java web各种路径获取

对于java web各种路径的获取一直有点混乱，找个时间用代码实际测试了一下，做一下记录~

代码：

private void printPath(HttpServletRequest request){
        printStr("request.getScheme()", request.getScheme());
        printStr("request.getServerName()", request.getServerName());
        printStr("request.getServerPort()", request.getServerPort());
        printStr("request.getContextPath()", request.getContextPath());
        printStr("request.getServletPath()", request.getServletPath());
        printStr("request.getRequestURI()", request.getRequestURI());
        printStr("request.getPathInfo()", request.getPathInfo());
        printStr("request.getLocalPort()", request.getLocalPort());
        printStr("request.getLocalAddr()", request.getLocalAddr());
        printStr("request.getLocalName()", request.getLocalName());
        System.out.println("=========session========"); 
        ServletContext servletContext = request.getSession().getServletContext();
        printStr("servletContext.getRealPath('\\')", servletContext.getRealPath("/"));
        printStr("servletContext.getContextPath()", servletContext.getContextPath());
        printStr("servletContext.getServerInfo()", servletContext.getServerInfo());
    }

   private void printStr(String name, Object value){
     System.out.println(name + ":" + value);
  }

输出：

request.getScheme():http
  request.getServerName():localhost
  request.getServerPort():8080
  request.getContextPath():/myweb
  request.getServletPath():/test
  request.getRequestURI():/myweb/test
  request.getPathInfo():null
  request.getLocalPort():8080
  request.getLocalAddr():0:0:0:0:0:0:0:1
  request.getLocalName():0:0:0:0:0:0:0:1
  =========session========
  servletContext.getRealPath('\'):D:\Develop\tomcat\apache-tomcat-7.0.57_jdk8\webapps\myweb\
  servletContext.getContextPath():/myweb
  servletContext.getServerInfo():Apache Tomcat/7.0.57

-------------------------------------------------万恶的分割线-------------------------------------------------

此处注意一下这个方法：获取绝对路径

servletContext.getRealPath("/")

在web后台，如果想创建一个file对象，需使用到绝对路径。使用时的传值与返回值还是以示例说明：

printStr("servletContext.getRealPath('\\')", servletContext.getRealPath("\\"));
输出：D:\Develop\tomcat\apache-tomcat-7.0.57_jdk8\webapps\myweb\

printStr("servletContext.getRealPath('\\')", servletContext.getRealPath("/"))

输出：D:\Develop\tomcat\apache-tomcat-7.0.57_jdk8\webapps\myweb\

printStr("servletContext.getRealPath('\\')", servletContext.getRealPath("key.txt"));

输出：D:\Develop\tomcat\apache-tomcat-7.0.57_jdk8\webapps\myweb\key.txt

//一下几种传值输出一样的

printStr("servletContext.getRealPath('\\')", servletContext.getRealPath("//"));

printStr("servletContext.getRealPath('\\')", servletContext.getRealPath(""));

输出：D:\Develop\tomcat\apache-tomcat-7.0.57_jdk8\webapps\myweb

在来看一下getRealPath的源码：

 @Override
	public String getRealPath(String path) {
		Resource resource = this.resourceLoader.getResource(getResourceLocation(path));
		try {
			return resource.getFile().getAbsolutePath();
		}
		catch (IOException ex) {
			logger.warn("Couldn't determine real path of resource " + resource, ex);
			return null;
		}
	}

getResourceLocation(path)的源码：

        /**
	 * Build a full resource location for the given path, prepending the resource
	 * base path of this {@code MockServletContext}.
	 * @param path the path as specified
	 * @return the full resource path
	 */
	protected String getResourceLocation(String path) {
		if (!path.startsWith("/")) {
			path = "/" + path;
		}
		return this.resourceBasePath + path;
	}

到此就明白了，要是获取web根目录的绝对路径，传个空字符串（“”）就ok了，要是根目录下的其他路径，直接跟路径就好咯~

java web各种路径获取

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