SpringBoot2 基础篇 3
转载：https://blog.csdn.net/u011863024/article/details/113667634
1. 视图解析-Thymeleaf初体验
Thymeleaf is a modern server-side Java template engine for both web and standalone environments.
Thymeleaf’s main goal is to bring elegant natural templates to your development workflow — HTML that can be correctly displayed in browsers and also work as static prototypes, allowing for stronger collaboration in development teams.
With modules for Spring Framework, a host of integrations with your favourite tools, and the ability to plug in your own functionality, Thymeleaf is ideal for modern-day HTML5 JVM web development — although there is much more it can do.
Thymeleaf官方文档：https://www.thymeleaf.org/documentation.html
thymeleaf使用
引入Starter
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
自动配置好了thymeleaf
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(ThymeleafProperties.class)
@ConditionalOnClass({ TemplateMode.class, SpringTemplateEngine.class })
@AutoConfigureAfter({ WebMvcAutoConfiguration.class, WebFluxAutoConfiguration.class })
public class ThymeleafAutoConfiguration {
...
}
自动配好的策略
1. 所有thymeleaf的配置值都在 ThymeleafProperties
2. 配置好了 SpringTemplateEngine
3. 配好了 ThymeleafViewResolver
4. 我们只需要直接开发页面
public static final String DEFAULT_PREFIX = "classpath:/templates/";//模板放置处
public static final String DEFAULT_SUFFIX = ".html";//文件的后缀名
编写一个控制层：
@Controller
public class ViewTestController {
@GetMapping("/hello")
public String hello(Model model){
//model中的数据会被放在请求域中 request.setAttribute("a",aa)
model.addAttribute("msg","一定要大力发展工业文化");
model.addAttribute("link","http://www.baidu.com");
return "success";
}
}
/templates/success.html：
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1 th:text="${msg}">nice</h1>
<h2>
<a href="www.baidu.com" th:href="${link}">去百度</a> <br/>
<a href="www.google.com" th:href="@{/link}">去百度</a>
</h2>
</body>
</html>
application.yml
server:
servlet:
context-path: /app #设置应用名
这个设置后，URL要插入/app, 如http://localhost:8080/app/hello.html。
基本语法
表达式
| 表达式名字 | 语法 | 用途 |
|---|---|---|
| 变量取值 | ${…} | 获取请求域、session域、对象等值 |
| 选择变量 | *{…} | 获取上下文对象值 |
| 消息 | #{…} | 获取国际化等值 |
| 链接 | @{…} | 生成链接 |
| 片段表达式 | ~{…} | jsp:include 作用，引入公共页面片段 |
字面量
文本值: ‘one text’ , ‘Another one!’ ,…
数字: 0 , 34 , 3.0 , 12.3 ,…
布尔值: true , false
空值: null
变量： one，two，… 变量不能有空格
文本操作
字符串拼接: +
变量替换: |The name is ${name}|
数学运算
运算符: + , - , * , / , %
布尔运算
运算符: and , or
一元运算: ! , not
比较运算
比较: > , < , >= , <= ( gt , lt , ge , le )
等式: == , != ( eq , ne )
条件运算
If-then: (if) ? (then)
If-then-else: (if) ? (then) : (else)
Default: (value) ?: (defaultvalue)
特殊操作
无操作： _
设置属性值-th:attr
设置单个值
<form action="subscribe.html" th:attr="action=@{/subscribe}">
<fieldset>
<input type="text" name="email" />
<input type="submit" value="Subscribe!" th:attr="value=#{subscribe.submit}"/>
</fieldset>
</form>
设置多个值
<img src="../../images/gtvglogo.png"
th:attr="src=@{/images/gtvglogo.png},title=#{logo},alt=#{logo}" />
官方文档
Setting Attribute Values：https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#setting-attribute-values
迭代
<tr th:each="prod : ${prods}">
<td th:text="${prod.name}">Onions</td>
<td th:text="${prod.price}">2.41</td>
<td th:text="${prod.inStock}? #{true} : #{false}">yes</td>
</tr>
<tr th:each="prod,iterStat : ${prods}" th:class="${iterStat.odd}? 'odd'">
<td th:text="${prod.name}">Onions</td>
<td th:text="${prod.price}">2.41</td>
<td th:text="${prod.inStock}? #{true} : #{false}">yes</td>
</tr>
件运算
<a href="comments.html"
th:href="@{/product/comments(prodId=${prod.id})}"
th:if="${not #lists.isEmpty(prod.comments)}">view</a>
<div th:switch="${user.role}">
<p th:case="'admin'">User is an administrator</p>
<p th:case="#{roles.manager}">User is a manager</p>
<p th:case="*">User is some other thing</p>
</div>
属性优先级
| Order | Feature | Attributes |
|---|---|---|
| 1 | Fragment inclusion | th:insert th:replace |
| 2 | Fragment iteration | th:each |
| 3 | Conditional evaluation | th:if th:unless th:switch th:case |
| 4 | Local variable definition | th:object th:with |
| 5 | General attribute modification | th:attr th:attrprepend th:attrappend |
| 6 | Specific attribute modification | th:value th:href th:src … |
| 7 | Text (tag body modification) | th:text th:utext |
| 8 | Fragment specification | th:fragment |
| 9 | Fragment removal | th:remove |
官方文档
Attribute Precedence： https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#attribute-precedence
2. web实验-后台管理系统基本功能
项目创建
使用IDEA的Spring Initializr。
thymeleaf、
web-starter、
devtools、
lombok
登陆页面
/static 放置 css，js等静态资源
/templates/login.html 登录页
<html lang="en" xmlns:th="http://www.thymeleaf.org"><!-- 要加这玩意thymeleaf才能用 -->
<form class="form-signin" action="index.html" method="post" th:action="@{/login}">
...
<!-- 消息提醒 -->
<label style="color: red" th:text="${msg}"></label>
<input type="text" name="userName" class="form-control" placeholder="User ID" autofocus>
<input type="password" name="password" class="form-control" placeholder="Password">
<button class="btn btn-lg btn-login btn-block" type="submit">
<i class="fa fa-check"></i>
</button>
...
</form>
/templates/main.html 主页
thymeleaf内联写法：
<p>Hello, [[${session.user.name}]]!</p>
登录控制层
@Controller
public class IndexController {
/**
* 来登录页
* @return
*/
@GetMapping(value = {"/","/login"})
public String loginPage(){
return "login";
}
@PostMapping("/login")
public String main(User user, HttpSession session, Model model){ //RedirectAttributes
if(StringUtils.hasLength(user.getUserName()) && "123456".equals(user.getPassword())){
//把登陆成功的用户保存起来
session.setAttribute("loginUser",user);
//登录成功重定向到main.html; 重定向防止表单重复提交
return "redirect:/main.html";
}else {
model.addAttribute("msg","账号密码错误");
//回到登录页面
return "login";
}
}
/**
* 去main页面
* @return
*/
@GetMapping("/main.html")
public String mainPage(HttpSession session, Model model){
//最好用拦截器,过滤器
Object loginUser = session.getAttribute("loginUser");
if(loginUser != null){
return "main";
}else {
//session过期，没有登陆过
//回到登录页面
model.addAttribute("msg","请重新登录");
return "login";
}
}
}
模型
@AllArgsConstructor
@NoArgsConstructor
@Data
public class User {
private String userName;
private String password;
}
3. web实验-抽取公共页面
官方文档
Template Layout: https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#template-layout
公共页面/templates/common.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org"><!--注意要添加xmlns:th才能添加thymeleaf的标签-->
<head th:fragment="commonheader">
<!--common-->
<link href="css/style.css" th:href="@{/css/style.css}" rel="stylesheet">
<link href="css/style-responsive.css" th:href="@{/css/style-responsive.css}" rel="stylesheet">
...
</head>
<body>
<!-- left side start-->
<div id="leftmenu" class="left-side sticky-left-side">
...
<div class="left-side-inner">
...
<!--sidebar nav start-->
<ul class="nav nav-pills nav-stacked custom-nav">
<li><a th:href="@{/main.html}"><i class="fa fa-home"></i> <span>Dashboard</span></a></li>
...
<li class="menu-list nav-active"><a href="#"><i class="fa fa-th-list"></i> <span>Data Tables</span></a>
<ul class="sub-menu-list">
<li><a th:href="@{/basic_table}"> Basic Table</a></li>
<li><a th:href="@{/dynamic_table}"> Advanced Table</a></li>
<li><a th:href="@{/responsive_table}"> Responsive Table</a></li>
<li><a th:href="@{/editable_table}"> Edit Table</a></li>
</ul>
</li>
...
</ul>
<!--sidebar nav end-->
</div>
</div>
<!-- left side end-->
<!-- header section start-->
<div th:fragment="headermenu" class="header-section">
<!--toggle button start-->
<a class="toggle-btn"><i class="fa fa-bars"></i></a>
<!--toggle button end-->
...
</div>
<!-- header section end-->
<div id="commonscript">
<!-- Placed js at the end of the document so the pages load faster -->
<script th:src="@{/js/jquery-1.10.2.min.js}"></script>
<script th:src="@{/js/jquery-ui-1.9.2.custom.min.js}"></script>
<script th:src="@{/js/jquery-migrate-1.2.1.min.js}"></script>
<script th:src="@{/js/bootstrap.min.js}"></script>
<script th:src="@{/js/modernizr.min.js}"></script>
<script th:src="@{/js/jquery.nicescroll.js}"></script>
<!--common scripts for all pages-->
<script th:src="@{/js/scripts.js}"></script>
</div>
</body>
</html>
/templates/table/basic_table.html
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0">
<meta name="description" content="">
<meta name="author" content="ThemeBucket">
<link rel="shortcut icon" href="#" type="image/png">
<title>Basic Table</title>
<div th:include="common :: commonheader"> </div><!--将common.html的代码段 插进来-->
</head>
<body class="sticky-header">
<section>
<div th:replace="common :: #leftmenu"></div>
<!-- main content start-->
<div class="main-content" >
<div th:replace="common :: headermenu"></div>
...
</div>
<!-- main content end-->
</section>
<!-- Placed js at the end of the document so the pages load faster -->
<div th:replace="common :: #commonscript"></div>
</body>
</html>
Difference between th:insert and th:replace (and th:include)
官方文档：https://www.thymeleaf.org/doc/tutorials/3.0/usingthymeleaf.html#difference-between-thinsert-and-threplace-and-thinclude
4. web实验-遍历数据与页面bug修改
控制层代码：
@GetMapping("/dynamic_table")
public String dynamic_table(Model model){
//表格内容的遍历
List<User> users = Arrays.asList(new User("zhangsan", "123456"),
new User("lisi", "123444"),
new User("haha", "aaaaa"),
new User("hehe ", "aaddd"));
model.addAttribute("users",users);
return "table/dynamic_table";
}
页面代码：
<table class="display table table-bordered" id="hidden-table-info">
<thead>
<tr>
<th>#</th>
<th>用户名</th>
<th>密码</th>
</tr>
</thead>
<tbody>
<tr class="gradeX" th:each="user,stats:${users}">
<td th:text="${stats.count}">Trident</td>
<td th:text="${user.userName}">Internet</td>
<td >[[${user.password}]]</td>
</tr>
</tbody>
</table>
5. 视图解析-【源码分析】-视图解析器与视图
视图解析原理流程：
1. 目标方法处理的过程中（阅读DispatcherServlet源码），所有数据都会被放在 ModelAndViewContainer 里面，其中包括数据和视图地址。
2. 方法的参数是一个自定义类型对象（从请求参数中确定的），把他重新放在 ModelAndViewContainer 。
3. 任何目标方法执行完成以后都会返回ModelAndView（数据和视图地址）。
4. processDispatchResult()处理派发结果（页面改如何响应）
1. render(mv, request, response); 进行页面渲染逻辑
1. 根据方法的String返回值得到 View 对象【定义了页面的渲染逻辑】
1. 所有的视图解析器尝试是否能根据当前返回值得到View对象
2. 得到了 redirect:/main.html --> Thymeleaf new RedirectView()。
3. ContentNegotiationViewResolver 里面包含了下面所有的视图解析器，内部还是利用下面所有视图解析器得到视图对象。
4. view.render(mv.getModelInternal(), request, response); 视图对象调用自定义的render进行页面渲染工作。
2. RedirectView 如何渲染【重定向到一个页面】
3. 获取目标url地址
4. response.sendRedirect(encodedURL);
视图解析：
- 返回值以 forward: 开始： new InternalResourceView(forwardUrl); --> 转发request.getRequestDispatcher(path).forward(request, response);
- 返回值以 redirect: 开始： new RedirectView() --> render就是重定向
- 返回值是普通字符串：new ThymeleafView()—>
阅读源码：最好自己在IDE，打断点，且Debug模式运行实例，这样比较没那么沉闷。
6. 拦截器-登录检查与静态资源放行
1. 编写一个拦截器实现HandlerInterceptor接口
2. 拦截器注册到容器中（实现WebMvcConfigurer的addInterceptors()）
3. 指定拦截规则（注意，如果是拦截所有，静态资源也会被拦截）
编写一个实现HandlerInterceptor接口的拦截器：
@Slf4j
public class LoginInterceptor implements HandlerInterceptor {
/**
* 目标方法执行之前
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
String requestURI = request.getRequestURI();
log.info("preHandle拦截的请求路径是{}",requestURI);
//登录检查逻辑
HttpSession session = request.getSession();
Object loginUser = session.getAttribute("loginUser");
if(loginUser != null){
//放行
return true;
}
//拦截住。未登录。跳转到登录页
request.setAttribute("msg","请先登录");
// re.sendRedirect("/");
request.getRequestDispatcher("/").forward(request,response);
return false;
}
/**
* 目标方法执行完成以后
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
log.info("postHandle执行{}",modelAndView);
}
/**
* 页面渲染以后
*/
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
log.info("afterCompletion执行异常{}",ex);
}
}
拦截器注册到容器中 && 指定拦截规则：
@Configuration
public class AdminWebConfig implements WebMvcConfigurer{
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(new LoginInterceptor())//拦截器注册到容器中
.addPathPatterns("/**") //所有请求都被拦截包括静态资源
.excludePathPatterns("/","/login","/css/**","/fonts/**","/images/**",
"/js/**","/aa/**"); //放行的请求
}
7. 拦截器-【源码分析】-拦截器的执行时机和原理
1. 根据当前请求，找到HandlerExecutionChain（可以处理请求的handler以及handler的所有 拦截器）
2. 先来顺序执行 所有拦截器的 preHandle()方法。
1. 如果当前拦截器preHandle()返回为true。则执行下一个拦截器的preHandle()
2. 如果当前拦截器返回为false。直接倒序执行所有已经执行了的拦截器的 afterCompletion();。
3. 如果任何一个拦截器返回false，直接跳出不执行目标方法。
4. 所有拦截器都返回true，才执行目标方法。
5. 倒序执行所有拦截器的postHandle()方法。
6. 前面的步骤有任何异常都会直接倒序触发 afterCompletion()。
7. 页面成功渲染完成以后，也会倒序触发 afterCompletion()。
DispatcherServlet中涉及到HandlerInterceptor的地方：
public class DispatcherServlet extends FrameworkServlet {
...
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;
WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
try {
ModelAndView mv = null;
Exception dispatchException = null;
...
//该方法内调用HandlerInterceptor的preHandle()
if (!mappedHandler.applyPreHandle(processedRequest, response)) {
return;
}
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
...
//该方法内调用HandlerInterceptor的postHandle()
mappedHandler.applyPostHandle(processedRequest, response, mv);
}
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
}
catch (Exception ex) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
}
catch (Throwable err) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
triggerAfterCompletion(processedRequest, response, mappedHandler,
new NestedServletException("Handler processing failed", err));
}
finally {
...
}
}
private void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, Exception ex) throws Exception {
if (mappedHandler != null) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
mappedHandler.triggerAfterCompletion(request, response, ex);
}
throw ex;
}
private void processDispatchResult(HttpServletRequest request, HttpServletResponse response,
@Nullable HandlerExecutionChain mappedHandler, @Nullable ModelAndView mv,
@Nullable Exception exception) throws Exception {
...
if (mappedHandler != null) {
//该方法内调用HandlerInterceptor接口的afterCompletion方法
// Exception (if any) is already handled..
mappedHandler.triggerAfterCompletion(request, response, null);
}
}
}
public class HandlerExecutionChain {
...
boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
for (int i = 0; i < this.interceptorList.size(); i++) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
//HandlerInterceptor的preHandle方法
if (!interceptor.preHandle(request, response, this.handler)) {
triggerAfterCompletion(request, response, null);
return false;
}
this.interceptorIndex = i;
}
return true;
}
void applyPostHandle(HttpServletRequest request, HttpServletResponse response, @Nullable ModelAndView mv)
throws Exception {
for (int i = this.interceptorList.size() - 1; i >= 0; i--) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
//HandlerInterceptor接口的postHandle方法
interceptor.postHandle(request, response, this.handler, mv);
}
}
void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, @Nullable Exception ex) {
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = this.interceptorList.get(i);
try {
//HandlerInterceptor接口的afterCompletion方法
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
}
}
8. 文件上传-单文件与多文件上传的使用
页面代码/static/form/form_layouts.html
<form role="form" th:action="@{/upload}" method="post" enctype="multipart/form-data">
<div class="form-group">
<label for="exampleInputEmail1">邮箱</label>
<input type="email" name="email" class="form-control" id="exampleInputEmail1" placeholder="Enter email">
</div>
<div class="form-group">
<label for="exampleInputPassword1">名字</label>
<input type="text" name="username" class="form-control" id="exampleInputPassword1" placeholder="Password">
</div>
<div class="form-group">
<label for="exampleInputFile">头像</label>
<input type="file" name="headerImg" id="exampleInputFile">
</div>
<div class="form-group">
<label for="exampleInputFile">生活照</label>
<input type="file" name="photos" multiple>
</div>
<div class="checkbox">
<label>
<input type="checkbox"> Check me out
</label>
</div>
<button type="submit" class="btn btn-primary">提交</button>
</form>
控制层代码
@Slf4j
@Controller
public class FormTestController {
@GetMapping("/form_layouts")
public String form_layouts(){
return "form/form_layouts";
}
@PostMapping("/upload")
public String upload(@RequestParam("email") String email,
@RequestParam("username") String username,
@RequestPart("headerImg") MultipartFile headerImg,
@RequestPart("photos") MultipartFile[] photos) throws IOException {
log.info("上传的信息：email={}，username={}，headerImg={}，photos={}",
email,username,headerImg.getSize(),photos.length);
if(!headerImg.isEmpty()){
//保存到文件服务器，OSS服务器
String originalFilename = headerImg.getOriginalFilename();
headerImg.transferTo(new File("H:\\cache\\"+originalFilename));
}
if(photos.length > 0){
for (MultipartFile photo : photos) {
if(!photo.isEmpty()){
String originalFilename = photo.getOriginalFilename();
photo.transferTo(new File("H:\\cache\\"+originalFilename));
}
}
}
return "main";
}
}
文件上传相关的配置类：
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.MultipartProperties
文件大小相关配置项：
spring.servlet.multipart.max-file-size=10MB
spring.servlet.multipart.max-request-size=100MB
9. 文件上传-【源码流程】文件上传参数解析器
文件上传相关的自动配置类MultipartAutoConfiguration有创建文件上传参数解析器StandardServletMultipartResolver。
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass({ Servlet.class, StandardServletMultipartResolver.class, MultipartConfigElement.class })
@ConditionalOnProperty(prefix = "spring.servlet.multipart", name = "enabled", matchIfMissing = true)
@ConditionalOnWebApplication(type = Type.SERVLET)
@EnableConfigurationProperties(MultipartProperties.class)
public class MultipartAutoConfiguration {
private final MultipartProperties multipartProperties;
public MultipartAutoConfiguration(MultipartProperties multipartProperties) {
this.multipartProperties = multipartProperties;
}
@Bean
@ConditionalOnMissingBean({ MultipartConfigElement.class, CommonsMultipartResolver.class })
public MultipartConfigElement multipartConfigElement() {
return this.multipartProperties.createMultipartConfig();
}
@Bean(name = DispatcherServlet.MULTIPART_RESOLVER_BEAN_NAME)
@ConditionalOnMissingBean(MultipartResolver.class)
public StandardServletMultipartResolver multipartResolver() {
//配置好文件上传解析器
StandardServletMultipartResolver multipartResolver = new StandardServletMultipartResolver();
multipartResolver.setResolveLazily(this.multipartProperties.isResolveLazily());
return multipartResolver;
}
}
//文件上传解析器
public class StandardServletMultipartResolver implements MultipartResolver {
private boolean resolveLazily = false;
public void setResolveLazily(boolean resolveLazily) {
this.resolveLazily = resolveLazily;
}
@Override
public boolean isMultipart(HttpServletRequest request) {
return StringUtils.startsWithIgnoreCase(request.getContentType(), "multipart/");
}
@Override
public MultipartHttpServletRequest resolveMultipart(HttpServletRequest request) throws MultipartException {
return new StandardMultipartHttpServletRequest(request, this.resolveLazily);
}
@Override
public void cleanupMultipart(MultipartHttpServletRequest request) {
if (!(request instanceof AbstractMultipartHttpServletRequest) ||
((AbstractMultipartHttpServletRequest) request).isResolved()) {
// To be on the safe side: explicitly delete the parts,
// but only actual file parts (for Resin compatibility)
try {
for (Part part : request.getParts()) {
if (request.getFile(part.getName()) != null) {
part.delete();
}
}
}
catch (Throwable ex) {
LogFactory.getLog(getClass()).warn("Failed to perform cleanup of multipart items", ex);
}
}
}
}
public class DispatcherServlet extends FrameworkServlet {
@Nullable
private MultipartResolver multipartResolver;
private void initMultipartResolver(ApplicationContext context) {
...
//这个就是配置类配置的StandardServletMultipartResolver文件上传解析器
this.multipartResolver = context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class);
...
}
protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
HttpServletRequest processedRequest = request;
HandlerExecutionChain mappedHandler = null;
boolean multipartRequestParsed = false;//最后finally的回收flag
...
try {
ModelAndView mv = null;
Exception dispatchException = null;
try {
//做预处理,如果有上传文件 就new StandardMultipartHttpServletRequest包装类
processedRequest = checkMultipart(request);
multipartRequestParsed = (processedRequest != request);
// Determine handler for the current request.
mappedHandler = getHandler(processedRequest);
...
// Determine handler adapter for the current request.
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
...
// Actually invoke the handler.
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
}
....
finally {
...
if (multipartRequestParsed) {
cleanupMultipart(processedRequest);
}
}
}
protected HttpServletRequest checkMultipart(HttpServletRequest request) throws MultipartException {
if (this.multipartResolver != null && this.multipartResolver.isMultipart(request)) {
...
return this.multipartResolver.resolveMultipart(request);
...
}
}
protected void cleanupMultipart(HttpServletRequest request) {
if (this.multipartResolver != null) {
MultipartHttpServletRequest multipartRequest =
WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
if (multipartRequest != null) {
this.multipartResolver.cleanupMultipart(multipartRequest);
}
}
}
}
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());跳到以下的类
public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
implements BeanFactoryAware, InitializingBean {
@Override
protected ModelAndView handleInternal(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ModelAndView mav;
...
mav = invokeHandlerMethod(request, response, handlerMethod);
...
return mav;
}
@Nullable
protected ModelAndView invokeHandlerMethod(HttpServletRequest request,
HttpServletResponse response, HandlerMethod handlerMethod) throws Exception {
ServletWebRequest webRequest = new ServletWebRequest(request, response);
try {
WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod);
if (this.argumentResolvers != null) {//关注点
invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
}
...
invocableMethod.invokeAndHandle(webRequest, mavContainer);
...
return getModelAndView(mavContainer, modelFactory, webRequest);
}
finally {
webRequest.requestCompleted();
}
}
}
this.argumentResolvers其中主角类RequestPartMethodArgumentResolver用来生成
public class ServletInvocableHandlerMethod extends InvocableHandlerMethod {
...
public void invokeAndHandle(ServletWebRequest webRequest, ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
Object returnValue = invokeForRequest(webRequest, mavContainer, providedArgs);
...
}
@Nullable
public Object invokeForRequest(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
Object[] args = getMethodArgumentValues(request, mavContainer, providedArgs);
...
return doInvoke(args);//反射调用
}
@Nullable
protected Object doInvoke(Object... args) throws Exception {
Method method = getBridgedMethod();
ReflectionUtils.makeAccessible(method);
return method.invoke(getBean(), args);
...
}
//处理得出multipart参数，准备稍后的反射调用（@PostMapping标记的上传方法）
protected Object[] getMethodArgumentValues(NativeWebRequest request, @Nullable ModelAndViewContainer mavContainer,
Object... providedArgs) throws Exception {
MethodParameter[] parameters = getMethodParameters();
...
Object[] args = new Object[parameters.length];
for (int i = 0; i < parameters.length; i++) {
MethodParameter parameter = parameters[i];
parameter.initParameterNameDiscovery(this.parameterNameDiscoverer);
args[i] = findProvidedArgument(parameter, providedArgs);
if (args[i] != null) {
continue;
}
//关注点1
if (!this.resolvers.supportsParameter(parameter)) {
throw new IllegalStateException(formatArgumentError(parameter, "No suitable resolver"));
}
try {
//关注点2
args[i] = this.resolvers.resolveArgument(parameter, mavContainer, request, this.dataBinderFactory);
}
catch (Exception ex) {
...
}
}
return args;
}
}
public class RequestPartMethodArgumentResolver extends AbstractMessageConverterMethodArgumentResolver {
//对应上面代码关注点1
@Override
public boolean supportsParameter(MethodParameter parameter) {
//标注@RequestPart的参数
if (parameter.hasParameterAnnotation(RequestPart.class)) {
return true;
}
else {
if (parameter.hasParameterAnnotation(RequestParam.class)) {
return false;
}
return MultipartResolutionDelegate.isMultipartArgument(parameter.nestedIfOptional());
}
}
//对应上面代码关注点2
@Override
@Nullable
public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
NativeWebRequest request, @Nullable WebDataBinderFactory binderFactory) throws Exception {
HttpServletRequest servletRequest = request.getNativeRequest(HttpServletRequest.class);
Assert.state(servletRequest != null, "No HttpServletRequest");
RequestPart requestPart = parameter.getParameterAnnotation(RequestPart.class);
boolean isRequired = ((requestPart == null || requestPart.required()) && !parameter.isOptional());
String name = getPartName(parameter, requestPart);
parameter = parameter.nestedIfOptional();
Object arg = null;
//封装成MultipartFile类型的对象作参数
Object mpArg = MultipartResolutionDelegate.resolveMultipartArgument(name, parameter, servletRequest);
if (mpArg != MultipartResolutionDelegate.UNRESOLVABLE) {
arg = mpArg;
}
...
return adaptArgumentIfNecessary(arg, parameter);
}
}
public final class MultipartResolutionDelegate {
...
@Nullable
public static Object resolveMultipartArgument(String name, MethodParameter parameter, HttpServletRequest request)
throws Exception {
MultipartHttpServletRequest multipartRequest =
WebUtils.getNativeRequest(request, MultipartHttpServletRequest.class);
boolean isMultipart = (multipartRequest != null || isMultipartContent(request));
if (MultipartFile.class == parameter.getNestedParameterType()) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
return multipartRequest.getFile(name);
}
else if (isMultipartFileCollection(parameter)) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
List<MultipartFile> files = multipartRequest.getFiles(name);
return (!files.isEmpty() ? files : null);
}
else if (isMultipartFileArray(parameter)) {
if (!isMultipart) {
return null;
}
if (multipartRequest == null) {
multipartRequest = new StandardMultipartHttpServletRequest(request);
}
List<MultipartFile> files = multipartRequest.getFiles(name);
return (!files.isEmpty() ? files.toArray(new MultipartFile[0]) : null);
}
else if (Part.class == parameter.getNestedParameterType()) {
if (!isMultipart) {
return null;
}
return request.getPart(name);
}
else if (isPartCollection(parameter)) {
if (!isMultipart) {
return null;
}
List<Part> parts = resolvePartList(request, name);
return (!parts.isEmpty() ? parts : null);
}
else if (isPartArray(parameter)) {
if (!isMultipart) {
return null;
}
List<Part> parts = resolvePartList(request, name);
return (!parts.isEmpty() ? parts.toArray(new Part[0]) : null);
}
else {
return UNRESOLVABLE;
}
}
...
}