Mysql与JSP网页中文乱码问题的解决方案

自从以前学习JSP开始，中文乱码问题就一直不断，苦不堪言。这次在项目开始之前，我们要解决的第一个问题就是把mysql的中文乱码问题搞定。经过多天的努力，终于成功的解决了中文乱码问题，特写在这里，以备后用。软件及环境：Windows XP(2000), j2sdk1.4.2, Tomcat 5.0.25, mysql 4.1,  EMS Mysql Manager 2(方便建表，版本2.8.5.1)，驱动为mysql-connector-java-3.1.4-beta-bin.jar。目标：在该环境下，实现中文的正常显示，读取与插入数据库。

注：我只在此环境下测试通过，别的系统及不同版本未测试要点：统一字符集（JSP页面编码，mysql建库时字符集选择，连接数据库URL，request设定等）下面我以GBK为例讲解。如果要使用utf-8，只要在相应的GBK处换成utf-8即可

---------------------------   

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;

/**
*   中文过滤器
*/
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);

}

}//EOC

该代码来自于www.javawebstudio.com，特此感谢！然后我们在web.xml中加一些配置，就可以了，配置如下：

<filter>
    <filter-name>Set Character Encoding</filter-name>
    <filter-class>javawebstudio.struts_db.SetCharacterEncodingFilter</filter-class>
    <init-param>
        <param-name>encoding</param-name>
        <param-value>GBK</param-value>
    </init-param>
    <init-param>
        <param-name>ignore</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>Set Character Encoding</filter-name>
    <servlet-name>action</servlet-name>
</filter-mapping>放在web.xml的合适位置。一般在最后，<jsp-config>标签之前(如果有的话)经过以上步骤，JSP和mysql的中文显示及插入就都正常了。在STRUTS中也正常。但是，此时如果你用EMS或mysql的命令行控制台来看表中的数据，却发现它们都是????。这是怎么回事呢？不用担心，只要我们运行下面的这几行命令，就能看到正常的中文了!

SET character_set_client = gbk;
SET character_set_connection = gbk;
SET character_set_database = gbk;
SET character_set_results = gbk;
SET character_set_server = gbk;

SET collation_connection = gbk_bin;
SET collation_database = gbk_bin;
SET collation_server = gbk_bin;如果你用的是mysql的命令行，则直接输入就好。如果是EMS，则在工具栏中有一个Show SQL Editor按钮,点一下，把上面的命令输入，再按一个execute的按钮，就行了!而且在这种情况下，你可以甚至可以用中文名来建数据库，表名和字段名!!!!

----------------------------------------------------------------------------------------------------

</T