[javaEE] jsp入门

发布时间：2021-05-21 06:43:21 所属栏目：大数据来源： https://www.jb51.cc

导读：Servlet 写 java 代码很好，但是拼接 html 的时候，非常不方便 JSP 可以在 html 中嵌套 java 代码，这样在展示的时候，就会比较方便 ? Tomcat 帮我们把 jsp 的页面翻译成了 Servlet 去运行的，查看目录 Tomcat 目录 workCatalinalocalhost 生成一个 xxx_

Servlet写java代码很好，但是拼接html的时候，非常不方便

JSP可以在html中嵌套java代码，这样在展示的时候，就会比较方便

Tomcat帮我们把jsp的页面翻译成了Servlet去运行的，查看目录

Tomcat目录workCatalinalocalhost

生成一个xxx_jsp.java的Servlet文件，jsp的脚本片段放在了_jspService()方法里面

使用eclipse创建项目以后，修改一下发布路径，直接发布到Tomcat的webapps目录下，

在Servers标签栏，先删除下面的项目，在右键点open，选择use Tomcat installation

jsp声明：<%! 若干java代码%>，此处的代码会解析到类的成员的地方

jsp注释：<%--注释的内容--%>

index.jsp

<%@page import="org.apache.jasper.tagplugins.jstl.core.Out"%>
<%@page import="java.util.Date"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<Meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>首页</title>
</head>
<body>
<%!
public void test(){
    int a=0;
}
%>
<% 
for(int i=0;i<5;i++){
    out.write(i+"");
}
%>
<%-- 
Date date=new Date();
out.write(date.toLocaleString());
--%>
你好，JSP
</body>
</html>

index_jsp.java

final class index_jsp extends org.apache.jasper.runtime.HttpJspBase
    implements org.apache.jasper.runtime.JspSourceDependent {


;
}
 void _jspService(final javax.servlet.http.HttpServletRequest request,final javax.servlet.http.HttpServletResponse response)
        throws java.io.IOException,javax.servlet.ServletException {

     javax.servlet.jsp.PageContext pageContext;
    javax.servlet.http.HttpSession session = null;
     javax.servlet.ServletContext application;
     javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = final java.lang.Object page = this;
    javax.servlet.jsp.JspWriter _jspx_out = ;
    javax.servlet.jsp.PageContext _jspx_page_context = ;


    try {
      response.setContentType("text/html; charset=utf-8");
      pageContext = _jspxFactory.getPageContext(,request,response,null,1)">true,8192,1)">true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;

      out.write("rn");
      out.write("rn");
      out.write("<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">rn");
      out.write("<html>rn");
      out.write("<head>rn");
      out.write("<Meta http-equiv="Content-Type" content="text/html; charset=utf-8">rn");
      out.write("<title>首页</title>rn");
      out.write("</head>rn");
      out.write("<body>rn");
      out.write('r');
      out.write('n');
 
);
}

      out.write('r');
      out.write("你好，JSPrn");
      out.write("</body>rn");
      out.write("</html>");
    } catch (java.lang.Throwable t) {
      if (!(t instanceof javax.servlet.jsp.SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
           {
            if (response.isCommitted()) {
              out.flush();
            } else {
              out.clearBuffer();
            }
          }  (java.io.IOException e) {}
        if (_jspx_page_context != ) _jspx_page_context.handlePageException(t);
        else throw  ServletException(t);
      }
    } finally {
      _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }

（编辑：北几岛）

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