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