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如何通过Servlet类获取初始化参数

2016-11-05 22:11 585 查看

在web.xml中配置servlet时，可以配置一些初始化参数。而在servlet中能够通过ServletConfig接口提供的方法来取得这些参数。

1、在web.xml中配置初始化参数username：admin；password：12345

2、在index.jsp中添加超链接，超链接默认是get访问，但我们可以在doGet（）方法中添加doPost（），使其做post访问

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

doPost(request,response);
}

3、在init（）方法中获得初始化参数

运行效果

最后贴出Servlet类代码

package servlet;

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 GetInitParameterServlet extends HttpServlet {

private String username;//用户名
private String password; //密码

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

/**
* Constructor of the object.
*/
public GetInitParameterServlet() {
super();
}

/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}

/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

doPost(request,response);
}

/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println("  <BODY>");
out.println("<h2>"+"用户名："+this.getUsername()+"</h2>");
out.println("<h2>"+"密码："+this.getPassword()+"</h2>");
out.println("  </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}

/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
//在init()方法中获得初始化参数
public void init() throws ServletException {
// 通过this.getInitParameter("要读取的参数名")
//即可获得初始化参数，返回字符串类型
this.setUsername(this.getInitParameter("username"));
this.setPassword(this.getInitParameter("password"));
}

}

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标签： servlet

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