【SSM直击大厂】第五章：SpringMVC数据响应

目录

SpringMVC的数据响应方式

1）页面跳转  

2）回写数据

3）配置注解驱动

4）知识要点

SpringMVC的数据响应方式

1）页面跳转  

• 直接返回字符串：此种方式会将返回的字符串与视图解析器的前后缀拼接后跳转。 

• 通过ModelAndView对象返回

@RequestMapping("/quick2")
public ModelAndView quickMethod2(){
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("redirect:index.jsp");
    return modelAndView;
}
@RequestMapping("/quick3")
public ModelAndView quickMethod3(){
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("forward:/WEB-INF/views/index.jsp");
    return modelAndView;
}

 在进行转发时，往往要向request域中存储数据，在jsp页面中显示，那么Controller中怎样向request 域中存储数据呢？

@RequestMapping("/quick")
public String quickMethod(HttpServletRequest request){
    request.setAttribute("name","zhangsan");
    return "index";
}

@RequestMapping("/quick3")
public ModelAndView quickMethod3(){
    ModelAndView modelAndView = new ModelAndView();
    modelAndView.setViewName("forward:/WEB-INF/views/index.jsp");
    modelAndView.addObject("name","lisi");
    return modelAndView;
}

2）回写数据

• 直接返回字符串：Web基础阶段，客户端访问服务器端，如果想直接回写字符串作为响应体返回的话，只需要使用response.getWriter().print(“hello world”) 即可，那么在Controller中想直接回写字符串该怎样呢？

@RequestMapping("/quick4")
public void quickMethod4(HttpServletResponse response) throws IOException {
    response.getWriter().print("hello world");
}

@RequestMapping("/quick5")
@ResponseBody
public String quickMethod5() throws IOException {
    return "hello springMVC!!!"; 
}

        1.在pom.xml中导入jackson坐标。

<!--jackson-->
<dependency>
 <groupId>com.fasterxml.jackson.core</groupId>
 <artifactId>jackson-core</artifactId>
 <version>2.9.0</version>
</dependency>
<dependency>
 <groupId>com.fasterxml.jackson.core</groupId>
 <artifactId>jackson-databind</artifactId>
 <version>2.9.0</version>
</dependency> 
<dependency>
 <groupId>com.fasterxml.jackson.core</groupId>
 <artifactId>jackson-annotations</artifactId>
 <version>2.9.0</version>
</dependency>

        2.通过jackson转换json格式字符串，回写字符串。  

@RequestMapping("/quick7")
@ResponseBody
public String quickMethod7() throws IOException {
    User user = new User();
    user.setUsername("zhangsan");
    user.setAge(18);
    ObjectMapper objectMapper = new ObjectMapper();
    String s = objectMapper.writeValueAsString(user);
    return s;
}

• 返回对象或集合

<bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
 <property name="messageConverters">
     <list>
        <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"></bean>
     </list>
 </property>
</bean>

@RequestMapping("/quick8")
@ResponseBody
public User quickMethod8() throws IOException {
    User user = new User();
    user.setUsername("zhangsan");
    user.setAge(18);
    return user;
}

3）配置注解驱动

<!--在spring-mvc.xml中配置mvc的注解驱动--> 
<mvc:annotation-driven/>

4）知识要点

SpringMVC的数据响应方式

1） 页面跳转

        直接返回字符串

        通过ModelAndView对象返回

2） 回写数据

        直接返回字符串

        返回对象或集合