实现的目标，将页面中的字符转为对象，如Larry;123456 转为 User对象，username为Larry，password为123456。
如何实现：
Struts的类型转换，对于8个原生数据类型以及Date，String等常见类型，
Struts2可以使用内建的类型转换器实现自动转换；但对于自定义的对象
来说，就需要我们自己指定类型转换的方式了。
一、原始的类型转换方式 （局部类型转换）
工程用到的文件如下图所示
1、创建测试页面test.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>使用分号隔开用户名和密码</h1>
<form action="userAction">
user info: <input type="text" name="user"> <br>
<input type="submit" value="submit">
</form>
</body>
</html>
2、创建userAction
public class UserAction extends ActionSupport {
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
@Override
public String execute() throws Exception {
System.out.println("username:" + user.getUsername());
System.out.println("password:" + user.getPassword());
return SUCCESS;
}
}
输出用户名和密码
3、在struts.xml中添加配置
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.5//EN"
"http://struts.apache.org/dtds/struts-2.5.dtd">
<struts>
<!-- 是否开启动态方法调用 -->
<constant name="struts.enable.DynamicMethodInvocation" value="false" />
<package name="default" namespace="/" extends="struts-default">
<action name="login" class="com.example.struts2.LoginAction" method="login">
<result name="success">/success.jsp</result>
<result name="error">/error.jsp</result>
<result name="result">/result.jsp</result>
</action>
<action name="helloworld" class="com.example.struts2.HelloWorldAction">
<result name="success">/success.jsp</result>
<result name="result">/result.jsp</result>
</action>
<action name="userAction" class="com.example.struts2.UserAction">
<result name="success">/output.jsp</result>
</action>
</package>
</struts>
output.jsp文件如下：
<%@ page language="java" contentType="text/html;charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<s:property value="user" />
</body>
</html>
4、创建转换器
public class UserConverter extends DefaultTypeConverter {
@Override
public Object convertValue(Map<String, Object> context, Object value, Class toType) {
if(User.class == toType){ //从页面向后台对象转换
String[] str = (String[])value;
String firstValue = str[0];
StringTokenizer st = new StringTokenizer(firstValue,";");
String username = st.nextToken();
String password = st.nextToken();
User user = new User();
user.setUsername(username);
user.setPassword(password);
return user;
}
return null;
}
}
并且增加配置文件UserAction-conversion.properties
内容为：user=com.example.converter.UserConverter
位于UserAction中的user变量使用com.example.converter.UserConverter转换器
5、测试
打开test.jsp
然后点击提交
控制台输出如下
提交后页面结果
二、Struts自带的类型转换 （局部类型转换）
可以使用Struts2框架自带的类型转换器StrutsTypeConverter简化类型转换代码的编，
StrutsTypeConverter继承于DefaultTypeConverter父类，并且提供了两个抽象方法
convertFromString与convertToString，分别表示从页面的字符串转换为后台对象以及
从后台对象转换为页面的字符串，我们只需实现这两个抽象方法即可实现类型转换。
1、单个类型转换
创建类型转换器
public class UserConverter2 extends StrutsTypeConverter {
@Override
public Object convertFromString(Map arg0, String[] arg1, Class arg2) {
User user = new User();
String value = arg1[0];
StringTokenizer st = new StringTokenizer(value,";");
user.setUsername(st.nextToken());
user.setPassword(st.nextToken());
return user;
}
@Override
public String convertToString(Map arg0, Object arg1) {
User user = (User)arg1;
String username = user.getUsername();
String password = user.getPassword();
String userInfo = "username :" + username + ",password :" + password;
return userInfo;
}
}
修改配置文件
输出结果和上面是一致的。
2、批量类型转换（局部类型转换）
1）增加input.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>使用分号隔开用户名和密码</h1>
<form action="userAction2">
user info 1: <input type="text" name="user"> <br>
user info 2: <input type="text" name="user"> <br>
user info 3: <input type="text" name="user"> <br>
user info 4: <input type="text" name="user"> <br>
<input type="submit" value="submit">
</form>
</body>
</html>
2）UserAction2
public class UserAction2 extends ActionSupport {
private List<User> user;
public List<User> getUser() {
return user;
}
public void setUser(List<User> user) {
this.user = user;
}
@Override
public String execute() throws Exception {
for(User u: user){
System.out.println("username:" + u.getUsername());
System.out.println("password:" + u.getPassword());
}
return SUCCESS;
}
}
3）struts.xml增加配置
<action name="userAction2" class="com.example.struts2.UserAction2"> <result name="success">/output.jsp</result> </action>
4、增加转换器
public class UserConverter3 extends StrutsTypeConverter {
@Override
public Object convertFromString(Map arg0, String[] arg1, Class arg2) {
List<User> list = new ArrayList<>();
for(String value : arg1){
User user = new User();
StringTokenizer st = new StringTokenizer(value,";");
user.setUsername(st.nextToken());
user.setPassword(st.nextToken());
list.add(user);
}
return list;
}
@Override
public String convertToString(Map arg0, Object arg1) {
List<User> list = (List<User>)arg1;
StringBuffer buffer = new StringBuffer();
for(User user : list){
String username = user.getUsername();
String password = user.getPassword();
buffer.append("username:").append(username).append(",password:" ).append(password).append(" ");
}
return buffer.toString();
}
}
增加属性文件
5)测试结果
点击提交后返回
三、全局类型转换
在src目录下创建xwork-conversion.properties，该文件的内容是待转换的类=转换器的名字，即
com.example.bean.User=com.exmaple.converter.UserConverter2
1、创建全局配置属性文件
2、修改input.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>使用分号隔开用户名和密码</h1>
<form action="userAction">
user info 1: <input type="text" name="user"> <br>
<input type="submit" value="submit">
</form>
</body>
</html>
3、提交后显示
