SpringMVC乱码问题解决

乱码问题

1. 编写一个提交的表单

<form action="/t" method="post">
    <input type="text" name="name">
    <input type="submit">
  </form>

2. 编写Controller进行处理表单提交的数据并返回视图给前端

@Controller
public class TestEncoding {
    
    

    @PostMapping("/t")
    public String test(@RequestParam("name") String name, Model model){
    
    
        System.out.println(name);
        model.addAttribute("msg",name);
        return "hello";
    }
}

在java层面已经产生乱码情况

解决方法

以前乱码问题通过过滤器解决 , 而SpringMVC给我们提供了一个过滤器 , 可以在web.xml中配置

    <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>
<!--        /*处理所有请求-->
        <url-pattern>/*</url-pattern>
    </filter-mapping>

修改了web.xml文件需要重启Tomcat服务器

如果SpringMVC过滤器还是不够处理乱码问题，可以自定义过滤器解决

public class GenericEncodingFilter implements Filter {
    
    
    public void destroy() {
    
    
    }


    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);
    }


    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

    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

    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

    public String[] getParameterValues(String name) {
    
    
        Map<String, String[]> parameterMap = getParameterMap();
        String[] values = parameterMap.get(name);
        return values;
    }

}

一般情况下，SpringMVC默认的乱码处理就已经能够很好的解决了，要使用自定义过滤器在web.xml中配置过滤器即可