后端解决跨域

方式：
js前端请求：
function getOcrInfo(imageData){
$.ajax({
   url: 'http://localhost:8080/LSWS/ws/ocr/getWebImageRecognitionJsonStringByBase64Image',
   type: 'post',
   dataType:'json',
   //async:false,
   data: {
        "imageData" : imageData
   },
   success:function(data){
      if(data.flag==0){
       var name=decodeURIComponent(data.name);
   var position=decodeURIComponent(data.position);

      }else{
      FR.Msg.alert("错误提示","获取识别结果失败，请重试！");
      } 
      
   },
   error:function(data){
       FR.Msg.alert("错误提示","获取识别结果失败，请重试！");
   }
});
服务器后端：
@RequestMapping(value="/getWebImageRecognitionJsonStringByBase64Image", method = RequestMethod.POST)
@ResponseBody
public String getWebImageRecognitionJsonStringByBase64Image(HttpServletRequest request,HttpServletResponse response,String imageData) {
String result = "";
//System.out.println(imageData);
try{
WebImageRecognition gr = new WebImageRecognition();
result = gr.getWebImageRecognitionJsonObjectByBase64Image(imageData);

response.addHeader("Access-Control-Allow-Origin", "*");   //用于ajax post跨域（*，最好指定确定的http等协议+ip+端口号）
response.setCharacterEncoding("utf-8");
//response.getWriter().write(result);
//response.getWriter().close();
}catch(Exception e){
e.printStackTrace();
logger.error("getGeneralRecognition:"+e);
result = "{\"flag\":\"1\",\"errorMessage\":\"server change error at OcrController!\"}";
}
   return result;
}



2、CORS 请求（可以发送跨域的post、put、get等请求） 
在JSP或者Java代码中设置response的响应头 
下面是是用过滤器简单的实现跨域请求放行

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;

public class TestFilter implements Filter {

    @Override
    public void destroy() {

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse servletResponse,
            FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse)servletResponse;
        response.setHeader("Access-Control-Allow-Origin","*");
        response.setHeader("Access-Control-Allow-Methods","GET,POST,PUT,OPTIONS");
        response.setHeader("Access-Control-Allow-Credentials","true");
        chain.doFilter(request, response);
        System.out.println(" **********************CROS  执行了 **********************");
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub

    }

}
在web.xml中配置相应的拦截路径

    <filter>
        <filter-name>webAppW</filter-name>
        <filter-class>com.TestFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>webAppW</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
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作者：启示收藏 
来源：CSDN 
原文：https://blog.csdn.net/u012737182/article/details/62041890 
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