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spring boot第二天

程序员文章站 2022-05-06 21:15:05
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SpringBoot增删改查实例

完整的项目结构

spring boot第二天

Controller的使用

@Controller chu处理http请求

@RestController Spring4 之后新加的注解,原来返回json需要@ResponseBody配合@Controller

@RequestMapping 配置url映射
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对于 REST 风格的请求 
spring boot第二天

对于 Controller 中的方法上的注解

@RequestMapping(value = "/hello",method = RequestMethod.GET)
@RequestMapping(value = "/hello",method = RequestMethod.POST)
@RequestMapping(value = "/hello",method = RequestMethod.DELETE)
@RequestMapping(value = "/hello",method = RequestMethod.PUT)
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SpringBoot 对上面的注解进行了简化

@GetMapping(value = "/girls")
@PostMapping(value = "/girls")
@PutMapping(value = "/girls/{id}")
@DeleteMapping(value = "/girls/{id}")
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浏览器需要发送不同方式的请求,可以安装HttpRequester插件,火狐浏览器可以直接搜索该组件安装。

spring boot第二天

spring boot第二天

spring-data-jpa

JPA全称Java Persistence API.JPA通过JDK 5.0注解或XML描述对象-关系表的映射关系,并将运行期的实体对象持久化到数据库中。

Hibernate3.2+TopLink 10.1.3以及OpenJPA都提供了JPA的实现。

利用JPA创建MySQL数据库

pom.xml加入JPAMySQL的依赖

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
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配置JPA和数据库

application.yml

spring:
  profiles:
    active: a
  datasource:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://127.0.0.1:3306/db_person
      username: root
      password: root

  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
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格式很重要 
需要自己手动去创建 db_person 数据库

创建与数据表对应的实体类Person

spring boot第二天

Person.java

package com.jxust.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

/**
 * Created by Peng
 * Time: 2016/12/16 17:56
 */
@Entity
public class Person {
    @Id
    @GeneratedValue
    private  Integer id;
    private String name;
    private Integer age;

    //必须要有构造函数
    public Person() {
    }

    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;
    }
}
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运行项目后,查看数据库,会自动创建表 person

mysql> use db_person;
Database changed
mysql> desc person;
+-------+--------------+------+-----+---------+----------------+
| Field | Type         | Null | Key | Default | Extra          |
+-------+--------------+------+-----+---------+----------------+
| id    | int(11)      | NO   | PRI | NULL    | auto_increment |
| age   | int(11)      | YES  |     | NULL    |                |
| name  | varchar(255) | YES  |     | NULL    |                |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.09 sec)
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接下来就可以进行person表的增删改查了

创建控制器PersonController.java

spring boot第二天

首先创建一个接口PersonRepository,位于dao包下,PersonController调用该接口继承自JpaRepository的方法,来实现和数据库交互

这个PersonRepository接口的功能,与SSM框架中 dao 层接口功能有异曲同工之妙;在SSM框架中,Service层通过该接口,间接执行Mybatis数据库映射文件(.xml)里的相应sql语句,执行数据库增删改查的操作。(Mapper自动实现DAO接口)

PersonRepository.java

package com.jxust.dao;

import com.jxust.entity.Person;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * Created by Peng
 * Time: 2016/12/16 18:07
 */
public interface PersonRepository extends JpaRepository<Person,Integer> {
}

PersonController.java

package com.jxust.controller;

import com.jxust.dao.PersonRepository;
import com.jxust.entity.Person;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/**
 * Created by Peng
 * Time: 2016/12/16 18:04
 */
@RestController
public class PersonController {
    @Autowired
    PersonRepository personRepository;
    @GetMapping(value = "/person")
    private List<Person> personList() {
        return personRepository.findAll();
    }
}

在数据库中添加两条数据

mysql> select * from person;
+----+------+--------+
| id | age  | name   |
+----+------+--------+
|  1 |   23 | 夏洛   |
|  2 |   21 | 马冬梅 |
+----+------+--------+
2 rows in set (0.04 sec)

启动项目执行请求http://localhost:8081/springboot/person

spring boot第二天

控制台输出的sql语句:

Hibernate: select person0_.id as id1_0_, person0_.age as age2_0_, person0_.name as name3_0_ from person person0_
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其他增删改查的方法

PersonController.java

....
    /**
     * 添加一个人员
     *
     * @param name
     * @param age
     * @return
     */
    @PostMapping(value = "/person")
    public Person personAdd(@RequestParam("name") String name,
                        @RequestParam("age") Integer age) {
        Person person = new Person();
        person.setName(name);
        person.setAge(age);

        return personRepository.save(person);
    }

    /**
     * 查询一个人员
     *
     * @param id
     * @return
     */
    @GetMapping(value = "/person/{id}")
    public Person personFindOne(@PathVariable("id") Integer id) {
        return personRepository.findOne(id);
    }

    /**
     * 删除一个人员
     *
     * @param id
     */
    @DeleteMapping(value = "/person/{id}")
    public void personDelete(@PathVariable("id") Integer id) {
        personRepository.delete(id);
    }

    /**
     * 更新一个人员
     *
     * @param id
     * @param name
     * @param age
     * @return
     */
    @PutMapping(value = "/person/{id}")
    public Person personUpdate(@PathVariable("id") Integer id,
                           @RequestParam("name") String name,
                           @RequestParam("age") Integer age) {
        Person person = new Person();
        person.setId(id);
        person.setName(name);
        person.setAge(age);
        return personRepository.save(person);
    }

对应的请求方式为:

  • 查询一个用户: 
    spring boot第二天

  • 添加一个用户 
    spring boot第二天

  • 删除一个用户(无返回值) 
    spring boot第二天

  • 更新一个用户 
    spring boot第二天

那么根据年龄查询,可不可以呢。答案是此刻还不行

从控制台的语句可以看出,sql 语句都是根据id来查询的

Hibernate: select person0_.id as id1_0_0_, person0_.age as age2_0_0_, person0_.name as name3_0_0_ from person person0_ where person0_.id=?
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根据年龄查询

PersonRepository增加一个方法findByAge(Integer age)

public interface PersonRepository extends JpaRepository<Person,Integer> {
    /**
     *  通过年龄来查询
     *  方法名固定findByAge
     * @param age
     * @return
     */
    public List<Person> findByAge(Integer age);
}

PersonController中加入相应的查询方法

....
    /**
     * 通过年龄来查询
     * @param age
     * @return
     */
    @GetMapping(value = "/person/age/{age}")
    public List<Person> personListByAge(@PathVariable("age") Integer age) {
        return personRepository.findByAge(age);
    }

输入请求http://localhost:8081/springboot/person/age/23,查询年龄为23的人员

spring boot第二天

控制台输出SQL语句:

Hibernate: select person0_.id as id1_0_, person0_.age as age2_0_, person0_.name as name3_0_ from person person0_ where person0_.age=?
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事务管理

两条 sql 语句同时在一个方法中执行,为了防止一个 sql 语句执行成功而另一个 sql 语句执行失败,引入了事务管理,需要在方法上加 @Transactional事务注解

事务确保了数据库数据的完整性和一致性

spring boot第二天

PersonService.java

package com.jxust.service;

import com.jxust.dao.PersonRepository;
import com.jxust.entity.Person;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.transaction.Transactional;
/**
 * Created by Peng
 * Time: 2016/12/16 19:30
 */
@Service
public class PersonService {
    @Autowired
    private PersonRepository personRepository;

    /**
     * 事务管理测试
     * 两条数据同时成功,或者同时不成功
     * 保证数据库数据的完整性和一致性
     */
    @Transactional
    public void insertTwo(){
        Person personA = new Person();
        personA.setName("秋雅");
        personA.setAge(19);
        personRepository.save(personA);

        System.out.print(1/0);

        Person personB = new Person();
        personB.setName("梦特娇");
        personB.setAge(25);
        personRepository.save(personB);
    }
}

PersonController测试

    ...
    @Autowired
    private PersonService personService;
    ...
     /**
     * 事务测试
     */
    @PostMapping("/person/two")
    public void personTwo(){
        personService.insertTwo();
    }

重新运行项目,执行请求 post方式http://localhost:8081/springboot/person/two 
数据库并没有添加第一条数据,说明存在事务管理

完整的PersonController.javaPersonRepository.javapom.xml

PersonController.java

package com.jxust.controller;

import com.jxust.dao.PersonRepository;
import com.jxust.entity.Person;
import com.jxust.service.PersonService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

/**
 * Created by Peng
 * Time: 2016/12/16 18:04
 */
@RestController
public class PersonController {
    @Autowired
    PersonRepository personRepository;
    @Autowired
    private PersonService personService;
    /**
     * 查询所有人员列表
     *
     * @return
     */
    @GetMapping(value = "/person")
    private List<Person> personList() {
        return personRepository.findAll();
    }

    /**
     * 添加一个人员
     *
     * @param name
     * @param age
     * @return
     */
    @PostMapping(value = "/person")
    public Person personAdd(@RequestParam("name") String name,
                        @RequestParam("age") Integer age) {
        Person person = new Person();
        person.setName(name);
        person.setAge(age);

        return personRepository.save(person);
    }

    /**
     * 查询一个人员
     *
     * @param id
     * @return
     */
    @GetMapping(value = "/person/{id}")
    public Person personFindOne(@PathVariable("id") Integer id) {
        return personRepository.findOne(id);
    }

    /**
     * 删除一个人员
     *
     * @param id
     */
    @DeleteMapping(value = "/person/{id}")
    public void personDelete(@PathVariable("id") Integer id) {
        personRepository.delete(id);
    }

    /**
     * 更新一个人员
     *
     * @param id
     * @param name
     * @param age
     * @return
     */
    @PutMapping(value = "/person/{id}")
    public Person personUpdate(@PathVariable("id") Integer id,
                           @RequestParam("name") String name,
                           @RequestParam("age") Integer age) {
        Person person = new Person();
        person.setId(id);
        person.setName(name);
        person.setAge(age);
        return personRepository.save(person);
    }

    /**
     * 通过年龄来查询
     * @param age
     * @return
     */
    @GetMapping(value = "/person/age/{age}")
    public List<Person> personListByAge(@PathVariable("age") Integer age) {
        return personRepository.findByAge(age);
    }

   /**
     * 事务测试
     */
    @PostMapping("/person/two")
    public void personTwo(){
        personService.insertTwo();
    }
}

PersonRepository.java

package com.jxust.dao;

import com.jxust.entity.Person;
import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

/**
 * Created by Peng
 * Time: 2016/12/16 18:07
 */
public interface PersonRepository extends JpaRepository<Person,Integer> {
    /**
     *  通过年龄来查询
     *  方法名固定
     * @param age
     * @return
     */
    public List<Person> findByAge(Integer age);
}

pom.xml

<?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>com.jxust</groupId>
    <artifactId>spirngbootdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>spirngbootdemo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <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-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>