03点睛Spring MVC 4.1-REST

转发：https://www.iteye.com/blog/wiselyman-2214290

3.1 REST

• REST:Representational State Transfer;
• REST是一种数据导向web service,相对于SOAP是一种操作操作和处理导向的web service;
• Spring为对REST的支持提供了@RestController;
  • 在没有@RestController可以通过@Controller,@ResponseBody组合实现REST控制器;
  • 但是我们经常会使用@ResponseBody这样很麻烦,且易忘记;
  • 使用@RestController替代@Controller,我们就不用使用@ResponseBody;
• REST支持的http method(通过@RequestMapping的method属性控制)
  • POST:新增
  • GET:读取
  • PUT/PATCH:更新
  • DELETE:删除

• produces的内容是指定返回的媒体类型让浏览器识别

  • 如返回text/plain的话,浏览器上的js回掉拿到的是字符串,需要自己转换对象;
  • 如返回application/json的话,浏览器上的js拿到的就是js对象而不是字符串,就不需要进行转换;

• 本例演示向控制器提交json数据,返回结果分别为json和xml格式;

3.2 示例

3.2.1 @RestController源码

从@RestController看出,@RestController是一个元注解,组合了@Controller,@ResponseBody,相当于同时使用了@Controller @ResponseBody

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Controller
@ResponseBody
public @interface RestController {

    /**
     * The value may indicate a suggestion for a logical component name,
     * to be turned into a Spring bean in case of an autodetected component.
     * @return the suggested component name, if any
     * @since 4.0.1
     */
    String value() default "";

}

3.2.2 代码

• 添加jackson依赖

jackson-dataformat-xml依赖jackson-bind,这样我们能同时返回xml和json

<dependency>
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-xml</artifactId>
    <version>2.5.3</version>
</dependency>

若只需返回json数据(大多数项目都是这样),将上面依赖更换为

 <dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.5.3</version>
</dependency>

• 传值对象

package com.wisely.web;

public class DemoObj {
    private Long id;
    private String name;
    //此处一定要有空构造,不然会有400 bad request,主要是jackson将json参数转换为对象需要
    public DemoObj() {
        super();
    }
    public DemoObj(Long id, String name) {
        super();
        this.id = id;
        this.name = name;
    }
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

}

• DemoMVCConfig注册静态资源

    // 静态资源映射
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/js/**").addResourceLocations("/js/");
    }

• 控制器

package com.wisely.web;

import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api")
public class RESTController {
    @RequestMapping(value = "/getjson",produces={"application/json;charset=UTF-8"})
    public DemoObj getjson(@RequestBody DemoObj obj){
        return new DemoObj(obj.getId()+1, obj.getName()+"yy");
    }
    @RequestMapping(value = "/getxml",produces={"application/xml;charset=UTF-8"})
    public DemoObj getxml(@RequestBody DemoObj obj){
        return new DemoObj(obj.getId()+1, obj.getName()+"yy");
    }

}

• 页面代码

<script type="text/javascript" src="<c:url value="/js/jquery.js" />"></script>
<script type="text/javascript">
var json = {"id":456,"name":"phy"};

$.ajax({
      url: "api/getjson",
      data: JSON.stringify(json),
      type:"POST",
      contentType:"application/json",
      success: function(data){
          console.log(data);
      }
    });
$.ajax({
      url: "api/getxml",
      data: JSON.stringify(json),
      type:"POST",
      contentType:"application/json",
      success: function(data){
          console.log(data);
      }
    });
</script>

• 结果