Java-Filter过滤器用于过滤整个项目的编码

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

package cn.itcast.itcaststore.web.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;
/**
 * 编码过滤器（用于统一项目编码）
 */
public class EncodingFilter implements Filter {
	public void init(FilterConfig filterConfig) throws ServletException {
}
public void doFilter(ServletRequest request, ServletResponse response,
		FilterChain chain) throws IOException, ServletException {
	// 处理请求乱码
	HttpServletRequest httpServletRequest = (HttpServletRequest) request;
	HttpServletRequest myRequest = new MyRequest(httpServletRequest);
	// 处理响应乱码
	response.setContentType("text/html;charset=utf-8");
	chain.doFilter(myRequest, response);
}
public void destroy() {

}
}
// 自定义request对象
class MyRequest extends HttpServletRequestWrapper {
private HttpServletRequest request;
private boolean hasEncode;
public MyRequest(HttpServletRequest request) {
super(request);// super必须写
this.request = request;
}
// 对需要增强方法 进行覆盖
@SuppressWarnings({ “unchecked”, “rawtypes” })
@Override
public Map getParameterMap() {
// 先获得请求方式
String method = request.getMethod();
if (method.equalsIgnoreCase(“post”)) {
// post请求
try {
// 处理post乱码
request.setCharacterEncoding(“utf-8”);
return request.getParameterMap();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
} else if (method.equalsIgnoreCase(“get”)) {
// get请求
Map<string, string[]=""> parameterMap = request.getParameterMap();
if (!hasEncode) { // 确保get手动编码逻辑只运行一次
for (String parameterName : parameterMap.keySet()) {
String[] values = parameterMap.get(parameterName);
if (values != null) {
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();
}
}
}
}
hasEncode = true;
}
return parameterMap;
}
return super.getParameterMap();
}
@Override
public String getParameter(String name) {
@SuppressWarnings(“unchecked”)
Map<string, string[]=""> parameterMap = getParameterMap();
String[] values = parameterMap.get(name);
if (values == null) {
return null;
}
return values[0]; // 取回参数的第一个值
}
@Override
public String[] getParameterValues(String name) {
@SuppressWarnings(“unchecked”)
Map<string, string[]=""> parameterMap = getParameterMap();
String[] values = parameterMap.get(name);
return values;
}
}
</string,></string,></string,>

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>