springboot快速入门

1. 设置spring boot的parent

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
    </parent>

说明：Spring boot的项目必须要将parent设置为spring boot的parent，该parent包含了大量默认的配置，大大简化了我们的开发。

2. 导入spring boot的web支持

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

3. 添加Spring boot的插件

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

最终的pom.xml：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>cn.qiaoliqiang</groupId>
    <artifactId>spring-boot</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.2.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>4.3.7.RELEASE</version>
        </dependency>
        <!-- 连接池 -->
        <dependency>
            <groupId>com.jolbox</groupId>
            <artifactId>bonecp-spring</artifactId>
            <version>0.8.0.RELEASE</version>
        </dependency>
    </dependencies>
    <build>
        <finalName>${project.artifactId}</finalName>
        <plugins>
        <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <!-- 资源文件拷贝插件 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-resources-plugin</artifactId>
                <configuration>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <!-- java编译插件 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
        </plugins>
        <pluginManagement>
            <plugins>
                <!-- 配置Tomcat插件 -->
                <plugin>
                    <groupId>org.apache.tomcat.maven</groupId>
                    <artifactId>tomcat7-maven-plugin</artifactId>
                    <version>2.2</version>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>




</project>

4. 编写第一个Spring Boot的应用

@Controller
@SpringBootApplication
@Configuration
public class HelloApplication {
    
    @RequestMapping("hello")
    @ResponseBody
    public String hello(){
        return "hello world！";
    }
    
    public static void main(String[] args) {
        SpringApplication.run(HelloApplication.class, args);
    }

}

代码说明：

1、@SpringBootApplication：Spring Boot项目的核心注解，主要目的是开启自动配置。；

2、@Configuration：这是一个配置Spring的配置类；

3、@Controller：标明这是一个SpringMVC的Controller控制器；

4、main方法：在main方法中启动一个应用，即：这个应用的入口；

5. 启动应用

在Spring Boot项目中，启动的方式有两种，一种是直接run Java Application另外一种是通过Spring Boot的Maven插件运行。

第一种：

结果:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.2.RELEASE)

2018-01-11 16:54:36.745  INFO 882716 --- [           main] cn.qlq.springboot.HelloApplication       : Starting HelloApplication on root with PID 882716 (E:\MavenEclipseWorkspace\spring-boot\target\classes started by liqiang in E:\MavenEclipseWorkspace\spring-boot)
2018-01-11 16:54:36.750  INFO 882716 --- [           main] cn.qlq.springboot.HelloApplication       : No active profile set, falling back to default profiles: default
2018-01-11 16:54:36.872  INFO 882716 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@67dd2285: startup date [Thu Jan 11 16:54:36 CST 2018]; root of context hierarchy
2018-01-11 16:54:40.517  INFO 882716 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2018-01-11 16:54:40.678  INFO 882716 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
2018-01-11 16:54:40.680  INFO 882716 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.11
2018-01-11 16:54:40.998  INFO 882716 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-01-11 16:54:40.999  INFO 882716 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 4131 ms
2018-01-11 16:54:41.365  INFO 882716 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2018-01-11 16:54:41.372  INFO 882716 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-01-11 16:54:41.373  INFO 882716 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-01-11 16:54:41.373  INFO 882716 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-01-11 16:54:41.373  INFO 882716 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-01-11 16:54:42.097  INFO 882716 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@67dd2285: startup date [Thu Jan 11 16:54:36 CST 2018]; root of context hierarchy
2018-01-11 16:54:42.240  INFO 882716 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello]}" onto public java.lang.String cn.qlq.springboot.HelloApplication.hello()
2018-01-11 16:54:42.250  INFO 882716 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-01-11 16:54:42.251  INFO 882716 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-01-11 16:54:42.351  INFO 882716 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-01-11 16:54:42.351  INFO 882716 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-01-11 16:54:42.481  INFO 882716 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-01-11 16:54:43.241  INFO 882716 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-01-11 16:54:43.414  INFO 882716 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2018-01-11 16:54:43.429  INFO 882716 --- [           main] cn.qlq.springboot.HelloApplication       : Started HelloApplication in 8.809 seconds (JVM running for 9.52)
2018-01-11 17:04:05.722  INFO 882716 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'
2018-01-11 17:04:05.722  INFO 882716 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started
2018-01-11 17:04:05.804  INFO 882716 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 82 ms

访问:

第二种：以spring-boot插件的方式运行:

(1)添加一个maven常用命令

（2）运行上面建的maven命令:

结果与上面一样

看到如下信息就说明启动成功了：

2018-01-11 18:01:42.242  INFO 1021040 --- [           main] cn.qlq.springboot.HelloApplication       : Started HelloApplication in 6.845 seconds (JVM running for 16.07)

测试:

补充：SpringBootApplication 注解是一个组合注解，源码如下：

/** <a href="http://www.cpupk.com/decompiler">Eclipse Class Decompiler</a> plugin, Copyright (c) 2017 Chen Chao. */
package org.springframework.boot.autoconfigure;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.context.TypeExcludeFilter;
import org.springframework.context.annotation.AnnotationBeanNameGenerator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.core.annotation.AliasFor;
import org.springframework.data.repository.Repository;

@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 {

    /**
     * Exclude specific auto-configuration classes such that they will never be applied.
     * @return the classes to exclude
     */
    @AliasFor(annotation = EnableAutoConfiguration.class)
    Class<?>[] exclude() default {};

    @AliasFor(annotation = EnableAutoConfiguration.class)
    String[] excludeName() default {};

    @AliasFor(annotation = ComponentScan.class, attribute = "basePackages")
    String[] scanBasePackages() default {};

    @AliasFor(annotation = ComponentScan.class, attribute = "basePackageClasses")
    Class<?>[] scanBasePackageClasses() default {};


    @AliasFor(annotation = ComponentScan.class, attribute = "nameGenerator")
    Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;

    @AliasFor(annotation = Configuration.class)
    boolean proxyBeanMethods() default true;

}

　　@SpringBootApplication注解是一个组合注解，其中包括：@SpringBootConfiguration、@EnableAutoCOnfiguration、@ComponentScan

(1) SpringBootConfiguration如下：组合了@Configuration，标注当前类是配置类，并会将当前类内声名的以@Bean注解标注的方法实例纳入Spring容器中，实例名就是方法名。

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

    @AliasFor(annotation = Configuration.class)
    boolean proxyBeanMethods() default true;

}

(2) EnableAutoConfiguration: 是借助@Import将所有符合自动配置条件的Bean加载到IOC容器。

/** <a href="http://www.cpupk.com/decompiler">Eclipse Class Decompiler</a> plugin, Copyright (c) 2017 Chen Chao. */
package org.springframework.boot.autoconfigure;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.core.io.support.SpringFactoriesLoader;

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {

    String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";

    Class<?>[] exclude() default {};

    String[] excludeName() default {};

}

　　其中，最关键的是@Import(AutoConfigurationImportSelector.class)，借助AutoConfigurationImportSelector这个类，@EnableAutoConfiguration可以帮助SpringBoot应用将所有符合条件的@Configuration都加载IOC容器中，从classpath中搜寻出所有的META/Spring.factories配置文件，并将其中org.springframework.boot.autoconfigure.EnableAutoConfiguration对应的配置项，也就是一个自动配置类列表加载到IOC容器。

　　@EnableAutoConfiguration注解让SpringBoot根据类路径下的jar包依赖为当前项目进行自动配置，例如添加spring-boot-starter-web依赖，会自动添加Tomcat和SpringMVC依赖。对于所有使用@Configuration标注的配置类，统一由ConfigurationClassParser解析。

(3) @ComponentScan的作用是自动扫描并加载符合条件的的组件或Bean定义，最终将这些Bean加载到容器中。我们可以通过basePackages属性指定扫描的范围，如果不指定，默认扫描当前包及其子包下面的类。

/** <a href="http://www.cpupk.com/decompiler">Eclipse Class Decompiler</a> plugin, Copyright (c) 2017 Chen Chao. */
package org.springframework.context.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.core.annotation.AliasFor;
import org.springframework.core.type.filter.TypeFilter;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Repeatable(ComponentScans.class)
public @interface ComponentScan {

    @AliasFor("basePackages")
    String[] value() default {};

    @AliasFor("value")
    String[] basePackages() default {};

    Class<?>[] basePackageClasses() default {};

    Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;

    Class<? extends ScopeMetadataResolver> scopeResolver() default AnnotationScopeMetadataResolver.class;

    ScopedProxyMode scopedProxy() default ScopedProxyMode.DEFAULT;

    String resourcePattern() default ClassPathScanningCandidateComponentProvider.DEFAULT_RESOURCE_PATTERN;

    boolean useDefaultFilters() default true;

    Filter[] includeFilters() default {};

    Filter[] excludeFilters() default {};

    boolean lazyInit() default false;


    @Retention(RetentionPolicy.RUNTIME)
    @Target({})
    @interface Filter {

        FilterType type() default FilterType.ANNOTATION;

        @AliasFor("classes")
        Class<?>[] value() default {};

        @AliasFor("value")
        Class<?>[] classes() default {};

        String[] pattern() default {};

    }

}

posted @ 2018-01-11 18:11 QiaoZhi 阅读(644) 评论(0) 编辑收藏举报

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