转:过滤器的编写（过滤字符编码）

过滤器的编写（过滤字符编码）
程序可以直接运行，将代码加入工程即可使用。
1.   Filter 类

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class SetCharacterEncodingFilter implements Filter {
    protected String encoding = null;
    protected FilterConfig filterConfig = null;
    protected boolean ignore = true;

    public void destroy() {
        this.encoding = null;
        this.filterConfig = null;
    }

    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        // Conditionally select and set the character encoding to be used
        if (ignore || (request.getCharacterEncoding() == null)) {
            String encoding = selectEncoding(request);
            if (encoding != null)
                request.setCharacterEncoding(encoding);
        }
        // Pass control on to the next filter
        chain.doFilter(request, response);
    }

    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
        String value = filterConfig.getInitParameter("ignore");
        if (value == null)
            this.ignore = true;
        else if (value.equalsIgnoreCase("true"))
            this.ignore = true;
        else if (value.equalsIgnoreCase("yes"))
            this.ignore = true;
        else
            this.ignore = false;
    }

    protected String selectEncoding(ServletRequest request) {
        return (this.encoding);
    }
}

 

2. 在web.xml 配置过滤器

<filter>
    <filter-name>SetCharsetEncodingFilter</filter-name>
    <filter-class>com.netstore.util.SetCharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>GBK</param-value>
    </init-param>
</filter>

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