application/json 与 application/x-www-form-urlencoded的简单比较

在用HttpUrlConnection请求极光推送restful时（http://docs.jiguang.cn/jpush/server/old/rest_api_v2_push/），

涉及到一个参数序列化问题，对方要求

HTTP Post 的Content-Type 需采用 application/x-www-form-urlencoded

然后序列化时用了json（Map.tostring）导致对方的服务器没有接收到参数，于是改成 后者，

代码参数做了调整

    private static String json2String(JSONObject json) throws UnsupportedEncodingException {
        Iterator<String> sIterator = json.keys();
        String urlpara = "";
        while (sIterator.hasNext()) {
            String key = sIterator.next();
            //根据键获得值，值也可以是JSONObject，JSONArray，使用对应的参数接收即可
            String value = json.getString(key);

            urlpara += key + "=" + URLEncoder.encode(value, "UTF-8") + "&";
        }

        return  urlpara;
    }

done

（一）

参考：http://blog.csdn.net/mygoon/article/details/48546781

package wzq.j2se;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;

public class HttpURLConnectionPost {

 /**
  * @param args
  * @throws IOException 
  */
 public static void main(String[] args) throws IOException {
  readContentFromPost();
 }
 public static void readContentFromPost() throws IOException {
        // Post请求的url，与get不同的是不需要带参数
        URL postUrl = new URL("http://www.wangzhiqiang87.cn");
        // 打开连接
        HttpURLConnection connection = (HttpURLConnection) postUrl.openConnection();
      
        // 设置是否向connection输出，因为这个是post请求，参数要放在
        // http正文内，因此需要设为true
        connection.setDoOutput(true);
        // Read from the connection. Default is true.
        connection.setDoInput(true);
        // 默认是 GET方式
        connection.setRequestMethod("POST");
       
        // Post 请求不能使用缓存
        connection.setUseCaches(false);
       
        connection.setInstanceFollowRedirects(true);
       
        // 配置本次连接的Content-type，配置为application/x-www-form-urlencoded的
        // 意思是正文是urlencoded编码过的form参数，下面我们可以看到我们对正文内容使用URLEncoder.encode
        // 进行编码
        connection.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
        // 连接，从postUrl.openConnection()至此的配置必须要在connect之前完成，
        // 要注意的是connection.getOutputStream会隐含的进行connect。
        connection.connect();
        DataOutputStream out = new DataOutputStream(connection
                .getOutputStream());
        // The URL-encoded contend
        // 正文，正文内容其实跟get的URL中 '? '后的参数字符串一致
        String content = "account=" + URLEncoder.encode("一个大肥人", "UTF-8");
        content +="&pswd="+URLEncoder.encode("两个个大肥人", "UTF-8");;
        // DataOutputStream.writeBytes将字符串中的16位的unicode字符以8位的字符形式写到流里面
        out.writeBytes(content);

        out.flush();
        out.close(); 
        
        BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        String line;
        
        while ((line = reader.readLine()) != null){
            System.out.println(line);
        }
      
        reader.close();
        connection.disconnect();
}

}

在接收端，这样获取参数：
String name = request.getParameter("account");
String pswd = request.getParameter("pswd");
 
 System.out.println(new String(name.getBytes("iso-8859-1"),"UTF-8")); 
 System.out.println(new String(pswd.getBytes("iso-8859-1"),"UTF-8"));

（二）

https://segmentfault.com/a/1190000007252829

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