application/json 与 application/x-www-form-urlencoded的比较

application/x-www-form-urlencoded

提交请求示例

curl -X POST 'http://localhost:8080/formPost' -d 'id=1&name=foo&mobile=13612345678'

wireshark抓包结果

对应的服务端解析参数源码

//org.springframework.web.method.annotation.RequestParamMethodArgumentResolver#resolveName
if (arg == null) {
   String[] paramValues = webRequest.getParameterValues(name);
   if (paramValues != null) {
      arg = paramValues.length == 1 ? paramValues[0] : paramValues;
   }
}

application/json

提交请求示例

curl -X POST -H "Content-Type: application/json" 'http://localhost:8080/jsonPost' -d '{"id":2,"name":"foo","mobile":"13656635451"}'

wireshark抓包结果

对应的服务端解析参数源码

//com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter#readInternal
protected Object readInternal(Class<? extends Object> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    InputStream in = inputMessage.getBody();
    byte[] buf = new byte[1024];

    while(true) {
        int bytes = in.read(buf);
        if(bytes == -1) {
            byte[] bytes1 = baos.toByteArray();
            return JSON.parseObject(bytes1, 0, bytes1.length, this.charset.newDecoder(), clazz, new Feature[0]);
        }

        if(bytes > 0) {
            baos.write(buf, 0, bytes);
        }
    }
}

混用示例

web层代码

    @RequestMapping(value="/mixPost", method=RequestMethod.POST )
    public Result<Void> mixPostTest(@RequestBody @Valid Foo foo, @RequestParam Integer sex)

提交请求

curl -X POST -H "Content-Type: application/json" 'http://localhost:8080/mixPost?sex=1' -d '{"id":2,"name":"foo","mobile":"13656635451"}'

补充--如何定位对应的源码

找到post请求解析参数源码

    @RequestMapping(value="/formPost", method=RequestMethod.POST )
    public Result<Void> formPostTest(@RequestParam int id, @RequestParam String name, @RequestParam String mobile)

因为id是必填参数 如果请求参数中不含id的话 会报错 如下所示

org.springframework.web.bind.MissingServletRequestParameterException: Required int parameter 'id' is not present
    at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.handleMissingValue(RequestParamMethodArgumentResolver.java:255)
    at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:95)
    at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:79)
    at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:157)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:124)

通过此方法可以快速定位到源码

找到json请求解析参数的源码

    @RequestMapping(value="/jsonPost", method=RequestMethod.POST )
    public Result<Void> jsonPostTest(@RequestBody @Valid Foo foo)

因为肯定要先构造一个空Foo对象 然后才能注入各属性值 所以在Foo的无参构造函数中加断点， 可以定位到json请求解析参数的源码