java——mybatis——Mybatis注解开发——@Select查询——查询所有数据

pom.xml配置：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         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">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>sunxl</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.27</version>
    </dependency>

    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>2.17.2</version>
    </dependency>
</dependencies>
</project>

 

 

 

 

 

 

 

 

 

 

 

mybatis-config.xml配置：

<?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>

    <typeAliases>
        <package name="com.sunxl.pojo"/>
    </typeAliases>
    <!-- 配置mybatis运行环境 -->
    <environments default="development">
        <environment id="development">
            <!-- 使用JDBC的事务管理 -->
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <!-- MySQL数据库驱动 -->
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <!-- 连接数据库的URL -->
                <property name="url" value="jdbc:mysql://localhost:3306/mysql8?characterEncoding=utf8" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    <!-- 将mapper文件加入到配置文件中 -->
    <mappers>
        <package name="com.sunxl.dao"></package>
    </mappers>
</configuration>

 

 

 

 

 

 

 

 

 

 

user的pojo类：

package com.sunxl.pojo;

public class User {

    Integer id;
    String name;
    Integer age;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "Users{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }

}

 

 

 

 

 

 

 

 

 

 

 

 

 

DAO接口文件：

package com.sunxl.dao;

import com.sunxl.pojo.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface UserDao {

    @Select("select * from users")
    List<User> findAll();

//    int saveUser(User user);
//
//    int updateUser(User user);
//
//    int deleteUser(Integer id);
//
//    User findById(Integer id);
//
//    List<User> findByName(String name);
//
//    int findTotal();
//
//    int saveInsertUser(User user);

}

 

 

 

 

 

 

 

 

 

 

 

测试结果：

import com.sunxl.dao.UserDao;
import com.sunxl.pojo.User;
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;
import java.util.List;

public class MybatisTest {

    public static void main(String[] args) throws IOException {

        InputStream config = Resources.getResourceAsStream("mybatis-config.xml");

        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(config);
        SqlSession ss = factory.openSession();
        UserDao userdao = ss.getMapper(UserDao.class);

        
        List<User> users = userdao.findAll();

        for (User user: users){
            System.out.println(user);
        }

        
        ss.commit();
        ss.close();
        config.close();


    }
}

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

表结构：