在寫javaweb項(xiàng)目的時(shí)候，總會(huì)遇到路徑書寫的問(wèn)題，現(xiàn)在將其作個(gè)總結(jié)。

在javaweb中需要書寫路徑的地方主要有這四大類：

客服端路徑

超鏈接

表單

重定向

服務(wù)器端路徑

轉(zhuǎn)發(fā)

包含

資源獲取路徑

servletContext獲取資源

ClassLoader獲取資源

Class獲取資源

路徑

現(xiàn)分別作介紹

其構(gòu)建的javaweb如下：

1客服端路徑

A超鏈接

pageEncoding="UTF-8"%>

html?PUBLIC?"-//W3C//DTD?HTML?4.01?Transitional//EN"?"http://www.w3.org/TR/html4/loose.dtd">

頁(yè)面A

這是絕對(duì)地址超鏈接

這是以"/"開(kāi)頭的相對(duì)地址超鏈接

這是不以"/"開(kāi)頭的相對(duì)地址超鏈接

B表單

pageEncoding="UTF-8"%>

html?PUBLIC?"-//W3C//DTD?HTML?4.01?Transitional//EN"?"http://www.w3.org/TR/html4/loose.dtd">

Insert?title?here

username:

username:

username:

username:

username:

username:

C重定向

package?cn.ccnu.path;

import?java.io.IOException;

import?javax.servlet.ServletException;

import?javax.servlet.http.HttpServlet;

import?javax.servlet.http.HttpServletRequest;

import?javax.servlet.http.HttpServletResponse;

/*

*?重定向有三種路徑書寫方式

*??????1.絕對(duì)路徑

*??????2.以"/"開(kāi)頭的相對(duì)路徑

*??????3.不以"/"開(kāi)頭的相對(duì)路徑

*/

public?class?RedirectServlet?extends?HttpServlet?{

public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

response.sendRedirect("http://localhost:8080/javaee/jsp/b.jsp");

/*

*?2.以"/"開(kāi)頭的相對(duì)路徑

*??????此時(shí)，/代表整個(gè)web工程的路徑，即http://localhost:8080/

*/

//??????response.sendRedirect("/javaee/jsp/b.jsp");

/*

*?3.不以"/"開(kāi)頭的相對(duì)路徑

*??????此時(shí)是相對(duì)于當(dāng)前資源的相對(duì)路徑

*??????當(dāng)前資源路徑為:http://localhost:8080/javaee/RedirectServlet

*??????即表示:RedirectServlet在路徑http://localhost:8080/javaee之下

*??????而b.jsp在http://localhost:8080/javaee/jsp/b.jsp

*??????所以最終地址寫為:jsp/b.jsp

*/

//??????response.sendRedirect("jsp/b.jsp");

}

public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

doGet(request,?response);

}

}

2服務(wù)器端路徑

A請(qǐng)求轉(zhuǎn)發(fā)

package?cn.ccnu.path;

import?java.io.IOException;

import?javax.servlet.ServletException;

import?javax.servlet.http.HttpServlet;

import?javax.servlet.http.HttpServletRequest;

import?javax.servlet.http.HttpServletResponse;

/*

*?服務(wù)器端的路徑不能是絕對(duì)路徑，只能是相對(duì)路徑，也分為以/開(kāi)頭和不以/開(kāi)頭兩種

*??????1.以"/"開(kāi)頭的相對(duì)路徑

*??????2.不以"/"開(kāi)頭的相對(duì)路徑

*/

public?class?DispatcherServlet?extends?HttpServlet?{

public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

/*

*?1.以"/"開(kāi)頭的相對(duì)路徑

*??????此時(shí)，/代表當(dāng)前web項(xiàng)目，即:http://localhost:8080/javaee

*/

//??????request.getRequestDispatcher("/jsp/b.jsp").forward(request,?response);

/*

*?2.不以"/"開(kāi)頭的相對(duì)路徑

*??????相對(duì)于當(dāng)前資源的相對(duì)路徑

*??此時(shí)，當(dāng)前資源的路徑為:http://localhost:8080/javaee/DispatcherServlet

*??所以要轉(zhuǎn)發(fā)去的資源的路徑以:http://localhost:8080/javaee開(kāi)頭

*/

request.getRequestDispatcher("jsp/b.jsp").forward(request,?response);

}

public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

doGet(request,?response);

}

}

B請(qǐng)求包含

package?cn.ccnu.path;

import?java.io.IOException;

import?javax.servlet.ServletException;

import?javax.servlet.http.HttpServlet;

import?javax.servlet.http.HttpServletRequest;

import?javax.servlet.http.HttpServletResponse;

/*

*?請(qǐng)求包含不能書寫絕對(duì)地址，只能書寫相對(duì)地址

*??????1.以"/"開(kāi)頭的相對(duì)路徑

*??????2.不以"/"開(kāi)頭的相對(duì)路徑

*

*/

public?class?IncludeServlet?extends?HttpServlet?{

public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

/*

*?1.以"/"開(kāi)頭的相對(duì)路徑

*??????此時(shí)，/代表當(dāng)前web項(xiàng)目，即:http://localhost:8080/javaee

*/

//??????request.getRequestDispatcher("/jsp/b.jsp").include(request,?response);

/*

*?2.不以"/"開(kāi)頭的相對(duì)路徑

*??????相對(duì)于當(dāng)前資源的相對(duì)路徑

*??此時(shí)，當(dāng)前資源的路徑為:http://localhost:8080/javaee/IncludeServlet

*??所以要轉(zhuǎn)發(fā)去的資源的路徑以:http://localhost:8080/javaee開(kāi)頭

*/

request.getRequestDispatcher("jsp/b.jsp").include(request,?response);

}

public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

doGet(request,?response);

}

}

3資源獲取路徑

AServletContext獲取資源

package?cn.ccnu.path;

import?java.io.IOException;

import?java.io.InputStream;

import?java.util.Properties;

import?javax.servlet.ServletException;

import?javax.servlet.http.HttpServlet;

import?javax.servlet.http.HttpServletRequest;

import?javax.servlet.http.HttpServletResponse;

/*

*?ServletContext獲取資源必須是相對(duì)路徑，不能是絕對(duì)路徑，但不管是以/開(kāi)頭，還是不以/開(kāi)頭，

*?都是相對(duì)于當(dāng)前資源的相對(duì)路徑

*

*/

public?class?ServletContextServlet?extends?HttpServlet?{

public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

String?path1?=?this.getServletContext().getRealPath("/a.properties");

String?path2?=?this.getServletContext().getRealPath("a.properties");

System.out.println(path1);

System.out.println(path2);

//輸出的地址一樣

}

public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

doGet(request,?response);

}

}

BClassLoader獲取資源

package?cn.ccnu.classloaderpath;

import?java.io.IOException;

import?java.io.InputStream;

import?java.util.Properties;

import?javax.servlet.ServletException;

import?javax.servlet.http.HttpServlet;

import?javax.servlet.http.HttpServletRequest;

import?javax.servlet.http.HttpServletResponse;

/*

*?ClassLoader類加載器不能通過(guò)絕對(duì)地址來(lái)加載資源，只能通過(guò)相對(duì)地址來(lái)加載資源

*?但相對(duì)地址不管前面加不加/都是相當(dāng)于類路徑的相對(duì)地址

*

*/

public?class?ClassLoaderServlet?extends?HttpServlet?{

public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

/*

*?加了/,其地址是相對(duì)于類路徑的相對(duì)地址

*/

//??????InputStream?in?=?this.getClass().getClassLoader().getResourceAsStream("/cn/ccnu/classloaderpath/c.properties");

//??????Properties?prop?=?new?Properties();

//??????prop.load(in);

//??????System.out.println(prop.getProperty("url"));

/*

*?不加/,其地址是相對(duì)于類路徑的相對(duì)地址

*/

InputStream?in?=?this.getClass().getClassLoader().getResourceAsStream("cn/ccnu/classloaderpath/c.properties");

Properties?prop?=?new?Properties();

prop.load(in);

System.out.println(prop.getProperty("url"));

/*

*?總結(jié):不能使用絕對(duì)地址，而只能只用相對(duì)地址

*?且不管加不加/的相對(duì)地址，都是相對(duì)于類路徑的相對(duì)地址

*

*/

}

public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

doGet(request,?response);

}

}

CClass獲取資源

package?cn.ccnu.classpath;

import?java.io.IOException;

import?java.io.InputStream;

import?java.util.Properties;

import?javax.servlet.ServletException;

import?javax.servlet.http.HttpServlet;

import?javax.servlet.http.HttpServletRequest;

import?javax.servlet.http.HttpServletResponse;

/*

*?Class讀取資源不能是絕對(duì)路徑，只能是相對(duì)路徑，又分為以/開(kāi)頭或者是不以/開(kāi)頭

*??????1.以/開(kāi)頭的相對(duì)路徑

*??????2.不以/開(kāi)頭的相對(duì)路徑

*/

public?class?ClassServlet?extends?HttpServlet?{

public?void?doGet(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

/*

*?1.以/開(kāi)頭的相對(duì)路徑

*??????此時(shí)的/代表類路徑，即:/javaee/WEB-INF/classes

*/

//??????InputStream?in?=?ClassServlet.class.getResourceAsStream("/cn/ccnu/classpath/b.properties");

//??????Properties?porp?=?new?Properties();

//??????porp.load(in);

//??????System.out.println(porp.getProperty("url"));

/*

*?2.不以/開(kāi)頭的相對(duì)路徑

*??????此時(shí)相對(duì)的是：類ClassServlet.class的路徑，即:\javaee\WEB-INF\classes\cn\ccnu\classpath

*??????即:/javaee/WEB-INF/classes/cn/ccnu/classpath

*/

InputStream?in?=?ClassServlet.class.getResourceAsStream("b.properties");

Properties?porp?=?new?Properties();

porp.load(in);

System.out.println(porp.getProperty("url"));

}

public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)

throws?ServletException,?IOException?{

doGet(request,?response);

}

}

4路徑

要么以“*”開(kāi)關(guān)，要么為“/”開(kāi)頭,當(dāng)通常情況看下，我們都會(huì)以"/"開(kāi)頭。

Servlet的路徑跳轉(zhuǎn)

一、JSP跳轉(zhuǎn)到Servlet

1、相對(duì)路徑,如href="servlet/TestServlet"

如果寫成"/servlet/TestServlet"會(huì)報(bào)錯(cuò)，因?yàn)榈谝粋€(gè)“/”表示的是【服務(wù)器根目錄】

2、絕對(duì)路徑，通過(guò)內(nèi)置成員變量path實(shí)現(xiàn)，如href="/servlet/TestServlet"

path得到的是項(xiàng)目根目錄，如【http://localhost:8080/ServletDemo】

二、Servlet跳轉(zhuǎn)JSP1、請(qǐng)求重定向：response.sendRedirect(request.getContextPath()+"/xxx.jsp");

request.getContextPath()獲得項(xiàng)目根目錄，或者通過(guò)"../xxx.jsp"取得上層路徑得到

2、服務(wù)器內(nèi)部轉(zhuǎn)發(fā)：

request.getRequestDispatcher("../xxx.jsp").forward(req,resp);

request.getRequestDispatcher("/test.jsp").forward(request, response); //斜線表示項(xiàng)目的根目錄

小結(jié)：Servlet都可以通過(guò)../xxx.jsp獲取路徑

三、web.xml的路徑

web.xml的必須以“/”開(kāi)頭，“/”表示項(xiàng)目的根目錄

在JSP頁(yè)面上使用相對(duì)路徑和絕對(duì)路徑調(diào)用servlet

web.xml的必須以“/”開(kāi)頭，“/”表示項(xiàng)目的根目錄

如果在Servlet中使用請(qǐng)求重定向方式跳轉(zhuǎn)到其他jsp頁(yè)面，則需要：

response.sendRedirect(request.getContextPath()+"/test.jsp");

服務(wù)器內(nèi)部跳轉(zhuǎn)路徑：

request.getRequestDispatcher("/test.jsp").forward(request,response);//這里的斜線表示項(xiàng)目的根目錄

或者request.getRequestDispatcher("../test.jsp").forward(request,response);//“..”表示回到上層目錄也就是根目錄；

PS：如果帶一層路徑 如：/servlet/loginServlet，則內(nèi)部轉(zhuǎn)發(fā)的時(shí)會(huì)從WebRoot/servlet/路徑下找jsp頁(yè)面，如果要轉(zhuǎn)發(fā)的頁(yè)面不在WebRoot/servlet/路徑下，則需要“..”回到上層或根目錄再定位到j(luò)sp頁(yè)面，如下：request.getRequestDispatcher("../test.jsp").forward(request,response);

如果要轉(zhuǎn)發(fā)的頁(yè)面在WebRoot/servlet/路徑下，則如下：request.getRequestDispatcher("/test.jsp").forward(request,response);

總結(jié)

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