SpringMVC 中如何解决POST和GET请求中文乱码问题？（面试题）

这个只是问题只需要添加一个简单的配置就可以了，并且对应的代码在程序中是死的，我们只需要按照对应的格式进行编码就可以了。

一.POST 乱码

1. 在web.xml中配置

SpringMVC中，已经为我们提供了过滤器 CharacterEncodingFilter 类

在CharacterEncodingFilter 类中，有一个核心的方法：

public class CharacterEncodingFilter extends OncePerRequestFilter {
    @Nullable
    private String encoding;
    private boolean forceRequestEncoding;
    private boolean forceResponseEncoding;

    public CharacterEncodingFilter() {
        this.forceRequestEncoding = false;
        this.forceResponseEncoding = false;
    }

    public CharacterEncodingFilter(String encoding) {
        this(encoding, false);
    }

    public CharacterEncodingFilter(String encoding, boolean forceEncoding) {
        this(encoding, forceEncoding, forceEncoding);
    }

    public CharacterEncodingFilter(String encoding, boolean forceRequestEncoding, boolean forceResponseEncoding) {
        this.forceRequestEncoding = false;
        this.forceResponseEncoding = false;
        Assert.hasLength(encoding, "Encoding must not be empty");
        this.encoding = encoding;
        this.forceRequestEncoding = forceRequestEncoding;
        this.forceResponseEncoding = forceResponseEncoding;
    }

    public void setEncoding(@Nullable String encoding) {
        this.encoding = encoding;
    }

    @Nullable
    public String getEncoding() {
        return this.encoding;
    }

    public void setForceEncoding(boolean forceEncoding) {
        this.forceRequestEncoding = forceEncoding;
        this.forceResponseEncoding = forceEncoding;
    }

    public void setForceRequestEncoding(boolean forceRequestEncoding) {
        this.forceRequestEncoding = forceRequestEncoding;
    }

    public boolean isForceRequestEncoding() {
        return this.forceRequestEncoding;
    }

    public void setForceResponseEncoding(boolean forceResponseEncoding) {
        this.forceResponseEncoding = forceResponseEncoding;
    }

    public boolean isForceResponseEncoding() {
        return this.forceResponseEncoding;
    }

    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        String encoding = this.getEncoding();
        if (encoding != null) {
            if (this.isForceRequestEncoding() || request.getCharacterEncoding() == null) {
                request.setCharacterEncoding(encoding);
            }

            if (this.isForceResponseEncoding()) {
                response.setCharacterEncoding(encoding);
            }
        }

        filterChain.doFilter(request, response);
    }
}

我们只需要对该类中的核心的方法进行对应的配置，就可以完成对应的POST请求中文乱码

具体方法如下：

2. 具体的处理方式

在web.xml中添加如下的配置代码：

    encoding
    org.springframework.web.filter.CharacterEncodingFilter
    
        encoding
        utf-8
        
        forceEncoding
        true
    


    encoding
    /*

可能你会遇到浏览器显示正常，但是控制台是乱码解决方案：奇葩乱码

解决 IDEA 控制台输出中文乱码

二. GET 乱码

1. 在 tomcat 服务器中添加编码

apache-tomcat-8.5.37 --> conf --> server.xml

在第一个 Connector 标签中，添加对应的 UTF 编码

三.使用一个万能的配置类(解决POST和GET)

编写对应的过滤器类，然后在web.xml中配置这个过滤器即可！

package com.kuang.filter;

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 GenericEncodingFilter 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 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 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 parameterMap = getParameterMap();
        String[] values = parameterMap.get(name);
        return values;
    }
}

修改web.xml，添加如下配置：

    文件名
    新的过滤器的包名
    
        encoding
        utf-8
        
        forceEncoding
        true
    


    encoding
    /*

也可以实现乱码解决，但是推荐上面第一种和第二种，实在解决不了再用第三种。