过滤器解决请求中文乱码

一、配置一个过滤器，拦截全部请求

package cn.demo.filter;

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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 全栈乱码过滤器
 * 
 */
public class MyFilter implements Filter {
	private String value;
	private String type;

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		value = filterConfig.getInitParameter("encoding");
		type = filterConfig.getInitParameter("type");
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		// 强转成子接口类型，使用更多api
		HttpServletRequest httpServletRequest = (HttpServletRequest) request;
		HttpServletResponse httpServletResponse = (HttpServletResponse) response;

		MyRequest myRequest = new MyRequest(httpServletRequest);// 构造方法注入，MyResquest中重写三个方法，解决乱码
		httpServletResponse.setContentType(type + ";charSet=" + value);

		chain.doFilter(myRequest, httpServletResponse);
	}

	@Override
	public void destroy() {
	}

}


web.xml配置
<display-name></display-name>
	<filter>
		<filter-name>MyFilter</filter-name>
		<filter-class>cn.demo.filter.MyFilter</filter-class>
		<init-param>
			<param-name>encoding</param-name>
			<param-value>utf-8</param-value>
		</init-param>
		<init-param>
			<param-name>type</param-name>
			<param-value>text/html</param-value>
		</init-param>
	</filter>


	<filter-mapping>
		<filter-name>MyFilter</filter-name>
		<!-- 拦截全部请求，解决乱码 -->
		<url-pattern>/*</url-pattern>
	</filter-mapping>

二、MyRequest类重写三个方法

package cn.demo.filter;

import java.io.UnsupportedEncodingException;
import java.util.Map;

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

public class MyRequest extends HttpServletRequestWrapper {

	private HttpServletRequest request;
	private boolean flag = false;

	public MyRequest(HttpServletRequest request) {
		super(request);
		this.request = request;
	}

	// 重写三个方法
	@Override
	public Map getParameterMap() {

		String method = request.getMethod();
		if ("post".equalsIgnoreCase(method)) {
			try {
				request.setCharacterEncoding("utf-8");
				return request.getParameterMap();
			} catch (UnsupportedEncodingException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

		// 遍历取出每一个元素，先编码，再解码
		if ("get".equalsIgnoreCase(method)) {
			if (!flag) {
				Map<String, String[]> map = request.getParameterMap();
				if (map != null && map.size() != 0) {
					// 遍历
					for (String key : map.keySet()) {
						String[] values = map.get(key);
						if (values != null && values.length != 0) {
							for (int i = 0; i < values.length; i++) {
								try {
									// 每个元素先编码再解码
									values[i] = new String(values[i].getBytes("iso-8859-1"), "utf-8");
								} catch (UnsupportedEncodingException e) {
									// TODO Auto-generated catch block
									e.printStackTrace();
								}
							}
						}
					}
				}
				flag = true;
				return map;
			}
		}
		return super.getParameterMap();
	}

	@Override
	public String[] getParameterValues(String name) {
		Map<String, String[]> map = getParameterMap();
		if (map != null && map.size() != 0) {
			String[] values = map.get(name);
			if (values != null && values.length != 0) {
				return values;
			}
		}
		return super.getParameterValues(name);
	}

	@Override
	public String getParameter(String name) {
		Map<String, String[]> map = getParameterMap();
		if (map != null && map.size() != 0) {
			String[] values = map.get(name);
			if (values != null && values.length != 0) {
				return values[0];
			}
		}
		return super.getParameter(name);
	}

}