Springboot复习

一、创建工程

首先是IDEA创建项目，具体不多说，下面直接进入正题

1.核心pom.xml引入：

首先引入核心依赖

	<parent>
        <artifactId>spring-boot-starter-parentartifactId>
        <groupId>org.springframework.bootgroupId>
        <version>2.1.5.RELEASEversion>
    parent>

所有的springboot项目都需要引入parent
如果使用的是web项目，我们还需要引入一个web依赖

	<dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-starter-webartifactId>
        dependency>
    dependencies>

剩下可以自己选配
比如：

<properties>
	<java.version>1.8java.version>
properies>

<plugin>
	<groupId>org.springframework.bootgroupId>
	<artifactId>spring-boot-maven-pluginartifactId>
plugin>

2.创建启动引导类。

创建Application类，使用注解，同时使用run。

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

3.创建控制类

package hit.karlyn.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @GetMapping("hello")
    public String hello(){
        return "hello";
    }
}

具体代码如上，使用注解@RestController进行控制类的注解

二、Java配置

1.一些注解

Java中一些比较常件的注释：

@Configuration //声明一个类为配置类，代替xml文件
@Bean //声明在方法上，讲方法的返回值加入Bean容器，代替标签
@value //属性注入
@PropertySource //指定外部属性文件

下面使用Java代码配置数据库连接池，并可以在处理器中注入并使用。
实现步骤
1.添加依赖：
2.创建数据库：
3.创建数据库连接参数的配置文件：jdbc.properties;
4.创建配置类；
5.改造处理器注入数据源并使用

实现方法：

package hit.karlyn.config;


import com.alibaba.druid.pool.DruidAbstractDataSource;
import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

import javax.sql.DataSource;

@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;
    }
}

进一步使用@CongigurationProperties在类上注释

package hit.karlyn.config;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

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

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getDriverClassName() {
        return driverClassName;
    }

    public void setDriverClassName(String driverClassName) {
        this.driverClassName = driverClassName;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

package hit.karlyn.config;


import com.alibaba.druid.pool.DruidAbstractDataSource;
import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.context.annotation.PropertySource;

import javax.sql.DataSource;

@Configuration
//@PropertySource("classpath:jdbc.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;
    */
    @Bean
    public DataSource dataSource(JdbcProperties jdbcProperties){
        DruidDataSource dataSource=new DruidDataSource();
        dataSource.setDriverClassName(jdbcProperties.getDriverClassName());
        dataSource.setUrl(jdbcProperties.getUrl());
        dataSource.setUsername(jdbcProperties.getUsername());
        dataSource.setPassword(jdbcProperties.getPassword());
        return dataSource;
    }
}

或者再进一步直接在方法上注释

package hit.karlyn.config;


import com.alibaba.druid.pool.DruidAbstractDataSource;
import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.context.annotation.PropertySource;

import javax.sql.DataSource;

@Configuration
//@PropertySource("classpath:jdbc.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;
    */
    @Bean
    @ConfigurationProperties(prefix = "jdbc")
    public DataSource dataSource(){
        /*
        DruidDataSource dataSource=new DruidDataSource();
        dataSource.setDriverClassName(jdbcProperties.getDriverClassName());
        dataSource.setUrl(jdbcProperties.getUrl());
        dataSource.setUsername(jdbcProperties.getUsername());
        dataSource.setPassword(jdbcProperties.getPassword());
        return dataSource;
        */
         return new DruidDataSource();
    }
}