【Spring MVC框架】乱码问题解决

使用方法：

• 在web.xml中配置Spring MVC的乱码过滤器

  <!--在web.xml中配置Spring MVC的乱码过滤器-->
   <filter>
       <filter-name>encoding</filter-name>
       <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
       <init-param>
           <param-name>encoding</param-name>
           <param-value>utf-8</param-value>
       </init-param>
   </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/</url-pattern>
    </filter-mapping>

---

• 极端情况下，可以使用自定义过滤器
  EncodingFilter.java:

package filter;

/**
 * @author jitwxs
 * @date 2021年04月20日 19:41
 */
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;

/**
 * 解决get和post请求 全部乱码的过滤器
 */
public class EncodingFilter implements Filter {

        @Override
        public void destroy() {
        }

        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
                //处理response的字符编码
                HttpServletResponse myResponse=(HttpServletResponse) response;
                myResponse.setContentType("text/html;charset=UTF-8");

                // 转型为与协议相关对象
                HttpServletRequest httpServletRequest = (HttpServletRequest) request;
                // 对request包装增强
                HttpServletRequest myrequest = new MyRequest(httpServletRequest);
                chain.doFilter(myrequest, response);
        }

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

}

//自定义request对象，HttpServletRequest的包装类
class MyRequest extends HttpServletRequestWrapper {

        private HttpServletRequest request;
        //是否编码的标记
        private boolean hasEncode;
        //定义一个可以传入HttpServletRequest对象的构造函数，以便对其进行装饰
        public MyRequest(HttpServletRequest request) {
                super(request);// super必须写
                this.request = request;
        }

        // 对需要增强方法 进行覆盖
        @Override
        public Map getParameterMap() {
                // 先获得请求方式
                String method = request.getMethod();
                if (method.equalsIgnoreCase("post")) {
                        // post请求
                        try {
                                // 处理post乱码
                                request.setCharacterEncoding("utf-8");
                                return request.getParameterMap();
                        } catch (UnsupportedEncodingException e) {
                                e.printStackTrace();
                        }
                } else if (method.equalsIgnoreCase("get")) {
                        // get请求
                        Map<String, String[]> parameterMap = request.getParameterMap();
                        if (!hasEncode) { // 确保get手动编码逻辑只运行一次
                                for (String parameterName : parameterMap.keySet()) {
                                        String[] values = parameterMap.get(parameterName);
                                        if (values != null) {
                                                for (int i = 0; i < values.length; i++) {
                                                        try {
                                                                // 处理get乱码
                                                                values[i] = new String(values[i]
                                                                        .getBytes("ISO-8859-1"), "utf-8");
                                                        } catch (UnsupportedEncodingException e) {
                                                                e.printStackTrace();
                                                        }
                                                }
                                        }
                                }
                                hasEncode = true;
                        }
                        return parameterMap;
                }
                return super.getParameterMap();
        }

        //取一个值
        @Override
        public String getParameter(String name) {
                Map<String, String[]> parameterMap = getParameterMap();
                String[] values = parameterMap.get(name);
                if (values == null) {
                        return null;
                }
                return values[0]; // 取回参数的第一个值
        }

        //取所有值
        @Override
        public String[] getParameterValues(String name) {
                Map<String, String[]> parameterMap = getParameterMap();
                String[] values = parameterMap.get(name);
                return values;
        }
}

web.xml:

<filter>
        <filter-name>encoding</filter-name>
        <filter-class>filter.EncodingFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>encoding</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>