JavaWEB 乱码总结

post 提交的参数乱码特别容易解决；麻烦的就是 get 方式提交的参数；

1) post 提交的参数

request.setCharacterEncoding("utf-8");response.setCharacterEncoding("text/html;charset=utf-8");

2)get 提交

Map<String, String[]> parameterMap = request.getParameterMap();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();            }        }    }}

实例代码1

import java.io.IOException;import java.io.UnsupportedEncodingException;import java.util.Map;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.HttpServletRequestWrapper;/** * 通用解决 get 和 post乱码过滤器  */public class EncodingFilter implements Filter {@Overridepublic void destroy() {}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {// 处理请求乱码HttpServletRequest httpServletRequest = (HttpServletRequest) request;HttpServletRequest myRequest = new MyRequest(httpServletRequest);// 处理响应乱码response.setContentType("text/html;charset=utf-8");chain.doFilter(myRequest, response);}@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}}// 自定义request对象class MyRequest extends HttpServletRequestWrapper {private HttpServletRequest request;private boolean hasEncode;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();}@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}@Overridepublic String[] getParameterValues(String name) {Map<String, String[]> parameterMap = getParameterMap();String[] values = parameterMap.get(name);return values;}}

实例代码2

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;/** * 字符编码 */public class FileEncoding implements Filter{private String encoding = null;@Overridepublic void destroy() {encoding = null;}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain filterChain) throws IOException, ServletException {if (encoding != null) {HttpServletRequest req = (HttpServletRequest) request;//have a answer about value[] & nameif (req.getMethod().equals("GET")) {String url = req.getRequestURL().toString();Enumeration<String> enumerations =  req.getParameterNames();if (enumerations.hasMoreElements()) {url += "?";}while (enumerations.hasMoreElements()) {String name = (String) enumerations.nextElement();String[] values = req.getParameterValues(name);for (String value : values) {System.out.println("设置编码");value = new String(value.getBytes("ISO-8859-1"), encoding);url += name + "=" + value;}//answer - nextElement()if (enumerations.nextElement() != null && !enumerations.nextElement().equals("")) {url += "&";}}System.out.println("拦截器中拦截GET后处理后的URL: " + url);request = req;//System.out.println("name: " + new String(request.getParameter("name").getBytes("ISO-8859-1"), "UTF-8"));} else if (req.getMethod().equals("POST")) {request.setCharacterEncoding(encoding);response.setCharacterEncoding(encoding);}} else {request.setCharacterEncoding("utf-8");response.setCharacterEncoding("text/html;charset=utf-8");}filterChain.doFilter(request, response);}@Overridepublic void init(FilterConfig filterConfig) throws ServletException {encoding = filterConfig.getInitParameter("encoding");}}

最后总结一下

post 提交没什么可说的

但是get 中却大有文章

第一种情况利用a标签传参数

<a href="url?name=中文"> 连接 </a>

直接点击连接是没有乱码的

第二种情况是在浏览器URL地址栏中直接输入与a标签相同的中文参数 (至少访问过一次相同参数的a标签)

url?name=中文

参数传递到后台没有乱码

第三种情况是在浏览器URL地址栏中直接输入与a标签相同的中文参数 (没有访问过相同参数的a标签)

url?name=中文

参数传递到后台会出现乱码

第四种情况是在浏览器URL地址栏中直接输入没有在a标签中出现过的中文参数

url?name=其他中文参数

参数传递到后台会出现中文乱码