SpringBoot快速入门

一、创建一个Maven项目不选框架
1.首先引入需要的依赖

 <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

2.建一个类，写一个启动springboot的主函数并加上相应注解

@SpringBootApplication
public class BootDemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(BootDemoApplication.class,args);
    }
}

3.创建一个Controller

加@RestController注解，返回json就不需要在方法上加@ResponseBody了

@RestController
public class HelloController {
    @RequestMapping("/hello")
    public String hello(){
        return "你好springboot!";
    }

请求：

二、配置连接池
1.首先加入依赖

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>RELEASE</version>
  </dependency>

2.加入配置文件config.properties

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/test
jdbc.username=root
jdbc.password=123456

3.java配置注入
类上加上@Configuration就相当于一个配置文件了

@Configuration
@PropertySource("classpath:jdbc.properties")
public class JdbcConfig {

    @Value("${jdbc.url}")
    String url;
    @Value("${jdbc.driverClassName}")
    String driverClassName;
    @Value("${jdbc.username}")
    String username;
    @Value("${jdbc.password}")
    String password;

    @Bean
    public DataSource dataSource(){
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(driverClassName);
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        return dataSource;
    }

4.注入datasource

@RestController
public class HelloController {

    @Autowired
    private DataSource dataSource;

    @RequestMapping("/hello")
    public String hello(){
        return "你好springboot!";
    }
}

5.debug运行
注入成功

springboot注入方式一：
1.加入依赖

<dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
   </dependency>

2.把上面的jdbc.properties改名成application.properties
3.创建一个properties类

@ConfigurationProperties(prefix = "jdbc")
@Data
public class JdbcProperties {
    String url;
    String driverClassName;
    String username;
    String password;
}

4.JdbcConfig类更改如下

@Configuration
//@PropertySource("classpath:application.properties")
@EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfig {

/*
    @Value("${jdbc.url}")
    String url;
    @Value("${jdbc.driverClassName}")
    String driverClassName;
    @Value("${jdbc.username}")
    String username;
    @Value("${jdbc.password}")
    String password;
*/
   /* //注解注入
    @Autowired
    JdbcProperties jdbcProperties;
    //构造方法注入
    public JdbcConfig(JdbcProperties jdbcProperties){
        this.jdbcProperties = jdbcProperties;
    }*/

    //参数输入
    @Bean
    public DataSource dataSource(JdbcProperties prop){
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(prop.getDriverClassName());
        dataSource.setUrl(prop.getUrl());
        dataSource.setUsername(prop.getUsername());
        dataSource.setPassword(prop.getPassword());
        return dataSource;
    }

断点调试：
datasource成功注入

springboot属性注入方式二：
更改如下

//@ConfigurationProperties(prefix = "jdbc")
@Data
public class JdbcProperties {
    String url;
    String driverClassName;
    String username;
    String password;
}

@Configuration
//@PropertySource("classpath:application.properties")
//@EnableConfigurationProperties(JdbcProperties.class)
public class JdbcConfig {

/*
    @Value("${jdbc.url}")
    String url;
    @Value("${jdbc.driverClassName}")
    String driverClassName;
    @Value("${jdbc.username}")
    String username;
    @Value("${jdbc.password}")
    String password;
*/
   /* //注解注入
    @Autowired
    JdbcProperties jdbcProperties;
    //构造方法注入
    public JdbcConfig(JdbcProperties jdbcProperties){
        this.jdbcProperties = jdbcProperties;
    }*/

    //参数输入
 /*   @Bean
    public DataSource dataSource(JdbcProperties prop){
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(prop.getDriverClassName());
        dataSource.setUrl(prop.getUrl());
        dataSource.setUsername(prop.getUsername());
        dataSource.setPassword(prop.getPassword());
        return dataSource;
    }*/

    @Bean
    @ConfigurationProperties(prefix = "jdbc")
    public DataSource dataSource() {
        return new DruidDataSource();
    }

三、yaml配置文件
除了可以用application.properties配置文件外，还可以用application.yaml配置文件

jdbc
  driverClassName: com.mysql.jdbc.Driver
  url: jdbc:mysql://localhost:3306/test
  username: root
  password: 123456
  user:
    name: jack
    age: 21
    language:
      - java
      - php
      - ios
      - python
      - scala

@Data
public class JdbcProperties {
    String url;
    String driverClassName;
    String username;
    String password;
    User user = new User();

    class User{
        String name;
        int age;
        List<String> language;
    }