史上最全web.xml配置文件元素详解

落日映苍穹つ 2022-05-21 11:12 102阅读 0赞

### 一、web.xml配置文件常用元素及其意义预览 ###

1 <web-app>
     2 
     3      
     4      <display-name></display-name>
     5 
     6      
     7      <description></description>
     8 
     9      
    10      <context-param></context-param>
    11 
    12      
    13      <filter></filter>
    14 
    15      
    16      <filter-mapping></filter-mapping>
    17 
    18      
    20      <listener></listener>
    21 
    22      
    24      <servlet></servlet>
    25 
    26      
    29      <servlet-mapping></servlet-mapping>
    30 
    31      
    33      <session-config></session-config>
    34 
    35      
    36      <mime-mapping></mime-mapping>
    37 
    38      
    39      <welcome-file-list></welcome-file-list>
    40 
    41      
    42      <error-page></error-page>
    43 
    44      
    46      <taglib></taglib>
    47 
    48      
    49      <resource-env-ref></resource-env-ref>
    50 
    51      
    52      <resource-ref></resource-ref>
    53 
    54      
    55      <security-constraint></security-constraint>
    56 
    57      
    58      <login-config></login-config>
    59 
    60      
    62      <security-role></security-role>
    63 
    64      
    65      <env-entry></env-entry>
    66 
    67      
    68      <ejb-ref></ejb-ref>
    69 
    70      
    71      <ejb-local-ref></ejb-local-ref>
    72 
    73  </web-app>

### 二、各个配置元素详解 ###

1.Web应用图标：指出IDE和GUI工具用来表示Web应用的大图标和小图标

1 <icon>  
    2      <small-icon>/images/app_small.gif</small-icon>  
    3      <large-icon>/images/app_large.gif</large-icon>  
    4  </icon>

2.Web 应用名称：提供GUI工具可能会用来标记这个特定的Web应用的一个名称

<display-name>Tomcat Example</display-name>

3.Web 应用描述：给出于此相关的说明性文本

<desciption>Tomcat Example servlets and JSP pages.</desciption>

4.上下文参数：声明应用范围内的初始化参数

1 <context-param>
    2      <param-name>参数名</para-name>
    3      <param-value>参数值</param-value>
    4      <description>参数描述</description>
    5  </context-param>

在servlet里面可以通过 getServletContext().getInitParameter(“context/param”)得到

5.过滤器配置：将一个名字与一个实现javaxs.servlet.Filter接口的类相关联

1 <filter>
     2      <filter-name>setCharacterEncoding</filter-name>
     3      <filter-class>com.myTest.setCharacterEncodingFilter</filter-class>
     4      <init-param>
     5          <param-name>encoding</param-name>
     6          <param-value>GB2312</param-value>
     7      </init-param>
     8  </filter>
     9  <filter-mapping>
    10      <filter-name>setCharacterEncoding</filter-name>
    11      <url-pattern>/*</url-pattern>
    12  </filter-mapping>

6.监听器配置

1 <listener>
    2      <listerner-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    3  </listener>

7.Servlet配置

1 <servlet>
     2    <servlet-name>servlet名称</servlet-name>
     3    <servlet-class>servlet类全路径</servlet-class>
     4    <init-param>
     5        <param-name>参数名</param-name>
     6        <param-value>参数值</param-value>
     7    </init-param>
     8    <run-as>
     9        <description>Security role for anonymous access</description>
    10        <role-name>tomcat</role-name>
    11    </run-as>
    12 　 <load-on-startup>指定当Web应用启动时，装载Servlet的次序</load-on-startup>
    13 </servlet>
    14 <servlet-mapping>
    15   <servlet-name>servlet名称</servlet-name>
    16   <url-pattern>映射路径</url-pattern>
    17 </servlet-mapping>

8.会话超时配置（单位为分钟）

1 <session-config>
    2      <session-timeout>120</session-timeout>
    3  </session-config>

9.MIME类型配置

1 <mime-mapping>
    2      <extension>htm</extension>
    3      <mime-type>text/html</mime-type>
    4  </mime-mapping>

10.指定欢迎文件页配置

1  <welcome-file-list>
    2      <welcome-file>index.jsp</welcome-file>
    3      <welcome-file>index.html</welcome-file>
    4      <welcome-file>index.htm</welcome-file>
    5  </welcome-file-list>

11.配置错误页面

(1).通过错误码来配置error-page

1 
    2 <error-page>
    3       <error-code>404</error-code>
    4       <location>/NotFound.jsp</location>
    5  </error-page>

(2).通过异常的类型配置error-page

1 
    2 <error-page>
    3       <exception-type>java.lang.NullException</exception-type>
    4       <location>/error.jsp</location>
    5 </error-page>

12.TLD配置

1 <taglib>
    2      <taglib-uri>http://jakarta.apache.org/tomcat/debug-taglib</taglib-uri>
    3      <taglib-location>/WEB-INF/jsp/debug-taglib.tld</taglib-location>
    4  </taglib>

如果开发工具一直在报错,应该把<taglib> 放到 <jsp-config>中

1 <jsp-config>
    2      <taglib>
    3          <taglib-uri>http://jakarta.apache.org/tomcat/debug-taglib</taglib-uri>
    4          <taglib-location>/WEB-INF/pager-taglib.tld</taglib-location>
    5      </taglib>
    6  </jsp-config>

13.资源管理对象配置

1 <resource-env-ref>
    2      <resource-env-ref-name>jms/StockQueue</resource-env-ref-name>
    3  </resource-env-ref>

14.资源工厂配置

1 <resource-ref>
    2      <res-ref-name>mail/Session</res-ref-name>
    3      <res-type>javax.mail.Session</res-type>
    4      <res-auth>Container</res-auth>
    5 </resource-ref>

配置数据库连接池就可在此配置

1  <resource-ref>
    2      <description>JNDI JDBC DataSource of shop</description>
    3      <res-ref-name>jdbc/sample_db</res-ref-name>
    4      <res-type>javax.sql.DataSource</res-type>
    5      <res-auth>Container</res-auth>
    6  </resource-ref>

15.安全限制配置

1 <security-constraint>
     2      <display-name>Example Security Constraint</display-name>
     3      <web-resource-collection>
     4          <web-resource-name>Protected Area</web-resource-name>
     5          <url-pattern>/jsp/security/protected/*</url-pattern>
     6          <http-method>DELETE</http-method>
     7          <http-method>GET</http-method>
     8          <http-method>POST</http-method>
     9          <http-method>PUT</http-method>
    10      </web-resource-collection>
    11      <auth-constraint>
    12          <role-name>tomcat</role-name>
    13          <role-name>role1</role-name>
    14      </auth-constraint>
    15 </security-constraint>

16.登陆验证配置

1  <login-config>
    2      <auth-method>FORM</auth-method>
    3      <realm-name>Example-Based Authentiation Area</realm-name>
    4      <form-login-config>
    5          <form-login-page>/jsp/security/protected/login.jsp</form-login-page>
    6          <form-error-page>/jsp/security/protected/error.jsp</form-error-page>
    7      </form-login-config>
    8  </login-config>

17.安全角色：security-role元素给出安全角色的一个列表，这些角色将出现在servlet元素内的security-role-ref元素的role-name子元素中。  
分别地声明角色可使高级IDE处理安全信息更为容易。

1 <security-role>
    2      <role-name>tomcat</role-name>
    3  </security-role>

18.Web环境参数：env-entry元素声明Web应用的环境项

1 <env-entry>
    2      <env-entry-name>minExemptions</env-entry-name>
    3      <env-entry-value>1</env-entry-value>
    4      <env-entry-type>java.lang.Integer</env-entry-type>
    5 </env-entry>

19.EJB 声明

1 <ejb-ref>
    2      <description>Example EJB reference</decription>
    3      <ejb-ref-name>ejb/Account</ejb-ref-name>
    4      <ejb-ref-type>Entity</ejb-ref-type>
    5      <home>com.mycompany.mypackage.AccountHome</home>
    6      <remote>com.mycompany.mypackage.Account</remote>
    7  </ejb-ref>

20.本地EJB声明

1  <ejb-local-ref>
    2      <description>Example Loacal EJB reference</decription>
    3      <ejb-ref-name>ejb/ProcessOrder</ejb-ref-name>
    4      <ejb-ref-type>Session</ejb-ref-type>
    5      <local-home>com.mycompany.mypackage.ProcessOrderHome</local-home>
    6      <local>com.mycompany.mypackage.ProcessOrder</local>
    7  </ejb-local-ref>

### 三、总结 ###

以上就是常用的web.xml中元素的配置以及作用了，欢迎提出异议和不适当的地方共同学习。