8. 乱码问题

网络编程中乱码绝大部分都与编码格式有关，常常在涉及到中文的文件编译或者数据传输中出现。

Spring MVC 使用 post 方式传输带中文数据时便会出现乱码，get 方式则不会，解决方式如下：

(1) 自定义过滤器

过滤器

public class EncodingFilter implements Filter {public void init(FilterConfig filterConfig) throws ServletException {}public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {request.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");chain.doFilter(request, response);}public void destroy() {}
}

<!--web.xml-->
<filter><filter-name>encoding</filter-name><filter-class>com.why.filter.EncodingFilter</filter-class>
</filter>
<filter-mapping><filter-name>encoding</filter-name><url-pattern>/*</url-pattern>
</filter-mapping>

注意：<url-pattern> 设置为 /* ，否则过滤器匹配不到 jsp 页面

(2) 配置 Spring MVC 的字符编码过滤器

<!--web.xml-->
<!--Spring MVC 字符编码过滤器-->
<filter><filter-name>encoding</filter-name><filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class><init-param><param-name>encoding</param-name><param-value>utf-8</param-value></init-param>
</filter><filter-mapping><filter-name>encoding</filter-name><url-pattern>/*</url-pattern>
</filter-mapping>

(3) 修改 Tomcat 配置文件文件

<Connector executor="tomcatThreadPool"port="8080" protocol="HTTP/1.1"connectionTimeout="20000"redirectPort="8443" URIEncoding="UTF-8"/>

(4) 网络大神的过滤器

package com.why.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 {@Overridepublic void destroy() {}@Overridepublic 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);}@Overridepublic 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@Overridepublic 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@Overridepublic 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@Overridepublic String[] getParameterValues(String name) {Map<String, String[]> parameterMap = getParameterMap();String[] values = parameterMap.get(name);return values;}
}