java Filter___ 顺序(一)

• Z时代
• 2024-01-10
• 分类：综合

一直没有仔细去研究下filter ，最近系统的测试了下：

先看代码吧

Java代码

1. FirstFilter.java   
2. ==================   

3. package com.test.filter;   

4.   

5. import java.io.IOException;   

6.   

7. import javax.servlet.Filter;   

8. import javax.servlet.FilterChain;   

9. import javax.servlet.FilterConfig;   

10. import javax.servlet.ServletException;   

11. import javax.servlet.ServletRequest;   

12. import javax.servlet.ServletResponse;   

13.   

14. public class FirstFilter implements Filter {   

15.   

16.     @Override  

17.     public void destroy() {   

18.   
19.     }   
20.   

21.     @Override  

22.     public void doFilter(ServletRequest request, ServletResponse response,   

23.             FilterChain chain) throws IOException, ServletException {   

24.         System.out.println("before invoke firstFilter's chain.doFilter() ..");   

25.         chain.doFilter(request, response);   

26.         System.out.println("after invoke firstFilter's chain.doFilter() ..");   

27.     }   
28.   

29.     @Override  

30.     public void init(FilterConfig arg0) throws ServletException {   

31.         System.out.println("firstFilter init()...");   

32.   
33.     }   
34.   
35. }   
36.   
37.   
38. ============   
39.   
40. SecondFilter.java   
41. ==============   
42.   

43. package com.test.filter;   

44.   

45. import java.io.IOException;   

46.   

47. import javax.servlet.Filter;   

48. import javax.servlet.FilterChain;   

49. import javax.servlet.FilterConfig;   

50. import javax.servlet.ServletException;   

51. import javax.servlet.ServletRequest;   

52. import javax.servlet.ServletResponse;   

53.   

54. public class SecondFilter implements Filter {   

55.   

56.     @Override  

57.     public void destroy() {   

58.   
59.     }   
60.   

61.     @Override  

62.     public void doFilter(ServletRequest request, ServletResponse response,   

63.             FilterChain chain) throws IOException, ServletException {   

64.         System.out.println("before invoke secondFilter's chain.doFilter() ..");   

65.         chain.doFilter(request, response);   

66.         System.out.println("after invoke secondFilter's chain.doFilter() ..");   

67.     }   
68.   

69.     @Override  

70.     public void init(FilterConfig filterConfig) throws ServletException {   

71.         System.out.println("secondFilter init()...");   

72.     }   
73.   
74. }   
75. ==========   
76.   
77. FirstServlet.java   
78. =============   

79. package com.test.servlet;   

80.   

81. import java.io.IOException;   

82.   

83. import javax.servlet.ServletException;   

84. import javax.servlet.http.HttpServlet;   

85. import javax.servlet.http.HttpServletRequest;   

86. import javax.servlet.http.HttpServletResponse;   

87.   

88. public class FirstServlet extends HttpServlet {   

89.   

90.     @Override  

91.     protected void doGet(HttpServletRequest req, HttpServletResponse resp)   

92.             throws ServletException, IOException {   

93.         System.out.println("servlet doGet be invoked...");   

94.         req.getRequestDispatcher("test.jsp").forward(req, resp);   

95.     }   
96.   

97.     @Override  

98.     protected void doPost(HttpServletRequest req, HttpServletResponse resp)   

99.             throws ServletException, IOException {   

100.         // TODO Auto-generated method stub   

101.         doGet(req, resp);   
102.     }   
103.        
104. }   
105.   
106. =========   
107.   
108. web.xml   
109.   
110. ===========   

111. <?xml version="1.0" encoding="UTF-8"?>   

112. <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"  

113.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  

114.     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee    

115.     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">   

116.     <welcome-file-list>   
117.         <welcome-file>index.jsp</welcome-file>   
118.     </welcome-file-list>   
119.     <filter>   
120.         <filter-name>firstFilter</filter-name>   

121.         <filter-class>com.test.filter.FirstFilter</filter-class>   

122.     </filter>   
123.     <filter>   
124.         <filter-name>secondFilter</filter-name>   

125.         <filter-class>com.test.filter.SecondFilter</filter-class>   

126.     </filter>   
127.     <filter-mapping>   
128.         <filter-name>secondFilter</filter-name>   
129.         <url-pattern>/*</url-pattern>   
130.     </filter-mapping>   
131.     <filter-mapping>   
132.         <filter-name>firstFilter</filter-name>   
133.         <url-pattern>/*</url-pattern>   
134.     </filter-mapping>   
135.   
136.     <servlet>   
137.         <servlet-name>firstServlet</servlet-name>   

138.         <servlet-class>com.alimama.servlet.FirstServlet</servlet-class>   

139.     </servlet>   
140.     <servlet-mapping>   
141.         <servlet-name>firstServlet</servlet-name>   
142.         <url-pattern>/firstServlet</url-pattern>   
143.     </servlet-mapping>   
144. </web-app>   
145.   
146. ============  

FirstFilter.java
==================
package com.test.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class FirstFilter implements Filter {
	@Override
	public void destroy() {
	}
	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		System.out.println("before invoke firstFilter's chain.doFilter() ..");
		chain.doFilter(request, response);
		System.out.println("after invoke firstFilter's chain.doFilter() ..");
	}
	@Override
	public void init(FilterConfig arg0) throws ServletException {
		System.out.println("firstFilter init()...");
	}
}
============
SecondFilter.java
==============
package com.test.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class SecondFilter implements Filter {
	@Override
	public void destroy() {
	}
	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		System.out.println("before invoke secondFilter's chain.doFilter() ..");
		chain.doFilter(request, response);
		System.out.println("after invoke secondFilter's chain.doFilter() ..");
	}
	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		System.out.println("secondFilter init()...");
	}
}
==========
FirstServlet.java
=============
package com.test.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class FirstServlet extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		System.out.println("servlet doGet be invoked...");
		req.getRequestDispatcher("test.jsp").forward(req, resp);
	}
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(req, resp);
	}
}
=========
web.xml
===========
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
	<filter>
		<filter-name>firstFilter</filter-name>
		<filter-class>com.test.filter.FirstFilter</filter-class>
	</filter>
	<filter>
		<filter-name>secondFilter</filter-name>
		<filter-class>com.test.filter.SecondFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>secondFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>firstFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	<servlet>
		<servlet-name>firstServlet</servlet-name>
		<servlet-class>com.alimama.servlet.FirstServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>firstServlet</servlet-name>
		<url-pattern>/firstServlet</url-pattern>
	</servlet-mapping>
</web-app>
============

 然后发布，发现打印的日志如下：

。。。

firstFilter init()...
secondFilter init()...

。。。

2008-10-23 11:36:43 org.apache.catalina.startup.Catalina start
信息: Server startup in 3665 ms

这里过滤器初始化好了。

当我们访问我们的 应用：http://127.0.0.1:8080/appName

发现打印日记如下：

before invoke secondFilter's chain.doFilter() ..
before invoke firstFilter's chain.doFilter() ..
after invoke firstFilter's chain.doFilter() ..
after invoke secondFilter's chain.doFilter() ..

当我们将web.xml中filter的位置进行调整后：

Xml代码

1. <?xml version="1.0" encoding="UTF-8"?>  

2. <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"  

3.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  

4.     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee    

5.     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  

6.     <welcome-file-list>  

7.         <welcome-file>index.jsp</welcome-file>  

8.     </welcome-file-list>  

9.     <filter>  

10.         <filter-name>firstFilter</filter-name>  

11.         <filter-class>com.test.filter.FirstFilter</filter-class>  

12.     </filter>  

13.     <filter>  

14.         <filter-name>secondFilter</filter-name>  

15.         <filter-class>com.test.filter.SecondFilter</filter-class>  

16.     </filter>  

17.             <SPAN style="COLOR: #ff0000"> <filter-mapping>  

18.         <filter-name>firstFilter</filter-name>  

19.         <url-pattern>/*</url-pattern>  

20.     </filter-mapping>  

21.   

22.     <filter-mapping>  

23.         <filter-name>secondFilter</filter-name>  

24.         <url-pattern>/*</url-pattern>  

25.     </filter-mapping></SPAN>  

26.        

27.     <servlet>  

28.         <servlet-name>firstServlet</servlet-name>  

29.         <servlet-class>com.alimama.servlet.FirstServlet</servlet-class>  

30.     </servlet>  

31.     <servlet-mapping>  

32.         <servlet-name>firstServlet</servlet-name>  

33.         <url-pattern>/firstServlet</url-pattern>  

34.     </servlet-mapping>  

35. </web-app>  

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
	<filter>
		<filter-name>firstFilter</filter-name>
		<filter-class>com.test.filter.FirstFilter</filter-class>
	</filter>
	<filter>
		<filter-name>secondFilter</filter-name>
		<filter-class>com.test.filter.SecondFilter</filter-class>
	</filter>
             <filter-mapping>
		<filter-name>firstFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	<filter-mapping>
		<filter-name>secondFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	<servlet>
		<servlet-name>firstServlet</servlet-name>
		<servlet-class>com.alimama.servlet.FirstServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>firstServlet</servlet-name>
		<url-pattern>/firstServlet</url-pattern>
	</servlet-mapping>
</web-app>

  然后在启动应用，会看到打印：

before invoke firstFilter's chain.doFilter() ..

before invoke secondFilter's chain.doFilter() ..
after invoke secondFilter's chain.doFilter() ..

after invoke firstFilter's chain.doFilter() ..

总结：

filter的执行顺序是按照web.xml中定义的顺序进行执行的（当多个filter都匹配的时候），执行顺序如下图表示。

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