Spring+SpringMVC+MyBatis深入学习及搭建(十三)——SpringMVC入门程序（二）

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{

    @Override
    public 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
 *
 */
@Controller
public 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ModelAndView
        ModelAndView 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 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)

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");