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Javaweb获取表单数据的多种方式

2019年07月22日  | 移动技术网IT编程  | 我要评论

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)
getparameternames():返回form表单中的所有key值。

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

@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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