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  • 2小时学会SpringBoot

    1.课程介绍

    2.第一个springBoot应用

    2.1新建项目

    2.2创建HelloController类

    package com.example.demo;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {
    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String say(){
        return "hello,spring boot!";
    }
}

    2.3运行测试

    2.4第二种启动方式

    2.5第三种启动方式

     

     

    3.项目属性配置

    3.1在application.properties配置

    server.port=8081
server.servlet.context-path=/girl

    3.2在application.yml中配置

    server:
  port: 8082
  servlet:
    context-path: /girl

    3.3例子

    修改application.yml文件

    server:
  port: 8080

cupSize: B

    修改HelloController.java

    package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @Value("${cupSize}")
    private String cupSize;

    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String say(){
        return cupSize;
    }
}

     

    server:
  port: 8080

cupSize: B

age: 18
    package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @Value("${cupSize}")
    private String cupSize;

    @Value("${age}")
    private int age;

    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String say(){
        return cupSize+age;
    }
}

    server:
  port: 8080

cupSize: B

age: 18

content: "cupSize: ${cupSize},age:${age}"
    package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @Value("${cupSize}")
    private String cupSize;

    @Value("${age}")
    private int age;

    @Value("${content}")
    private String content;

    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String say(){
        return content;
    }
}

    application.yml

    server:
  port: 8080

girl:
  cupSize: B
  age: 18

    GirlProperties.java

    package com.example.demo;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@ConfigurationProperties(prefix = "girl")
public class GirlProperties {
    private String cupSize;
    private Integer age;

    public String getCupSize() {
        return cupSize;
    }

    public void setCupSize(String cupSize) {
        this.cupSize = cupSize;
    }

    public Integer getAge() {
        return age;
    }

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

    HelloController.java

    package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @Autowired
    private GirlProperties girlProperties;

    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String say(){
        return girlProperties.getCupSize();
    }
}

       

    3.4创建一个生产和一个开发配置文件

     application.yml

    spring:
  profiles:
    active: dev

    application-dev.yml

    server:
  port: 8082

girl:
  cupSize: B
  age: 18

    application-prod.yml

    server:
  port: 8081

girl:
  cupSize: F
  age: 18

    4.Controller的使用

     

    4.1@controller

     必须配合模板使用，否则报错

     

     

    4.2@RestController

    @RestController等同于@Controller和@ResponseBody的组合

    4.3@RequestMapping

    映射成两个url，或的关系

    映射一个类

    4.4@PathVariable

    获取url中的数据

     

     

    4.5@RequestParam

    获取请求参数的值

    参数缺省

    4.6@GetMapping

    组合注解：url+请求方式get

    5.数据库操作

    5.1自动建表

    application.yml

    spring:
  profiles:
    active: dev
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/dbgirl
    username: root
    password: 123456
  jpa:
    hibernate:
      ddl-auto: create
    show-sql: true

    Girl.java

    package com.example.demo;

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

@Entity
public class Girl {
    @Id
    @GeneratedValue
    private Integer id;
    private String cupSize;
    private Integer age;

    public Girl() {
    }
}

    5.2create和update的区别

    若dbgirl表存在，且有数据，配置create会将dbgirl表删除，然后新建一个dbgirl；update则不会删除表

    create

    update

     

    5.3示例

    package com.example.demo;

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

@Entity
public class Girl {
    @Id
    @GeneratedValue
    private Integer id;
    private String cupSize;
    private Integer age;

    public Girl() {
    }

    public Integer getId() {
        return id;
    }

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

    public String getCupSize() {
        return cupSize;
    }

    public void setCupSize(String cupSize) {
        this.cupSize = cupSize;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}
    package com.example.demo;

import org.springframework.data.jpa.repository.JpaRepository;

public interface GirlRepository extends JpaRepository<Girl, Integer> {
}
    package com.example.demo;

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;
import java.util.Map;

@RestController
public class GirlController {
    @Autowired
    private GirlRepository girlRepository;


    @GetMapping(value = "/girls")
    public List<Girl> girlList() {
        List<Girl> ls = girlRepository.findAll();
        for (Girl girl:ls) {
            System.out.println(girl);
        }
        return ls;
    }
}
    spring:
  profiles:
    active: dev
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/dbgirl
    username: root
    password: 123456
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true

    5.4增删改和id查询

    package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import javax.websocket.server.PathParam;
import java.util.List;

@RestController
public class GirlController {
    @Autowired
    private GirlRepository girlRepository;

    /**
     * 查询女生列表
     *
     * @return
     */
    @GetMapping(value = "/girls")
    public List<Girl> girlList() {
        return girlRepository.findAll();
    }

    /**
     * 添加一个女生
     *
     * @param id
     * @param cupSize
     * @param age
     * @return
     */
    @PostMapping("/girls")
    public Girl girlAdd(@RequestParam("id") Integer id,
                        @RequestParam("cupSize") String cupSize, @RequestParam("age") Integer age) {
        Girl girl = new Girl();
        girl.setId(id);
        girl.setCupSize(cupSize);
        girl.setAge(age);

        return girlRepository.save(girl);
    }

    /**
     * 查询一个女生
     */
    @GetMapping(value = "/girls/{id}")
    public Girl girlFindOne(@PathVariable("id") Integer id) {
        return girlRepository.findById(id).orElse(null);
    }

    /**
     * 更新一个女生
     */
    @PutMapping("girls/{id}")
    public Girl girlUpdate(@PathVariable("id") Integer id,
                           @RequestParam("cupSize") String cupSize,
                           @RequestParam("age") Integer age) {
        Girl girl = new Girl();
        girl.setId(id);
        girl.setCupSize(cupSize);
        girl.setAge(age);
        return girlRepository.save(girl);
    }


    /**
     * 删除一个女生
     */
    @DeleteMapping("girls/{id}")
    public void girlDelete(@PathVariable("id") Integer id){
        girlRepository.deleteById(id);
    }
}

    5.5where查询

    GirlRepository .java

    package com.example.demo;

import org.springframework.data.jpa.repository.JpaRepository;

import java.util.List;

public interface GirlRepository extends JpaRepository<Girl, Integer> {
    //通过年龄来查询
    public List<Girl> findByAge(Integer age);
}
    package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;

import javax.websocket.server.PathParam;
import java.util.List;

@RestController
public class GirlController {
    @Autowired
    private GirlRepository girlRepository;


    /**
     * 通过年龄来查询
     */
    @GetMapping("/girls/age/{age}")
    public List<Girl> girlListByAge(@PathVariable("age") Integer age){
        return girlRepository.findByAge(age);
    }
}

    6.事务管理

    场景：插入两个女生，要么都插入成功，要么都插入失败，不要一个成功一个失败。

    为了模拟上述场景，故意将数据库中的cupSize字段设置为长度1

    package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class GirlService {

    @Autowired
    private GirlRepository girlRepository;

    public void insertTwo(){
        Girl girlA = new Girl();
        girlA.setCupSize("A");
        girlA.setAge(18);
        girlRepository.save(girlA);

        Girl girlB = new Girl();
        girlB.setCupSize("BBBB");
        girlB.setAge(18);
        girlRepository.save(girlB);
    }
}
    package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;

import javax.websocket.server.PathParam;
import java.util.List;

@RestController
public class GirlController {

    @Autowired
    private GirlService girlService;


    @PostMapping("/girls/two")
    public void girlTwo(){
        girlService.insertTwo();
    }

}

     

    package com.example.demo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import javax.transaction.Transactional;

@Service
public class GirlService {

    @Autowired
    private GirlRepository girlRepository;

    @Transactional
    public void insertTwo(){
        Girl girlA = new Girl();
        girlA.setCupSize("A");
        girlA.setAge(18);
        girlRepository.save(girlA);

        Girl girlB = new Girl();
        girlB.setCupSize("BBBB");
        girlB.setAge(18);
        girlRepository.save(girlB);
    }
}

    增加了@Transactional注解之后，发现A和BBBB都没增加成功
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  • 原文地址：https://www.cnblogs.com/xinmomoyan/p/15111797.html
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