weblucene 更新备忘-实现类似google 的多编码支持

来源:百度文库 编辑:神马文学网 时间:2024/04/28 16:41:14
当初在设计WebLucene 的时候,为了能够正确的截取请求中的中文q参数,在执行request.getParameter("q")之前先调用了request.setCharacterEncoding("gb2312")方法。这样虽然避免了乱码问题的出现,但却使得WebLucene 同时只能对一种编码进行处理,无法实现类似于Google 的搜索效果,例如下面两个链接:
http://www.google.com/search?ie=UTF-8&q=%E5%8C%97%E4%BA%AC
http://www.google.com/search?ie=gb2312&q=%B1%B1%BE%A9 查找的都是关键字为“北京”的内容,只是前者的 Url 是以UTF-8 方式进行UrlEncode 得的,而后者则采用的是Gb2312。
在Google 上查找了很多关于setCharacterEncoding 和“多语言支持” 的文章,最后还是用最古老的方法解决了问题,见下面一段代码:
String ie = request.getParameter("encoding");
String q = new String(request.getParameter("q").getBytes("ISO-8859-1"), ie);
这样,只要$q 是以$encodig 方式进行提交/UrlEncode 的,那么我们就可以得到正确的q参数了——但有一点需要注意,就是要用 “ISO-8859-1” 的形式对字符串q 进行getBytes() 操作,而不能采用Utf-8的形式(至少我目前的试验结果是这样的)。
之所以不能用UTF-8 是因为一些应用服务器,如resin2.*,在试图用UTF-8 编码解析参数的时候,往往会因为参数中含有了不合法的UTF-8 字符而产生异常,从而导致无法正常的解析参数。
稍后请见详细描述。
大家可以用我后面的程序作一个试验:
首先把resin的缺省编码设为UTF-8:


....

character
com.chedong.weblucene.CharacterEncodingTest


character
/character

....

然后访问http://localhost:8080/weblucene/search?encoding=UTF-8&q=%E5%8C%97%E4%BA%AC,在resin 的log 中你会发现:
[19:10:52.484] java.io.CharConversionException: illegal utf8 encoding
at com.caucho.vfs.i18n.UTF8Reader.read(UTF8Reader.java:102)
at com.caucho.vfs.ByteToChar.readChar(ByteToChar.java:179)
at com.caucho.vfs.ByteToChar.getConvertedString(ByteToChar.java:126)
at com.caucho.server.http.Form.parseQueryString(Form.java:100)
at com.caucho.server.http.Request.parseQuery(Request.java:1352)
at com.caucho.server.http.Request.getParameterValues(Request.java:1449)
at com.caucho.server.http.Request.getParameter(Request.java:1459)
at com.chedong.weblucene.CharacterEncodingTest.doGet(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:126)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:103)
at com.caucho.server.http.FilterChainServlet.doFilter(FilterChainServlet.java:96)
at com.caucho.server.http.Invocation.service(Invocation.java:315)
at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:246)
at com.caucho.server.http.HttpRequest.handleConnection(HttpRequest.java:163)
at com.caucho.server.TcpConnection.run(TcpConnection.java:139)
at java.lang.Thread.run(Thread.java:536)
附:
1.测试程序
package com.chedong.weblucene;
import org.apache.log4j.Logger;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CharacterEncodingTest extends HttpServlet {
//~ Static fields/initializers ---------------------------------------------
/** The global logger, it will be configured when the servlet loaded */
private static Logger logger = Logger.getLogger(CharacterEncodingTest.class.getName());
//~ Methods ----------------------------------------------------------------
public void destroy() {
super.destroy();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
//request.setCharacterEncoding("ISO-8859-1");
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");
System.out.println("i get a request, with encoding: " + request.getCharacterEncoding() + "
");
String q = "empty";
if(request.getParameter("q") != null) {
String ie = request.getParameter("ie");
if(ie == null) {
ie = "gb2312";
}
q = request.getParameter("q");
System.out.println("raw q:" + q + ".");
q = new String(q.getBytes("iso-8859-1"), ie);
System.out.println("parsed q with(" + ie + "):" + q);
} else {
q = "null";
Enumeration params = request.getParameterNames();
while(params.hasMoreElements()) {
String param = (String) params.nextElement();
System.out.println("param: " + param + "-" + request.getParameter(param) + ".
");
}
}
out.println(q);
out.println("");
out.println("");
/* flush the buffer */
out.flush();
out.close();
}
public void init(ServletConfig servletConfig) throws ServletException {
super.init(servletConfig);
}
}
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