日韩在线精品强乱中文字幕,久草在线一免费新视频,日韩免费观看的一级毛片

1.一級緩存: 基于PerpetualCache 的 HashMap本地緩存，其存儲作用域為 Session ，當 Session flush 或 close 之后，該Session中的所有 Cache 就將清空。

2. 二級緩存與一級緩存其機制相同，默認也是采用 PerpetualCache，HashMap存儲，不同在于其存儲作用域為 Mapper(Namespace)，并且可自定義存儲源，如 Ehcache。

3. 對于緩存數據更新機制，當某一個作用域(一級緩存Session/二級緩存Namespaces)的進行了 C/U/D 操作后，默認該作用域下所有 select 中的緩存將被clear。

準備數據庫

      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);

與數據庫表對應的javabean，需要序列化（用于二級緩存）

      package com.hb.bean;

import java.io.Serializable;

public class User implements Serializable{
	private int id;
	private String name;
	private int age;
	private int minAge;
	private int maxAge;
    
	public int getMinAge() {
		return minAge;
	}
	public void setMinAge(int minAge) {
		this.minAge = minAge;
	}
	public int getMaxAge() {
		return maxAge;
	}
	public void setMaxAge(int maxAge) {
		this.maxAge = maxAge;
	}
	//get,set方法
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	
	public User(int id, String name, int age) {
		super();
		this.id = id;
		this.name = name;
		this.age = age;
	}
	
	public User() {
	}
	
	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
	}
	
	
}

開啟二級緩存使用<cache/>標簽

      <?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">
	<!-- 這里namespace必須是“包名 + xml文件名”，不然要運行的時候要報錯 “is not known to the MapperRegistry” -->
<mapper namespace="com.hb.bean.userMapper">
	<cache/>
	
	<select id="getUser" parameterType="int" resultType="com.hb.bean.User">
		select *
		from user where id=#{id}
	</select>

	<update id="updateUser" parameterType="com.hb.bean.User">
		update user set
		name=#{name}, age=#{age} where id=#{id}S
	</update>


</mapper>

      package com.hb.test5;

import java.io.InputStream;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;

import com.hb.bean.User;

/**
 * 一級緩存測試
 * @author Think
 *
 */
public class Test5 {

	public static SqlSessionFactory sqlSessionFactory;
	public static SqlSession sqlSession;
	
	@Before
	public void init(){
		//"/"表示是在src根目錄下
		String source = "config.xml";
		InputStream inputStream = Test5.class.getClassLoader().getResourceAsStream(source);
		
		try {
			sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//			sqlSession = sqlSessionFactory.openSession();
			//是否自動提交，默認不是自動提交的
			sqlSession = sqlSessionFactory.openSession(true);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	
	@Test
	public void selectByCondition(){
		/*
		 1. 必須是同一個Session,如果session對象已經close()過了就不可能用了 
		 */
		String stament = "com.hb.bean.userMapper.getUser";
		User user = sqlSession.selectOne(stament, 8);
		System.out.println(user);
		
		User user1 = sqlSession.selectOne(stament, 8);
		System.out.println(user1);
//2015-02-24 14:21:18,717 [main] DEBUG [com.hb.bean.userMapper.getUser] - ooo Using Connection [com.mysql.jdbc.Connection@1f54031]
//2015-02-24 14:21:18,717 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==>  Preparing: select * from user where id=? 
//2015-02-24 14:21:18,780 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==> Parameters: 8(Integer)
//User [id=8, name=Tom, age=12]
//User [id=8, name=Tom, age=12]

	}
	
	@Test
	public void selectByCondition1(){
		/*
		 1. 必須是同一個Session,如果session對象已經close()過了就不可能用了 
		 */
		String stament = "com.hb.bean.userMapper.getUser";
		User user = sqlSession.selectOne(stament, 8);
		System.out.println(user);
		sqlSession.clearCache();
		
		User user1 = sqlSession.selectOne(stament, 8);
		System.out.println(user1);
//2015-02-24 14:21:40,560 [main] DEBUG [com.hb.bean.userMapper.getUser] - ooo Using Connection [com.mysql.jdbc.Connection@10cb191]
//2015-02-24 14:21:40,560 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==>  Preparing: select * from user where id=? 
//2015-02-24 14:21:40,623 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==> Parameters: 8(Integer)
//User [id=8, name=Tom, age=12]
//2015-02-24 14:21:40,670 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==> Parameters: 8(Integer)
//User [id=8, name=Tom, age=12]
	}
	
	@Test
	public void selectByCondition2(){
		/*
		 4. 沒有執行過增刪改的操作(這些操作都會清理緩存)
		 */
		String statement = "com.hb.bean.userMapper.getUser";
		User user = sqlSession.selectOne(statement, 10);
		System.out.println(user);
		sqlSession.update("com.hb.bean.userMapper.updateUser",
				new User(10, "user", 23));
		User user1 = sqlSession.selectOne(statement, 10);
		System.out.println(user1);

//2015-02-24 14:20:37,788 [main] DEBUG [com.hb.bean.userMapper.getUser] - ooo Using Connection [com.mysql.jdbc.Connection@5dae4f]
//2015-02-24 14:20:37,788 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==>  Preparing: select * from user where id=? 
//2015-02-24 14:20:37,851 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==> Parameters: 10(Integer)
//User [id=10, name=user, age=18]
//2015-02-24 14:20:37,882 [main] DEBUG [com.hb.bean.userMapper.updateUser] - ooo Using Connection [com.mysql.jdbc.Connection@5dae4f]
//2015-02-24 14:20:37,882 [main] DEBUG [com.hb.bean.userMapper.updateUser] - ==>  Preparing: update user set name=?, age=? where id=? 
//2015-02-24 14:20:37,882 [main] DEBUG [com.hb.bean.userMapper.updateUser] - ==> Parameters: user(String), 23(Integer), 10(Integer)
//2015-02-24 14:20:37,914 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==> Parameters: 10(Integer)
//User [id=10, name=user, age=23]
		
	}
	
}

從selectByCondition()結果中可以看出，兩次調用getUserById方法，但是只有一次查詢數據庫的過程，這種現象產生的原因就是mybatis的一級緩存，并且一級緩存是默認開啟的。?

      package com.hb.test5;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;

import com.hb.bean.User;

/**
 * 二級緩存測試
 * @author Think
 *
 */
public class Test5_1 {

	public static SqlSessionFactory sqlSessionFactory;
	public static SqlSession sqlSession;
	
	@Before
	public void init(){
		//"/"表示是在src根目錄下
		String source = "config.xml";
		InputStream inputStream = Test5_1.class.getClassLoader().getResourceAsStream(source);
		
		try {
			sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
//			sqlSession = sqlSessionFactory.openSession();
			//是否自動提交，默認不是自動提交的
			sqlSession = sqlSessionFactory.openSession(true);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	
	@Test
	public void selectByCondition(){
		String statement = "com.hb.bean.userMapper.getUser";
		SqlSession session = sqlSessionFactory.openSession();
		User user = session.selectOne(statement, 8);
		session.commit();
		System.out.println("user="+user);
		session.close();
		
		SqlSession session2 = sqlSessionFactory.openSession();
		user = session2.selectOne(statement, 8);
		session2.commit();
		System.out.println("user2="+user);
		session2.close();
//2015-02-24 14:42:19,606 [main] DEBUG [com.hb.bean.userMapper.getUser] - ooo Using Connection [com.mysql.jdbc.Connection@11666b7]
//2015-02-24 14:42:19,606 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==>  Preparing: select * from user where id=? 
//2015-02-24 14:42:19,670 [main] DEBUG [com.hb.bean.userMapper.getUser] - ==> Parameters: 8(Integer)
//user=User [id=8, name=Tom, age=12]
//user2=User [id=8, name=Tom, age=12]
	}
	
}

在mybatis配置文件中可以開啟全局二級緩存。

      <?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>

		<!-- changes from the defaults for testing 
	<settings>
		<setting name="cacheEnabled" value="false" />
		<setting name="useGeneratedKeys" value="true" />
		<setting name="defaultExecutorType" value="REUSE" />
	</settings>
	-->

	<environments default="development">
		<environment id="development">
			<transactionManager type="jdbc" />
			<dataSource type="POOLED">
				<!-- 
				<property name="driver" value="oracle.jdbc.driver.OracleDriver"/> 
				<property name="url" value="jdbc:oracle:thin:@192.168.56.201:1521:system"/> 
				-->
				<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="123456" />
			</dataSource>
		</environment>
	</environments>

	<mappers>
		<mapper resource="com/hb/bean/userMapper.xml" />
	</mappers>

</configuration>

      實體類實現可序列化接口:
public class User implements Serializable {...}
    如果實體類不實現可序列化接口，使用二級緩存，那么會報下列異常:
org.apache.ibatis.cache.CacheException: Error serializing object.  Cause: java.io.NotSerializableException:

一、二級緩存（[尚硅谷]_張曉飛_Mybatis 學習筆記六）

更多文章、技術交流、商務合作、聯系博主

微信掃碼或搜索：z360901061

微信掃一掃加我為好友

QQ號聯系： 360901061

您的支持是博主寫作最大的動力，如果您喜歡我的文章，感覺我的文章對您有幫助，請用微信掃描下面二維碼支持博主2元、5元、10元、20元等您想捐的金額吧，狠狠點擊下面給點支持吧，站長非常感激您！手機微信長按不能支付解決辦法：請將微信支付二維碼保存到相冊，切換到微信，然后點擊微信右上角掃一掃功能，選擇支付二維碼完成支付。

【本文對您有幫助就好】元

2元

5元

10元

20元

自定義

欧美三区_成人在线免费观看视频_欧美极品少妇xxxxⅹ免费视频_a级毛片免费播放_鲁一鲁中文字幕久久_亚洲一级特黄