struts2 的 map支持！！高手帮忙

[云飞_]

LoginAction。java

public class LoginAction implements Action {
	private Map user;

	private String tip;

	public void setTip(String tip) {
		this.tip = tip;
	}

	public String getTip() {
		return (this.tip);
	}

	public String execute() throws Exception {

		System.out.println("((User)getUser().get(0)).getName()================"
				+ ((User) getUser().get(0)).getName());
		if (((User) getUser().get(0)).getName().equals("scott")
				&& ((User) getUser().get(0)).getPass().equals("tiger")) {
			setTip("转换成功");
			return SUCCESS;
		} else {
			setTip("转换失败");
			return ERROR;
		}
	}

	public Map getUser() {
		return user;
	}

	public void setUser(Map user) {
		this.user = user;
	}

}
===========================================
User。java
package com.cai.map;

/**
 * @author yeeku.H.lee [e-mail]
 * @version 1.0 <br>
 *          Copyright (C), 2005-2008, yeeku.H.Lee <br>
 *          This program is protected by copyright laws. <br>
 *          Program Name: <br>
 *          Date:
 */
public class User {
	private String name;

	private String pass;

	public void setName(String name) {
		this.name = name;
	}

	public void setPass(String pass) {
		this.pass = pass;
	}

	public String getName() {
		return (this.name);
	}

	public String getPass() {
		return (this.pass);
	}
}
==============================
UserConverter。java
package com.cai.map;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.struts2.util.StrutsTypeConverter;

/**
 * @author yeeku.H.lee [e-mail]
 * @version 1.0 <br>
 *          Copyright (C), 2005-2008, yeeku.H.Lee <br>
 *          This program is protected by copyright laws. <br>
 *          Program Name: <br>
 *          Date:
 */

public class UserConverter extends StrutsTypeConverter {
	// 字符串转向复合类
	public Object convertFromString(Map context, String[] values, Class toClass) {
		System.out.println("values.length:" + values.length);
		if (values.length > 1) {

			Map result = new HashMap();
			for (int i = 0; i < values.length; i++) {
				User u = new User();
				String[] uservalues = values[i].split(",");

				u.setName(uservalues[0]);
				u.setPass(uservalues[1]);
				result.put(u.getName(), u);
			}
			return result;

		} else {
			// 长度为1的情况
			User user = new User();
			String[] uservalues = values[0].split(",");
			user.setName(uservalues[0]);
			user.setPass(uservalues[1]);
			return user;
		}

	}

	// 复合类型转换成字符串类型
	public String convertToString(Map context, Object o) {
		// 单个的User类型
		if (o instanceof User) {
			User u = (User) o;
			return u.getName() + "," + u.getPass();
		} else if (o instanceof Map) {
			Map u = (Map) o;

			String result = "[";
			Set iter = u.keySet();
			while (iter.iterator().hasNext()) {

				User user = (User) iter.iterator().next();
				result += "<" + user.getName() + "," + user.getPass() + ">";
			}

			return result + "]";

		} else {
			return "";
		}

	}

}
==========================================
LoginAction-conversion.properties

key_user=com.cai.map.User
Element_user=com.cai.map.User
==========================================
xwork-conversion.properties
com.cai.map.User=com.cai.map.UserConverter
===========================================
struts。xml
 <package name="s" extends="struts-default"> 
		<action name="map"
			class="com.cai.map.LoginAction">
			 
			<result name="success">/mapwelcome.jsp</result>
			<result name="error">/error.jsp</result>
		</action>
	</package>
=========================================
login。jsp
   <s:form action="map">
      <s:textfield name="user" label="用户"></s:textfield>
      <s:submit value="登陆"></s:submit>
    </s:form>
=======================================
mapwelcome.jsp
<s:property value="user[0].name"/><br>
    <s:property value="user[0].pass"/>
====================================
以上这些配置我的工程。但是总是报错。找不出高手指点。
报错如下：
java.lang.ClassCastException: com.cai.map.User
Caused by: java.lang.NullPointerException
 	at com.cai.map.LoginAction.execute(LoginAction.java:37)

[huangyangweiyue]

路过，帮顶下，没用过struts2

[lemon520]

Map不支持索引的get(n)方法,所以你的getUser().get(0)其实是一个null,因为没有0为key的user

[zidasine]

((User)getUser().get(0)).getName()
以Integer 0 为key的user 不存在((User)getUser().get(0)) 这部分为null
再getName()就是java.lang.NullPointerException

[luhao]

空指针错

<s:textfield name="user" label="用户"></s:textfield>
这里传给ACTION的是一个String

而你接收的时候却是 private Map user;

[luhao]

另外 zidasine 说的也正确
MAP 是 KEY-VALUE对应的
不是list

[xiaoxinkuaile100]

怎么不用db那?

[云飞_]

List 是这样封装的，怎样才能获取值呢？

[richard_2010]

[Quote=引用 2 楼 lemon520 的回复:]

Map不支持索引的get(n)方法,所以你的getUser().get(0)其实是一个null,因为没有0为key的user


         
[/Quote]

建议改成list，如何取值可以查查jdk文档，效果比别人直接告诉你答案好多了。

[云飞_]

恩。list的例子做过。我也是看的一本struts2的 书，照着做的。但是，关于map的例子。很少。去网上搜多数是关于list的