Getting started with springBoot

Environmental preparation

1. A competent text editor (eg Vim, Emacs, Sublime Text) or IDE (Eclipse, Idea Intellij)
2. Java environment (JDK 1.7 or above)
3. Maven 3.0+ (Eclipse and Idea IntelliJ built-in, if Can be installed without using an IDE and without using command line tools)

Generate a web project for the springBoot framework

idea can automatically generate the
address : http://start.spring.io/

Startup items (3 types)

1. Code running
2. Command: mvn spring-boot:run under the project
3. First compile java install
cd target
java -jar project name-0.0.1-SNAPSHOT.jar

Writing the application.yml file

application.properties is changed to application.yml.

1 、 application.yml 中

```
    cupSize: B
```

Get in java

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

2. There are configuration parameters in the configuration parameters in application.yml

 cupSize: B
 age: 18
 content: "cupSize: ${cupSize},age: ${age}"

3. Objects in application.yml

```
girl:
 cupSize: B
 age: 18
```

You can create an object in java to accept configuration parameters

```
@Component
@ConfigurationProperties(prefix="girl")
public class GirlParam {

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;
}

}
“`

4. Reference other application-dev.yml files

spring:
  profiles:
    active: dev

Use of Controller

@Controller handles http requests
@RestController The newly added annotations after spring4, the original return json format requires @ResponseBody and @Controller

1. Controller returns the template

pom.xml needs to be added

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
            <scope>模板</scope>
        </dependency>

Templates are placed in this folder. This method is not recommended, because the current development is basically the separation of front and back ends.

database operations

Spring-data-jpa is required. JPA (Java Persistence API) defines a series of standards for object persistence. Currently, products that implement this specification include Hibernate, TopLinkD and so on.
I am using mysql database.

pom.xml needs to be added

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

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

application.yml needs to be added

spring:
    datasource:
        driver-class-name: com.mysql.jdbc.Driver
        url: jdbc:mysql://127.0.0.1:3306/test
        username: root
        password: root

    jpa:
       hibernate:
         ddl-auto: update
       show-sql: true

Create a new class (database field)

The object class must have a no-argument constructor.

package com.yj.entity;

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

@Entity//对应数据库的一个
public class Girl {

    @Id
    @GeneratedValue//自增的
    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;
    }
}