解决全站字符乱码（POST和GET中文编码问题）

乱码问题：获取请求参数中的乱码问题； POST请求：request.setCharacterEncoding(“utf-8”)；GET请求：newString(request.getParameter(“xxx”).getBytes(“iso-8859-1”), “utf-8”)；响应的乱码问题：response.setContextType(“text/html;charset=utf-8”)。
　　基本上在每个Servlet中都要处理乱码问题，所以应该把这个工作放到过滤器中来完成。

package cn.itcast.web.filter;

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;

public class EncodingFilter implements Filter {
public void destroy() {

}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// 处理post请求编码问题,只对post请求起作用
request.setCharacterEncoding("utf-8");

HttpServletRequest req = (HttpServletRequest) request;

/*
* 调包request
* 1. 写一个request的装饰类
* 2. 在放行时，使用我们自己的request
*/
if(req.getMethod().equals("GET")) {
EncodingRequest er = new EncodingRequest(req);//调包request
chain.doFilter(er, response);
} else if(req.getMethod().equals("POST")) {
chain.doFilter(request, response);
}
}

public void init(FilterConfig fConfig) throws ServletException {

}
}

装饰者模式实现增强的request类 ,覆写getParameter方法

package cn.itcast.web.filter;

import java.io.UnsupportedEncodingException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

/**
* 装饰reqeust
* @author cxf
*
*/
public class EncodingRequest extends HttpServletRequestWrapper {
private HttpServletRequest req;

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

public String getParameter(String name) {
String value = req.getParameter(name);

// 处理编码问题
try {
value = new String(value.getBytes("iso-8859-1"), "utf-8");
} catch (UnsupportedEncodingException e) {
throw new RuntimeException(e);
}

return value;
}
}

一般如果method设置为“post”，将不会出现乱码，如果将method设置为“get”，可能在汉字传入到后台后会出现乱码问题。

get方式传递中文参数乱码后台可以
将请求参数使用ISO-8859-1分解成字节数组，再将字节数组解码成字符串
String name = new String(request.getParameter("name").getBytes("ISO-8859-1"),"utf-8");