Spring中过滤器+监听器的使用
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过滤器：
过滤器放在web资源之前，可以在请求抵达它所应用的web资源(可以是一个Servlet、一个Jsp页面，甚至是一个html页面)之前截获进入的请求，并且在它返回到客户之前截获输出请求。Filter：用来拦截请求，处于客户端与被请求资源之间，目的是重用代码。Filter链，在web.xml中哪个先配置，哪个就先调用。在filter中也可以配置一些初始化参数。
Filter 有如下几个种类：
用户授权的Filter: Filter 负责检查用户请求，根据请求过滤用户非法请求。
日志Filter: 详细记录某些特殊的用户请求。
负责解码的Filter: 包括对非标准编码的请求解码。
创建一个Filter 只需两个步骤:
(1)创建Filter 处理类:
(2)在web.xml 文件中配置Filter 。
Spring中固有的过滤器：
<filter><!--创建过滤器--> <filter-name>encodingFilter</filter-name><!--过滤器的名字--> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class><!--过滤器的类--> <init-param><!--初始化过滤器参数--> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping><!--过滤器映射的地址--> <filter-name>encodingFilter</filter-name> <url-pattern>*</url-pattern> </filter-mapping>
自定义过滤器：
1、 指定ip访问的过滤器：
<filter>
<filter-name>ipFilter</filter-name>
<filter-class>com.common.filter.RequestIPFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>ipFilter</filter-name>
<url-pattern>*</url-pattern>
</filter-mapping>
package http;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class RequestIPFilter implements Filter{
@Override
public void destroy() {
// TODO Auto-generated method stub
}
@Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
// TODO Auto-generated method stub
String allowIps="";
try {
allowIps = PropertiesUtils.getInstance().getProperties("ip.filter");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
if(allowIps.isEmpty()){
chain.doFilter(req, res);
}else{
String[] ips = allowIps.split(";");
Map<String,String> map = new HashMap<String,String>();
for(int i=0;i<ips.length;i++){
map.put(ips[i], ips[i]);
}
String ip = HttpHelper.getClientIp(request);
if(map.containsKey(ip)){
chain.doFilter(req, res);
}else{
response.sendError(response.SC_UNAUTHORIZED, request.getRequestURI());
}
}
}
@Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
}
}
2、加载请求时间过滤器
1 <filter> 2 <filter-name>timeFilter</filter-name> 3 <filter-class>com.common.filter.RequestTimeFilter</filter-class> 4 </filter> 5 <filter-mapping> 6 <filter-name>timeFilter</filter-name> 7 <url-pattern>*</url-pattern> 8 </filter-mapping>
1 import java.io.IOException; 2 import java.text.DateFormat; 3 import java.text.SimpleDateFormat; 4 import java.util.Date; 5 import java.util.LinkedHashMap; 6 import java.util.Map; 7 8 import javax.servlet.Filter; 9 import javax.servlet.FilterChain; 10 import javax.servlet.FilterConfig; 11 import javax.servlet.ServletException; 12 import javax.servlet.ServletRequest; 13 import javax.servlet.ServletResponse; 14 import javax.servlet.http.HttpServletRequest; 15 import javax.servlet.http.HttpServletResponse; 16 17 import org.slf4j.Logger; 18 import org.slf4j.LoggerFactory; 19 import org.springframework.util.StringUtils; 20 public class RequestTimeFilter implements Filter{ 21 private static Logger logger = LoggerFactory.getLogger(RequestTimeFilter.class); 22 @Override 23 public void destroy() { 24 // TODO Auto-generated method stub 25 26 } 27 28 @Override 29 public void doFilter(ServletRequest req, ServletResponse res, FilterChain filterChain) 30 throws IOException, ServletException { 31 // TODO Auto-generated method stub 32 HttpServletRequest request = (HttpServletRequest) req; 33 HttpServletResponse response = (HttpServletResponse) res; 34 DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 35 logger.info("{}----{}接收请求时间：{}-------", request.getRequestURL(),df.format(new Date())); 36 long begin = System.currentTimeMillis(); 37 filterChain.doFilter(req, res); 38 logger.info("{}-----{}处理请求的时间ms:------", request.getRequestURL(), System.currentTimeMillis()-begin); 39 } 40 41 @Override 42 public void init(FilterConfig arg0) throws ServletException { 43 // TODO Auto-generated method stub 44 45 } 46 47 }
3、加载数据库连接过滤器
1 <!-- 加载连接过滤器 --> 2 <filter> 3 <filter-name>connectionFilter</filter-name> 4 <filter-class>com.common.filter.RequestConnectionFilter</filter-class> 5 </filter> 6 <filter-mapping> 7 <filter-name>connectionFilter</filter-name> 8 <url-pattern>*</url-pattern> 9 </filter-mapping>
1 import java.io.IOException; 2 import java.sql.SQLException; 3 4 import javax.servlet.Filter; 5 import javax.servlet.FilterChain; 6 import javax.servlet.FilterConfig; 7 import javax.servlet.ServletException; 8 import javax.servlet.ServletRequest; 9 import javax.servlet.ServletResponse; 10 import javax.servlet.http.HttpServletRequest; 11 import javax.servlet.http.HttpServletResponse; 12 13 public class RequestConnectionFilter implements Filter{ 14 15 @Override 16 public void destroy() { 17 // TODO Auto-generated method stub 18 19 } 20 21 @Override 22 public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) 23 throws IOException, ServletException { 24 // TODO Auto-generated method stub 25 try{ 26 filterChain.doFilter(request, response); 27 }finally{ 28 try { 29 CommonDao.closeConnection(); 30 } catch (SQLException e) { 31 // TODO Auto-generated catch block 32 e.printStackTrace(); 33 } 34 } 35 } 36 37 @Override 38 public void init(FilterConfig arg0) throws ServletException { 39 // TODO Auto-generated method stub 40 41 }
监听器：
现在来说说Servlet的监听器Listener，它是实现了javax.servlet.ServletContextListener 接口的服务器端程序，它也是随web应用的启动而启动，只初始化一次，随web应用的停止而销毁。主要作用是：做一些初始化的内容添加工作、设置一些基本的内容、比如一些参数或者是一些固定的对象等等。
1、ContextLoaderListener监听器
1 <!-- ContextLoaderListener监听器启动Web容器 --> 2 <listener> 3 <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> 4 </listener>
2、读取配置文件监听器
1 <!-- 读取配置文件的监听器 --> 2 <listener> 3 <listener-class>com.kingdee.opensys.common.util.ReadPropertiesListener</listener-class> 4 </listener>
1 import javax.servlet.ServletContextEvent; 2 import javax.servlet.ServletContextListener; 3 4 public class ReadPropertiesListener implements ServletContextListener{ 5 6 public void contextDestroyed(ServletContextEvent sce) { 7 // TODO Auto-generated method stub 8 9 } 10 11 public void contextInitialized(ServletContextEvent sce) { 12 // TODO Auto-generated method stub 13 String path = sce.getServletContext().getRealPath("/WEB-INF/config/common.properties"); 14 PropertiesUtils.init(path); 15 } 16 17 } 18 19 20 21 import java.io.File; 22 import java.io.FileInputStream; 23 import java.io.FileNotFoundException; 24 import java.util.Properties; 25 26 public class PropertiesUtils { 27 28 private static PropertiesUtils parse = new PropertiesUtils(); 29 private static Properties properties; 30 private static String path; 31 32 public static void init(String path){ 33 parse.path = path; 34 System.out.println("properties================="+path); 35 } 36 37 public static String getProperties(String host) { 38 return properties.getProperty(host); 39 } 40 41 public static void setProperties(String key,String value) { 42 properties.setProperty(key, value); 43 } 44 45 public PropertiesUtils(){ 46 47 } 48 49 public static PropertiesUtils getInstance() throws Exception{ 50 if(properties==null){ 51 properties = new Properties(); 52 FileInputStream in = new FileInputStream(new File(path)); 53 properties.load(in); 54 } 55 return parse; 56 } 57 } 58 59 60 61 public class URLHelper { 62 63 public static String getBaseUrl(String hostKey) throws Exception{ 64 return PropertiesUtils.getInstance().getProperties(hostKey); 65 } 66 }
3、Spring日志监听器
1 <!-- log4j配置文件位置 --> 2 <context-param> 3 <param-name>log4jConfigLocation</param-name> 4 <param-value>/WEB-INF/classes/config/log4.properties</param-value> 5 </context-param> 6 <!-- 利用spring来使用log4j --> 7 <listener> 8 <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class> 9 </listener>
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