解决JavaScript 与Servlet之间的通讯

转贴地址：http://blog.csdn.net/dxmdxs/archive/2006/03/23/636170.aspx

http://blog.csdn.net/crackcell/archive/2007/09/03/1769654.aspx

解决JavaScript 与Servlet之间的通讯．通过测试，得出如下代码不会出现中文问题，当然这断代码有很多不足之处，或许是巧合．由此，系统可以通过JavaScript直接访问JavaBeans 读取数据库的记录并进行操作．

JavaScript代码如下：

URL="http://localhost:8080/xml/servlet/xml"

 function SendXML()

 {

    xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

      xmlhttp.Open("GET",URL,false);       

      xmlhttp.setRequestHeader("Charset","gb2312");

      xmlhttp.send("唯思");    

      // 测试发送是否成功? 

      if ( xmlhttp.status == 200 )

      {

alert(xmlhttp.responseText);

      } else{

alert("服务器错误,状态代码:"+xmlhttp.status+",原因:"+xmlhttp.reason);

}

 }

 

Servlet代码如下：

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class xml extends HttpServlet {

      public xml() {

           super();

      }

public void doPost(HttpServletRequest request, HttpServletResponse response)

                 throws ServletException, IOException {

           PrintWriter out = response.getWriter();        

           out.print(request.getReader().readLine());               

           out.flush();

           out.close();

      }

}

 

解决JavaScript 通过XML与Servlet之间的通讯.即可以传递一个XMLDOM交给Servlet进行处理.

JavaScript源代码如下:

<script>

 URL="http://localhost:8080/xml/servlet/xml"

 var xml="<?xml version='1.0' encoding='utf-8'?><root>唯思</root>" 

 function SendXML()

 {

  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

    xmlhttp.Open("POST",URL,false);

    xmlhttp.setRequestHeader("charset", "utf-8");

    xmlDoc = new ActiveXObject("Microsoft.XMLDOM");

    xmlDoc.async="false";

    xmlDoc.loadXML(xml);

    xmlhttp.send(xmlDoc);   

    // 测试发送是否成功?

     if ( xmlhttp.status == 200 )

         { //alert(SendMessage);           

             xmlDoc.loadXML(xmlhttp.responseText); document.getElementById("ws").innerHTML=xmlDoc.selectSingleNode("/root").text;

         } else

        {

        alert("服务器错误,状态代码:"+xmlhttp.status+",原因:"+xmlhttp.reason);

        }

 }

</script>

Servlet代码如下:

public class xml extends HttpServlet {

      public void doGet(HttpServletRequest request, HttpServletResponse response)

                 throws ServletException, IOException {

      }

      public void doPost(HttpServletRequest request, HttpServletResponse response)

                 throws ServletException, IOException {

           response.setCharacterEncoding("utf-8");

           PrintWriter out = response.getWriter();

           DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();

           factory.setValidating(false);

           Document doc;

           try {

                 doc = factory.newDocumentBuilder().parse(request.getInputStream());

                 DOMSource source = new DOMSource(doc);

                 Result result = new StreamResult(out);

                 Transformer xformer = TransformerFactory.newInstance()

                            .newTransformer();           

                 xformer.transform(source, result);             

           } catch (SAXException e) {

                 e.printStackTrace();

           } catch (IOException e) {

                 e.printStackTrace();

           } catch (ParserConfigurationException e) {

                 e.printStackTrace();

           } catch (TransformerException e) {             

                 e.printStackTrace();

           } catch (TransformerFactoryConfigurationError e) {              

                 e.printStackTrace();

           }

           out.flush();

           out.close();

      }

}

测试结果:唯思. 由此,我们可以通过javax.xml.parsers和org.w3c.dom在Servlet内部解析XML并将所要求的请求发送到Hibernate操作MySQL实现更方便快速的进行查询及更改.

注意: 1.在写JavaScript验证的时候,并不能完全代替后台的数据验证,这是因为攻击者完全可以伪造浏览进行非法递交. 对于安全非常重要的环节,绝对不可以忽略这一点. 2.在写JavaScript生成XML于Servlet进行通讯的时候,当递交和返回都含有整个数据库的内容时,此方法并不可取. 这是因为,当需求发生更改时,将导致大理代码的修改. 所以,此方法只比较合适用于简单操作上,如用户名是否重复,删除某一用户等,只需要简单数据,并且这些数据的变更非常小.