实现Filter类的servlet的写法
package filtertest;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
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.HttpServlet;
public class FilterEncoding extends HttpServlet implements Filter {
String encoding;
private static final String DEFAULT_CHARACTER_ENCODING = "UTF-8";
public void init(FilterConfig arg0) throws ServletException {
//get encoding from config
encoding = arg0.getInitParameter("encoding");
}
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException {
try{
if ((encoding != null)&&(encoding.length()>0)){
arg0.setCharacterEncoding(encoding);
System.out.println("in filter and encoding = " + encoding);
}else{
arg0.setCharacterEncoding(DEFAULT_CHARACTER_ENCODING);
}
}
catch(UnsupportedEncodingException e){
arg0.setCharacterEncoding(DEFAULT_CHARACTER_ENCODING);
e.printStackTrace();
}
//filterChain
arg2.doFilter(arg0,arg1);
}
}
web.xml中的配置
<filter>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<filter-name>FilterEncoding</filter-name>
<filter-class>filtertest.FilterEncoding</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>FilterEncoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>