JavaWeb----Servlet使用_javamsit-优快云博客

本文链接：https://blog.youkuaiyun.com/Cyn3465/article/details/38347579

1. 实现Servlet的方式

1).是使用继承

继承HttpServlet

2).使用接口

/**

* 实现Servlet方式二--实现Servlet接口

* @author admin

publicclassServletTest implements Servlet {

/**

* 销毁方法

@Override

publicvoid destroy() {

}

/**

* 得到Servlet上下文配置对象

@Override

public ServletConfiggetServletConfig() {

returnnull;

}

/**

* 得到Servlet信息

@Override

public String getServletInfo(){

returnnull;

}

/**

* 初始化方法

@Override

publicvoid init(ServletConfigarg0) throwsServletException {

}

/**

* Servlet服务方法

@Override

publicvoid service(ServletRequestrequest, ServletResponse response)

throws ServletException,IOException {

response.setContentType("text/html");

response.setCharacterEncoding("utf-8");

PrintWriterout = response.getWriter();

out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML4.01 Transitional//EN\">");

out.println("<HTML>");

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

out.println(" <BODY>");

out.println("<h1>欢迎进入Servlet编程世界!</h1>");

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

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

out.flush();

out.close();

}

6.使用Servlet读取文件

response.setContentType("text/html,charset=utf-8");

response.setCharacterEncoding("utf-8");

// 创建一个输出对象

PrintWriterout = response.getWriter();

Stringfn = request.getParameter("fileName");

// 得到读取路径

@SuppressWarnings("deprecation")

Stringpath = request.~~getRealPath~~(fn);

// 根据路径创建文件对象

Filefile = newFile(path);

// 判断文件是否存在

if (file.exists()) {

// 创建文件读取对象

FileReaderread = newFileReader(file);

// 缓冲读取字符对象

BufferedReaderbufferedReader = newBufferedReader(read);

Stringline = null;

// 将读取的数据存放在字符串变量中

while ((line =bufferedReader.readLine()) != null) {

out.print("<h3>"+ line + "</h3><br>");

}

}else{

out.print("文件不存在!");

}

out.flush();

out.close();

7.使用Servlet写入文件

// 使用get方法提交表单会将表单数据通过url方式拼凑传递

// 读取的编码

response.setCharacterEncoding("gb2312");

StringfileName = "new.txt";

// 获取表单数据

Stringn1 = request.getParameter("n1");

// n1=newString(n1.getBytes("ISO-8859-1"),"gb2312");

Stringn2 = request.getParameter("n2");

// n2=newString(n2.getBytes("ISO-8859-1"),"gb2312");

Stringn3 = request.getParameter("n3");

// n3=newString(n3.getBytes("ISO-8859-1"),"gb2312");

// 创建文件对象

Filefile = newFile(request.~~getRealPath~~(fileName));

// 创建写文件对象

FileWriterfw = newFileWriter(file, true);

// 创建缓冲文件写入对象

BufferedWriterbw = newBufferedWriter(fw);

// 开始写入文件

bw.newLine();

bw.write(n1);

bw.newLine();

bw.write(n2);

bw.newLine();

bw.write(n3);

// 刷新和关闭文件写入对象

bw.flush();

bw.close();

fw.close();

8.请求和转发对象

response.setContentType("text/html,charset=utf-8");

response.setCharacterEncoding("utf-8");

PrintWriterout = response.getWriter();

out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML4.01 Transitional//EN\">");

out.println("<HTML>");

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

out.println(" <BODY>");

// 获得表单数据

Stringuser = request.getParameter("user");

Stringpwd = request.getParameter("pwd");

// 创建一个请求转发对象

RequestDispatcherdisp = null;

if (user.equals("msit") &&pwd.equals("msit")){

// 成功就做转发

request.setAttribute("user", user);

disp=request.getRequestDispatcher("ok.jsp");

disp.forward(request,response);

}else{

// 失败就重定向

response.sendRedirect("MyLogin.jsp");

}

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

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

out.flush();

out.close();