jsp转成serlet解析

最新推荐文章于 2025-08-31 22:37:59 发布

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本文详细解析了JSP文件转换为Servlet类的过程，并深入讲解了Servlet类的生命周期方法：init、service和destroy。通过具体代码示例，展示了如何将JSP页面映射为Servlet类，并在不同请求类型下执行相应的服务处理。

在服务器里，jsp文件转换成java类，即是servlet类，本文解析下详情。

servlet类首次调用时，首先调用init方法（只调用一次），再调用service方法服务请求，卸载调用destroy方法。

javax.servlet.Servlet

package javax.servlet;

import java.io.IOException;
public abstract interface Servlet{
  public abstract void init(ServletConfig paramServletConfig)throws ServletException;

  public abstract ServletConfig getServletConfig();

  public abstract void service(ServletRequest paramServletRequest, ServletResponse paramServletResponse)
 throws ServletException, IOException;

  public abstract String getServletInfo();

  public abstract void destroy();
}

javax.servlet.GenericServlet

package javax.servlet;
public abstract class GenericServlet
  implements Servlet, ServletConfig, Serializable
{
…
public abstract void service(ServletRequest paramServletRequest, ServletResponse paramServletResponse)
throws ServletException, IOException;

…
}

javax.servlet.http.HttpServlet

package javax.servlet.http;
public abstract class HttpServlet extends GenericServlet
{
protected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{ … }

protected void doHead(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{…}

protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{…}

protected void doPut(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{…}

protected void doDelete(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{…}

protected void doOptions(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{…}

protected void doTrace(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{…}

protected void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{
 //根据http协议请求不同的method，调用对应的方法…
}

public void service(ServletRequest req, ServletResponse res)
    throws ServletException, IOException{
    HttpServletRequest request;
    HttpServletResponse response;
    try{
      request = (HttpServletRequest)req;
      response = (HttpServletResponse)res;
    } catch (ClassCastException e) {
      throw new ServletException("non-HTTP request or response");
    }
    service(request, response);
  }

}

org.apache.jasper.runtime.HttpJspBase

package org.apache.jasper.runtime;
public abstract  class  HttpJspBase extends HttpServlet  implements HttpJspPage {
//…
public abstract void _jspService(HttpServletRequest paramHttpServletRequest, HttpServletResponse paramHttpServletResponse)
    throws ServletException, IOException;

public final void service(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException
  {
    _jspService(request, response);
  }
//…
}

例如，index.jsp转成index_jsp.java

public class index_jsp  extends  org.apache.jasper.runtime.HttpJspBase  
                          implements org.apache.jasper.runtime.JspSourceDependent{
//…
public void _jspService(HttpServletRequest request, HttpServletResponse response){
//将jsp文件中的内容调用out.write(…)返回给客户端
}
//…
}