网上图书商城项目学习笔记-037工具类之BaseServlet及统一中文编码

Posted 2020-06-13

1.统一中文编码分析

tomcat默认esetISO-8859-1编码，在servlet中，可能通过request的setCharacterEncoding(charset)和response.setContentType("text/html;charset=UTF-8");处理post请求编码,但get请求的编码控制不了，所以，如果请求类型是get，则用装饰者模式把request整个调包

 

2.EncodingFilter.java

 1 package cn.itcast.filter;
 2 
 3 import java.io.IOException;
 4 
 5 import javax.servlet.Filter;
 6 import javax.servlet.FilterChain;
 7 import javax.servlet.FilterConfig;
 8 import javax.servlet.ServletException;
 9 import javax.servlet.ServletRequest;
10 import javax.servlet.ServletResponse;
11 import javax.servlet.http.HttpServletRequest;
12 
13 
14 public class EncodingFilter implements Filter {
15     private String charset = "UTF-8";
16     @Override
17     public void destroy() {}
18 
19     @Override
20     public void doFilter(ServletRequest request, ServletResponse response,
21             FilterChain chain) throws IOException, ServletException {
22         HttpServletRequest req = (HttpServletRequest) request;
23         if(req.getMethod().equalsIgnoreCase("GET")) {
24             if(!(req instanceof GetRequest)) {
25                 req = new GetRequest(req, charset);//处理get请求编码
26             }
27         } else {
28             req.setCharacterEncoding(charset);//处理post请求编码
29         }
30         chain.doFilter(req, response);
31     }
32 
33     @Override
34     public void init(FilterConfig fConfig) throws ServletException {
35         String charset = fConfig.getInitParameter("charset");
36         if(charset != null && !charset.isEmpty()) {
37             this.charset = charset;
38         }
39     }
40 }

3.GetRequest.java  装饰者模式

 1 package cn.itcast.filter;
 2 
 3 import java.io.UnsupportedEncodingException;
 4 import java.util.Enumeration;
 5 import java.util.Map;
 6 import javax.servlet.http.HttpServletRequest;
 7 import javax.servlet.http.HttpServletRequestWrapper;
 8 
 9 /**
10  * 对GET请求参数加以处理！
11  * @author qdmmy6
12  *
13  */
14 public class GetRequest extends HttpServletRequestWrapper {
15     private HttpServletRequest request;
16     private String charset;
17     
18     public GetRequest(HttpServletRequest request, String charset) {
19         super(request);
20         this.request = request;
21         this.charset = charset;
22     }
23 
24     @Override
25     public String getParameter(String name) {
26         // 获取参数
27         String value = request.getParameter(name);
28         if(value == null) return null;//如果为null，直接返回null
29         try {
30             // 对参数进行编码处理后返回
31             return new String(value.getBytes("ISO-8859-1"), charset);
32         } catch (UnsupportedEncodingException e) {
33             throw new RuntimeException(e);
34         }
35     }
36     
37     @SuppressWarnings({ "unchecked", "rawtypes" })
38     @Override
39     public Map getParameterMap() {
40         Map<String,String[]> map = request.getParameterMap();
41         if(map == null) return map;
42         // 遍历map，对每个值进行编码处理
43         for(String key : map.keySet()) {
44             String[] values = map.get(key);
45             for(int i = 0; i < values.length; i++) {
46                 try {
47                     values[i] = new String(values[i].getBytes("ISO-8859-1"), charset);
48                 } catch (UnsupportedEncodingException e) {
49                     throw new RuntimeException(e);
50                 }
51             }
52         }
53         // 处理后返回
54         return map;
55     }
56     
57     @Override
58     public String[] getParameterValues(String name) {
59         String[] values = super.getParameterValues(name);
60         for(int i = 0; i < values.length; i++) {
61             try {
62                 values[i] = new String(values[i].getBytes("ISO-8859-1"), charset);
63             } catch (UnsupportedEncodingException e) {
64                 throw new RuntimeException(e);
65             }
66         }
67         return values;
68     }
69 }

3.BaseServlet.java

 1 package cn.itcast.servlet;
 2 
 3 import java.io.IOException;
 4 import java.lang.reflect.Method;
 5 
 6 import javax.servlet.ServletException;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10 
11 /**
12  * BaseServlet用来作为其它Servlet的父类
13  * 
14  * @author qdmmy6
15  * 
16  *         一个类多个请求处理方法，每个请求处理方法的原型与service相同！ 原型 = 返回值类型 + 方法名称 + 参数列表
17  */
18 @SuppressWarnings("serial")
19 public class BaseServlet extends HttpServlet {
20     @Override
21     public void service(HttpServletRequest request, HttpServletResponse response)
22             throws ServletException, IOException {
23         response.setContentType("text/html;charset=UTF-8");//处理响应编码
24         
25         /**
26          * 1. 获取method参数，它是用户想调用的方法 2. 把方法名称变成Method类的实例对象 3. 通过invoke()来调用这个方法
27          */
28         String methodName = request.getParameter("method");
29         Method method = null;
30         /**
31          * 2. 通过方法名称获取Method对象
32          */
33         try {
34             method = this.getClass().getMethod(methodName,
35                     HttpServletRequest.class, HttpServletResponse.class);
36         } catch (Exception e) {
37             throw new RuntimeException("您要调用的方法：" + methodName + "它不存在！", e);
38         }
39         
40         /**
41          * 3. 通过method对象来调用它
42          */
43         try {
44             String result = (String)method.invoke(this, request, response);
45             if(result != null && !result.trim().isEmpty()) {//如果请求处理方法返回不为空
46                 int index = result.indexOf(":");//获取第一个冒号的位置
47                 if(index == -1) {//如果没有冒号，使用转发
48                     request.getRequestDispatcher(result).forward(request, response);
49                 } else {//如果存在冒号
50                     String start = result.substring(0, index);//分割出前缀
51                     String path = result.substring(index + 1);//分割出路径
52                     if(start.equals("f")) {//前缀为f表示转发
53                         request.getRequestDispatcher(path).forward(request, response);
54                     } else if(start.equals("r")) {//前缀为r表示重定向
55                         response.sendRedirect(request.getContextPath() + path);
56                     }
57                 }
58             }
59         } catch (Exception e) {
60             throw new RuntimeException(e);
61         }
62     }
63 }