设置请求编码格式

req.setCharacterEncoding(“utf-8”)
请求的数据包基于字节在网络上传输，Tomcat接收到请求的数据包后会将数据包中的字节转换为字符。在Tomcat中使用的是ISO-8859-1的单字节编码完成字节与字符的转换，所以数据中含有中文就会出现乱码，可以通过req.setCharacterEncoding(“utf-8”)方法来对提交的数据根据指定的编码方式重新做编码处理。

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;
/**
 * 获取请求数据
 */
public class GetRequestDataServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //设置请求编码
        req.setCharacterEncoding("utf-8");
        //获取用户名
        String username = req.getParameter("username");
//        String name = new String(username.getBytes("ISO-8859-1"),"UTF-8");
//        System.out.println(name);
        System.out.println(username);
        //获取用户密码
        String pwd = req.getParameter("userpwd");
        //获取复选框的数据
        String[] userlike = req.getParameterValues("userlike");
        List<String> list = Arrays.asList(userlike);
        //获取表单中所有的key
        Enumeration<String> parameterNames = req.getParameterNames();
        List<String> paraList = new ArrayList<>();
        while (parameterNames.hasMoreElements()){
            paraList.add(parameterNames.nextElement());
        }
        //使用Map结构获取提交的数据
        Map<String,String[]> parameterMap =req.getParameterMap();
        Iterator<Map.Entry<String,String[]>> iterator = parameterMap.entrySet().iterator();
        PrintWriter printWriter = resp.getWriter();
        printWriter.println(username);
        printWriter.println(pwd);
        printWriter.println(list);
        printWriter.println(paraList);
        while (iterator.hasNext()){
            Map.Entry<String,String[]> entry = iterator.next();
            String key = entry.getKey();
            String[] value = entry.getValue();
            printWriter.println(key+"="+Arrays.asList(value));
        }
        printWriter.flush();
        printWriter.close();
    }
}