struts2启程3

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Struts JSP Bean Cache 应用服务器

struts2启程之类型转换

类型转换要考虑两点：从客户端向服务器、从服务器向客户端。

1、从客户端向服务器转换，肯定是String类型转换成javaBean类型

2、从服务器端向客户端转换，肯定是javaBean类型转换成String类型

所以，这个转换类就需要考虑这两点

类型转换的流程：

通过JSP页面将其中的一个元素值转换成javaBean值，在页面输出时，将取得的javaBean自动转换成了String类型，并输出。

要点文件：转换类、配置文件-维系转换类与Action类之间的纽带

一、写转换类的注意点：

1、继承ognl.DefaultTypeConverter类

2、重写convertValue(Map context, Object value, Class toType)方法

示例代码：

java 代码

package com.test.convert;
import java.util.Map;
import com.test.bean.Point;
import ognl.DefaultTypeConverter;
public class PointConverter extends DefaultTypeConverter {
@Override
public Object convertValue(Map context, Object value, Class toType) {
if(Point.class == toType)
{
Point point = new Point();
String[] str = (String[]) value;
String[] points = str[0].split(",");
int x = Integer.parseInt(points[0]);
int y = Integer.parseInt(points[1]);
point.setX(x);
point.setY(y);
return point;
}
if(String.class == toType)
{
Point point = (Point) value;
String str = "[x=" + point.getX() + " , y=" + point.getY() + "]";
return str;
}
return null;
}
}

二、写配置文件的注意点：

1、配置文件名的位置：必须与应用这个转换类的Action类在同一个包中

2、配置文件名称命名：必须是要应用这个转换类的Action类的名字加"-conversion.properties"

3、配置文件内容："="号的左边是Action类中要转换的Bean所对应的属性名字，"="号的右边是转换类的全称（包名加类名）

示例：

pointAction-conversion.properties

point=com.test.convert.PointConverter

java 代码

package com.test.bean;
public class Point {
private int x;
private int y;
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
}

java 代码

package com.test.action;
import java.util.Date;
import com.opensymphony.xwork2.ActionSupport;
import com.test.bean.Point;
public class PointAction extends ActionSupport {
private Point point;
private String username;
private int age;
private Date date;
public Point getPoint() {
return point;
}
public void setPoint(Point point) {
this.point = point;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
@Override
public String execute() throws Exception {
return SUCCESS;
}
}

java 代码

"1.0" encoding="UTF-8" ?>
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts></struts>
<package name="wjl_struts" extends="struts-default">
"login" class="com.test.action.LoginAction">
"input">/login.jsp
"success">/result.jsp
"failed">/login.jsp
"pointConvert" class="com.test.action.PointAction">
"success">/output.jsp
package>

xml 代码

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
>
<html>
<head>
<base href="">
<title>My JSP 'input.jsp' starting pagetitle>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
head>
<body>
<s:form action="pointConvert">
<s:textfield name="point" label="Point">s:textfield>
<s:textfield name="username" label="username">s:textfield>
<s:textfield name="age" label="age">s:textfield>
<s:textfield name="date" label="date">s:textfield>
<s:submit label="submit">s:submit>
s:form>
body>
html>

xml 代码

<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
>
<html>
<head>
<base href="">
<title>My JSP 'output.jsp' starting pagetitle>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
head>
<body>
Point:<s:property value="point"/><br/>
Username:<s:property value="username"/><br/>
Age:<s:property value="age"/><br/>
Date:<s:property value="date"/><br/>
body>
html>