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This article mainly introduces the relevant knowledge of "how to achieve an add, delete, change and search program in Mybatis". The editor shows you the operation process through an actual case. The operation method is simple and fast, and it is practical. I hope that this article "how to achieve an add, delete, change and search program in Mybatis" can help you solve the problem.

1.idea New Maven Project Mybatis-study deletes the src folder in the project and then takes this project as the parent project

two。 Create a new module mybatis-01 in Mybatis-study

In the pom file of mybatis, you can see that the parent project is ybatis-study

MyBatis-study

Org.example

1.0-SNAPSHOT

3. Introduce the following jar package into the pom.xml of Mybatis-study

Junit junit 4.11 test org.mybatis mybatis 3.5.9 mysql mysql-connector-java 8.0.29

4. Establish a connection between IDEA and the MySQL database:

Fill in user and password according to the actual situation, then click Test Connection

After the test is successful, click Schemas to select the database you want to link to

5. Create a new mybatis-config.xml configuration file to introduce database resources

6. Create entity class User Note: the name of the member variable in the entity class should be exactly the same as the field name in the database table

Package com.kero.pojo;public class User {private int id; private String name; private String password; public User () {} public User (int id, String name, String password) {this.id = id; this.name = name; this.password = password;} 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 String getpassword () {return password;} public void setpassword (String pwd) {this.password = pwd } @ Override public String toString () {return "User {" + "id=" + id + ", name='" + name +'\'+ ", pwd='" + password +'\'+'}';}}

7. Write the tool class Utils

Package com.kero.utils;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 java.io.IOException;import java.io.InputStream;//sqlSessionFactorypublic class MyBatisUtils {private static SqlSessionFactory sqlSessionFactory; static {try {/ / the first step of using Mybatis to get the sqlSessionFactory object String resource = "mybatis-config.xml" InputStream inputStream = Resources.getResourceAsStream (resource); sqlSessionFactory = new SqlSessionFactoryBuilder (). Build (inputStream);} catch (IOException e) {throw new RuntimeException (e);}} / * now that we have SqlSessionFactory, as the name implies, we can get an instance of SqlSession from it. SqlSession provides all the methods needed to execute SQL commands in the database. You can execute the mapped SQL statement directly through the SqlSession instance. For example: * / public static SqlSession getSqlSession () {return sqlSessionFactory.openSession ();}}

8. Define Interfac

Package com.kero.dao;import com.kero.pojo.User;import java.util.List;public interface UserMapper {/ / query all users List getUserList (); / / query users User getUserByID (int id) according to ID; / / insert a user int addUser (User user); / / modify a user int updateUser (User user); / / delete a user int deleteUser (int id);}

9. Define the Mapper file the Mapper file here is equivalent to the implementation class of the interface in the original traditional way

Select * from smbms.user select * from smbms.user where id = # {id} insert into smbms.user (id, name, password) VALUES (# {id}, # {name}, # {password}) update smbms.user set name=# {name}, password=# {password} where id = # {id} delete from smbms.user where id = # {id}

10. Write test classes

Import com.kero.dao.UserMapper;import com.kero.pojo.User;import com.kero.utils.MyBatisUtils;import org.apache.ibatis.session.SqlSession;import org.junit.Test;import java.util.List;public class test {@ Test public void test () {SqlSession session = MyBatisUtils.getSqlSession (); UserMapper mapper = session.getMapper (UserMapper.class); List userList = mapper.getUserList () For (User l:userList) {System.out.println (l.toString ());} session.close ();} @ Test public void testgetUserByID () {SqlSession session = MyBatisUtils.getSqlSession (); UserMapper mapper = session.getMapper (UserMapper.class); User userByID = mapper.getUserByID (1); System.out.println (userByID); session.close () } / / need to commit transaction @ Test public void testaddUser () {SqlSession session = MyBatisUtils.getSqlSession (); UserMapper mapper = session.getMapper (UserMapper.class); int zhhgf = mapper.addUser (new User (10, "zhhgf", "1k23jbjk")); System.out.println (zhhgf); session.commit (); / / commit transaction session.close () } @ Test public void testupdateUser () {SqlSession session = MyBatisUtils.getSqlSession (); UserMapper mapper = session.getMapper (UserMapper.class); int I = mapper.updateUser (new User (8, "asdfsdf", "234sdfs")); session.commit (); / / commit transaction session.close ();} @ Test public void testdeleteUser () {SqlSession session = MyBatisUtils.getSqlSession () UserMapper mapper = session.getMapper (UserMapper.class); int I = mapper.deleteUser (8); session.commit (); / / commit transaction session.close ();}}

11. Test query function: output results and data in database tables

User {id=1, name='Sugawara Ryota', pwd='8X8Jq7HVNs'}

User {id=2, name='Shawn Mills', pwd='R78IHGDSXr'}

User {id=3, name='Matsuda Hina', pwd='mUi3CVA7mc'}

User {id=4, name='Cynthia Hawkins', pwd='NO1EwWbOs9'}

User {id=5, name='Rachel Bennett', pwd='YefuPVxzb9'}

Tips:

If everything is configured properly, but java.lang.ExceptionInInitializerError appears.

Caused by org.apache.ibatis.execeptions.PersistenceExecepyion error

Because: maven because its convention is larger than the configuration, the configuration file we wrote may have a problem solution that cannot be exported or take effect. Add the following code to the pom.xml file

Src/main/resources * * / * .properties * * / * .xml true src/main/java * * / * .properties * * / * .xml true on "how to implement an add, delete, modify and search program for Mybatis" is introduced here. Thank you for your reading. If you want to know more about the industry, you can follow the industry information channel. The editor will update different knowledge points for you every day.

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