JavaWeb乱码问题及统一全站编码(通过Filter实现)

1.

public class CharacterFilter implements Filter {
    private String characterEncoding = null;
    FilterConfig fc;
    public void init(FilterConfig filterConfig) throws ServletException {
        fc = filterConfig;
        if (null != fc &&
                null != fc.getInitParameter("encoding") &&
                !"".equals(fc.getInitParameter("encoding"))) {
            characterEncoding = fc.getInitParameter("encoding");
        } else {
            characterEncoding = "UTF-8";
        }
    }
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;
        // 拦截所有的请求 解决全站中文乱码
        // 指定 request 和 response 的编码
        request.setCharacterEncoding(characterEncoding);
        //将response对象中的数据以UTF-8解码后发向浏览器
        response.setCharacterEncoding(characterEncoding);
        //告诉浏览器输出内容为HTML,并使用UTF-8对HTML内容进行解码
        response.setContentType("text/html;charset="+characterEncoding);
        chain.doFilter(request, response);
    }

    public void destroy() {
    }
}

2.配置Filter,注意编码Filter注册要放到最前面

<filter>
    <filter-name>CharacterFilter</filter-name>
    <filter-class>com.hbxy.web.c04.filter.CharacterFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>CharacterFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping

补充：关千编码问题

在Servlet中，request/response处理中文时，使用默认配置往往会出现乱码，如：

public void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        OutputStream out = response.getOutputStream();
        String data =“张三”;
        out.write(data.getBytes("UTF-8"));
}

输出乱码的问题是程序用UTF-8编码，而如果浏览器用GB2312解码，会出现乱码

Servlet乱码分为request乱码和response乱码

Response响应乱码解决办法

• 1、response.setCharacterEncoding(“UTF-8”); 用千response.getWriter()输出的字符流的乱码问题，如果是response.getOutputStream()是不需要设置（因为数据里已经进行了编码）
• 2、response.setContentType("text/html;charset=UTF-8"); 是为了控制浏览器的行为，即控制浏览器用UTF-8进行解码
• 3、建议全站设置统一的编码：JSP/Servlet统一设置成UTF-8或者GBK
• 也即在Filter中Response设置：
  • response.setCharacterEncoding(“UTF-8”);
  • response.setContentType("text/html;charset=UTF-8");

RequestPOST请求

RequestGET请求