标签：
在页面建个表单
<form action="login.do" method="post"> <input type="text" name="username" /> <input type="submit" value="确定" /> </form>
建个servlet
web.xml
<servlet> <servlet-name>LoginServlert</servlet-name> <servlet-class>servlet.LoginServlert</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlert</servlet-name> <url-pattern>/login.do</url-pattern> </servlet-mapping>
package servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class LoginServlert extends HttpServlet { public LoginServlert() { super(); } public void destroy() { super.destroy(); } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String username = request.getParameter("username"); System.out.println("获取的username:>>>>>>"+username); } public void init() throws ServletException { } }
后台情况是这样的:
乱码了.
可以通过过滤器来解决
新建一个过滤器EncodingFilter.java
package 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; public class EncodingFilter implements Filter{ private String encoding = ""; private String filterName = ""; public void init(FilterConfig filterConfig) throws ServletException { encoding = filterConfig.getInitParameter("encoding"); filterName = filterConfig.getFilterName(); if (encoding == null || "".equals(encoding)) { encoding = "UTF-8"; } System.out.println("获得编码值......"); } public void doFilter(ServletRequest request, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest req=(HttpServletRequest)request; System.out.println("请求被" + filterName + "过滤了......."); // 分别对请求和响应进行编码设置 request.setCharacterEncoding(encoding); res.setCharacterEncoding(encoding); chain.doFilter(req, res); System.out.println("响应被被" + filterName + "过滤了......."); } public void destroy() { System.out.println("请求被销毁......"); } }
在web.xml中配置filter
<filter> <filter-name>EncodingFilter</filter-name> <filter-class>filter.EncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>utf-8</param-value> </init-param> </filter> <filter-mapping> <filter-name>EncodingFilter</filter-name> <url-pattern>*.do</url-pattern> </filter-mapping>
跑起来:
正常了.
我们换在地址栏里输入汉字,看看是否乱码.
结果是这样的
过滤器不起作用了,怎么办.
其实request.setCharacterEncoding(encoding);只对消息体中的数据起作用,对url中的参数不起作用了.
对上面的过滤器进行优化.
编写RequestEncodingWrapper.java
package filter; import java.io.UnsupportedEncodingException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; public class RequestEncodingWrapper extends HttpServletRequestWrapper { private String encoding = ""; public RequestEncodingWrapper(HttpServletRequest request) { // 必须调用父类构造方法 super(request); } public RequestEncodingWrapper(HttpServletRequest request,String encoding){ // 必须调用父类构造方法 super(request); this.encoding=encoding; } @Override public String getParameter(String name) { String value=getRequest().getParameter(name); try { //将参数值进行编码转换 if(value!=null&&!"".equals(value)){ value=new String(value.trim().getBytes("iso-8859-1"),encoding); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } return value; } }
优化EncodingFilter.java后
package 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; public class EncodingFilter implements Filter { private String encoding = ""; private String filterName = ""; public void init(FilterConfig filterConfig) throws ServletException { encoding = filterConfig.getInitParameter("encoding"); filterName = filterConfig.getFilterName(); if (encoding == null || "".equals(encoding)) { encoding = "UTF-8"; } System.out.println("获得编码值......"); } public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { HttpServletRequest req=(HttpServletRequest)request; System.out.println("请求被" + filterName + "过滤了......."); if("GET".equals(req.getMethod())){ req=new RequestEncodingWrapper(req,encoding); }else { request.setCharacterEncoding(encoding); } // 分别对请求和响应进行编码设置 response.setCharacterEncoding(encoding); chain.doFilter(req, response); System.out.println("响应被被" + filterName + "过滤了......."); } public void destroy() { System.out.println("请求被销毁......"); } }
好了.
Filter接口有三个方法:
init(FilterConfig filterConfig) 初始化过滤器,filterConfig参数可以得到过滤器初始化的配置参数信息.
doFilter(ServletRequest request, ServletResponse res,FilterChain chain)
request表示客户端的请求,rewponse表示对应请求的响应,chain是过滤器对象,.在该方法中的特定过滤器完成后,
可调用doFilter请求传给过滤器中的下一个过滤器,也可以直接返回响应内容,还可以将目标重定向.
destroy():释放过滤器中使用的资源.
参数FilterConfig filterConfig有四个方法:
public String getFilterName() 得到过滤器的名字
public String getInitParameter(String name) 得到过滤器中初始化的参数值.
publi Enumeration getInitParameterNames() 得到过滤器配置中的所有初始化参数名字的枚举类型.
publi ServletContext getServlet() 得到Servlet上下文对象.
标签：
原文地址：http://www.cnblogs.com/guoyansi19900907/p/4999248.html
