如下：
@Override
public void setNonNullParameter(PreparedStatement ps, int i, E parameter, JdbcType jdbcType) throws SQLException {
if (jdbcType == null) {
ps.setString(i, parameter.name());
} else {
ps.setObject(i, parameter.name(), jdbcType.TYPE_CODE); // see r3589
}
}
可见保存的是枚举的名字。
变更处理器
可以改变使用EnumOrdinalTypeHandler，
在全局配置器中设置：
<!-- 处理指定enum类型，不指定则处理所有enum类型 -->
<typeHandlers>
<typeHandler handler="org.apache.ibatis.type.EnumOrdinalTypeHandler" javaType="com.mybatis.bean.EnumUtils.EmployeeStaus"/>
</typeHandlers>
执行报错：
## The error may exist in SQL Mapper Configuration
### Cause: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.mybatis.bean.EnumUtils.EmployeeStaus'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.mybatis.bean.EnumUtils.EmployeeStaus
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:80)
at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:64)
at com.mybatis.bean.Mytest_eum_test.getSqlSessionFactory(Mytest_eum_test.java:45)
at com.mybatis.bean.Mytest_eum_test.main(Mytest_eum_test.java:29)
Caused by: org.apache.ibatis.builder.BuilderException: Error parsing SQL Mapper Configuration. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.mybatis.bean.EnumUtils.EmployeeStaus'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.mybatis.bean.EnumUtils.EmployeeStaus
at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:120)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.parse(XMLConfigBuilder.java:98)
at org.apache.ibatis.session.SqlSessionFactoryBuilder.build(SqlSessionFactoryBuilder.java:78)
... 3 more
Caused by: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.mybatis.bean.EnumUtils.EmployeeStaus'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.mybatis.bean.EnumUtils.EmployeeStaus
at org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:118)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.typeHandlerElement(XMLConfigBuilder.java:337)
at org.apache.ibatis.builder.xml.XMLConfigBuilder.parseConfiguration(XMLConfigBuilder.java:117)
... 5 more
Caused by: org.apache.ibatis.type.TypeException: Could not resolve type alias 'com.mybatis.bean.EnumUtils.EmployeeStaus'. Cause: java.lang.ClassNotFoundException: Cannot find class: com.mybatis.bean.EnumUtils.EmployeeStaus
at org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:120)
at org.apache.ibatis.builder.BaseBuilder.resolveAlias(BaseBuilder.java:149)
at org.apache.ibatis.builder.BaseBuilder.resolveClass(BaseBuilder.java:116)
... 7 more
Caused by: java.lang.ClassNotFoundException: Cannot find class: com.mybatis.bean.EnumUtils.EmployeeStaus
at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:200)
at org.apache.ibatis.io.ClassLoaderWrapper.classForName(ClassLoaderWrapper.java:89)
at org.apache.ibatis.io.Resources.classForName(Resources.java:261)
at org.apache.ibatis.type.TypeAliasRegistry.resolveAlias(TypeAliasRegistry.java:116)
使用另一种方式（不在全局配置中配置，仅在执行处指定）
<insert id="addEmp" parameterType="com.mybatis.bean.Employee">
insert into myemployeee(last_name,email,gender,dept_id,status)
values (#{lastName,jdbcType=VARCHAR},#{email,jdbcType=VARCHAR},
#{gender,jdbcType=VARCHAR},#{deptId,jdbcType=INTEGER},#{status,typeHandler=org.apache.ibatis.type.EnumOrdinalTypeHandler})
</insert>
测试：
EmployeeMapper mapper=session.getMapper(EmployeeMapper.class);
mapper.addEmp(new Employee("test22", "test22@com.cn",
1+"", 1, null, EmployeeStaus.LONGOUT));
session.commit();
查看数据库：
