j2EE中的过滤器的用法(过滤乱码)

乱码是j2ee中一个比较常见的问题。遇到1，2个情况下，可以用new String(request.getParameter(xxx).getBytes("ISO-8859-1"),"UTF-8")来解决。遇到多的情况下，就最好用过滤器了。
1个过滤器只需要注意2个地方，类和在web.xml上面的发布。

1。在web.xml上面的发布如下：

<filter>
      <filter-name>SetCharsetEncodingFilter</filter-name>  //这个是类名
      <filter-class>org.SetCharacter</filter-class>        //这个是类的位置
      <init-param>
          <param-name>encoding</param-name>
          <param-value>utf-8</param-value>
      </init-param>
  </filter>
  <filter-mapping>
      <filter-name>SetCharsetEncodingFilter</filter-name>
      <url-pattern> /* </url-pattern>   //这个代表所有的文件遇到过滤器都要被拦截
  </filter-mapping>

2。过滤的这个类如下：

package org;

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 SetCharacter implements Filter {
    protected String encoding = null;
    protected FilterConfig filterConfig = null;
    protected boolean ignore = true;

    public void init(FilterConfig arg0) throws ServletException {
        this.encoding = arg0.getInitParameter("encoding");
        String value = arg0.getInitParameter("imnore");
        if(value==null){
            this.ignore = true;
        }else if (value.equalsIgnoreCase("true")){
            this.ignore = true;
        }else if(value.equalsIgnoreCase("yes")){
            this.ignore = true;
        }
        
    }

    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2) throws IOException, ServletException {
        if(ignore||(arg0.getCharacterEncoding() == null)){
            String encoding =selectEncoding(arg0);
            if(encoding!=null)
                arg0.setCharacterEncoding(encoding);
        }
        arg2.doFilter(arg0,arg1);
    }

    private String selectEncoding(ServletRequest arg0) {
        return (this.encoding);
    }

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

}

评论

1 楼 blue3377 2009-12-25  

为什么，我一吧这个加入我的项目里面。他就报错了：
org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/myblog] has not been started
2009-12-25 14:59:35 org.apache.catalina.core.StandardContext filterStart
严重: Exception starting filter SetCharsetEncodingFilter
java.lang.ClassNotFoundException: cn.blue.SetCharacter

2009-12-25 14:59:35 org.apache.catalina.core.StandardContext start
严重: Error filterStart
2009-12-25 14:59:35 org.apache.catalina.core.StandardContext start
严重: Context [/myblog] startup failed due to previous errors
？能解释下么？