解决汉字乱码（过滤器Filter）

***仅需在web.xml中更改所需的文字转码格式，即可更改所有页面的文字转码格式。

1、创建一个filter文件，指定位置添加以下内容：

String enconding=null; //定义一个全局变量，用来设置编码方式
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
		HttpServletRequest req=(HttpServletRequest)request; //强转
		HttpServletResponse res=(HttpServletResponse)response;
		req.setCharacterEncoding(enconding); //设置
		res.setCharacterEncoding(enconding);
		res.setContentType("text/html;charset="+enconding);
		myRequest myReq=new myRequest(req);
		chain.doFilter(myReq, res);
	}
	public void init(FilterConfig fConfig) throws ServletException {
		enconding=fConfig.getInitParameter("enconding");  //获取编码方式
	}

2、创建myRequest.java，粘贴以下代码：

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class myRequest  extends HttpServletRequestWrapper {

	private HttpServletRequest request;
	public myRequest(HttpServletRequest request) {
		super(request);
		this.request = request;
		// TODO Auto-generated constructor stub
	}
	
	public String getParameter(String name) {
		try{
			String value = request.getParameter(name);
			if(value == null){
				return value;
			}
			if(!request.getMethod().equalsIgnoreCase("get")){
				return value;
			}
			if(!request.getMethod().equalsIgnoreCase("post")){
				return value;
			}
			String enconding = request.getCharacterEncoding();
			//System.out.println(encoding+"-----");
			value = new String(value.getBytes("ISO-8859-1"), enconding);
			return value;
		}catch(Exception e){
			throw new RuntimeException(e);
		}

	}
}

3、在web.xml中写入配置文件，编入以下代码：

***注：写在<web-app></web-app>之间。

<filter>
  	<filter-name>languageFilter</filter-name>  //设置filter名字
  	<filter-class>com.stx.filter.languageFilter</filter-class>  //添加languageFilter路径
  	<init-param> //设置编码方式
  		<param-name>enconding</param-name>
  		<param-value>utf-8</param-value>
  	</init-param>
  </filter>
  <filter-mapping>  //设置该filter作用范围
  	<filter-name>languageFilter</filter-name>
  	<url-pattern>/*</url-pattern>  //其中"/*"代表作用于所有jsp文件
  </filter-mapping>
</filter>

4、OK