一、添加拦截器

@WebFilter中的filterName首字母一定要小写！！！

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package com.xiaohang.socialcard.pre.filter;

import com.xiaohang.socialcard.pre.utils.SM4Util;
import lombok.extern.slf4j.Slf4j;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

@Slf4j
@WebFilter(urlPatterns = {"/api/v1/get/getToken", "/api/v1/get/query", "/api/v1/get/page"}, filterName = "signAutheFilter")
public class SignAutheFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;

        String param = request.getParameter("param");
        try {
            param = SM4Util.encryptEcb("1234567890", param);
        } catch (Exception e) {
            e.printStackTrace();
        }
        MyRequestWrapper parameterRequestWrapper = new MyRequestWrapper(request);
        parameterRequestWrapper.addParameter("param", param);
        chain.doFilter(parameterRequestWrapper, res);// 替换原始请求参数

    }

    @Override
    public void destroy() {

    }
}

class MyRequestWrapper extends HttpServletRequestWrapper {

    private Map params = new HashMap();

    @SuppressWarnings("unchecked")
    public MyRequestWrapper(HttpServletRequest request) {
        // 将request交给父类，以便于调用对应方法的时候，将其输出，其实父亲类的实现方式和第一种new的方式类似
        super(request);
        //将参数表，赋予给当前的Map以便于持有request中的参数
        this.params.putAll(request.getParameterMap());
    }

    //重载一个构造方法
    public MyRequestWrapper(HttpServletRequest request, Map extendParams) {
        this(request);
        addAllParameters(extendParams);//这里将扩展参数写入参数表
    }

    @Override
    public String getParameter(String name) {//重写getParameter，代表参数从当前类中的map获取
        String[] values = params.get(name);
        if (values == null || values.length == 0) {
            return null;
        }
        return values[0];
    }

    public String[] getParameterValues(String name) {//同上
        return params.get(name);
    }

    public void addAllParameters(Map otherParams) {//增加多个参数
        for (Map.Entry entry : otherParams.entrySet()) {
            addParameter(entry.getKey(), entry.getValue());
        }
    }

    public void addParameter(String name, Object value) {//增加参数
        if (value != null) {
            if (value instanceof ArrayList) {
                String value1 = String.valueOf(value).substring(1, String.valueOf(value).length());
                value = value1.substring(0, value1.length() - 1);
                params.put(name, new String[]{(String) value});
            } else if (value instanceof String[]) {
                params.put(name, (String[]) value);
            } else if (value instanceof String) {
                params.put(name, new String[]{(String) value});
            } else {
                params.put(name, new String[]{String.valueOf(value)});
            }
        }
    }
}

二、Application.class这里一定要加上ServletComponentScan注解用于扫描Filter过滤器

package com.xiaohang.socialcard.pre;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.cloud.netflix.feign.EnableFeignClients;

@EnableFeignClients
@SpringBootApplication
@ServletComponentScan
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

本文题目：SpringCloud使用Filter过滤器实现@RequestParam参数加密
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