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In-depth learning and construction of Spring+SpringMVC+MyBatis - SpringMVC entry program (2)

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Release： 2017-06-26 11:12:12
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As mentioned earlier: Spring+SpringMVC+MyBatis in-depth learning and construction (12) - SpringMVC entry program (1)

1. Non-annotation Processor mappers and adapters

1.1 Non-annotated processor mapper

The org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping we configured earlier is a non-annotated processor mapper. In fact, a problem with this kind of mapper is that a url must be configured in a bean.

Now we configure another non-annotation mapper

org.springframework.web.servlet.handler.SimpleUrlHandlerMapping, which will configure the url and handler centrally. 

    <!-- 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>
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Question: Can these two mappers be configured at the same time?

Answer: Multiple mappers can coexist. The front-end controller determines which mappers the URL can map and lets the correct mapper handle it.

1.2 Non-annotated processor adapter

The org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter we configured earlier is a non-annotated adapter. It requires that the Handler you write must implement the Controller interface.

Let’s talk about another non-annotated adapter:

org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter. It requires that the Handler written implements the HttpRequestHandler interface. 

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");    }
}
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Configured in springmvc.xml:

##2.DispatcherServlet.properties

The front-end controller loads processing mappers, adapters, view parsers and other components from the above files. If not configured in springmvc.xml, the default loaded ones will be used.

3. Annotated processor mappers and adapters

Use org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping annotation mapper before spring3.1.

Use org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping annotation mapper after spring3.1.

Use org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter annotation adapter before spring3.1.

Use org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter annotation adapter after spring3.1.

3.1 Configure annotation mappers and adapters

    <!--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> -->
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3.2 Develop annotation Handler

Use annotated mappers and annotated adapters. (Annotated mappers and annotated adapters must be used in pairs. It is understood that non-annotated mappers cannot be used for mapping) 

/**
 * 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}
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3.3 Loading Handler in the spring container

    <!-- 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>
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Using the component scanner eliminates the tediousness of configuring each controller class in the spring container. Use to automatically scan control classes marked @Controller.

3.4 Deployment and debugging

Visit: http://localhost:8080/SpringMVC/jyqueryItems.action

Note: Single configuration during testing There is no problem with the annotated Handler running. When configuring the component scanner to run, an error message is reported when starting Tomcat:

##
严重: Context initialization failed
java.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.Throwable
java.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() exception
java.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)
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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>
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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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