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前面讲到：Spring+SpringMVC+MyBatis深入学习及搭建(十二)——SpringMVC入门程序（一）
1.非注解的处理器映射器和适配器1.1非注解的处理器映射器
前面我们配置的org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping是非注解的处理器映射器。这种映射器其实有一个问题就是要一个bean里面配置一个url。
现在我们再配置另一个非注解映射器
org.springframework.web.servlet.handler.SimpleUrlHandlerMapping，它会将url和handler集中进行配置。
<!-- 配置Handler --><bean id="ItemsController1" name="/queryItems.action" class="joanna.yan.ssm.controller.ItemsController1"/><!-- 配置处理器映射器 将bean的name作为url进行查找，需要在配置Handler时指定beanname（就是url）--><bean class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping"/><!-- 简单url映射 simpleUrlHandlerMapping是BeanNameUrlHandlerMapping的增强版， 它可以将url和处理器bean的id进行统一映射配置。 --> <bean class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping"><property name="mappings"><props><!-- 对ItemsController1进行url映射，url是/queryItems1.action --><prop key="/queryItems1.action">ItemsController1</prop><prop key="/queryItems2.action">ItemsController1</prop></props></property></bean>
疑问：可以同时配置这两个映射器吗？
解答：多个映射器可以并存，前端控制器判断url能让哪些映射器映射，就让正确的映射器处理。
1.2非注解的处理器适配器
前面我们配置的org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter是一个非注解的适配器。它要求你编写的Handler要实现Controller接口。
再说另一个非注解的适配器：
org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter。它要求编写的Handler实现HttpRequestHandler接口。
public class ItemsController2 implements HttpRequestHandler{ @Overridepublic void handleRequest(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//调用service查找数据库，查询商品列表，这里使用静态数据模拟List<Items> itemsList=new ArrayList<Items>(); Items items_1=new Items(); items_1.setName("联想笔记本"); items_1.setPrice(6000f); items_1.setDetail("ThinkPad T430 联想笔记本电脑！"); Items items_2 = new Items(); items_2.setName("苹果手机"); items_2.setPrice(5000f); items_2.setDetail("iphone6苹果手机！"); itemsList.add(items_1); itemsList.add(items_2);//设置模型数据request.setAttribute("itemsList", itemsList);//设置转发的视图request.getRequestDispatcher("/WEB-INF/jsp/items/itemsList.jsp").forward(request, response); // 从上边可以看出此适配器器的handleRequest方法没有返回ModelAndView，可通过response修改定义响应内容，比如返回json数据：// response.setCharacterEncoding("utf-8");// response.setContentType("application/json;charset=utf-8");// response.getWriter().write("json串"); }}
在springmvc.xml中配置：
2.DispatcherServlet.properties
前端控制器从上边的文件中加载处理映射器、适配器、视图解析器等组件，如果不在springmvc.xml中配置，则使用默认加载的。
3.注解的处理器映射器和适配器
在spring3.1之前使用org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping注解映射器。
在spring3.1之后使用org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping注解映射器。
在spring3.1之前使用org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter注解适配器。
在spring3.1之后使用org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter注解适配器。
3.1配置注解映射器和适配器
<!--注解映射器 --><bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping"/><!--注解适配器 --><bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter"/><!--使用mvc:annotation-driven代替上边注解映射器和注解适配器 配置 mvc:annotation-driven默认加载很多的参数绑定方法， 比如json转换解析器就默认加载了，如果使用mvc:annotation-driven就不用配置上面的RequestMappingHandlerMapping和RequestMappingHandlerAdapter 实际开发时使用mvc:annotation-driven --><!-- <mvc:annotation-driven></mvc:annotation-driven> -->
3.2开发注解Handler
使用注解的映射器和注解的适配器。（注解的映射器和注解的适配器必须配对使用，理解为不能使用非注解映射器进行映射）
/** * 开发注解Handler * 使用@Controller标明它是一个控制器 * @author Joanna.Yan * */@Controllerpublic class ItemsController3{ //商品查询列表//@RequestMapping实现对queryItems方法和url进行映射，一个方法对应一个url//一般建议将url和方法名写成一样，方便维护@RequestMapping("/queryItems")public ModelAndView queryItems() throws Exception{//调用service查找数据库，查询商品列表，这里使用静态数据模拟List<Items> itemsList=new ArrayList<Items>(); Items items_1=new Items(); items_1.setName("联想笔记本"); items_1.setPrice(6000f); items_1.setDetail("ThinkPad T430 联想笔记本电脑！"); Items items_2 = new Items(); items_2.setName("苹果手机"); items_2.setPrice(5000f); items_2.setDetail("iphone6苹果手机！"); itemsList.add(items_1); itemsList.add(items_2);//返回ModelAndViewModelAndView modelAndView=new ModelAndView(); modelAndView.addObject("itemsList", itemsList);//指定视图modelAndView.setViewName("/WEB-INF/jsp/items/itemsList.jsp");return modelAndView; }//定义其它方法//商品添加//商品修改}
3.3在spring容器中加载Handler
<!-- 对于注解的Handler可以单个配置 实际开发中建议使用组件扫描 --><!-- <bean class="joanna.yan.ssm.controller.ItemsController3" /> --><!-- 可以扫描controller、service、... 这里让扫描controller,指定controller的包 --><context:component-scan base-package="joanna.yan.ssm.controller"></context:component-scan>
使用组件扫描器省去在spring容器配置每个controller类的繁琐。使用<context:component-scan/>自动扫描标记@Controller的控制类。
3.4 部署调试
访问:http://localhost:8080/SpringMVC/jyqueryItems.action
注意：在测试过程中单个配置注解的Handler运行没有问题，在配置组件扫描器运行时，启动Tomcat报错：
严重: Context initialization failedjava.lang.IllegalArgumentException at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:52) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80) at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:76) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:298) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300) at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:230) at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:153) at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:130) at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:285) at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:223) at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:630) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:647) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:598) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:661) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:517) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:458) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:138) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5266) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5554) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652) at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1258) at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1918) at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source)六月 14, 2017 4:43:03 下午 org.apache.catalina.core.ApplicationContext log严重: StandardWrapper.Throwablejava.lang.IllegalArgumentException at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:52) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80) at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:76) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:298) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300) at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:230) at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:153) at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:130) at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:285) at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:223) at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:630) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:647) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:598) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:661) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:517) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:458) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:138) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5266) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5554) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652) at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1258) at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1918) at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source)六月 14, 2017 4:43:03 下午 org.apache.catalina.core.StandardContext loadOnStartup严重: Servlet [springmvc] in web application [/SpringMVC] threw load() exceptionjava.lang.IllegalArgumentException at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.asm.ClassReader.<init>(Unknown Source) at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:52) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80) at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101) at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:76) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:298) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300) at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300) at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:230) at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:153) at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:130) at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:285) at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:223) at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:630) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461) at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:647) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:598) at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:661) at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:517) at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:458) at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:138) at javax.servlet.GenericServlet.init(GenericServlet.java:158) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197) at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087) at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5266) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5554) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652) at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1258) at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1918) at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source)
View Code
原因是：我的Tomcat的jdk是1.8，项目的jdk版本是1.7，两者不一样造成的。记得要统一版本！
4.前端控制器源码分析
通过前端控制器源码分析springmvc的执行过程。
第一步：前端控制器接收请求
调用doDispatch
第二步：前端控制器调用处理器映射器查找Handler
第三步：调用处理器适配器执行Handler,得到执行结果ModeAndView
第四步：视图渲染，将model数据填充到request域。
视图解析，得到view:
调用view的渲染方法，将model数据填充到request域。
渲染方法：
5.视图解析器配置前缀和后缀
springmvc.xml中：
<!-- 配置视图解析器 解析jsp视图，默认使用jstl标签，所有classpath下得有jstl的包--><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"><!--配置jsp路径的前缀 --><property name="prefix" value="/WEB-INF/jsp/"/><!--配置jsp路径的后缀 --><property name="suffix" value=".jsp"/></bean>
程序中不用指定前缀和后缀：
//指定视图// modelAndView.setViewName("/WEB-INF/jsp/items/itemsList.jsp");//下边的路径，如果在视图解析器中配置jsp路径的前缀和jsp路径的后缀，修改为modelAndView.setViewName("items/itemsList");
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宁愿停歇在你门前的那棵树上，看着你，守护你。
