Basic configuration of MyBatis: entity class, configuration file, mapping file, tool class, Mapper interface

Building projects

One: Lib (Jar package for the framework and database-driven jar package)

1, the first step: first put MyBatis Core class library into Lib

2, Step two: Import a third-party class library (in Lib). The core class library of MyBatis also relies on some third-party class libraries at run time

3, Step three: Import the connection database driver jar Package

Two: Create a mybatis configuration file

1, the first step: to create a physical package, against the table structure to write the entity class . Package is to write Get,set method------Unlike hibernate, you can automatically match the Name field name to the entity class, not your own hand-realistic body class and mapping file

2, the second step: Create an XML file, the file name can be casually written here, refer to Hibernate's canonical wording: Mybatis.cfg.xml

No next is required because MyEclipse does not have a built-in MyBatis document declaration

3, the configuration file consists of four parts:

(1) Configuration log

(2) Configuration type Alias

Alias The classes you use frequently, and use aliases later, to simplify your code---Custom entity class settings aliases

(3) Configuring the database connection and transaction manager

(4) Import the mapping file

The complete configuration file is as follows:

<?xml version= "1.0" encoding= "UTF-8"? ><! DOCTYPE configurationpublic "-//mybatis.org//dtd Config 3.0//en" "Http://mybatis.org/dtd/mybatis-3-config.dtd" > <configuration><!--Set Some of the operating parameters of the Mtbatis: log, is directly output to the console or output to the log4j file--><settings><!--name can not be written casually Can only be called this name; value has several options here choose to output--><setting name= "Logimpl" value= "stdout_logging" to the console/></settings><! --Set type alias: If the alias is not set when executing the SQL statement. Each time you specify a package name + class name, a long--><typealiases>< to write!--type is the full entity class name,--><tapealias type= " Cn.bdqn.mybatis.entity.User "alias=" User "/></typealiases><!--the properties of the database connection, different phases of development are connected to different stages of the database development-- Development environment: Connect the Programmer's own database testing phase-test environment: Connect the test database to run on-line-production environment: Connect to the official database you can write multiple environment--><environments default= "Dev" > <!--development environment--><environment id= "Dev" ><!--manage Transactions--><transactionmanager type= "jdbc"/><! through JDBC --Do not use connection pooling--><datasource type= "unpooled" ><property name= "Driver" value= "Com.mysql.jdbc.Driver"/>< Property name= "url" value= "Jdbc:mysql://locAlhost:3306:test "/><property name=" username "value=" Test "/><property name=" password "value=" 123456 "/ ></dataSource></environment></environments><!--path to the SQL mapping file--><mappers><!-- Introduce the SQL file to be loaded--><mapper resource= "Cn/bdqn/mybatis/mapper/user.sql.xml"/></mappers></ Configuration>

                                                   authoring Tool class

Package Cn.bdqn.mybatis.util;import Java.io.ioexception;import Java.io.reader;import Org.apache.ibatis.io.resources;import Org.apache.ibatis.session.sqlsession;import Org.apache.ibatis.session.sqlsessionfactory;import Org.apache.ibatis.session.sqlsessionfactorybuilder;public Class Mybatisutil {private static sqlsessionfactory Sessionfactory;static{try {//gets the input stream character stream used to load the configuration file  reader reader= Resources.getresourceasreader ("Mybatis.cfg.xml");//builder, through which Sqlsessionfactorybuilder builder=new Sqlsessionfactorybuilder (); Sessionfactory=builder.build (reader);} catch (Exception e) {e.printstacktrace ();}} public static sqlsession Getsqlsession () {return sessionfactory.opensession (true);}}

Mapping Files

<?xml version= "1.0" encoding= "UTF-8"? ><! DOCTYPE mapperpublic "-//mybatis.org//dtd Mapper 3.0//en" "Http://mybatis.org/dtd/mybatis-3-mapper.dtd" >< Mapper namespace= "Cn.bdqn.mybatis.mapper.UserMapper" ><insert id= "adduser  "parametertype=" user " >insert into User (username,password,email) VALUES (#{username},#{password},#{email}) </insert><select id= "GetUser" resulttype= "User" >select ID, Username,password,email from User WHERE id=#{id}</select><select id= "Finduser" resulttype= "User" >SELECT Id,username,password,email from the user ORDER by Id;</select><update id= "UpdateUser" parametertype= "User" > UPDATE User SET Username=#{username},password=#{password},email=#{email} WHERE id=#{id}</update><delete id= "Deluser" >delete from User WHERE id=#{id}</delete></mapper> 

Mapper Interface

Package Cn.bdqn.mybatis.mapper;import Java.util.list;import cn.bdqn.mybatis.entity.user;//invokes the corresponding statement via an abstract method inside the interface interface corresponding to the mapping file----The SQL statement namespace set to the full class name of the interface//equivalent to the original DAO layer, I only need to define the DAO interface, the specific implementation of the class now do not have to write their own, just get Mapper interface class can   addUser (User User);p ublic user getUser (Integer ID);p ublic list<user> finduser ();p ublic int updateUser (user user );p ublic void Deluser (Integer id);}

Test class

The first method of invoking an SQL statement
Save a user
int Rows=session.insert ("User.adduser", user);//Get a user User=session.selectone by ID ("User.getuser", 2);

The second most commonly used method of calling SQL statements is to define a mapper interface    Mapper interface, return value type, parameter, corresponding to; method name consistent with SQL statement ID
Tell the session first, and the following session finds the namespace based on the Mapper class.
Usermapper Mapper=session.getmapper (Usermapper.class);
int Rows=mapper.adduser (user);

Basic configuration of MyBatis: entity class, configuration file, mapping file, tool class, Mapper interface