首页 > 代码库 > 过滤器和包装类设计模式的应用
过滤器和包装类设计模式的应用
1.中文乱码过滤器。get和set中文字体的设置
public class AllCharacterEncodingFilter implements Filter {
private FilterConfig filterConfig;
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse)resp;
//获取配置的过滤器参数encoding的值：如果没有，给定一个默认值
String encoding = filterConfig.getInitParameter("encoding");
if(encoding==null)
encoding = "UTF-8";
//设置POST请求方式的中文请求参数的编码
request.setCharacterEncoding(encoding);
//设置响应输出时的编码：字符流和字节流
response.setCharacterEncoding(encoding);//字节流输出时通知客户端的解码码表
response.setContentType("text/html;charset="+encoding);//字节流输出时通知客户端的解码码表；字符流：字符流输出时使用的码表及通知客户端解码用的码表
MyHttpServletRequest mrequest = new MyHttpServletRequest(request);
//放行
chain.doFilter(mrequest, response);
}
public void destroy() {
}
}
//使用包装类设计模式
//HttpServletRequestWrapper内部的代码与连接池原理中那个默认适配器一样
class MyHttpServletRequest extends HttpServletRequestWrapper{
public MyHttpServletRequest(HttpServletRequest request){
super(request);
}
//只对get请求方式进行改写
public String getParameter(String name) {
String value = http://www.mamicode.com/super.getParameter(name);>
2.脏话过滤器public class DirtyWordsFilter implements Filter {
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse)resp;
DirtyWordsHttpServletRequest drequest = new DirtyWordsHttpServletRequest(request);
chain.doFilter(drequest, response);
}
public void init(FilterConfig filterConfig) throws ServletException {
}
}
class DirtyWordsHttpServletRequest extends HttpServletRequestWrapper{
private String words[] = {"傻B","畜生","禽兽"};
public DirtyWordsHttpServletRequest(HttpServletRequest request){
super(request);
}
@Override
public String getParameter(String name) {
String value = http://www.mamicode.com/super.getParameter(name);>
3. HTML特殊标记过滤器
//HTML标记过滤器：< <
public class HtmlFilter implements Filter {
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse)resp;
HtmlHttpServletRequest hrequest = new HtmlHttpServletRequest(request);
chain.doFilter(hrequest, response);
}
public void init(FilterConfig filterConfig) throws ServletException {
}
}
class HtmlHttpServletRequest extends HttpServletRequestWrapper{
public HtmlHttpServletRequest(HttpServletRequest request){
super(request);
}
@Override
public String getParameter(String name) {
String value = http://www.mamicode.com/super.getParameter(name);>
web.xml中配置
<filter>
<filter-name>AllCharacterEncodingFilter</filter-name>
<filter-class>cn.itcast.filter.AllCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>GBK</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>AllCharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>DirtyWordsFilter</filter-name>
<filter-class>cn.itcast.filter.DirtyWordsFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>DirtyWordsFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>HtmlFilter</filter-name>
<filter-class>cn.itcast.filter.HtmlFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>HtmlFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
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