接收参数 示例源码下载
Struts2接收参数有三种方式,
Servlet API
getter和Setter方法
模型驱动
Servlet API
@Action(value = "register") public void register() {
ActionContext context = ActionContext.getContext();
HttpServletRequest httpServletRequest = (HttpServletRequest) context.get(StrutsStatics.HTTP_REQUEST);
String username = httpServletRequest.getParameter("username");
String password = httpServletRequest.getParameter("password");
System.out.println("username:" + username + " password:" + password);
}getter和Setter方法
private String username;
private String password; public String getUsername() { return username;
} public void setUsername(String username) { this.username = username;
} public String getPassword() { return password;
} public void setPassword(String password) { this.password = password;
}
@Action(value = "register") public void register() {
System.out.println("username:" + username + " password:" + password);
}当然你也可以使用JavaBean进行接收参数,类似下面这样,前端传递的name属性需要有些变动,name属性需要改成xxxx.xxx与属性名一致
<form action="register.action" method="get"> <input name="user.username" type="text"> <input name="user.password" type="text"> <input type="submit"> </form>
private User user; public User getUser() { return user;
} public void setUser(User user) { this.user = user;
}
@Action(value = "register") public void register() {
System.out.println("username:" + user.getUsername() + " password:" + user.getPassword());
}模型驱动
@ParentPackage("default")public class RegisterAction implements ModelDriven<User> { private User user = new User(); @Override
public User getModel() { return user;
}
@Action(value = "register") public void register() {
System.out.println("username:" + user.getUsername() + " password:" + user.getPassword());
}
}
参数校验 示例源码下载
对于前端传递的参数来讲,存在太多不稳定性,所以对于参数的校验是必不可少的,对于校验来说大体上分为两种,一种是前端校验,一种是后端校验,前端校验的方法在这里就不再累述,这里仅仅讲述Struts2如何使用Validation校验框架
获取参数
private String username; private String password; getter and setter......
在Action同级目录增加
<!DOCTYPE validators PUBLIC "-//Apache Struts//XWork Validator 1.0.2//EN" "http://struts.apache.org/dtds/xwork-validator-1.0.2.dtd"><validators> <!-- 要对哪个属性进行验证 --> <field name="username"> <!-- 验证规则 --> <field-validator type="requiredstring"> <!-- 违反规则的提示 --> <message>用户名不能为null!</message> </field-validator> </field> <field name="password"> <field-validator type="requiredstring"> <message>密码不能为null</message> </field-validator> </field></validators>
核心Action(这里可以看到如果校验正确跳转 "/success.jsp",如果校验失败错误信息输出在"/form.jsp")
@Override
@Action(value = "register", results = { @Result(name = SUCCESS, location = "/success.jsp"), @Result(name = INPUT,location = "/form.jsp")
})
public String execute() throws Exception { System.out.println("username"+username+"password:"+password); return SUCCESS;
}下载本小节源码访问http://localhost:8080/form.jsp
数据转换 示例源码下载
WEB系统都是基于网页形式的,接收到的信息都是字符串,Java又是强类型的语言,所以必须需要一个转换的过程.而Struts2的类型转换是基于OGNL表达式的,只需要将表单中的name属性根据OGNL规则命名就能转换成相应的Java类型,通常情况下哦我们无需建立自己的类型转换器,Struts2的内建转换器完全能帮助我们完成任务
例如我们有下面一个需求(包含Integer,Date,数组的转换)
我们该怎么办呢?不不不~~~~我们什么都不用做正常编写Action就行了,Struts2会自动帮我们进行转换
public class RegisterAction extends ActionSupport implements ModelDriven<User> { private User user = new User(); @Override
public User getModel() { return user;
} @Override
@Action(value = "register", results = { @Result(name = SUCCESS, location = "/success.jsp")
})
public String execute() throws Exception { System.out.println(user.toString()); return SUCCESS;
}
}好吧,真的没什么挑战力,下面我们要自己实现转换器了
例如:我们需要将字符串"自行车,1033,100"转换为Java的Product对象
自定义转换器
public class StringToProductTypeConverter extends DefaultTypeConverter {
@Override
public Object convertValue(Map context, Object value, Class toType) { if (toType == Product.class) { String[] params = (String[]) value; Product product = new Product(); String[] productValues = params[0].split(",");
product.setProductName(productValues[0].trim());
product.setPrice(Float.parseFloat(productValues[1].trim()));
product.setCount(Integer.parseInt(productValues[2].trim())); return product;
} else if (toType == String.class) { Product product = (Product) value; return product.toString();
} return null;
}
}配置全局转换器(在WEB-INF\classes目录新建xwork-conversion.properties)
com.jimisun.action.Product=com.jimisun.action.StringToProductTypeConverter
在Action中接收(不要使用模型驱动方式接收参数,接收不到)
public class ProductAction extends ActionSupport { private Product product;
public Product getProduct() { return product;
}
public void setProduct(Product product) { this.product = product;
} @Override
@Action(value = "register", results = { @Result(name = SUCCESS, location = "/success.jsp")
})
public String execute() throws Exception { System.out.println(product.toString()); return SUCCESS;
}
}响应数据 示例源码下载
我们一直都没有探讨一个问题,那就是Struts2的结果的响应.对于任何一个程序而言,最重要的莫过于输入和输出,当我们了解了Struts2接收参数后,现在我们一起来看一看Struts2如何响应参数吧
Servlet API存取值
属性值存取值
值栈Set方法存取值
值栈Push方法存取值
Servlet API存取值
ActionContext context = ActionContext.getContext();
HttpServletRequest request = (HttpServletRequest) context.get(StrutsStatics.HTTP_REQUEST); request.setAttribute("requestValue","requestValue");<%--从Servlet API的Request域对象中取值--%> Request取值:<s:property value="#request.requestValue"/>
属性值存取值
private User user = new User("jimisun", "jimisun");<%--获取属性值--%> 简单属性取值:<s:property value="user.username"/>
那么对于复杂的属性存取值我们可以这样,例如List
private List<User> list = new ArrayList<>();
User user1 = new User("list1","list1");
User user2 = new User("list2","list2"); list.add(user1); list.add(user2);<%--获取属性List值--%>list属性取值:<br><s:iterator value="list" var="user"> <s:property value="#user.username"/> <s:property value="#user.password"/> <br/></s:iterator>
值栈Set方法存取值
ActionContext context = ActionContext.getContext();
ValueStack valueStack = context.getValueStack();
valueStack.set("valueStackDemo", "valueStackDemoSet");<%--值栈Set方法取值--%> 值栈set取值:<s:property value="valueStackDemo"/>
值栈Push方法存取值
ActionContext context = ActionContext.getContext();
ValueStack valueStack = context.getValueStack();
valueStack.push("valueStackPush");<%--值栈Push方法取值--%> 值栈push取值:<s:property value="[0].top"/>
OK,现在对于Struts2的几种数据的响应方式我们大概已经知道了,现在我们来看一看这几种存储数据方式在值栈中的结构,在本小节源码中运行项目直接访问http://localhost:8080/outputdate.action即可
注意点:使用OGNL表达式访问"根"对象中的对象及属性时,不需要前面加"#"号
文件上传 示例源码下载
对于文件上传功能Struts2并没有提出自己的解决方案,但是Struts2为文件上传提供了统一的接口,开发人员在使用上传文件的组件时,并不需要知道太多的细节就可以轻松使用他们,Struts2目前支持三种上传文件组件Commons-FileUpload,cos,pell,例如我们使用Commons-FileUpload为例来快速学习文件上传功能
commons-fileupload依赖(已经内置,无须再次添加)
struts.properties相关配置
struts.multipart.parser=jakarta struts.multipart.maxSize=2097152
核心上传代码
@Action(value = "UploadAction", params = {"uploadPath", "D:/"}, results = { @Result(name = "success", location = "/result.jsp")
}) public String execute() throws Exception {
String fn = ""; if (filename.equals("")) {
fn = uploadPath + uploadFileName;
} else {
fn = uploadPath + filename;
} if (new File(fn).exists()) {
result = "该文件已经存在!";
} else {
FileOutputStream fileOutputStream = new FileOutputStream(fn);
InputStream inputStream = new FileInputStream(upload); byte[] buffer = new byte[8192]; int count = 0; while ((count = inputStream.read(buffer)) > 0) {
fileOutputStream.write(buffer, 0, count);
}
fileOutputStream.close();
inputStream.close();
result = "文件上传成功!";
} return "success";
}下面我们再进行展示同时上传多个文件的示例,对于同时上传多个文件,我们仅仅需要做一点改变即可,即接收值的属性改成数组或者List集合
private File[] upload; private String[] uploadFileName;
@Action(value = "UploadAction", params = {"uploadPath", "D:/"}, results = { @Result(name = "success", location = "/result.jsp")
}) public String execute() throws Exception { for (int i = 0; i < uploadFileName.length; i++) {
String fn = uploadPath + uploadFileName[i];
FileOutputStream fileOutputStream = new FileOutputStream(fn);
InputStream inputStream = new FileInputStream(upload[i]); byte[] buffer = new byte[8192]; int count = 0; while ((count = inputStream.read(buffer)) > 0) {
fileOutputStream.write(buffer, 0, count);
}
fileOutputStream.close();
inputStream.close();
}
result = "文件上传成功!"; return "success";
}我们了解了文件上传那么现在我们再来一起看一下文件的下载,再Struts2中提供了一种使用Stream下载文件的方式,类似于文件和浏览器的一个"代理",通过这个"代理"我们就能控制某某下载文件,如下是一个Download的Action
public InputStream getFileInputStream() { // 以及文件的mime类型以及创建流
ServletContext context = ServletActionContext.getServletContext();
contentType = context.getMimeType(context.getRealPath(filePath + "/" + fileName));
setContentType(contentType); return context.getResourceAsStream(filePath + "/" + fileName);
} @Override
@Action(value = "download", params = {"filePath", "/file"}, results = { @Result(name = SUCCESS, type = "stream",
params = {"contentType", "${contentType}", "inputName", "fileInputStream", "contentDisposition", "attachment;filename=\"${fileName}\""})
}) public String execute() throws Exception { return SUCCESS;
}异常处理 示例源码下载
异常处理是任何成熟的MVC框架必备的功能,在Struts2中提供了异常的拦截器,我们可以在struts.xml文件中进行配置异常,以灵活的方式处理异常
配置全局异常
<package name="default" extends="struts-default" namespace="/"> <global-results> <result name="exception">/error.jsp</result> </global-results> <global-exception-mappings> <exception-mapping exception="java.sql.SQLException" result="exception"></exception-mapping> </global-exception-mappings> ... </package>
模拟异常
@ParentPackage("default")
public class ExceptionAction extends ActionSupport { @Override
@Action(value = "testerror", results = { @Result(name = SUCCESS, location = "/success.jsp")
})
public String execute() throws Exception { if ("a".equals("a")) { throw new SQLException("SQL错误!!!");
} return SUCCESS;
}
}当发生异常后就会跳转到所配置的error.jsp页面
国际化支持 示例源码下载
Struts2的国际化支持是建立在Java对国际化的支持之上的,对Java的国际化支持进行了封装,下面我们来针对一段优美的诗,我们我们将会展示中文和英文两种页面给访问者
我那美丽的女孩
我的挚爱
无论梦里梦外
去去来来抬头眺望云端
高不可攀
低头忆你容颜
温柔绚烂
配置Struts2全局资源文件(使用下面两种方式都可以)
在struts.properties中配置 struts.custom.i18n.resources=Resource
在struts.xml中配置<constant name="struts.custom.i18n.resources" value="Resource"/>
创建两个资源文件(中文和英文)
Resource_en_US.properties
welcome = hello,{0}content = My beautiful girl, my love, my dream, my dream, my dream, my dream, my dreamResource_zh_CN.properties
welcome = 你好,{0}content = 我那美丽的女孩 我的挚爱 无论梦里梦外 去去来来 抬头眺望云端 高不可攀 低头忆你容颜 温柔绚烂在Action中使用
public class BeautifulGirlAction extends ActionSupport { private String username; private String content; private String welcome; @Override
@Action(value = "girl", results = { @Result(name = SUCCESS, location = "/success.jsp")
})
public String execute() throws Exception {
welcome = getText("welcome", new String[]{username});
content = getText("content"); return SUCCESS;
}
...
}通过下载本小节示例源码访问http://localhost:8080/form.jsp
本章总结
在WEB应用中常见的功能是很多的,很多场景下Struts2都为我们提供了响应的解决方案,本章叙述中在下主要讲述了Struts2的常见的功能的基本使用,即只有广度而没有深度,更为深度的学习还希望小伙伴们查阅相关资料,例如OGNL表达式等...