248 lines
8.4 KiB
Markdown
248 lines
8.4 KiB
Markdown
# spring-boot 基础
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## 一、说明
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#### 1.1 项目结构说明
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1. 本项目搭建一个简单的hello spring 的 web工程，简单说明spring-boot 的开箱即用的特性；
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2. 模板引擎采用freemaker 和 thymeleaf 作为示例，分别对应模板文件makershow.ftl 和 leafShow.html；
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3. spring boot 2.x 默认是不支持jsp的，需要额外的配置，关于使用jsp的整合可以参考spring-boot-jsp项目。
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<div align="center"> <img src="https://github.com/heibaiying/spring-samples-for-all/blob/master/pictures/spring-boot-base.png"/> </div>
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#### 1.2 项目依赖
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导入相关的starter(启动器)
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<parent>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-parent</artifactId>
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<version>2.1.1.RELEASE</version>
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<relativePath/> <!-- lookup parent from repository -->
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</parent>
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<groupId>com.heibaiying</groupId>
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<artifactId>spring-boot-base</artifactId>
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<version>0.0.1-SNAPSHOT</version>
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<name>spring-boot-base</name>
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<description>Demo project for Spring Boot</description>
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<properties>
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<java.version>1.8</java.version>
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</properties>
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<dependencies>
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<!--模板引擎-->
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-freemarker</artifactId>
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</dependency>
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-thymeleaf</artifactId>
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</dependency>
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<!--web 启动器-->
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-web</artifactId>
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</dependency>
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<!--lombok 插件-->
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<dependency>
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<groupId>org.projectlombok</groupId>
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<artifactId>lombok</artifactId>
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<optional>true</optional>
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</dependency>
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<!--测试相关依赖-->
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<dependency>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-test</artifactId>
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<scope>test</scope>
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</dependency>
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</dependencies>
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<!--Spring Boot的Maven插件（Spring Boot Maven plugin）能够以Maven的方式为应用提供Spring Boot的支持-->
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<build>
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<plugins>
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<plugin>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-maven-plugin</artifactId>
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</plugin>
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</plugins>
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</build>
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</project>
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```
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1. spring boot 项目默认继承自spring-boot-starter-parent，而spring-boot-starter-parent继承自spring-boot-dependencies, spring-boot-dependencies中定义了关于spring boot 依赖的各种jar包的版本，是spring boot 的版本管理中心。
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<div align="center"> <img src="https://github.com/heibaiying/spring-samples-for-all/blob/master/pictures/spring-boot-dependencies.png"/> </div>
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2. 关于spring boot 2.x官方支持的所有starter 可以参见官方文档 [Table 13.1. Spring Boot application starters](https://docs.spring.io/spring-boot/docs/2.1.1.RELEASE/reference/htmlsingle/#using-boot-starter)
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## 二、spring boot 主启动类
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如果采用IDEA 或者 Spring Tool Suite (STS) 等开发工具创建的spring boot 工程，会默认创建启动类，如果没有创建，需要手动创建启动类
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```java
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package com.heibaiying.springbootbase;
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import org.springframework.boot.SpringApplication;
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import org.springframework.boot.autoconfigure.SpringBootApplication;
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@SpringBootApplication
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public class SpringBootBaseApplication {
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// 启动类默认开启包扫描，扫描与主程序所在包及其子包，对于本工程而言 默认扫描 com.heibaiying.springbootbase
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public static void main(String[] args) {
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SpringApplication.run(SpringBootBaseApplication.class, args);
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}
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}
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```
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@SpringBootApplication 注解是一个复合注解,里面包含了@ComponentScan注解，默认开启包扫描，扫描与主程序所在包及其子包，对于本工程而言 默认扫描 com.heibaiying.springbootbase
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```java
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@Target(ElementType.TYPE)
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@Retention(RetentionPolicy.RUNTIME)
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@Documented
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@Inherited
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@SpringBootConfiguration
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@EnableAutoConfiguration
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@ComponentScan(excludeFilters = {
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@Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
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@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
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public @interface SpringBootApplication {
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...
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}
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```
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## 三、开箱即用的web工程
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在springbootBaseApplication.java 的同级目录创建controller文件夹，并在其中创建RestfulController.java,启动项目访问localhost:8080/restful/programmers 即可看到项目搭建成功。
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```java
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/**
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* @author : heibaiying
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* @description : restful 控制器
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*/
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@RestController
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@RequestMapping("restful")
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public class RestfulController {
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@GetMapping("programmers")
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private List<Programmer> getProgrammers() {
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List<Programmer> programmers = new ArrayList<>();
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programmers.add(new Programmer("xiaoming", 12, 100000.00f, LocalDate.of(2019, Month.AUGUST, 2)));
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programmers.add(new Programmer("xiaohong", 23, 900000.00f, LocalDate.of(2013, Month.FEBRUARY, 2)));
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return programmers;
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}
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}
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```
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这里之所以能够开箱即用，是因为我们在项目中导入spring-boot-starter-web启动器，而@SpringBootApplication 复合注解中默认开启了@EnableAutoConfiguration注解允许开启自动化配置，spring在检查导入starter-web的依赖后就会开启web的自动化配置。
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## 四、模板引擎
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这里我们在一个项目中同时导入了freemaker 和 thymeleaf的starter（虽然并不推荐，但是在同一个项目中是可以混用这两种模板引擎的）。
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#### 4.1 freemarker
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```java
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/**
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* @author : heibaiying
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* @description : 跳转渲染模板引擎 默认模板的存放位置为classpath:templates
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*/
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@Controller
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@RequestMapping("freemarker")
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public class FreeMarkerController {
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@RequestMapping("show")
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private String programmerShow(ModelMap modelMap){
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List<Programmer> programmerList=new ArrayList<>();
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programmerList.add(new Programmer("xiaoming",12,100000.00f,LocalDate.of(2019,Month.AUGUST,2)));
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programmerList.add(new Programmer("xiaohong",23,900000.00f,LocalDate.of(2013,Month.FEBRUARY,2)));
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modelMap.addAttribute("programmers",programmerList);
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return "markerShow";
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}
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}
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```
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```html
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<!doctype html>
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<html lang="en">
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<head>
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<meta charset="UTF-8">
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<title>freemarker模板引擎</title>
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</head>
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<body>
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<ul>
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<#list programmers as programmer>
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<li>姓名: ${programmer.name} 年龄: ${programmer.age}</li>
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</#list>
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</ul>
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</body>
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</html>
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```
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#### 4.2 thymeleaf
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```java
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/**
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* @author : heibaiying
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* @description : 跳转渲染模板引擎 默认模板的存放位置为classpath:templates
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*/
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@Controller
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@RequestMapping("thymeleaf")
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public class ThymeleafController {
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@RequestMapping("show")
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private String programmerShow(ModelMap modelMap) {
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List<Programmer> programmerList = new ArrayList<>();
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programmerList.add(new Programmer("xiaoming", 12, 100000.00f, LocalDate.of(2019, Month.AUGUST, 2)));
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programmerList.add(new Programmer("xiaohong", 23, 900000.00f, LocalDate.of(2013, Month.FEBRUARY, 2)));
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modelMap.addAttribute("programmers", programmerList);
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return "leafShow";
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}
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}
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```
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```html
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<!doctype html>
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<html lang="en" xmlns:th="http://www.thymeleaf.org">
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<head>
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<meta charset="UTF-8">
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<title>thymeleaf模板引擎</title>
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</head>
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<body>
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<ul th:each="programmer:${programmers}">
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<li>
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姓名:<span th:text="${programmer.name}"></span>
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薪水:<span th:text="${programmer.salary}"></span>
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</li>
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</ul>
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</body>
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</html>
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```
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#### 4.3 文档说明
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freemarker：提供了完善的中文文档，地址 http://freemarker.foofun.cn/
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thymeleaf：官方英文文档地址：[thymeleaf 3.0.11RELEASE](https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.pdf)
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注：我在本仓库中也上传了一份[thymeleaf中文文档（gangzi828(刘明刚 译))](https://github.com/heibaiying/spring-samples-for-all/tree/master/referenced%20documents)，翻译的版本为3.0.5RELEASE
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