Java-Filter过滤器用于过滤整个项目的编码

Posted 2020-10-08 庞玉栋的个人博客

整个分为实现类以及在web.xml文件中对编写的filter类进行注册

 

代码如下

1. package cn.itcast.itcaststore.web.filter;
2. import java.io.IOException;
3. import java.io.UnsupportedEncodingException;
4. import java.util.Map;
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.HttpServletRequestWrapper;
13. /**
14. * 编码过滤器（用于统一项目编码）
15. */
16. public class EncodingFilter implements Filter {
17. public void init(FilterConfig filterConfig) throws ServletException {
18. }
19. public void doFilter(ServletRequest request, ServletResponse response,
20. FilterChain chain) throws IOException, ServletException {
21. // 处理请求乱码
22. HttpServletRequest httpServletRequest = (HttpServletRequest) request;
23. HttpServletRequest myRequest = new MyRequest(httpServletRequest);
24. // 处理响应乱码
25. response.setContentType("text/html;charset=utf-8");
26. chain.doFilter(myRequest, response);
27. }
28. public void destroy() {
29. }
30. }
31. // 自定义request对象
32. class MyRequest extends HttpServletRequestWrapper {
33. private HttpServletRequest request;
34. private boolean hasEncode;
35. public MyRequest(HttpServletRequest request) {
36. super(request);// super必须写
37. this.request = request;
38. }
39. // 对需要增强方法 进行覆盖
40. @SuppressWarnings({ "unchecked", "rawtypes" })
41. @Override
42. public Map getParameterMap() {
43. // 先获得请求方式
44. String method = request.getMethod();
45. if (method.equalsIgnoreCase("post")) {
46. // post请求
47. try {
48. // 处理post乱码
49. request.setCharacterEncoding("utf-8");
50. return request.getParameterMap();
51. } catch (UnsupportedEncodingException e) {
52. e.printStackTrace();
53. }
54. } else if (method.equalsIgnoreCase("get")) {
55. // get请求
56. Map<string, string[]=""> parameterMap = request.getParameterMap();
57. if (!hasEncode) { // 确保get手动编码逻辑只运行一次
58. for (String parameterName : parameterMap.keySet()) {
59. String[] values = parameterMap.get(parameterName);
60. if (values != null) {
61. for (int i = 0; i < values.length; i++) {
62. try {
63. values[i] = new String(values[i].getBytes("ISO-8859-1"),"utf-8");
64. } catch (UnsupportedEncodingException e) {
65. e.printStackTrace();
66. }
67. }
68. }
69. }
70. hasEncode = true;
71. }
72. return parameterMap;
73. }
74. return super.getParameterMap();
75. }
76. @Override
77. public String getParameter(String name) {
78. @SuppressWarnings("unchecked")
79. Map<string, string[]=""> parameterMap = getParameterMap();
80. String[] values = parameterMap.get(name);
81. if (values == null) {
82. return null;
83. }
84. return values[0]; // 取回参数的第一个值
85. }
86. @Override
87. public String[] getParameterValues(String name) {
88. @SuppressWarnings("unchecked")
89. Map<string, string[]=""> parameterMap = getParameterMap();
90. String[] values = parameterMap.get(name);
91. return values;
92. }
93. }

web.xml配置

<filter>

 

<filter-name>encodingFilter</filter-name>

<filter-class>cn.itcast.itcaststore.web.filter.EncodingFilter</filter-class>

</filter>

<filter-mapping>

<filter-name>encodingFilter</filter-name>

<url-pattern>/*</url-pattern>

 

</filter-mapping>