擴充套件一個簡單的實現 

@Intercepts({
        @Signature(type = StatementHandler.class,method = "parameterize",args = java.sql.Statement.class)
})
public class MyFirstPlugin implements Interceptor {
    /**
     * intercept:攔截
     *      攔截目標物件的方法的執行
     * @param invocation
* @return
* @throws Throwable
     */
 
@Override
public Object intercept(Invocation invocation) throws Throwable {
        System.out.println("MyFirstPlugin....interceptor:"+invocation.getMethod());
//動態改變sql執行的引數：以前1號員工，現在4號
Object target = invocation.getTarget();
System.out.println("當前攔截物件："+target);
//拿到StatementHandler====》ParameterHandler===》ParameterObject
 
        //拿到目標物件target的元資料
MetaObject metaObject = SystemMetaObject.forObject(target);
Object value = metaObject.getValue("parameterHandler.parameterObject");
System.out.println("SQL語句用的引數是"+value);
metaObject.setValue("parameterHandler.parameterObject",4);
//執行目標方法
Object proceed = invocation.proceed();
 
//返回執行後的返回值
return proceed;
}

    /**
     * plugin:包裝目標物件——包裝：為目標物件建立一個代理類
     * @param target
* @return
*/
@Override
public Object plugin(Object target) {
        System.out.println("MyFirstPlugin....plugin:mybatis將要包裝的物件"+target);
//我們可以藉助Plugin的wrap方法來使用當前的intercept包裝我們目標物件
Object wrap = Plugin.wrap(target, this);
//返回為當前target建立好的動態代理
return wrap;
}

    /**
     * setProperties:將外掛註冊時的property屬性設定進來
     * @param properties
*/
@Override
public void setProperties(Properties properties) {
        System.out.println("外掛配置的資訊"+properties);
}
}

@Test
public void testPlugin() throws IOException {
    SqlSession sqlSession = getSqlSession();
EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
Employee e = mapper.getEmps(1);
System.out.println(e);
}

分頁外掛pageHelper

配置依賴

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper</artifactId>
    <version>5.1.2</version>
</dependency>

在全域性配置檔案中配置攔截器

<plugins>
    <plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin>
</plugins>

在程式碼中使用PageHelper.startPage( )即可實現分頁

@Test
public void test() throws IOException {
    SqlSession sqlSession = getSqlSession();
EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
PageHelper.startPage(1,5);
List<Employee> employeeList = mapper.getEmps();
    for (Employee e:employeeList) {
        System.out.println(employeeList);
}
}

外掛會自動查詢數量和進行分頁的sql

其他資訊

@Test
public void test() throws IOException {
    SqlSession sqlSession = getSqlSession();
EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
Page<Object> page = PageHelper.startPage(1, 5);
List<Employee> employeeList = mapper.getEmps();
    for (Employee e:employeeList) {
        System.out.println(employeeList);
}

    System.out.println("當前頁碼"+page.getPageNum());
System.out.println("總記錄數"+page.getTotal());
System.out.println("每頁記錄數"+page.getPageSize());
System.out.println("總頁碼"+page.getPages());
}

還可以使用PageInfo達到更多分頁的資訊:

@Test
public void test() throws IOException {
    SqlSession sqlSession = getSqlSession();
EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
Page<Object> page = PageHelper.startPage(1, 5);
List<Employee> employeeList = mapper.getEmps();
PageInfo info = new PageInfo(employeeList);
    for (Employee e:employeeList) {
        System.out.println(employeeList);
}

    System.out.println("當前頁碼"+info.getPageNum());
System.out.println("總記錄數"+info.getTotal());
System.out.println("每頁記錄數"+info.getPageSize());
System.out.println("總頁碼"+info.getPages());
System.out.println("是否第一頁"+info.isIsFirstPage());
System.out.println("是否最後一頁"+info.isIsLastPage());

批量操作

可以使用<foreach>標籤做批量，但是使用這個標籤是對sql執行拼接，但是比如MySQL資料庫對於大量資料的這種處理是特別麻煩！

使用批量：

@Test
public void testBatch() throws IOException {
   String str = "mybatis-config.xml";
Reader reader = Resources.getResourceAsReader(str);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
//可以執行批量操作sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH);
    try {
        EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
        long start = System.currentTimeMillis();
        for (int i = 0; i < 10000; i++) {
            mapper.addEmployee(new Employee(UUID.randomUUID().toString().substring(1,5)+"lala","1","[email protected]"));
}
        sqlSession.commit();
        long end = System.currentTimeMillis();
System.out.println("執行的時長"+(end-start));
} finally {
        sqlSession.close();
}
}

預編譯SQL一次==》設定引數10000次==》資料庫執行（批量，1次）

非批量：

public void testBatch() throws IOException {
   String str = "mybatis-config.xml";
Reader reader = Resources.getResourceAsReader(str);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
//可以執行批量操作sqlSession
SqlSession sqlSession = sqlSessionFactory.openSession();
    try {
        EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
        long start = System.currentTimeMillis();
        for (int i = 0; i < 10000; i++) {
            mapper.addEmployee(new Employee(UUID.randomUUID().toString().substring(1,5)+"lala","1","[email protected]"));
}
        sqlSession.commit();
        long end = System.currentTimeMillis();
System.out.println("執行的時長"+(end-start));
} finally {
        sqlSession.close();
}
}

預編譯SQL==》設定引數==》執行——呼叫多少次執行多少次

與spring整合的時候，批量：

在spring配置檔案中：

<!--配置一個可以批量執行的SqlSession-->
<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
    <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactoryBean"/>
    <constructor-arg name="executorType" value="BATCH"/>
</bean>

使用：在service中

@Autowired
private SqlSession sqlSession;