HttpServletResponse#sendError如何更改ContentType [英] HttpServletResponse#sendError How to change ContentType

问题描述

我现在正在创建一个简单的Servlet来回答表单提交.该Servlet接收POST请求，并应响应Application/JSON数据.这运作良好. 现在，我想向我的servlet添加错误管理:如果servlet接收到错误的请求参数，我希望它通过简单的{"error":"ERROR MESSAGE"} JSON响应为客户端回答400 —错误的请求"响应.

I'm now creating a simple Servlet to answer a form submition. This servlet receive POST request and should response Application/JSON datas. This is working well. I want now to add errors managment to my servlet: If the servlet receive bad request parameters, I want it to answer the client a 400 — "Bad Request" response with a simple {"error":"ERROR MESSAGE"} JSON response.

我正在使用HttpServletResponse#sendError(int,String)正确发送错误，但是响应的ContentType始终设置为text/html，即使我以前使用过HttpServletResponse#setContentType("application/json").

I'm using the HttpServletResponse#sendError(int,String) to correctly send the error but the ContentType of the response is always set to text/html, even though I used HttpServletResponse#setContentType("application/json") before.

这是使用Servets发送错误的好方法吗?如何将响应的ContentType强制为application/json?

Is this the good way to send error using Servets ? How can I force the ContentType of the response to application/json?

我的测试Servlet的doPost()方法的示例代码:

EDIT : Sample code of the doPost() method of my test Servlet :

public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("application/json;charset=UTF-8");
        PrintWriter out = response.getWriter();
        out.print("{\"error\":1}");
        response.sendError(HttpServletResponse.SC_BAD_REQUEST);
}

推荐答案

有效

使用指定的状态向客户端发送错误响应，并 清除缓冲区.服务器默认为创建响应 看起来像一个HTML格式的服务器错误页面，其中包含指定的 消息，将内容类型设置为"text/html".

Sends an error response to the client using the specified status and clears the buffer. The server defaults to creating the response to look like an HTML-formatted server error page containing the specified message, setting the content type to "text/html".

HttpServletResponse.sendError(int)

另一方面，

没有此限制/功能.

on the other hand does not have this restriction/feature.

使用指定的状态码向客户端发送错误响应 并清除缓冲区.

Sends an error response to the client using the specified status code and clearing the buffer.

这意味着:设置内容类型，写入缓冲区，然后调用sendError(400).

This means: set the content type, write to the buffer, call sendError(400).

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