idea连接数据库实现增删改查

连接数据库，在application.properties中编写代码实现数据库连接

创建Student类，编写插入到数据库里的信息，id、name等，并创建set、get、tostring方法

创建接口

创建StudentImp类实现StudentDao接口里的方法

import com.mongodb.client.result.UpdateResult;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.data.mongodb.core.query.Update;
import org.springframework.stereotype.Component;

@Component      //标记StudentImp为一个bean，后面可以用@Autowired直接创建对象
public class StudentImp implements StudentDao {
    @Autowired
    private MongoTemplate mongoTemplate;

    @Override
    public void saveStudent(Student student) {
        mongoTemplate.save(student);
    }

    @Override
    public void removeStudent(int id) {
        Query query = new Query(Criteria.where("id").is(id));//查找其id字段的值与传入参数id相等的数据
        mongoTemplate.remove(query, Student.class);
    }

    @Override
    public Student findStudentByName(String name) {
        Query query = new Query(Criteria.where("name").is(name));
        Student student = mongoTemplate.findOne(query, Student.class);
        return student;
    }

    @Override
    public int updateStudent(Student student) {
        Query query = new Query(Criteria.where("id").is(student.getId()));
        Update update = new Update().set("name", student.getName()).set("stuno", student.getStuno());
        //更新查询返回的结果集的第一条数据
        UpdateResult result = mongoTemplate.updateFirst(query, update, Student.class);
        //更新查询到的所有结果集
        //UpdateResult all_result = mongoTemplate.updateMulti(query,update,User.class);
        if (result != null)
            return (int) result.getModifiedCount();
        else
            return 0;
    }
}

编写测试类

 SpringBootDemoApplication类不用修改我们直接运行就可以了

这是该项目的pom.xml提供给大家参考

<?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>2.7.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>springBoot_demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springBoot_demo</name>
    <description>springBoot_demo</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
      <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-web</artifactId>
       </dependency>
       <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-freemarker</artifactId>
       </dependency>
       <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <scope>runtime</scope>
       </dependency>

       <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-data-jpa</artifactId>
       </dependency>
       <dependency>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-thymeleaf</artifactId>
      </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>