spring4之搭建restful风格的web服务

通过spring mvc搭建一个提供Restful API的web服务。

准备工作

• 下载并安装Eclipse ee版本(4.5.2)

• 下载并安装Tomcat 8.0

• 下载spring framework 4.3.3

  http://repo.spring.io/release/org/springframework/spring/4.3.3.RELEASE/

• 下载commons-logging-1.2.jar

• 下载jackson的三个jar包

  jackson-annotations-2.7.0.jar

  jackson-core-2.7.5.jar

  jackson-databind-2.7.5.jar

Eclipse添加Tomcat

解压tomcat

进入Eclipse首选项，在Server-Runtime Environments添加刚解压的tomcat

创建web工程

1. 通过Eclipse创建Dynamic Web Project

   工程名：sh

   target runtime选择Apache Tomcat v8.0

   勾选自动生成web.xml

2. 配置lib

   拷贝spring framework相关jar包、jackson三个jar包、commons-logging到WEB-ING/lib下

3. 配置web.xml

   添加spring 调度servlet

<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

    添加encodingFilter
    
    ```xml
     <filter>
        <filter-name>encodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    ```
4. 配置springmvc-servlet.xml

    在WEB-INF下新建springmvc-servlet.xml，添加如下配置：
    
    指定spring在哪个报下扫描controller组件
    
    ```xml
    <context:component-scan base-package="sh.controller" />
    ```
    
    指定jsp路径（该配置和restful没有直接联系属于mvc常规配置）
    
    ```xml
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/" />
        <property name="suffix" value=".jsp" />
    </bean>
    ```
    
    指定contoller输出转换器
    
    ```xml
        <bean id="stringConverter" class="org.springframework.http.converter.StringHttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/plain;charset=UTF-8</value>
            </list>
        </property>
    </bean>
    <bean id="jsonConverter"
        class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"></bean>
    <bean
        class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="messageConverters">
            <list>
                <ref bean="stringConverter"/>
                <ref bean="jsonConverter" />
            </list>
        </property>
     </bean>
    ```
5. 编写restful api
    创建包sh.controller放置控制器
    创建包sh.vo放置前端数据对象
    
    在sh.vo下创建简单的Bean Person.java，用于测试java对象与json间的自动转换
    
    ```java
public class Person {
    private String name;
    private int age;
    public void setName(String name){
        this.name = name;
    }
    public String getName(){
        return this.name;
    }
    public void setAge(int age){
        this.age = age;
    }
    public int getAge(){
        return this.age;
    }
}
    ```
    
    在sh.controller下创建restful的控制器。方法参数加上RequestBody注解才能自动将json格式的数据转为输入对象，ResponseBody注解用来控制返回结果作为输出内容。
    ```java
    @Controller
    public class HelloController {  
    @RequestMapping(value = "/person", method = RequestMethod.POST)
    public @ResponseBody
    Person addPerson(@RequestBody Person person) {
        return person;
    }
    @RequestMapping(value = "/person", method = RequestMethod.GET)
    public @ResponseBody
    List<Person> getAllPerson() {
        List<Person> list= new ArrayList<Person>();
        Person p = new Person();
        p.setAge(1);
        p.setName("rbg");
        list.add(p);
        return list;
    }
}
    ```