javaweb终极解决乱码问题

1. 编写过滤器代码

package com.lzcu.filter;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;

/**
 * 解决get和post请求 全部乱码的过滤器
 */
public class GenericEncodingFilter implements Filter {
    
    

	public void destroy() {
    
    
	}


	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    
    
		//处理response的字符编码
		HttpServletResponse myResponse=(HttpServletResponse) response;
		myResponse.setContentType("text/html;charset=UTF-8");

		// 转型为与协议相关对象
		HttpServletRequest httpServletRequest = (HttpServletRequest) request;
		// 对request包装增强
		HttpServletRequest myrequest = new MyRequest(httpServletRequest);
		chain.doFilter(myrequest, response);
	}


	public void init(FilterConfig filterConfig) throws ServletException {
    
    
	}

}

//自定义request对象，HttpServletRequest的包装类
class MyRequest extends HttpServletRequestWrapper {
    
    

	private HttpServletRequest request;
	//是否编码的标记
	private boolean hasEncode;
	//定义一个可以传入HttpServletRequest对象的构造函数，以便对其进行装饰
	public MyRequest(HttpServletRequest request) {
    
    
		super(request);// super必须写
		this.request = request;
	}

	// 对需要增强方法 进行覆盖
	@Override
	public Map getParameterMap() {
    
    
		// 先获得请求方式
		String method = request.getMethod();
		if (method.equalsIgnoreCase("post")) {
    
    
			// post请求
			try {
    
    
				// 处理post乱码
				request.setCharacterEncoding("utf-8");
				return request.getParameterMap();
			} catch (UnsupportedEncodingException e) {
    
    
				e.printStackTrace();
			}
		} else if (method.equalsIgnoreCase("get")) {
    
    
			// get请求
			Map<String, String[]> parameterMap = request.getParameterMap();
			if (!hasEncode) {
    
     // 确保get手动编码逻辑只运行一次
				for (String parameterName : parameterMap.keySet()) {
    
    
					String[] values = parameterMap.get(parameterName);
					if (values != null) {
    
    
						for (int i = 0; i < values.length; i++) {
    
    
							try {
    
    
								// 处理get乱码
								values[i] = new String(values[i]
										.getBytes("ISO-8859-1"), "utf-8");
							} catch (UnsupportedEncodingException e) {
    
    
								e.printStackTrace();
							}
						}
					}
				}
				hasEncode = true;
			}
			return parameterMap;
		}
		return super.getParameterMap();
	}

	//取一个值
	@Override
	public String getParameter(String name) {
    
    
		Map<String, String[]> parameterMap = getParameterMap();
		String[] values = parameterMap.get(name);
		if (values == null) {
    
    
			return null;
		}
		return values[0]; // 取回参数的第一个值
	}

	//取所有值
	@Override
	public String[] getParameterValues(String name) {
    
    
		Map<String, String[]> parameterMap = getParameterMap();
		String[] values = parameterMap.get(name);
		return values;
	}
}

3. 配置web.xml

<!--    终极解决乱码-->
   <filter>
       <filter-name>GenericEncodingFilter</filter-name>
       <filter-class>com.lzcu.filter.GenericEncodingFilter</filter-class>
   </filter>
   <filter-mapping>
       <filter-name>GenericEncodingFilter</filter-name>
       <url-pattern>/*</url-pattern>
   </filter-mapping>

5. 重启tomcat,乱码问题解决！