Struts原理与实践(5)

package filters;
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.UnavailableException;

/**
* <p>Example filter that sets the character encoding to be used in parsing the
* incoming request, either unconditionally or only if the client did not
* specify a character encoding.  Configuration of this filter is based on
* the following initialization parameters:</p>
* <ul>
* <li><strong>encoding</strong> - The character encoding to be configured
*     for this request, either conditionally or unconditionally based on
*     the <code>ignore</code> initialization parameter.  This parameter
*     is required, so there is no default.</li>
* <li><strong>ignore</strong> - If set to "true", any character encoding
*     specified by the client is ignored, and the value returned by the
*     <code>selectEncoding()</code> method is set.  If set to "false,
*     <code>selectEncoding()</code> is called <strong>only</strong> if the
*     client has not already specified an encoding.  By default, this
*     parameter is set to "true".</li>
* </ul>
*
* <p>Although this filter can be used unchanged, it is also easy to
* subclass it and make the <code>selectEncoding()</code> method more
* intelligent about what encoding to choose, based on characteristics of
* the incoming request (such as the values of the <code>Accept-Language</code>
* and <code>User-Agent</code> headers, or a value stashed in the current
* user's session.</p>
*
* @author Craig McClanahan
* @version $Revision: 1.2 $ $Date: 2001/10/17 22:53:19 $
*/

public class SetCharacterEncodingFilter implements Filter {

// ----------------------------------------------------- Instance Variables

/**
* The default character encoding to set for requests that pass through
* this filter.
*/
protected String encoding = null;

/**
* The filter configuration object we are associated with.  If this value
* is null, this filter instance is not currently configured.
*/
protected FilterConfig filterConfig = null;

/**
* Should a character encoding specified by the client be ignored?
*/
protected boolean ignore = true;

// --------------------------------------------------------- Public Methods

/**
* Take this filter out of service.
*/
public void destroy() {

this.encoding = null;
this.filterConfig = null;

}

/**
* Select and set (if specified) the character encoding to be used to
* interpret request parameters for this request.
*
* @param request The servlet request we are processing
* @param result The servlet response we are creating
* @param chain The filter chain we are processing
*
* @exception IOException if an input/output error occurs
* @exception ServletException if a servlet error occurs
*/
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain)
throws IOException, ServletException {

// Conditionally select and set the character encoding to be used
if (ignore || (request.getCharacterEncoding() == null)) {
String encoding = selectEncoding(request);
if (encoding != null)
request.setCharacterEncoding(encoding);
}

// Pass control on to the next filter
chain.doFilter(request, response);

}

/**
* Place this filter into service.
*
* @param filterConfig The filter configuration object
*/
public void init(FilterConfig filterConfig) throws ServletException {

this.filterConfig = filterConfig;
this.encoding = filterConfig.getInitParameter("encoding");
String value = filterConfig.getInitParameter("ignore");
if (value == null)
this.ignore = true;
else if (value.equalsIgnoreCase("true"))
this.ignore = true;
else if (value.equalsIgnoreCase("yes"))
this.ignore = true;
else
this.ignore = false;

}

// ------------------------------------------------------ Protected Methods

/**
* Select an appropriate character encoding to be used, based on the
* characteristics of the current request and/or filter initialization
* parameters.  If no character encoding should be set, return
* <code>null</code>.
* <p>
* The default implementation unconditionally returns the value configured
* by the <strong>encoding</strong> initialization parameter for this
* filter.
*
* @param request The servlet request we are processing
*/
protected String selectEncoding(ServletRequest request) {

return (this.encoding);

}

}

<filter>
<filter-name>Set Character Encoding</filter-name>
<filter-class>filters.SetCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>Set Character Encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

#Application Resource for the logon.jsp
logon.jsp.title=登录页
logon.jsp.page.heading=欢迎 世界!
logon.jsp.prompt.username=用户名:
logon.jsp.prompt.password=口令:
logon.jsp.prompt.submit=提交
logon.jsp.prompt.reset=复位

#Application Resource for the main.jsp
main.jsp.title=主页
main.jsp.welcome=欢迎:

#Application Resource for the LogonAction.java
error.missing.username=<li><font color="red">没有输入用户名</font></li>
error.missing.password=<li><font color="red">没有输入口令</font></li>

#Application Resource for the UserInfoBo.java
error.noMatch=<li><font color="red">没有匹配的用户</font></li>

#Application Resource for the UserInfoBo.java
error.logon.invalid=<li><font color="red">用户名/口令是无效的</font></li>
error.removed.user=<li><font color="red">找不到该用户</font></li>
error.unexpected=<li><font color="red">不可预期的错误</font></li>

#Application Resource for the logon.jsp
logon.jsp.title=/u767b/u5f55/u9875
logon.jsp.page.heading=/u6b22/u8fce /u4e16/u754c!
logon.jsp.prompt.username=/u7528/u6237/u540d:
logon.jsp.prompt.password=/u53e3/u4ee4:
logon.jsp.prompt.submit=/u63d0/u4ea4
logon.jsp.prompt.reset=/u590d/u4f4d

#Application Resource for the main.jsp
main.jsp.title=/u4e3b/u9875
main.jsp.welcome=/u6b22/u8fce:

#Application Resource for the LogonAction.java
error.missing.username=<li><font color="red">/u6ca1/u6709/u8f93/u5165/u7528/u6237/u540d</font></li>
error.missing.password=<li><font color="red">/u6ca1/u6709/u8f93/u5165/u53e3/u4ee4</font></li>

#Application Resource for the UserInfoBo.java
error.noMatch=<li><font color="red">/u6ca1/u6709/u5339/u914d/u7684/u7528/u6237</font></li>

#Application Resource for the UserInfoBo.java
error.logon.invalid=<li><font color="red">/u7528/u6237/u540d//u53e3/u4ee4/u662f/u65e0/u6548/u7684</font></li>
error.removed.user=<li><font color="red">/u627e/u4e0d/u5230/u8be5/u7528/u6237</font></li>
error.unexpected=<li><font color="red">/u4e0d/u53ef/u9884/u671f/u7684/u9519/u8bef</font></li>