Spring mvc如何实现数据处理

@RequestMapping("/hello")
public String hello(String name){
  System.out.println(name);
  return "hello";
}

//@RequestParam("username") : username提交的域的名称 .
@RequestMapping("/hello")
public String hello(@RequestParam("username") String name){
  System.out.println(name);
  return "hello";
}

public class User {
  private int id;
  private String name;
  private int age;
  //构造
  //get/set
  //tostring()
}

@RequestMapping("/user")
public String user(User user){
  System.out.println(user);
  return "hello";
}

public class ControllerTest1 implements Controller {

  public ModelAndView handleRequest(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
    //返回一个模型视图对象
    ModelAndView mv = new ModelAndView();
    mv.addObject("msg","ControllerTest1");
    mv.setViewName("test");
    return mv;
  }
}

@RequestMapping("/hello")
public String hello(@RequestParam("username") String name, ModelMap model){
  //封装要显示到视图中的数据
  //相当于req.setAttribute("name",name);
  model.addAttribute("name",name);
  System.out.println(name);
  return "hello";
}

@RequestMapping("/ct2/hello")
public String hello(@RequestParam("username") String name, Model model){
  //封装要显示到视图中的数据
  //相当于req.setAttribute("name",name);
  model.addAttribute("msg",name);
  System.out.println(name);
  return "test";
}

<filter>
  <filter-name>encoding</filter-name>
  <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
  <init-param>
    <param-name>encoding</param-name>
    <param-value>utf-8</param-value>
  </init-param>
</filter>
<filter-mapping>
  <filter-name>encoding</filter-name>
  <url-pattern>/</url-pattern>
</filter-mapping>

<Connector URIEncoding="utf-8" port="8080" protocol="HTTP/1.1"
      connectionTimeout="20000"
      redirectPort="8443" />

package com.xiaohua.filter;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;

/**
 * 解决get和post请求 全部乱码的过滤器
 */
public class GenericEncodingFilter implements Filter {

  @Override
  public void destroy() {
  }

  @Override
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    //处理response的字符编码
    HttpServletResponse myResponse=(HttpServletResponse) response;
    myResponse.setContentType("text/html;charset=UTF-8");

    // 转型为与协议相关对象
    HttpServletRequest httpServletRequest = (HttpServletRequest) request;
    // 对request包装增强
    HttpServletRequest myrequest = new MyRequest(httpServletRequest);
    chain.doFilter(myrequest, response);
  }

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

}
//自定义request对象，HttpServletRequest的包装类
class MyRequest extends HttpServletRequestWrapper {

  private HttpServletRequest request;
  //是否编码的标记
  private boolean hasEncode;
  //定义一个可以传入HttpServletRequest对象的构造函数，以便对其进行装饰
  public MyRequest(HttpServletRequest request) {
    super(request);// super必须写
    this.request = request;
  }

  // 对需要增强方法 进行覆盖
  @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 {
                // 处理get乱码
                values[i] = new String(values[i]
                    .getBytes("ISO-8859-1"), "utf-8");
              } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
              }
            }
          }
        }
        hasEncode = true;
      }
      return parameterMap;
    }
    return super.getParameterMap();
  }
  //取一个值
  @Override
  public String getParameter(String name) {
    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
  }
  //取所有值
  @Override
  public String[] getParameterValues(String name) {
    Map<String, String[]> parameterMap = getParameterMap();
    String[] values = parameterMap.get(name);
    return values;
  }
}