JavaWEB中字符集问题,通过filter解决(包含tomcat不同版本)

字符集的问题,会很困扰开发者,不同版本的tomcat以及请求方式不同,其处理方式也不相同.

Version	get	post
5-7	arr[i]=new String(arr[i].getBytes("iso-8859-1"),"utf-8");	有乱码 设置request.setCharacterEncoding("UTF-8");
8-9	UTF-8(默认)	有乱码 设置request.setCharacterEncoding("UTF-8");

import org.apache.commons.beanutils.BeanUtils;

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.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
/**
 * 统一编码
 * @author Administrator
 *
 */
@WebFilter("/*")
public class EncodingFilter implements Filter {

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {

	}

	@Override
	public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
		resp.setContentType("text/html;charset=utf-8");

		//1.强转
		HttpServletRequest request=(HttpServletRequest) req;
		HttpServletResponse response=(HttpServletResponse) resp;
		
		//2.放行
		HttpServletRequest requestHigh = new MyRequest(request);
		chain.doFilter(requestHigh, response);
	}

	@Override
	public void destroy() {

	}

}
class MyRequest extends HttpServletRequestWrapper{
	private HttpServletRequest request;
	//若是get请求，只需要编码一次即可
	private boolean flag=true;
	
	
	public MyRequest(HttpServletRequest request) {
		super(request);
		this.request=request;
	}
	
	@Override
	public String getParameter(String name) {  
		if(name==null || name.trim().length()==0){
			return null;
		}
		String[] values = getParameterValues(name);
		if(values==null || values.length==0){
			return null;
		}
		
		return values[0];
	}
	
	@Override
	/**
	 * hobby=[eat,drink]
	 */
	public String[] getParameterValues(String name) {
		if(name==null || name.trim().length()==0){
			return null;
		}
		Map<String, String[]> map = getParameterMap();
		if(map==null || map.size()==0){
			return null;
		}
		
		return map.get(name);
	}
	
	@Override
	/**
	 * map{ username=[tom],password=[123],hobby=[eat,drink]}
	 */
	public Map<String,String[]> getParameterMap() {  
		
		/**
		 * 首先判断请求方式
		 * 若为post  request.setchar...(utf-8)
		 * 若为get 将map中的值遍历编码就可以了
		 */
		String method = request.getMethod();
		if("post".equalsIgnoreCase(method)){
			try {
				request.setCharacterEncoding("utf-8");
				return request.getParameterMap();
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
		}else if("get".equalsIgnoreCase(method)){
            //①获得web server(tomcat)的版本号
            String version = request.getServletContext().getServerInfo();
            int beginIndex = version.lastIndexOf('/')+1;
            int endIndex = version.indexOf('.');
            int versionNo = Integer.parseInt(version.substring(beginIndex,endIndex));			
			
            //②根据版本号进行相应的处理
            if(versionNo>=8){
                //i）若版本号>=8,不用处理，直接返回即可（原因：GET请求，字符集默认是：UTF-8）
                return super.getParameterMap();
            }else{
                //ii)若版本号<8,需要手动进行处理（原因：GET请求，字符集默认是：ISO-8859-1）
				Map<String,String[]> map = request.getParameterMap();

				if(flag){
					for (String key:map.keySet()) {
						String[] arr = map.get(key);
						//继续遍历数组
						for(int i=0;i<arr.length;i++){
							//编码
							try {
								arr[i]=new String(arr[i].getBytes("iso-8859-1"),"utf-8");
							} catch (UnsupportedEncodingException e) {
								e.printStackTrace();
							}
						}
					}
					flag=false;
				}
				//需要遍历map 修改value的每一个数据的编码

				return map;
            }
		}
		
		return super.getParameterMap();
	}
	
}