Mybatis延迟加载和查询缓存，java并发编程实践和并发编程实战

List userIncludeOrder();

TUser findUserById(Integer id);

List findAll();

void deleteById(Integer id);

}

UserMapper.xml

SELECT * from t_user

SELECt * from t_order where uid=#{id}

SELECt * from t_user

SELECt * FROM t_user where id=#{id}

SELECt * from t_user

DELETe from t_user WHERe id=#{id}

pom.xml

xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance”

xsi:schemaLocation=“http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd”>

4.0.0

groupId

dome02

1.0-SNAPSHOT

org.mybatis

mybatis

3.4.6

mysql

mysql-connector-java

5.1.47

junit

junit

4.12

log4j

log4j

1.2.14

sqlMapConfig.xml

log4j.properties

Global logging configuration

log4j.rootLogger=DEBUG, stdout

MyBatis logging configuration…

log4j.logger.org.mybatis.example.BlogMapper=TRACE

Console output…

log4j.appender.stdout=org.apache.log4j.ConsoleAppender

log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

TOrder.java

package com.xbj.po;

import java.io.Serializable;

import java.util.List;

public class TUser implements Serializable {

private int id;

private String username;

private String password;

private Integer age;

private List tOrders;

public List gettOrders() {

return tOrders;

}

public void settOrders(List tOrders) {

this.tOrders = tOrders;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

}

public Integer getAge() {

return age;

}

public void setAge(Integer age) {

this.age = age;

}

@Override

public boolean equals(Object o) {

if (this == o) return true;

if (o == null || getClass() != o.getClass()) return false;

TUser tUser = (TUser) o;

if (id != tUser.id) return false;

if (username != null ? !username.equals(tUser.username) : tUser.username != null) return false;

if (password != null ? !password.equals(tUser.password) : tUser.password != null) return false;

if (age != null ? !age.equals(tUser.age) : tUser.age != null) return false;

return true;

}

@Override

public int hashCode() {

int result = id;

result = 31 * result + (username != null ? username.hashCode() : 0);

result = 31 * result + (password != null ? password.hashCode() : 0);

result = 31 * result + (age != null ? age.hashCode() : 0);

return result;

}

@Override

public String toString() {

return “TUser{” +

“id=” + id +

“, username=’” + username + ‘’’ +

“, password=’” + password + ‘’’ +

“, age=” + age +

‘}’;

}

}

TUser.java

package com.xbj.po;

import java.io.Serializable;

import java.util.List;

public class TUser implements Serializable {

private int id;

private String username;

private String password;

private Integer age;

private List tOrders;

public List gettOrders() {

return tOrders;

}

public void settOrders(List tOrders) {

this.tOrders = tOrders;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

}

public Integer getAge() {

return age;

}

public void setAge(Integer age) {

this.age = age;

}

@Override

public boolean equals(Object o) {

if (this == o) return true;

if (o == null || getClass() != o.getClass()) return false;

TUser tUser = (TUser) o;

if (id != tUser.id) return false;

if (username != null ? !username.equals(tUser.username) : tUser.username != null) return false;

if (password != null ? !password.equals(tUser.password) : tUser.password != null) return false;

if (age != null ? !age.equals(tUser.age) : tUser.age != null) return false;

return true;

}

@Override

public int hashCode() {

int result = id;

result = 31 * result + (username != null ? username.hashCode() : 0);

result = 31 * result + (password != null ? password.hashCode() : 0);

result = 31 * result + (age != null ? age.hashCode() : 0);

return result;

}

@Override

public String toString() {

return “TUser{” +

“id=” + id +

“, username=’” + username + ‘’’ +

“, password=’” + password + ‘’’ +

“, age=” + age +

‘}’;

}

}

test.java

import org.apache.ibatis.io.Resources;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import org.junit.Before;

import org.junit.Test;

import com.xbj.mapper.UserMapper;

import com.xbj.po.TUser;

import java.io.IOException;

import java.io.InputStream;

import java.util.List;

public class test {

private UserMapper userMapper;

@Before

public void init() throws IOException {

InputStream is= Resources.getResourceAsStream(“sqlMapConfig.xml”);

userMapper=new SqlSessionFactoryBuilder().build(is).openSession(true).getMapper(UserMapper.class);

}

//测试延迟加载

@Test

public void t1(){

List infos=userMapper.userIncludeOrder();

System.out.println(infos);

}

//测试一级缓存

@Test

public void t2(){

TUser user1=userMapper.findUserById(1);

TUser user2=userMapper.findUserById(1);

}

/在进行增、改、删操作的时候会清空缓存/

@Test

public void t3(){

userMapper.findAll();

userMapper.deleteById(4);

userMapper.findAll();

}

}

Test02.java

import com.xbj.mapper.UserMapper;

import com.xbj.po.TUser;

import org.apache.ibatis.io.Resources;

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 java.io.IOException;

import java.io.InputStream;

public class Test02 {

private SqlSessionFactory factory;

private UserMapper userMapper;

private UserMapper userMapper2;

@Before

public void init() throws IOException {

InputStream is= Resources.getResourceAsStream(“sqlMapConfig.xml”);

factory=new SqlSessionFactoryBuilder().build(is);

userMapper=factory.openSession(true).getMapper(UserMapper.class);

userMapper2=factory.openSession(true).getMapper(UserMapper.class);

}

/测试在不同的mapper会话中，是访问不同的缓存区/

@Test

public void t1(){

TUser user1=userMapper.findUserById(1);

TUser user2=userMapper2.findUserById(1);

}

/在进行增、改、删操作的时候会清空缓存/

@Test

public void t2(){

userMapper.findAll();

userMapper.deleteById(4);

userMapper.findAll();

}

/测试二级缓存的时候，需要将第一个查询操作先关闭，否则程序不会进入缓存里面查找数据/

@Test

public void t3(){

SqlSession sqlSession1=factory.openSession(true);

SqlSession sqlSession2=factory.openSession(true);

sqlSession1.selectOne(“findUserById”,1);

sqlSession1.close(); //第一个人 调用后 会话结束 写入缓存

sqlSession2.selectOne(“findUserById”,1);

}

}

sql.sql

SET FOREIGN_KEY_CHECKS=0;

---

– Table structure for t_item

---

DROP TABLE IF EXISTS t_item;

CREATE TABLE t_item (