Mybatis 四大利器之四->查询(简单)

本文详细介绍使用MyBatis实现基于单一条件的数据库查询过程,包括定义DAO接口、配置XML映射文件、编写业务逻辑代码及运行测试。

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mybatis简单查询语句相对比较简单,主要步骤如下所示:
(1)在bao包中Huserdao.java类中新添查询方法,在接口实例中已经讲述了查询所有的代码编写,本章针对一个条件进行查询,首先建立代码块,代码如下所示:

public List<HUser> SelectHUserBySex(int sex);

(2)接下来就是在entity包HUser.xml中新添查询代码,代码如下所示:

<select id="SelectHUserBySex" parameterType="int" resultType="com.hevttc.lmj.entity.HUser">

        select * from h_user where sex=#{sex}
    </select>

(3)接下来就是在biz包HUserBiz.java代码块中新添查询代码,代码如下所示:

public List<HUser> getHUserBySex(String sex)
    {
        List<HUser> list=null;

        try {
            SqlSession session=SessionFactory.getSession();


            dao=session.getMapper(HUserdao.class);

            list=dao.SelectHUserBySex(sex.equals("男")?0:1);

            SessionFactory.ClosedSession(session);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        return list;
    }

(4)接下来就是使用主方法进行运行与执行结果,代码如下所示:

List<HUser> list=biz.getHUserBySex("男");

        System.out.println("ID号\t姓名\t年龄\t性别\t地址");
        for(HUser user:list)
        {
            System.out.println(user.getId()+"\t"+user.getUsername()+"\t"+user.getAge()+"\t"+(user.getSex()==0?"男":"女")+"\t"+user.getPlace());
        }
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>3.4.7</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>takeoutsystem</artifactId> <version>0.0.1-SNAPSHOT</version> <name>takeoutsystem</name> <description>takeoutsystem</description> <properties> <java.version>17</java.version> <!-- MyBatis 版本 --> <mybatis.version>3.5.15</mybatis.version> <mybatis-spring.version>3.0.3</mybatis-spring.version> <!-- 其他依赖版本 --> <jjwt.version>0.11.5</jjwt.version> <springdoc-openapi.version>2.8.5</springdoc-openapi.version> <thymeleaf-extras-springsecurity6.version>3.1.2.RELEASE</thymeleaf-extras-springsecurity6.version> </properties> <dependencyManagement> <dependencies> <!-- 强制所有模块使用此MyBatis版本 --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>${mybatis.version}</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> <version>${mybatis-spring.version}</version> </dependency> </dependencies> </dependencyManagement> <dependencies> <!-- Spring Boot 基础依赖 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-actuator</artifactId> </dependency> <!-- 原生 MyBatis Starter --> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>3.0.3</version> <exclusions> <!-- 排除旧版 MyBatis --> <exclusion> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> </exclusion> <exclusion> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> </exclusion> </exclusions> </dependency> <!-- 显式指定升级后的MyBatis版本 --> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>${mybatis.version}</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> <version>${mybatis-spring.version}</version> </dependency> <!-- 数据库依赖 --> <dependency> <groupId>com.mysql</groupId> <artifactId>mysql-connector-j</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>test</scope> </dependency> <!-- 安全与认证依赖 --> <dependency> <groupId>io.jsonwebtoken</groupId> <artifactId>jjwt-api</artifactId> <version>${jjwt.version}</version> </dependency> <dependency> <groupId>io.jsonwebtoken</groupId> <artifactId>jjwt-impl</artifactId> <version>${jjwt.version}</version> <scope>runtime</scope> </dependency> <dependency> <groupId>io.jsonwebtoken</groupId> <artifactId>jjwt-jackson</artifactId> <version>${jjwt.version}</version> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-security</artifactId> </dependency> <dependency> <groupId>org.thymeleaf.extras</groupId> <artifactId>thymeleaf-extras-springsecurity6</artifactId> <version>${thymeleaf-extras-springsecurity6.version}</version> </dependency> <!-- API文档 --> <dependency> <groupId>org.springdoc</groupId> <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId> <version>${springdoc-openapi.version}</version> </dependency> <!-- 测试依赖 - 修正后 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <exclusions> <exclusion> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework.security</groupId> <artifactId>spring-security-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <excludes> <exclude> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </exclude> </excludes> </configuration> </plugin> </plugins> </build> </project> 如何添加对应的mybatisplus依赖,springboot的版本是3.4.7
最新发布
07-15
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