spring boot第二天
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2022-05-06 21:15:05
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SpringBoot增删改查实例
完整的项目结构
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- 1
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对于 REST 风格的请求
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)- 1
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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}")- 1
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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-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JPA和MySQL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>
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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- 1
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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
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)- 1
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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
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
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_- 1
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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：
添加一个用户
删除一个用户（无返回值）
更新一个用户
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=?- 1
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根据年龄查询
在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);
}在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
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=?- 1
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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
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);
}
}在PersonController中测试
...
@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.java、PersonRepository.java和pom.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>上一篇： 关于Mysql的那些事
下一篇： Spring框架（三）AOP
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