过滤器--解决全站中文乱码问题

全站乱码案例:

     * 利用Servlet的doGet()和doPost()方法中,可以解决中文乱码:

[java] view plain copy print ?

1.      * doGet()  
2.        String value = request.getParameter("");  
3. value = new String(value.getBytes("ISO8859-1"),"utf-8");  
4.   
5. response.setContentType("text/html;charset=utf-8");  
6.      * doPost()  
7.        request.setCharacterEncoding("utf-8");  
8. response.setContentType("text/html;charset=utf-8");  

       * doGet()
         String value = request.getParameter("");
	 value = new String(value.getBytes("ISO8859-1"),"utf-8");

	 response.setContentType("text/html;charset=utf-8");
       * doPost()
         request.setCharacterEncoding("utf-8");
	 response.setContentType("text/html;charset=utf-8");

     * 以上问题:
       * 实际开发时,Web应用程序的逻辑比较复杂(多个Servlet).
       * 上述的解决方案,仅能解决当前Servlet的中文乱码问题.

       * 如果使用上述方案,解决中文乱码问题:代码重复性太多.

EncodingFilter：

[java] view plain copy print ?

1. package app.java.filter.demo1;  
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. import javax.servlet.http.HttpServletResponse;  
13.   
14. /** 
15.  * 当前Filter用于解决全站中文乱码问题. 
16.  * @author JYL 
17.  */  
18. public class EncodingFilter implements Filter {  
19.   
20.     public void destroy() {  
21.           
22.     }  
23.   
24.     public void doFilter(ServletRequest req, ServletResponse resp,  
25.             FilterChain chain) throws IOException, ServletException {  
26.           
27.         //1 进行Request与Response对象的类型强转  
28.         HttpServletRequest request = (HttpServletRequest)req;  
29.         HttpServletResponse response = (HttpServletResponse)resp;  
30.           
31.         //2 解决中文乱码问题:1)请求的中文乱码(GET\POST);2)响应的中文乱码.  
32.         request.setCharacterEncoding("utf-8");  
33.         response.setContentType("text/html;charset=utf-8");  
34.           
35.         //3 创建自定义的Request对象  
36.         MyRequest myRequest = new MyRequest(request);  
37.           
38.         //3 放行  
39.         chain.doFilter(myRequest, response);  
40.     }  
41.   
42.     public void init(FilterConfig arg0) throws ServletException {  
43.     }  
44.   
45. }  

package app.java.filter.demo1;

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;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 当前Filter用于解决全站中文乱码问题.
 * @author JYL
 */
public class EncodingFilter implements Filter {

	public void destroy() {
		
	}

	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		
		//1 进行Request与Response对象的类型强转
		HttpServletRequest request = (HttpServletRequest)req;
		HttpServletResponse response = (HttpServletResponse)resp;
		
		//2 解决中文乱码问题:1)请求的中文乱码(GET\POST);2)响应的中文乱码.
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		
		//3 创建自定义的Request对象
		MyRequest myRequest = new MyRequest(request);
		
		//3 放行
		chain.doFilter(myRequest, response);
	}

	public void init(FilterConfig arg0) throws ServletException {
	}

}

MyRequest:

[java] view plain copy print ?

1. package app.java.filter.demo1;  
2.   
3. import java.io.UnsupportedEncodingException;  
4.   
5. import javax.servlet.http.HttpServletRequest;  
6. import javax.servlet.http.HttpServletRequestWrapper;  
7. /** 
8.  * 自定义的Request对象 
9.  * @author JYL 
10.  */  
11. public class MyRequest extends HttpServletRequestWrapper {  
12.   
13.     public MyRequest(HttpServletRequest request) {  
14.         super(request);  
15.     }  
16.       
17.     @Override  
18.     public String getParameter(String name) {  
19.         String value = super.getParameter(name);  
20.         if(super.getMethod().equalsIgnoreCase("GET")){  
21.             try {  
22.                 value = new String(value.getBytes("ISO-8859-1"),"utf-8");  
23.             } catch (UnsupportedEncodingException e) {  
24.                 e.printStackTrace();  
25.             }  
26.         }  
27.         return value;  
28.     }  
29.   
30. }  

package app.java.filter.demo1;

import java.io.UnsupportedEncodingException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
/**
 * 自定义的Request对象
 * @author JYL
 */
public class MyRequest extends HttpServletRequestWrapper {

	public MyRequest(HttpServletRequest request) {
		super(request);
	}
	
	@Override
	public String getParameter(String name) {
		String value = super.getParameter(name);
		if(super.getMethod().equalsIgnoreCase("GET")){
			try {
				value = new String(value.getBytes("ISO-8859-1"),"utf-8");
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
		}
		return value;
	}

}

TestServlet:

[java] view plain copy print ?

1. package app.java.filter.demo1;  
2.   
3. import java.io.IOException;  
4. import java.io.PrintWriter;  
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. public class TestServlet extends HttpServlet {  
12.   
13.     public void doGet(HttpServletRequest request, HttpServletResponse response)  
14.             throws ServletException, IOException {  
15.   
16.         String username = request.getParameter("username");  
17.         String password = request.getParameter("password");  
18.           
19.         System.out.println(username+" : "+password);  
20.           
21.         response.getWriter().println("中文解决了,真好!!!!");  
22.     }  
23.   
24.     public void doPost(HttpServletRequest request, HttpServletResponse response)  
25.             throws ServletException, IOException {  
26.   
27.         String username = request.getParameter("username");  
28.         String password = request.getParameter("password");  
29.           
30.         System.out.println(username+" : "+password);  
31.           
32.         response.getWriter().println("中文解决了,真好!!!!");  
33.     }  
34.   
35. }  

package app.java.filter.demo1;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TestServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		String username = request.getParameter("username");
		String password = request.getParameter("password");
		
		System.out.println(username+" : "+password);
		
		response.getWriter().println("中文解决了,真好!!!!");
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		String username = request.getParameter("username");
		String password = request.getParameter("password");
		
		System.out.println(username+" : "+password);
		
		response.getWriter().println("中文解决了,真好!!!!");
	}

}

xml:

[html] view plain copy print ?

1. <filter>  
2.     <filter-name>EncodingFilter</filter-name>  
3.     <filter-class>demo1.EncodingFilter</filter-class>  
4.   </filter>  
5.   <filter-mapping>  
6.     <filter-name>EncodingFilter</filter-name>  
7.     <url-pattern>/*</url-pattern>  
8.   </filter-mapping>  

<filter>
  	<filter-name>EncodingFilter</filter-name>
  	<filter-class>demo1.EncodingFilter</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>EncodingFilter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>

jsp:

[html] view plain copy print ?

1. <form action="test" method="post">  
2.         用户名:<input type="text" name="username"><br>  
3.         密码:<input type="password" name="password"><br>  
4.         <input type="submit" value="提交">  
5.     </form>  
6.     <a href="test?username=张无忌&password=123">GET方式发送的请求</a>  

<form action="test" method="post">
    	用户名:<input type="text" name="username"><br>
    	密码:<input type="password" name="password"><br>
    	<input type="submit" value="提交">
    </form>
    <a href="test?username=张无忌&password=123">GET方式发送的请求</a>

另一种：

[java] view plain copy print ?

1. package com.itheima.filter;  
2.   
3. import java.io.IOException;  
4. import java.io.UnsupportedEncodingException;  
5. import java.util.Map;  
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. import javax.servlet.http.HttpServletRequest;  
14. import javax.servlet.http.HttpServletRequestWrapper;  
15.   
16. public class MyFilter implements Filter {  
17.   
18.     public void init(FilterConfig filterConfig) throws ServletException {  
19.   
20.     }  
21.   
22.     public void doFilter(ServletRequest request, ServletResponse response,  
23.             FilterChain chain) throws IOException, ServletException {  
24.         HttpServletRequest req = (HttpServletRequest) request;  
25.         // 解决post方式  
26.         // req.setCharacterEncoding("UTF-8");  
27.         req = new MyRequest(req);  
28.   
29.         chain.doFilter(req, response);  
30.     }  
31.   
32.     public void destroy() {  
33.     }  
34. }  
35.   
36. // 实现与被包装对象相同的接口  
37. // 定义一个与被包装类相对象的引用  
38. // 定义一个构造方法，把被包装对象传过来  
39. // 对于不需要改写方法，直接调用  
40. // 对于无需要改写方法，写自己的方法体  
41. class MyRequest extends HttpServletRequestWrapper {  
42.     HttpServletRequest request;  
43.   
44.     public MyRequest(HttpServletRequest request) {  
45.         super(request);  
46.         this.request = request;  
47.     }  
48.   
49.     /* 
50.      * @Override public String getParameter(String name) { name = 
51.      * request.getParameter(name);//乱码 try { return new 
52.      * String(name.getBytes("iso-8859-1"),"UTF-8"); } catch 
53.      * (UnsupportedEncodingException e) { e.printStackTrace(); } return null; } 
54.      */  
55.   
56.     @Override  
57.     public String getParameter(String name) {  
58.         Map<String, String[]> map = getParameterMap();  
59.         return map.get(name)[0];  
60.     }  
61.   
62.     @Override  
63.     public String[] getParameterValues(String name) {  
64.         Map<String, String[]> map = getParameterMap();  
65.         return map.get(name);  
66.     }  
67.   
68.     private boolean flag = true;  
69.   
70.     @Override  
71.     public Map<String, String[]> getParameterMap() {  
72.         Map<String, String[]> map = request.getParameterMap();// 乱码  
73.         if (flag) {  
74.             for (Map.Entry<String, String[]> m : map.entrySet()) {  
75.                 String[] values = m.getValue();  
76.                 for (int i = 0; i < values.length; i++) {  
77.                     try {  
78.                         values[i] = new String(  
79.                                 values[i].getBytes("iso-8859-1"), "UTF-8");  
80.                     } catch (UnsupportedEncodingException e) {  
81.                         e.printStackTrace();  
82.                     }  
83.                 }  
84.   
85.             }  
86.             flag = false;  
87.         }  
88.         return map;  
89.   
90.     }  
91.   
92. }  

package com.itheima.filter;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
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.HttpServletRequestWrapper;

public class MyFilter implements Filter {

	public void init(FilterConfig filterConfig) throws ServletException {

	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest req = (HttpServletRequest) request;
		// 解决post方式
		// req.setCharacterEncoding("UTF-8");
		req = new MyRequest(req);

		chain.doFilter(req, response);
	}

	public void destroy() {
	}
}

// 实现与被包装对象相同的接口
// 定义一个与被包装类相对象的引用
// 定义一个构造方法，把被包装对象传过来
// 对于不需要改写方法，直接调用
// 对于无需要改写方法，写自己的方法体
class MyRequest extends HttpServletRequestWrapper {
	HttpServletRequest request;

	public MyRequest(HttpServletRequest request) {
		super(request);
		this.request = request;
	}

	/*
	 * @Override public String getParameter(String name) { name =
	 * request.getParameter(name);//乱码 try { return new
	 * String(name.getBytes("iso-8859-1"),"UTF-8"); } catch
	 * (UnsupportedEncodingException e) { e.printStackTrace(); } return null; }
	 */

	@Override
	public String getParameter(String name) {
		Map<String, String[]> map = getParameterMap();
		return map.get(name)[0];
	}

	@Override
	public String[] getParameterValues(String name) {
		Map<String, String[]> map = getParameterMap();
		return map.get(name);
	}

	private boolean flag = true;

	@Override
	public Map<String, String[]> getParameterMap() {
		Map<String, String[]> map = request.getParameterMap();// 乱码
		if (flag) {
			for (Map.Entry<String, String[]> m : map.entrySet()) {
				String[] values = m.getValue();
				for (int i = 0; i < values.length; i++) {
					try {
						values[i] = new String(
								values[i].getBytes("iso-8859-1"), "UTF-8");
					} catch (UnsupportedEncodingException e) {
						e.printStackTrace();
					}
				}

			}
			flag = false;
		}
		return map;

	}

}

转载：https://blog.csdn.net/CSDN_GIA/article/details/54094426