一劳永逸的解决tomcat中文编码request请求

对于中文编码的http请求，一般我们只关心GET和POST两种。

在Tomcat中，这两种请求的编码处理方式是不同的。

前者中文出现在uri中，当然你看到的都是%ea%ab%07之类的东西，其实还是中文编码，

只不过uri不能有中文，所以w3c标准把这些都编码成%xx的形势，当然，现在很多浏览器也

接受直接的中文GET请求，例如你在地址栏输入http://www.xxx.com/xx?name=周杰伦。

但HTTP报文的uri是不会出现中文的，浏览器帮你做了工作。

后者中文出现在Http请求报文的content里面。

后者中文处理比较简单，任何一个接受request的servlet或者jsp，只需要使用request.se

tCharacterEncoding方法就可以了。

当然也可以使用JSTL的fmt标记功能，实质没有任何不同。

但是这里有个麻烦的地方，就是每个servlet或者jsp读入内容前都要setCharacterEncodin

g，让人心烦。

在struts里面，你可以通过扩展ActionServlet，或者使用扩展RequestProcessor的方法对

所有的请求进行这个处理，这样可以达到一劳永逸的效果。

但是更好的通用方法，应该是不管用不用struts，都可以解决这个问题。

最好的办法，就是使用filter。

如果你还不知道filter是什么，我以后有文章详细说明，这里简单说一下就是可以在任何s

ervlet/jsp处理之前，对request进行一定的处理，所谓filter，不就是过滤么。

Tomcat的例子jsp-example和servlet-example里面藏了同一段非常有用的源代码。

名叫SetCharacterEncodingFilter.java

/*

* Copyright 2004 The Apache Software Foundation

*

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

* http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*/

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: 2004/03/18 16:40:33 $

*/

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);

}

}

我们要做的很简单，在我们的src里面建立filters目录，把这个文件仍进去。

ant一下就好。

当然还要修改web.xml，添加这样的内容：

<filter>

<filter-name>setCharacterEncoding</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>setCharacterEncoding</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

我们假定所有的request都是utf-8编码，实际上这也是可以保障的，通过jsp的page命令以

及html的meta命令多重保障。

这里的意思是对任何请求都是用该filter。

于是乎post的中文编码问题就解决了。

再就是get，我们在tomcat/conf里面修改server.xml，看到connector 8080那个，增加

一个属性

<Connector port="8080" maxHttpHeaderSize="8192"

maxThreads="150" minSpareThreads="25" maxSpareThreads="75"

enableLookups="false" redirectPort="8443" acceptCount="100"

connectionTimeout="20000" disableUploadTimeout="true"

URIEncoding="UTF-8"/>

这样，所有的中文参数问题就解决了。