Mybatis Study ( 3、 … and )—Java journal (log4j) The implementation of the / Paging implementation /Mybatis Optimized use of ( Business / Alias / annotation )

01 Java Log implementation

Mybatis The built-in log factory of provides the log function , The built-in log factory gives the log to one of the following tools as an agent ：

• SLF4J
• Apache Commons Logging
• Log4j 2
• Log4j
• JDK logging

Preparation steps ：

1. Maven Warehouse downloading log4j Dependence

<!--log4j rely on -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>

2. stay resources Store in the directory log4j.properties file

### Log4j To configure ###
### And Spring The combination needs to be in web.xml The location of this file is specified in , And add a monitor ###
# Definition log4j Output level and output destination （ A destination can have a custom name , Corresponding to the following ）
#[ level ] , appenderName1 , appenderName2
log4j.rootLogger=DEBUG,console,file
#-----------------------------------#
#1 Define log output destination as console
log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.Threshold=DEBUG
#### Flexibility to specify log output format , The following line specifies the specific format ###
#%c: Category of output log information , Usually the full name of the class
#%m: The message specified in the output code , Specific information of the generated log
#%n: Output a carriage return line feed ,Windows The platform is "/r/n",Unix The platform is "/n" Output log information line feed
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=[%c]-%m%n
#-----------------------------------#
#2 A new file is generated when the file size reaches the specified size
log4j.appender.file = org.apache.log4j.RollingFileAppender
# Log file output directory
log4j.appender.file.File=log/tibet.log
# Define maximum file size
log4j.appender.file.MaxFileSize=10mb
### Output log information ###
# The lowest level
log4j.appender.file.Threshold=ERROR
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=[%p][%d{yy-MM-dd}][%c]%m%n
#-----------------------------------#
#3 druid
log4j.logger.druid.sql=INFO
log4j.logger.druid.sql.DataSource=info
log4j.logger.druid.sql.Connection=info
log4j.logger.druid.sql.Statement=info
log4j.logger.druid.sql.ResultSet=info
#4 mybatis Show SQL Statement part
log4j.logger.org.mybatis=DEBUG
#log4j.logger.cn.tibet.cas.dao=DEBUG
#log4j.logger.org.mybatis.common.jdbc.SimpleDataSource=DEBUG
#log4j.logger.org.mybatis.common.jdbc.ScriptRunner=DEBUG
#log4j.logger.org.mybatis.sqlmap.engine.impl.SqlMapClientDelegate=DEBUG
#log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.ResultSet=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

3. mybatis-config.xml To configure

<!-- Set the log implementation Note that property settings are strictly case sensitive mybatis Of Commons Logging by ：STDOUT_LOGGING-->
<settings>
<setting name="logImpl" value="STDOUT_LOGGING"/>
</settings>

<!-- Set the log implementation Note that property settings are strictly case sensitive logj Realization way ：LOG4J-->
<settings>
<setting name="logImpl" value="LOG4J"/>
</settings>

4. Test code

@Test
public void selectUser(){

SqlSessionFactory sqlSessionFactory = MybatisUtil.getSqlSessionFactory();
SqlSession session = sqlSessionFactory.openSession();
List<User> users = mapper.selectUser();
for (User user : users) {

System.out.println(user);
}
}

test result ：

Commons Logging Implementation log

[org.apache.ibatis.logging.LogFactory]-Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
Class not found: org.jboss.vfs.VFS
JBoss 6 VFS API is not available in this environment.
Class not found: org.jboss.vfs.VirtualFile
VFS implementation org.apache.ibatis.io.JBoss6VFS is not valid in this environment.
Using VFS adapter org.apache.ibatis.io.DefaultVFS
Find JAR URL: file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo
Not a JAR: file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo
Reader entry: User.class
Listing file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo
Find JAR URL: file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo/User.class
Not a JAR: file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo/User.class
Reader entry: ���� 3 <
Checking to see if class com.hooi.pojo.User matches criteria [is assignable to Object]
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
Opening JDBC Connection
Created connection 183284570.
Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@aecb35a]
==> Preparing: select * from user
==> Parameters:
<== Columns: id, name, pwd
<== Row: 1, HooiShieh, 123456
<== Row: 2, Zhang San , abcdef
<== Row: 3, Li Si , 987654
<== Total: 3
User{id=1, name='HooiShieh', password='123456'}
User{id=2, name=' Zhang San ', password='abcdef'}
User{id=3, name=' Li Si ', password='987654'}

log4j Implementation log

[org.apache.ibatis.logging.LogFactory]-Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
[org.apache.ibatis.logging.LogFactory]-Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
[org.apache.ibatis.io.VFS]-Class not found: org.jboss.vfs.VFS
[org.apache.ibatis.io.JBoss6VFS]-JBoss 6 VFS API is not available in this environment.
[org.apache.ibatis.io.VFS]-Class not found: org.jboss.vfs.VirtualFile
[org.apache.ibatis.io.VFS]-VFS implementation org.apache.ibatis.io.JBoss6VFS is not valid in this environment.
[org.apache.ibatis.io.VFS]-Using VFS adapter org.apache.ibatis.io.DefaultVFS
[org.apache.ibatis.io.DefaultVFS]-Find JAR URL: file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo
[org.apache.ibatis.io.DefaultVFS]-Not a JAR: file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo
[org.apache.ibatis.io.DefaultVFS]-Reader entry: User.class
[org.apache.ibatis.io.DefaultVFS]-Listing file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo
[org.apache.ibatis.io.DefaultVFS]-Find JAR URL: file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo/User.class
[org.apache.ibatis.io.DefaultVFS]-Not a JAR: file:/G:/IDEA%20Project/Mybatis/target/classes/com/hooi/pojo/User.class
[org.apache.ibatis.io.DefaultVFS]-Reader entry: ���� 3 <
[org.apache.ibatis.io.ResolverUtil]-Checking to see if class com.hooi.pojo.User matches criteria [is assignable to Object]
[org.apache.ibatis.datasource.pooled.PooledDataSource]-PooledDataSource forcefully closed/removed all connections.
[org.apache.ibatis.datasource.pooled.PooledDataSource]-PooledDataSource forcefully closed/removed all connections.
[org.apache.ibatis.datasource.pooled.PooledDataSource]-PooledDataSource forcefully closed/removed all connections.
[org.apache.ibatis.datasource.pooled.PooledDataSource]-PooledDataSource forcefully closed/removed all connections.
[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Opening JDBC Connection
[org.apache.ibatis.datasource.pooled.PooledDataSource]-Created connection 183284570.
[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@aecb35a]
[com.hooi.dao.UserMapper.selectUser]-==> Preparing: select * from user
[com.hooi.dao.UserMapper.selectUser]-==> Parameters:
[com.hooi.dao.UserMapper.selectUser]-<== Total: 3
User{id=1, name='HooiShieh', password='123456'}
User{id=2, name=' Zhang San ', password='abcdef'}
User{id=3, name=' Li Si ', password='987654'}

02 Mybatis Realize pagination display of query results

adopt limit Realize pagination display of query results

1. mapper Interface

// adopt limit Realize pagination display of query results 
public abstract List<User> selectUserByLimit(Map<String,Integer> map);

2. mapper The mapping file

 <select id="selectUserByLimit" parameterType="Map" resultMap="UserMap" >
select * from user limit #{startIndex},#{pageSize}
</select>

3. Junit Test code

@Test
public void selectUserByLimit(){

SqlSessionFactory sqlSessionFactory = MybatisUtil.getSqlSessionFactory();
SqlSession session = sqlSessionFactory.openSession();
// Simulate getting data from users , In general , The user will only pass in the current page currentPage And page size pageSize
// The current position can be based on startIndex =（currentPage -1）*pageSize Calculation 
int currentPage = 2;
int pageSize = 2;
// Repackage the user's incoming data 
Map<String, Integer> map = new HashMap<>();
map.put("startIndex",(currentPage-1)*pageSize);
map.put("pageSize",pageSize);
UserMapper mapper = session.getMapper(UserMapper.class);
List<User> users = mapper.selectUserByLimit(map);
for (User user : users) {

System.out.println(user);
}
}

4. test result

adopt RowBounds Realize pagination display of query results

1. mapper Interface

// adopt mybatis Provided rowBounds Realize pagination display of query results 
public abstract List<User> selectUserByRowBounds(Map<String,Integer> map);

2. mapper The mapping file

<select id="selectUserByRowBounds" resultMap="UserMap" >
select * from user
</select>

3. Junit Test code

@Test
public void selectUserByRowBounds(){

SqlSessionFactory sqlSessionFactory = MybatisUtil.getSqlSessionFactory();
SqlSession session = sqlSessionFactory.openSession();
// Simulate incoming data 
int currentPage = 1;
int pageSize = 3;
// Calculate the starting position 
int startIndex = (currentPage-1)*pageSize;
// Create a RowBounds object 
RowBounds rowBounds = new RowBounds(startIndex, pageSize);
// Be careful ; Use RowBounds Implement paging , You can't use it getMapper 了 
//selectList: Receive one List Need the parameter passed in 
//selectMap: Receive one Map
//selectOne ： When receiving only one object 
List<User> users = session.selectList("com.hooi.dao.UserMapper.selectUserByRowBounds", null, rowBounds);
for (User user : users) {

System.out.println(user);
}
}

4. test result

limit and rowBounds difference

• limit Is in SQL The layer implements paging , You need to get it first through reflection Mapper Interface , Re pass SqlSession get Mapper Implementation class of interface , Pass in parameters through the implementation class ( The starting position , Page size ), Realize paging display .
• rowBounds Paging at the code level , There is no need to obtain Mapper Implementation class of interface , It needs to be constructed by parameters （ Pass in paging parameters ） establish RowBounds object , Re pass SqlSession Object call selectList,selectMap perhaps selectOne Method to implement paging . The parameters passed in are in turn corresponding to mapper The full domain name of the abstract method in the interface , A designated Objec object ( It’s usually null), as well as RowBounds object , Such as selectList(“com.hooi.dao.UserMapper.selectUserByRowBounds”,null,rowBounds).RowBounds The essence is to encapsulate limit.

03 Mybatis Optimized use of

Optimized use of transactions

public static SqlSession getSqlSession(){

// Turn on transaction auto commit ,openSession Constructor if the parameter is true, Then the transaction will automatically commit .
return sqlSessionFactory.openSession(true);
}

Optimized use of aliases

Automatically set alias

<typeAliases>
<!-- by pojo The class under the whole package automatically takes the alias -->
<package name="com.hooi.pojo"/>
</typeAliases>

Use the idea of annotation development

In the early Mybatis Is to use xml To configure , later , annotation The emergence of the began to replace some xml Configuration of .

CRUD Annotations ：@insert() @delete() @update() @select()

Develop… Using annotations In essence An interface Development of

AnnotationDao.interface

package com.hooi.dao;
import com.hooi.pojo.User;
import org.apache.ibatis.annotations.*;
import java.util.List;
public interface AnnotationDao {

// Query all users 
@Select("select * from user")
public abstract List<User> getAllUsers();
// adopt id and name Query the user 
// Be careful ： Passing in a single parameter can be omitted @Param Multiple parameters passed in must use @Param And separated by commas 
@Select("select * from user where id = #{id}")
public abstract User getUserById(@Param("id") int id );
// adopt id Delete user 
@Delete("delete from user where id = #{id}")
public abstract int delUserById(@Param("id") int id);
// Update user 
@Update("update user set name = #{name}, pwd = #{password} where id = #{id}")
public abstract int updateUser(User user);
// Add users 
@Insert("insert into user (id,name,pwd) values (#{id},#{name},#{password})")
public abstract int addUser(User user);
}

Using annotations for development does not require configuration mapper The mapping file , But it needs to be configured mybatis Configuration file for

<mappers>
<mapper class="com.hooi.dao.AnnotationDao"/>
</mappers>

Junit Test code ：

package com.hooi.dao;
import com.hooi.pojo.User;
import com.hooi.utils.MybatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class AnnotationDaoTest {

@Test
public void getAllUsers(){

SqlSession session = MybatisUtil.getSqlSession();
AnnotationDao mapper = session.getMapper(AnnotationDao.class);
List<User> users = mapper.getAllUsers();
for (User user : users) {

System.out.println(user);
}
}
@Test
public void getUserById(){

SqlSession session = MybatisUtil.getSqlSession();
AnnotationDao mapper = session.getMapper(AnnotationDao.class);
User user = mapper.getUserById(3);
System.out.println(user);
}
@Test
public void delUserById(){

SqlSession session = MybatisUtil.getSqlSession();
AnnotationDao mapper = session.getMapper(AnnotationDao.class);
int updateRows = mapper.delUserById(6);
if (updateRows>0){

System.out.println("delete successfully");
}
}
@Test
public void updateUser(){

SqlSession session = MybatisUtil.getSqlSession();
AnnotationDao mapper = session.getMapper(AnnotationDao.class);
int updateRows = mapper.updateUser(new User(5,"lily","000000"));
if (updateRows>0){

System.out.println("update successfully");
}
}
@Test
public void addUser(){

SqlSession session = MybatisUtil.getSqlSession();
AnnotationDao mapper = session.getMapper(AnnotationDao.class);
int updateRows = mapper.addUser(new User(6,"Jackson","000000"));
if (updateRows>0){

System.out.println("add successfully");
}
}
}

test result ：

1. getAllUsers() test result

2. getUserById() test result

3. delUserById() test result

4. updateUser() test result

5. addUser() test result