SpringBoot構建Tip

pom配置

默認打成jar，在pom.xml中指定mainClass。項目根目錄下執行mvn package生成可執行的jar包， jar包中MANIFEST.MF文件會顯示mainclass。

<properties>
    <mainClass>com.noob.Bootstrap</mainClass>
</properties>

<plugins> 
  <plugin> 
    <groupId>org.springframework.boot</groupId>  
    <artifactId>spring-boot-maven-plugin</artifactId>  
    <version>${spring-boot.version}</version>  
    <configuration> 
      <fork>true</fork> 
    </configuration>  
  </plugin> 
</plugins>

啓動

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter</artifactId>
    <version>1.3.6.RELEASE</version>
</dependency>

@RestController = @Controller + @ResponseBody;

@SpringBootApplication =@Configuration + @EnableAutoConfiguration + @ComponentScan;

• 常規方式

  SpringApplication.run(CreditBootstrap.class, args);

• 可設置參數

  new SpringApplicationBuilder(CreditBootstrap.class).run(args)

返回一個ConfigurableApplicationContext對象

• org.springframework.context.annotation.AnnotationConfigApplicationContext
• org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext  在支持web模式下啓用（不一樣版本不同）

加載

啓動先加載bootstrap.yml，從遠端獲取application.yml覆蓋本地。

若指定scanBasePackages（包及子包下）則掃描指定路徑，不然默認加載啓動main方法類的包路徑。

@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class }, scanBasePackages={"com.noob.mics"})

WebEnvironment

（不一樣版本下的實現方式和ApplicationContext不同）

在SpringApplication的initialize方法：斷定Classloader成功加載接口類"javax.servlet.Servlet"、
"org.springframework.web.context.ConfigurableWebApplicationContext"中的任意一個即設置
webEnvironment = true ；

開啓Web環境，將加載AnnotationConfigEmbeddedWebApplicationContext 。

外部tomcat

可內嵌容器：

步驟：

1. 修改pom.xml:

   <packaging>war</packaging>
   
   <dependency>
   	<groupId>org.springframework.boot</groupId>
   	<artifactId>spring-boot-starter-web</artifactId>
   	<version>1.3.6.RELEASE</version>
       <!-- 移除嵌入式tomcat插件 -->
       <exclusions>
         <exclusion>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-tomcat</artifactId>
         </exclusion>
       </exclusions>
   </dependency>

   打成war包的名稱須和application.properties中server.context-path=/projectName 一致。

   <build>
       <finalName>projectName</finalName>
   </build>

   spring-boot-starter-web內嵌tomcat, 若是須要本地調試能夠不移除。
   

2. 添加servlet-api的依賴(二選一)

   <dependency>
     <groupId>javax.servlet</groupId>
     <artifactId>javax.servlet-api</artifactId>
     <version>3.1.0</version>
     <scope>provided</scope>
   </dependency>
   
   <dependency>
     <groupId>org.apache.tomcat</groupId>
     <artifactId>tomcat-servlet-api</artifactId>
     <version>8.0.36</version>
     <scope>provided</scope>
   </dependency>

3. 啓動類繼承SpringBootServletInitializer類：

   public abstract class SpringBootServletInitializer implements WebApplicationInitializer

   @SpringBootApplication(scanBasePackages = { "com.noob.loan.route" })
   @ImportResource(locations = "classpath*:spring/applicationContext-per.xml")
   @MapperScan(basePackages = "com.noob.loan.route.dao")
   @Slf4j
   public class RouteConsoleBootstrap extends SpringBootServletInitializer {
   
   	private static Class<RouteConsoleBootstrap> applicationClass = RouteConsoleBootstrap.class;
   
   	@Override
   	protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
   		return builder.sources(applicationClass);
   	}
   
   	/**
   	 * 還有一種：in a single line in application.properties:
   	 * server.context_parameters.p-name=-value
   	 * 
   	 */
   	@Override
   	public void onStartup(ServletContext servletContext) throws ServletException {
   		servletContext.setAttribute("contextConfigLocation",
              "classpath*:applicationContext-per.xml"); // 測試結果該設置無效,設置先後都爲<NONE>
   		servletContext.setAttribute("failUrl", "/");
   		servletContext.setAttribute("unauthorizedUrl", "/deny.jsp");
   		servletContext.setAttribute("notFilterUrl", "");
   		super.onStartup(servletContext);
   	}
   
   	/** 本地調試使用 **/
   	public static void main(String[] args) {
   		try {
   			new SpringApplicationBuilder(applicationClass).run(args);
   			Object lock = new Object();
   			synchronized (lock) {
   				try {
   					while (true)
   						lock.wait();
   				} catch (Exception e) {
   					log.error("application running exception.", e);
   				}
   			}
   		} catch (Exception ex) {
   			log.error("start application exception.", ex);
   		}
   
   	}
   
   }

Q&A

錯誤開啓webEnvironment

dubbo 2.8.4 中 依賴了 javax.servlet-api 3.1.0 , 致使斷定開啓webEnvironment =true;

啓動報錯：

Caused by: org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
	at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.getEmbeddedServletContainerFactory(EmbeddedWebApplicationContext.java:185) ~[spring-boot-1.3.6.RELEASE.jar:1.3.6.RELEASE]
	at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:158) ~[spring-boot-1.3.6.RELEASE.jar:1.3.6.RELEASE]
	at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:130) ~[spring-boot-1.3.6.RELEASE.jar:1.3.6.RELEASE]
	... 8 common frames omitted

解決方法：  關閉Web環境

new SpringApplicationBuilder(CreditBootstrap.class).web(false).run(args);

打war包報錯：提示缺乏web.xml

緣由

spring boot項目中引用了依賴包spring-boot-starter-web。該包中引用的spring-boot-starter-tomcat裏包含了tomcat嵌入式servlet容器，其不一樣版本實現的是不一樣的servlet版本規範。

解決方法

servlet 3.0 如下的必須有WEB-INF/web.xml；

servlet 3.0 以上（包括）且沒有web.xml： maven-war-plugin 下設置failOnMissingWebXml = flase;

<build>
	<plugins>
		<plugin>
			<groupId>org.apache.maven.plugins</groupId>
			<artifactId>maven-war-plugin</artifactId>
			<version>2.6</version>
			<configuration>
				<failOnMissingWebXml>false</failOnMissingWebXml>
			</configuration>
		</plugin>
	</plugins>
</build>