servlet返回application/json数据类型在ie浏览器中提示下载文件问题
概述
在servlet中设置response.setContentType（“application/json”）返回json格式数据类型时在ie浏览器中提示下载文件。这种现象是ie浏览不支持application/json数据格式引起的，只要在servlet中再填上一句response.setHeader("Content-Type", "text/html")就能解决问题（应为浏览器对数据格式的识别靠的是响应头里面的Content-Type，所以，此种情况下页面在处理返回数据的时候，要先利用js把文本格式转化为json格式：eval()函数可以实现此功能）。
（注意：有文章说，ie浏览器重ie10开始就开始支持application/json了，但是我亲测过后并不是这个样子，不说ie10，就连ie11也不支持，也有可能是我的浏览器问题）
乍一看response.setContentType（XX）和response.setHeader("Content-Type", XX)不是一样的概念吗，其实并不是这样子的，前者设置返回的数据的类型，和浏览器没多大关系（其实也有关系，在设置前者而不设置后者的情况下，后者的值默认为前者，但是两者确实是有本质的区别的），后者设置的是相应头参数，响应头中的Content-Type决定了浏览器以什么方式来处理相应内容。
response.setContentType（“application/json”）：表示响应数据类型是json
response.setHeader("Content-Type",“application/json”):表示响应头参数值
代码检验
服务器端只设置response.setContentType，出现浏览器接收到服务器端返回的数据类型和响应头Content-Type值都为response.setContentType设置的值：
代码:
package com.sends.test;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class TestServlet
*/
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public TestServlet() {
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("application/json");
response.setCharacterEncoding("utf-8");
//response.setHeader("Content-Type", "text/html");
PrintWriter writer = response.getWriter();
writer.write("{\"msg\":\"success\"}");
writer.flush();
writer.close();
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
浏览器效果:
服务器端同时设置response.setContentType("XXX")和response.setHeader("Content-Type"，"XXX"），浏览器显示返回数据类型为response.setContentType("XXX")设置值，响应头值为response.setHeader("Content-Type"，"XXX"）设置值：
代码：
package com.sends.test;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class TestServlet
*/
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public TestServlet() {
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("application/json");
response.setCharacterEncoding("utf-8");
response.setHeader("Content-Type", "text/html");
PrintWriter writer = response.getWriter();
writer.write("{\"msg\":\"success\"}");
writer.flush();
writer.close();
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
浏览器效果：
ie浏览器就要设置为此种情况程序才能正常工作：
为了进一步验证，来一个绝一点的例子，响应内容类型为text/html,响应头Content-Type参数值设置为application/json。结果显示，虽然响应内容为text/html格式,ie浏览器仍旧提示下载文件。
代码：
package com.sends.test;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class TestServlet
*/
@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* Default constructor.
*/
public TestServlet() {
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html");
response.setCharacterEncoding("utf-8");
response.setHeader("Content-Type", "application/json");
PrintWriter writer = response.getWriter();
writer.write("{\"msg\":\"success\"}");
writer.flush();
writer.close();
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
ie效果：
