Javaweb获取表单数据的几种方式

一、通过键值对的形式获取表单数据

  • getParameter(String name):通过key,返回一个value。
  • getParameterValues(String name):通过key返回一个string数组(多个值) 返回个String[]
  • getParameterNames():返回form表单中的所有key值。  Enumeration<String> names

下面介绍通过键值对获取form表单数据的数据的方法:

@WebServlet({ "/FormServlet", "/form" })
public class FormServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public FormServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/json;charset=utf-8");

        PrintWriter out = response.getWriter();

        Enumeration<String>  paramNames =  request.getParameterNames();

        while (paramNames.hasMoreElements()) {
            String  name = paramNames.nextElement();

            String[] values =  request.getParameterValues(name);

            if(values!=null && values.length>0){
                StringBuilder builder = new StringBuilder(); 
                for (int i = 0; i < values.length; i++) {
                    builder.append(values[i]+" ");
                }
                out.println(name+" : "+builder.toString());
            }
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

form表单:

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <form action="/TomcatDemo/form" method="post">

        用户名<input type="text" name="username"/><br/>
        密码    <input type="password" name="password"/><br/>
        性别    <input type="radio" name="sex" value="male" checked="checked"/><input type="radio" name="sex" value="female"/><br/>
        爱好    <input type="checkbox" name="hobby" value="basketball"/>篮球
              <input type="checkbox" name="hobby" value="football"/>足球
              <input type="checkbox" name="hobby" value="game"/>游戏
              <input type="checkbox" name="hobby" value="media"/>电影<br/>
               城市    <select name="city">
                    <option value="bj">北京</option>
                    <option value="sh">上海</option>
                    <option value="sz">深圳</option>
                    <option value="hz">杭州</option>
                  </select><br/>
                  <input type="submit" value="注册"/>
                  <input type="submit"  value="登入"/><br/>

    </form>
</body>
</html>

 


二、通过Map的形式获取表单数据

  • getParameterMap():获取form表单的数据,以map的格式封装起来

示例:

@WebServlet({ "/FormServlet", "/form" })
public class FormServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public FormServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/json;charset=utf-8");

        PrintWriter out = response.getWriter();

        User user = new User();
        out.println("获取表单数据之前:"+user.toString());

        Map<String,String[]> map = request.getParameterMap();

        for (Map.Entry<String, String[]> m : map.entrySet()) {

            String name = m.getKey();
            String[] values = m.getValue();
            //属性描述器:表示JavaBean类通过存储器导出一个属性
            PropertyDescriptor pd=null;
            try {
                 pd = new PropertyDescriptor(name, User.class);
            } catch (IntrospectionException e) {
                e.printStackTrace();
            }

            if (values!=null&& pd !=null) {

                Method setter = pd.getWriteMethod();
                try {
                    if (values.length==1) {
                        setter.invoke(user, values[0]);
                    }else {
                        setter.invoke(user, (Object)values);
                    }
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                } catch (IllegalArgumentException e) {
                    e.printStackTrace();
                } catch (InvocationTargetException e) {
                    e.printStackTrace();
                }
            }
        }
        out.println("获取表单数据之后:"+user.toString());
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }
}

 

PropertyDescriptor的使用

User类

public class User {
    private String username;//属性名称需要和表单数据中的name值保持一致
    private String password;
    private String sex;
    private String[] hobby;
    private String city;
    ...
    //set get方法省略
}

 

三、通过第三方jar包获取封装表单数据

使用第三方jar包:commons-beanutils-1.8.3.jar,下载

@WebServlet({ "/FormServlet", "/form" })
public class FormServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public FormServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/json;charset=utf-8");

        PrintWriter out = response.getWriter();

        User user = new User();
        out.println("获取表单数据之前:"+user.toString());

        try {
            //通过第三方jar包处理
            BeanUtils.populate(user, request.getParameterMap());
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }

        out.println("获取表单数据之后:"+user.toString());

    }


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}
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