SpringBoot学习记录(二)

一. SpringBoot日志框架

SpringBoot:底层是Spring框架,Spring框架默认是用JCL(commons-logging);

SpringBoot选用SLF4j和logback;

1.SLF4j使用

(1) 如何在系统中使用SLF4j 

  以后开发的时候,日志记录方法的调用,不应该直接调用日志的实现类,而是调用日志抽象层里面的方法;给系统里面导入slf4j的jar和logback的实现jar包

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class HelloWorld {
public static void main(String[] args) {
Logger logger = LoggerFactory.getLogger(HelloWorld.class);
logger.info("Hello World");
}
}

网上找的图例:每一个日志的实现框架都有自己的配置文件。使用slf4j以后,配置文件还是做成日志实现框架自己本身的配置文件

(2) 遗留问题

SpringBoot (slf4j+logback);Spring (commons-logging); Hibernate (jboss-logging); Mybatis

统一日志记录,即使是别的框架如何与SpringBoot一起使用slf4j进行输出?

1. 将系统中其他日志框架先排除出去;

2. 用中间包替换原有的日志框架;

3. 导入slf4j其他的实现

(3) SpringBoot日志关系

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

SpringBoot使用它来做日志功能;

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring‐boot‐starter‐logging</artifactId>
</dependency>

底层依赖关系

总结:

(1) SPringBoot底层也是使用slf4j+logback的方式进行日志记录

(2) SpringBoot也罢其他的日志都替换成了slf4j

(3) 中间替换包

@SuppressWarnings("rawtypes")
public abstract class LogFactory {
  static String UNSUPPORTED_OPERATION_IN_JCL_OVER_SLF4J =
      "http://www.slf4j.org/codes.html#unsupported_operation_in_jcl_over_slf4j";
  static LogFactory logFactory = new SLF4JLogFactory();

(4) 如果我们要引入其他框架一定要把这个框架的默认日志依赖移除掉

例如;Spring框架用的是commons-logging;那么如果要使用Spring就需要吧这个依赖移除

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring‐core</artifactId>
    <exclusions>
        <exclusion>
            <groupId>commons‐logging</groupId>
            <artifactId>commons‐logging</artifactId>
        </exclusion>
    </exclusions>
</dependency>            

SpringBoot能自动适配所有的日志,而且底层使用slf4j+logback的方式记录日志,引入其他框架的时候,只需要把这个框架的依赖的日志框架排除掉即可

2. SpringBoot的日志配置

SpringBoot默认帮我们配置了日志;

@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringBootLoggingApplicationTests {

	@Test
	public void contextLoads() {
//		System.out.println();
		Logger logger = LoggerFactory.getLogger(getClass());

		//日志的级别:由低到高 trace < debug < info < warn < error
		//可以调整输出的日志级别;日志就只会在这个级别以及之后的高级别生效
		logger.trace("这是trace日志。。。");
		logger.debug("这是debug日志。。。");

		//SpringBoot默认级别是从info开始,即root级别; 可以通过配置文件进行调节
		logger.info("这是info日志。。。");
		logger.warn("这是warn日志。。。");
		logger.error("这是error日志。。。");
	}

}
日志输出格式:
%d表示日期时间,
%thread表示线程名,
%‐5level:级别从左显示5个字符宽度
%logger{50} 表示logger名字最长50个字符,否则按照句点分割。
%msg:日志消息,
%n是换行符

%d{yyyy‐MM‐dd HH:mm:ss.SSS} [%thread] %‐5level %logger{50} ‐ %msg%n

SpringBoot修改日志的默认配置

logging.level.com.javaweb=trace

#在当前磁盘的根路径下创建spring文件夹和里面的log文件夹;使用spring.log作为默认文件
logging.path=/spring/log

#不指定路径在当前项目下生成springboot.log,也可以指定完胜的路径
#logging.file=springboot.log
#logging.file=D:/springboot.log

#在控制台输出日志的格式
logging.pattern.console=%d{yyyy-MM-dd} [%thread] %-5level %logger{50} - %msg%n
#在指定文件中日志的输出格式
logging.pattern.file=%d{yyyy-MM-dd} == [%thread == %-5level %logger{50} - %msg%n

二. SpringBoot的Web开发

1. 使用SpringBoot:

(1) 创建SpringBoot应用,选中我们需要的模块

(2) SpringBoot已经默认将这些场景配置好了,只需要在配置文件中指定少量配置就可以运行起来

(3) 自己编写业务代码

 

自动配置原理:

这个场景SpringBoot帮我们配置了什么?能不能修改?能修改那些配置?能不能扩展?

xxxxAutoConfiguration:帮我们给容器中自动配置组件;
xxxxProperties:配置类来封装配置文件的内容;

2. SpringBoot对静态济源的映射规则

@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties {
 

public void addResourceHandlers(ResourceHandlerRegistry registry) {
            if(!this.resourceProperties.isAddMappings()) {
                logger.debug("Default resource handling disabled");
            } else {
                Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
                CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
                if(!registry.hasMappingForPattern("/webjars/**")) {
                    this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{"/webjars/**"}).addResourceLocations(new String[]{"classpath:/META-INF/resources/webjars/"}).setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
                }
​
                String staticPathPattern = this.mvcProperties.getStaticPathPattern();
                if(!registry.hasMappingForPattern(staticPathPattern)) {
                    this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{staticPathPattern}).addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations())).setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
                }
​
            }
        }

 

(1) 所有/webjars/**,都去classpath:/META-INF/resource/webjars/ 找资源

以jar包的方式引入静态资源

http://www.webjars.org

 

 

localhost:8080/webjars/jquery/3.3.1/jquery.js

<!-- 引入jquery-webjars 在访问的时候只需要写webjars下面资源的名称即可--> 
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>jquery</artifactId>
            <version>3.3.1</version>
        </dependency>

 

(2) /** 访问当前项目的任何资源 (静态资源文件夹)

"classpath:/META-INF/resources/",
"classpath:/resources/",
"classpath:/static/",
"classpath:/public/",

 

localhost:8080/abc ===>自动去静态资源文件夹寻找abc资源

(3) 欢迎页;静态资源文件夹下的所有index.html页面;被"/**"映射;

(4) 所有的**/facivon.ico都是在静态资源文件下找

3. 模板引擎

JSP,Veloctiy,Freemarker,Thymeleaf;

 

SpringBoot推荐使用Thymeleaf:

语法更简单,功能更强大;

1. 引入thymeleaf

<!-- 引入模板引擎 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

 

2. 使用thymeleaf

@ConfigurationProperties(
    prefix = "spring.thymeleaf"
)
public class ThymeleafProperties {
    private static final Charset DEFAULT_ENCODING;
    public static final String DEFAULT_PREFIX = "classpath:/templates/";
    public static final String DEFAULT_SUFFIX = ".html";
    private boolean checkTemplate = true;
    private boolean checkTemplateLocation = true;
    
    //只要我们把html页面放在classpath:/templates/,thymeleaf就能自动渲染
    private String prefix = "classpath:/templates/";
    
    private String suffix = ".html";
    private String mode = "HTML";

 

只需要在页面中导入thymeleaf的空间,就可以使用thymeleaf的语法

<html lang="en" xmlns:th="http://www.thymeleaf.org">

 

3. thymeleaf语法规则

(1) th:text:改变当前元素里面的文本内容;

th:任意html属性;来替换原生属性:

 

<div th:text="${hello}" th:id="${hello}" th:class="${hello}"></div>

(2) 表达式

Simple expressions:(表达式语法)
    Variable Expressions: ${...}:获取变量值;OGNL;
        1)、获取对象的属性、调用方法
        2)、使用内置的基本对象:
            #ctx : the context object.
            #vars: the context variables.
​
            #vars: the context variables.
            #locale : the context locale.
            #request : (only in Web Contexts) the HttpServletRequest object.
            #response : (only in Web Contexts) the HttpServletResponse object.
            #session : (only in Web Contexts) the HttpSession object.
            #servletContext : (only in Web Contexts) the ServletContext object.
​
            ${session.foo}
        3)、内置的一些工具对象:
#execInfo : information about the template being processed.
#messages : methods for obtaining externalized messages inside variables expressions, in the
same way as they would be obtained using #{…} syntax.
#uris : methods for escaping parts of URLs/URIs
#conversions : methods for executing the configured conversion service (if any).
#dates : methods for java.util.Date objects: formatting, component extraction, etc.
#calendars : analogous to #dates , but for java.util.Calendar objects.
#numbers : methods for formatting numeric objects.
#strings : methods for String objects: contains, startsWith, prepending/appending, etc.
#objects : methods for objects in general.
#bools : methods for boolean evaluation.
#arrays : methods for arrays.
#lists : methods for lists.
#sets : methods for sets.
#maps : methods for maps.
#aggregates : methods for creating aggregates on arrays or collections.
#ids : methods for dealing with id attributes that might be repeated (for example, as a
result of an iteration).
​
Selection Variable Expressions: *{...}:选择表达式:和${}在功能上是一样;
补充:配合 th:object="${session.user}:
<div th:object="${session.user}">
    <p>Name: <span th:text="*{firstName}">Sebastian</span>.</p>
    <p>Surname: <span th:text="*{lastName}">Pepper</span>.</p>
    <p>Nationality: <span th:text="*{nationality}">Saturn</span>.</p>
</div>
​
Message Expressions: #{...}:获取国际化内容
​
Link URL Expressions: @{...}:定义URL;
@{/order/process(execId=${execId},execType='FAST')}
​
Fragment Expressions: ~{...}:片段引用表达式
<div th:insert="~{commons :: main}">...</div>
​
Literals(字面量)
Text literals: 'one text' , 'Another one!' ,…
Number literals: 0 , 34 , 3.0 , 12.3 ,…
Boolean literals: true , false
Null literal: null
Literal tokens: one , sometext , main ,…
Text operations:(文本操作)
String concatenation: +
Literal substitutions: |The name is ${name}|
Arithmetic operations:(数学运算)
Binary operators: + , ‐ , * , / , %
Minus sign (unary operator): ‐
Boolean operations:(布尔运算)
Binary operators: and , or
Boolean negation (unary operator): ! , not
Comparisons and equality:(比较运算)
Comparators: > , < , >= , <= ( gt , lt , ge , le )
Equality operators: == , != ( eq , ne )
Conditional operators:条件运算(三元运算符)
If‐then: (if) ? (then)
If‐then‐else: (if) ? (then) : (else)
Default: (value) ?: (defaultvalue)
Special tokens:
No‐Operation: _

 

例如:

我在业务层java编写:

/**
 * @program: spring-boot-web
 * @description:
 * @author: Yukai Fan
 * @create: 2018-10-20 09:46
 **/
@Controller
public class HelloController {
​
    //查处一些数据,在页面展示
    @RequestMapping("success")
    public String success(Map<String, Object> map) {
        map.put("hello","<h1>你好</h1>");
        map.put("users", Arrays.asList("zhangsan","lisi","wangwu"));
        //classpath:/templates/success.html
        return "success";
    }
}
​

 

根据thymeleaf可以默认从classpath:/templates/下寻找success.html

所以使用tyhmeleaf语法在success.html上:

<body>
    <h1>成功</h1>
    <!-- th:text 设置文本内容 -->
    <div th:text="${hello}"></div>
    <div th:utext="${hello}"></div>
<hr/><!-- th:each每次遍历都会生成当前标签 3个h4标签-->
    <h4 th:text="${user}" th:each="user:${users}"></h4>
    <hr/><h4>
        <span th:each="user:${users}"> [[${user}]] </span>
    </h4></body>

得到的效果为:

 

其中审查元素可知,有三个h4标签,3个span标签

 

 

posted @ 2018-10-19 21:28  MichaelKai  阅读(220)  评论(0编辑  收藏  举报