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  • 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"/>男
                  <input type="radio" name="sex" value="female"/>女<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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  • 原文地址:https://www.cnblogs.com/nextgg/p/7669893.html
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