jsp/servlet/javaBean三层架构小示例（1）

最新推荐文章于 2020-08-28 11:54:23 发布

最新推荐文章于 2020-08-28 11:54:23 发布 · 316 阅读

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#java #测试

本文介绍了一个简单的用户登录功能实现案例，使用MVC模式通过JSP、Servlet和JavaBean完成前后端分离。展示了如何利用数据库操作类进行用户验证。

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在java代码中写文档（html)，这是servlet;在文档中写java代码，这是jsp;而如何将两者分开，这就是MVC模式了。虽然是java的一小步，却是程序员们生活的一大步哦。
下面给出一个简单的用户登陆功能，采用jsp/servelt/javaBean来实现MVC模式（即经典的模式2）。

模型层：

packagecom.vitamin.DataAccess;

importjava.sql.*;

publicclassDBbase

{

StringsDBDriver="sun.jdbc.odbc.JdbcOdbcDriver";

StringsConnstr="jdbc:odbc:myDB";

Connectionconnect=null;

ResultSetrs=null;

Statementstmt=null;

publicDBbase()

{

try

{

Class.forName(sDBDriver);

}

catch(ClassNotFoundExceptionex)

{

System.err.println(ex.getMessage());

}

publicResultSetexecuteQuery(Stringsql)

{

try

{

this.connect=DriverManager.getConnection(sConnstr);

this.stmt=this.connect.createStatement();

rs=stmt.executeQuery(sql);

}

catch(SQLExceptionex)

{

System.err.println(ex.getMessage());

}

returnrs;

}

publicintexecuteUpdate(Stringsql)

{

intresult=0;

try

{

this.connect=DriverManager.getConnection(sConnstr);

this.stmt=this.connect.createStatement();

result=stmt.executeUpdate(sql);

}

catch(SQLExceptionex)

{

System.err.println(ex.getMessage());

}

returnresult;

}

控制层：

packagecom.vitamin.servlet;

importjava.io.IOException;

importjava.io.PrintWriter;

importjavax.servlet.ServletException;

importjavax.servlet.http.HttpServlet;

importjavax.servlet.http.HttpServletRequest;

importjavax.servlet.http.HttpServletResponse;

importcom.vitamin.DataAccess.*;

importjava.sql.*;

publicclassHelloextendsHttpServlet

{

/***//**

*Constructoroftheobject.

publicHello()

{

super();

}

/***//**

*Destructionoftheservlet.

publicvoiddestroy()

{

super.destroy();//Justputs"destroy"stringinlog

//Putyourcodehere

}

/***//**

*ThedoGetmethodoftheservlet.

*Thismethodiscalledwhenaformhasitstagvaluemethodequalstoget.

*@paramrequesttherequestsendbytheclienttotheserver

*@paramresponsetheresponsesendbytheservertotheclient

*@throwsServletExceptionifanerroroccurred

*@throwsIOExceptionifanerroroccurred

publicvoiddoGet(HttpServletRequestrequest,HttpServletResponseresponse)

throwsServletException,IOException

{

response.setContentType("text/html");

PrintWriterout=response.getWriter();

out.println("<!DOCTYPEHTMLPUBLIC/"-//W3C//DTDHTML4.01Transitional//EN/">");

out.println("<HTML>");

out.println("<HEAD><TITLE>AServlet</TITLE></HEAD>");

out.println("<BODY>");

out.print("Thisis");

out.print(this.getClass());

out.println(",usingtheGETmethod");

out.println("</BODY>");

out.println("</HTML>");

out.flush();

out.close();

}

/***//**

*ThedoPostmethodoftheservlet.

*Thismethodiscalledwhenaformhasitstagvaluemethodequalstopost.

*@paramrequesttherequestsendbytheclienttotheserver

*@paramresponsetheresponsesendbytheservertotheclient

*@throwsServletExceptionifanerroroccurred

*@throwsIOExceptionifanerroroccurred

publicvoiddoPost(HttpServletRequestrequest,HttpServletResponseresponse)

throwsServletException,IOException

{

response.setContentType("text/html");

response.setCharacterEncoding("GBK");

PrintWriterout=response.getWriter();

request.setCharacterEncoding("GBK");

Stringname=request.getParameter("name");

Stringpwd=request.getParameter("password");

DBbasemyDb=newDBbase();

ResultSetrs=null;

intresult=0;

Stringsql="selectcount(*)ascountfromuserswhereusername='"+name+"'andpassword='"+pwd+"'";

try

{

rs=myDb.executeQuery(sql);

if(rs.next())

{

result=rs.getInt("count");

}

catch(SQLExceptionex)

{

ex.printStackTrace();

}

if(result>0)

{

out.println("合法用户");

}

else

{

out.println("非法用户");

}

/***//**

*Initializationoftheservlet.

*@throwsServletExceptionifanerroroccure

publicvoidinit()throwsServletException

{

//Putyourcodehere

}

Web表示层:

<%@pagelanguage="java"import="java.util.*"pageEncoding="GBK"%>

Stringpath=request.getContextPath();

StringbasePath=request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

<!DOCTYPEHTMLPUBLIC"-//W3C//DTDHTML4.01Transitional//EN">

<html>

<head>

<basehref="<%=basePath%>">

<title>MyJSP'index.jsp'startingpage</title>

<metahttp-equiv="pragma"content="no-cache">

<metahttp-equiv="cache-control"content="no-cache">

<metahttp-equiv="expires"content="0">

<metahttp-equiv="keywords"content="keyword1,keyword2,keyword3">

<metahttp-equiv="description"content="Thisismypage">

<!--

<linkrel="stylesheet"type="text/css"href="styles.css">

-->

</head>

<body>

<FORMname="form1"method="POST"action="/servletTest/servlet/Hello">

用户名：  <INPUTtype="text"name="name"maxlength="20"/>

密码 <INPUTtype="password"name="password"maxlength="20"/>

<INPUTtype="Submit"name="button4"value="确定"/>  <INPUTtype="Reset"name="button5"value="重置">

</FORM>

</body>

</html>

看过一篇资料说，servlet能够与多个客户机连接，接受多个客户的输入，并将结果广播到多个客户机上，例如可以作为一个多人参与的游戏服务器，这点倒是让我挺吃惊的，不知道如何能够实现哪？如果是真的，那servlet是如何得知客户的详细信息的？难道可以象socket那样？不解。。。