一起学JAVA之《spring boot》03 - 开始spring boot基本配置及项目结构（转）

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                    <h3 id="一导航"><a name="t0"></a>一、导航</h3>

本节内容简介：
1. spring boot 配置文件，使用@SpringBootApplication注解
2. spring boot 修改Java版本和项目编码
3. 一个标准的spring boot 代码结构
4. 查看当前项目自动配置了那些模块
5. 禁用自动配置
6. 自定义banner及关闭banner

一、spring boot 配置文件，使用@SpringBootApplication注解

spring boot 默认使用application.properties或者application.yml,放置在src/main/resources目录或者类路径的/config下，一般建议就放在src/main/resources
这里我们使用application.properties来配置，这里我们试着修改下端口和访问路径
目录结构如下：

配置代码：

server.port=8081server.context-path=/boot

1
2

编写测试controller类

package com.likeoak.controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;/** * 测试Controller * The type Test controller. */@RestControllerpublic class TestController {    /**     * 返回 String 字符串，访问成功，返回“test ok”     * Test string.     *     * @return the string     */@RequestMapping("/test")    public String test(){        return  "test ok!";    }}

启动main方法，及运行APP启动类

package com.likeoak;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;/** * 默认启动类 */@SpringBootApplicationpublic class App{    public static void main( String[] args )    {        SpringApplication.run(App.class,args);    }}

访问：http://localhost:8081/boot/test
结果：test ok!

代码解释：
@SpringBootApplication 解释
先看下注解@SpringBootApplication的源码

@SpringBootApplication的源码

@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Inherited@SpringBootConfiguration@EnableAutoConfiguration@ComponentScan(excludeFilters = {        @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),        @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })public @interface SpringBootApplication {

里面包含@SpringBootConfiguration的源码

@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Configurationpublic @interface SpringBootConfiguration {

总结：@SpringBootApplication注解其实是@Configuration，@EnableAutoConfiguration，@ComponentScan这三个注解组合

注解解释
@Configuration 注解：标明该类使用Spring是基于java的配置
@EnableAutoConfiguration ：开启自动配置注解，有这个注解spring boot就会根据我们所引用的jar包来自动配置我们需要的配置，这正是spring boot 魔力。

@ComponentScan：spring扫描注解，有这个注解spring boot 就会扫描（默认是以根路径为准）所有的包，来加载所有的@Bean,所有这里的TestController 就是被扫描到的，我们就可以访问了。

二、spring boot 修改Java版本和项目编码

在使用spring bootde 过程中，想自定义java配置，可以使用以下配置,加载到pom.xml中即可

  <properties>        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>        <java.version>1.8</java.version>    </properties>

三、一个标准的spring boot 代码结构

一个典型的spring boot 项目结构，这也是官网推荐的

com +- example     +- myproject         +- Application.java         |         +- domain         |   +- Customer.java         |   +- CustomerRepository.java         |         +- service         |   +- CustomerService.java         |         +- web             +- CustomerController.java

四、查看当前项目自动配置了那些模块

查看当前项目有哪些自动配置，一共有三种方法
1. 直接运行jar -jar xxx.jar –debug
2. 在application中设置属性

debug=true

直接在启动的时候，增加启动参数

我们可以选着任何一种，访问结果如下
已启动配置:

Positive matches:


DispatcherServletAutoConfiguration matched:
- @ConditionalOnClass found required class ‘org.springframework.web.servlet.DispatcherServlet‘; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
- @ConditionalOnWebApplication (required) found StandardServletEnvironment (OnWebApplicationCondition)
DispatcherServletAutoConfiguration.DispatcherServletConfiguration matched:
- @ConditionalOnClass found required class ‘javax.servlet.ServletRegistration‘; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
- Default DispatcherServlet did not find dispatcher servlet beans (DispatcherServletAutoConfiguration.DefaultDispatcherServletCondition)
DispatcherServletAutoConfiguration.DispatcherServletRegistrationConfiguration matched:
- @ConditionalOnClass found required class ‘javax.servlet.ServletRegistration‘; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
- DispatcherServlet Registration did not find servlet registration bean (DispatcherServletAutoConfiguration.DispatcherServletRegistrationCondition)

....

未自动配置：

Negative matches:


ActiveMQAutoConfiguration:
Did not match:
- @ConditionalOnClass did not find required classes ‘javax.jms.ConnectionFactory‘, ‘org.apache.activemq.ActiveMQConnectionFactory‘ (OnClassCondition)
AopAutoConfiguration:
Did not match:
- @ConditionalOnClass did not find required classes ‘org.aspectj.lang.annotation.Aspect‘, ‘org.aspectj.lang.reflect.Advice‘ (OnClassCondition)
ArtemisAutoConfiguration:
Did not match:
- @ConditionalOnClass did not find required classes ‘javax.jms.ConnectionFactory‘, ‘org.apache.activemq.artemis.jms.client.ActiveMQConnectionFactory‘ (OnClassCondition)
BatchAutoConfiguration:
Did not match:
- @ConditionalOnClass did not find required classes ‘org.springframework.batch.core.launch.JobLauncher‘, ‘org.springframework.jdbc.core.JdbcOperations‘ (OnClassCondition)

...

五、禁用自动配置

比如不想自动配置数据库连接，就可以用如何代码来关掉自动配置

/** * 测试关闭数据库自动配置 * The type Data source config. */@Configuration@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class})public class DataSourceConfig {}

六、自定义banner及关闭banner

自定义spring boot 默认启动图案步骤：
1. 直接在src/main/resources下创建一个banner.txt
2. 访问网站http://patorjk.com/software/taag 生成字符，这里我们用”yiqixuejava”（一起学java）,将生成的字符复制到banner.txt中，启动应用即可

启动结果：

        .__         .__                              __ ___.__.|__|   _____|__| ___  _____ __   ____       |__|____ ___  _______<   |  ||  |  / ____/  | \  \/  /  |  \_/ __ \      |  \__  \\  \/ /\__  \ \___  ||  | < <_|  |  |  >    <|  |  /\  ___/      |  |/ __ \\   /  / __ \_ / ____||__|  \__   |__| /__/\_ \____/  \___  > /\__|  (____  /\_/  (____  / \/              |__|          \/           \/  \______|    \/           \/

后续会继续推出这一系列spring boot的文章

原文地址：http://blog.csdn.net/javastudyr/article/details/73824894

原文地址：https://www.cnblogs.com/jpfss/p/8339995.html

时间： 2024-10-03 14:55:40