1. 需求

使用SpringBoot使用过滤器去除@RequestBody参数两端的空格；一般我们去普通的请求我们都会对请求参数进行验证。Java也提供了@notNull和@notBlank这种验证方式，但是对@RequestBody 这种只能验证是不是非空，对数据两端的空格未进行处理，同时大家也不想遍历一遍参数然后再处理再封装到对象中，正好项目中有这个需要，所以就参考别的做了Post请求中针对application/json格式的有@RequestBody注解的参数进行了去空格处理

2. 解决方法

2.1 新建一个过滤器

@Component
@WebFilter(urlPatterns = "/**", filterName = "ParamsFilter", dispatcherTypes = DispatcherType.REQUEST)
public class ParamsFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        ParameterRequestWrapper parmsRequest = new ParameterRequestWrapper((HttpServletRequest) request);
        chain.doFilter(parmsRequest, response);
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void destroy() {

    }


}

2.2 实现ParameterRequestWrapper

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;

import com.alibaba.fastjson.JSON;

/**
 * @author :
 * @description
 * @date : 2021/4/22
 */
public class ParameterRequestWrapper extends HttpServletRequestWrapper {

    private Map<String , String[]> params = new HashMap<>();

    public ParameterRequestWrapper(HttpServletRequest request) {
        super(request);
        Map<String, String[]> requestMap=request.getParameterMap();
        this.params.putAll(requestMap);
        this.modifyParameterValues();
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        if(!super.getHeader(HttpHeaders.CONTENT_TYPE).equalsIgnoreCase(MediaType.APPLICATION_JSON_VALUE)){
            return super.getInputStream();
        }
        String json = IOUtils.toString(super.getInputStream(), "utf-8");
        if (StringUtils.isEmpty(json)) {
            return super.getInputStream();
        }
        Map<String,Object> map= jsonStringToMap(json);
        ByteArrayInputStream bis = new ByteArrayInputStream(JSON.toJSONString(map).getBytes("utf-8"));
        return new MyServletInputStream(bis);
    }

    public void modifyParameterValues(){
        Set<String> set = params.keySet();
        Iterator<String> it = set.iterator();
        while(it.hasNext()){
            String key= it.next();
            String[] values = params.get(key);
            for (int i = 0; i < values.length; i++) {
                values[i] = values[i].trim();
            }
            params.put(key, values);
        }
    }

    @Override
    public String getParameter(String name) {
        String[]values = params.get(name);
        if(values == null || values.length == 0) {
            return null;
        }
        return values[0];
    }

    @Override
    public String[] getParameterValues(String name) {
        return params.get(name);
    }

    class MyServletInputStream extends ServletInputStream {
        private ByteArrayInputStream bis;
        public MyServletInputStream(ByteArrayInputStream bis){
            this.bis=bis;
        }
        @Override
        public boolean isFinished() {
            return true;
        }

        @Override
        public boolean isReady() {
            return true;
        }

        @Override
        public void setReadListener(ReadListener listener) {

        }
        @Override
        public int read(){
            return bis.read();
        }
    }

    public static Map<String, Object> jsonStringToMap(String jsonString) {
        Map<String, Object> map = new HashMap<>();
        JSONObject jsonObject = JSONObject.parseObject(jsonString);
        for (Object k : jsonObject.keySet()) {
            Object o = jsonObject.get(k);
            if (o instanceof JSONArray) {
                List<Object> list = new ArrayList<>();
                Iterator<Object> it = ((JSONArray) o).iterator();
                while (it.hasNext()) {
                    Object obj = it.next();
                    if (obj instanceof JSONObject){
                        list.add(jsonStringToMap(obj.toString()));
                    }
                    if (obj instanceof String) {
                       list.add(obj.toString().trim());
                    } else {
                        list.add(obj);
                    }
                }
                map.put(k.toString(), list);
            } else if (o instanceof JSONObject) {
                map.put(k.toString(), jsonStringToMap(o.toString()));
            } else {
                if (o instanceof String) {
                    map.put(k.toString(), o.toString().trim());
                } else {
                    map.put(k.toString(), o);
                }
            }
        }
        return map;
    }


}

3. 完美解决

参数前后空格完美去除！

4. 拓展：去除特殊字符