Spring MVC 支持RestFul风格尝试

Spring MVC 核心流程

如今的java web开发，大致和以往我们在学校学习的SSH已经大不一样了，现在基本成熟的大公司都使用Spring MVC 快速开发WEB应用。当然小编我也是**Spring MVC**的长期实践者。
首先想和大家普及下我眼中的Spring mcv整个流程过程

Spring MVC 的 restFul风格

说实话自己用了这个久的Spring mvc 只知道他请求的链接格式是和restful风格一致的，但是并没有想过它同时也和resteasy，支持标准的JAX，接下来就带大家体会下，并且指出可能存在的坑哈

1. 搭建SpringMVC框架
   本系统采用的是开发工具是idea 同时使用的是springmvc +maven的方式实现的简单demo
   废话不多说，先给大家看看项目结构
   
   项目和大多是项目一样，java下放类，resources放一些配置文件和资源，webapp下存放静态资源
   当然这里需要和大家强调下web.xml的配置

<web-app version="2.4"
    xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

    <display-name>Spring MVC Applicationdisplay-name>

    <servlet>
        <servlet-name>springServletservlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
        <init-param>
            <param-name>contextConfigLocationparam-name>
            <param-value>classpath*:mvc-dispatcher-servlet.xmlparam-value>
        init-param>
        <load-on-startup>1load-on-startup>
    servlet>

    <servlet-mapping>
        <servlet-name>springServletservlet-name>
        <url-pattern>/url-pattern>
    servlet-mapping>
web-app>

pom文件也有需要注意的地方，如果要支持json格式的restful，需要导入jackson的相关的包，后面再说实现原理的时候会进一步说明

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0modelVersion>
    <groupId>com.springappgroupId>
    <artifactId>SpringWebFlowartifactId>
    <packaging>warpackaging>
    <version>1.0-SNAPSHOTversion>
    <name>SpringWebFlowname>

    <properties>
        <spring.version>4.1.1.RELEASEspring.version>
        <jackson.version>2.1.4jackson.version>
    properties>

    <dependencies>
        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-coreartifactId>
            <version>${spring.version}version>
        dependency>

        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-webartifactId>
            <version>${spring.version}version>
        dependency>

        <dependency>
            <groupId>javax.servletgroupId>
            <artifactId>servlet-apiartifactId>
            <version>2.5version>
        dependency>

        <dependency>
            <groupId>javax.servlet.jspgroupId>
            <artifactId>jsp-apiartifactId>
            <version>2.1version>
            <scope>providedscope>
        dependency>

        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-webmvcartifactId>
            <version>${spring.version}version>
        dependency>

        <dependency>
            <groupId>org.springframeworkgroupId>
            <artifactId>spring-testartifactId>
            <version>${spring.version}version>
            <scope>testscope>
        dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-coreartifactId>
            <version>${jackson.version}version>
        dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-databindartifactId>
            <version>${jackson.version}version>
        dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.coregroupId>
            <artifactId>jackson-annotationsartifactId>
            <version>${jackson.version}version>
        dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.modulegroupId>
            <artifactId>jackson-module-jaxb-annotationsartifactId>
            <version>${jackson.version}version>
        dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.jaxrsgroupId>
            <artifactId>jackson-jaxrs-json-providerartifactId>
            <version>${jackson.version}version>
            
            
            
        dependency>

        
        <dependency>
            <groupId>org.codehaus.jacksongroupId>
            <artifactId>jackson-mapper-aslartifactId>
            <version>1.9.0version>
        dependency>
        <dependency>
            <groupId>org.codehaus.jacksongroupId>
            <artifactId>jackson-core-aslartifactId>
            <version>1.9.0version>
        dependency>


        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.11version>
            <scope>testscope>
        dependency>
    dependencies>

    <build>
        <finalName>SpringWebFlowfinalName>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-pluginartifactId>
                <configuration>
                    <source>1.6source>
                    <target>1.6target>
                configuration>
            plugin>
            <plugin>
                <artifactId>maven-surefire-pluginartifactId>
                <configuration>
                    <includes>
                        <include>**/*Tests.javainclude>
                    includes>
                configuration>
            plugin>
        plugins>
    build>
project>

最后一个需要注意的是spring的配置文件，里面需要加下mvc的自动驱动注解，不然后面有些注解没法用

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:util="http://www.springframework.org/schema/util"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd">

    <mvc:annotation-driven/>

    <context:component-scan base-package="com.springapp.mvc"/>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"/>
        <property name="suffix" value=".jsp"/>
    bean>

beans>

最后就是Controller的代码了

package com.springapp.mvc;

import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("/test")
public class HelloController {

    @RequestMapping(value = "/hello",method = RequestMethod.GET)
    public String printWelcome(ModelMap model) {
        model.addAttribute("message", "Hello world!");
        return "hello";
    }

    @RequestMapping(value = "userInfo",method = RequestMethod.POST)
    @ResponseBody
    public  Person userInfo(@RequestBody Person person){

        System.out.println("人的姓名:"+person.getName()+"，人的年龄"+person.getAge());

        return person;
    }
}

这里可以看到使用了@RequestBody 表明接受的请求会先进过消息转化器(http conversion),消息转化器根据请求过来的请求做解析，当然也可以通过consumes进行指定值解析哪种格式contest-type格式
这也是为什么需要导入上文中说的jackson的包，内部消息转化器使用的jackson的方式转化的

最后当然是用postman进行调用了哈哈