struts2其实主要充当MVC模式的View层,主要是为了代替Servlet获取请求参数那些繁琐的操作。它提供的功能主要有如下2点:
1.通过属性绑定和模型绑定来简化传统servlet需要使用request对象来getParameter。
2.运用了AOP的设计思想,使用拦截器来扩展功能
3.提供了一个json库来处理异步请求
4.文件上传
下面就来说一下这两个功能的实现方式和遇到的坑,这里要特别注意的是,需要清楚自己的struts2版本,因为版本的差异会导致配置的细微差别,因为这个原因我也踩了很多坑,这里我的struts版本是2.5.8
一、传统的接收表单参数并获取(这里将会具体介绍struts2的配置)
1.首先在 web.xml
中加入过滤器配置,这里也是根据struts2的具体版本来配置,可以在官网下载完整版,看一下apps里面的源代码,拷贝过来即可。
<!-- struts2 filter -->
<filter>
<filter-name>action2</filter-name>
<filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<!-- END SNIPPET: filter -->
2.在项目的 src
目录下新建一个 struts.xml
文件,DOCTYPE头信息也可以拷贝下载回来的项目的代码,一下是配置文件的基本结构。
<?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>
</struts>
3.然后可以在这个文件中进行具体路由action的配置,也可以使用include命令把配置文件分出去,代码如下(要注意的是这里的file路径写的是src之后的路径,一开始不用带斜杠)
<include file="com/xiaoxiaohei/action/hello.xml"></include>
4.配置package。在这里,name属性是自定义的,唯一就好,extends固定为struts-default(后面说道json的时候才需要改),namespace以斜杠开始后面可以跟上一些自定义的名称:
<package name="demo2" extends="struts-default" namespace="/">
</package>
5.配置package列面的action,这就是具体的路由配置了,具体是一个url(name)指向一个类(class)里面的一个方法(method),如果没定义method,默认是execute方法(这里也要注意的是,不如果引入额外的包,可能导致默认调用的方法是index),代码如下:
<action name="data3" class="com.xiaoxiaohei.form.DataDemo3Action" ></action>
为了减少代码,也可以使用通配符进行配置。不过这里有个坑,我使用的2.5.8版本需要先在(package标签外面struts标签内部加上如下代码):
<constant name="struts.enable.DynamicMethodInvocation" value="true" />
然后在package里面加上如下代码:
<!-- 必须写action在前面 -->
<global-allowed-methods>regex:.*</global-allowed-methods>
才可以进行通配符的配置:
<action name="customer_*" class="com.xiaoxiaohei.interceptor.CustomerAction" method="{1}">
</action>
在action的里面,可以设置result标签,根据返回值来重定向到页面:
<result name="success">success.jsp</result>
6.配置好之后先上一个简单的表单页面:
<%@ page language="java" contentType="text/html; charset=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>login</h1>
<form action="${pageContext.request.contextPath}/customer_login.action" method="post" enctype="multipart/form-data">
username:<input name="username" type="text" > <br>
password:<input name="password" type="text" > <br>
ok:<input type="submit">
</form>
</body>
</html>
在页面中向服务器传username和password参数。
7.后台数据的获取:
首先需要创建一个action类来继承ActionSupport,然后实现execute方法,模板如下。
public class Form1DemoAction extends ActionSupport {
@Override
public String execute() {
return NONE;
}
}
a.第一种获取参数的方法:实现ServletRequestAware接口
public class Form1DemoAction extends ActionSupport implements ServletRequestAware {
private HttpServletRequest request;
@Override
public String execute() throws Exception {
// TODO Auto-generated method stub
System.out.println("start");
//1.get ActionContext
ActionContext context = ActionContext.getContext();
//2.get params
Map<String,Parameter> map = context.getParameters();
Set<String> keys = map.keySet();
for(String key : keys) {
Parameter obj = map.get(key);
System.out.println(key + "=" + Arrays.toString(obj.getMultipleValues()));
}
return NONE;
}
@Override
public void setServletRequest(HttpServletRequest request) {
// TODO Auto-generated method stub
this.request = request;
}
}
b.第二种方法:使用ServletActionContext对象类获取servlet的request对象:
public class Form2DemoAction extends ActionSupport {
@Override
public String execute() throws Exception {
// TODO Auto-generated method stub
HttpServletRequest request = ServletActionContext.getRequest();
request.setAttribute("req", "reqValue");
HttpSession session = request.getSession();
session.setAttribute("sess", "sessionValue");
ServletContext context = ServletActionContext.getServletContext();
context.setAttribute("context", "contextValue");
String username = request.getParameter("username");
String password = request.getParameter("password");
String address = request.getParameter("address");
System.out.println(username + ":" + password + ":" + address);
return NONE;
}
}
c.使用属性驱动的方式进行封装(在action中定义字段和相应的get set方法):
public class DataDemo1Action extends ActionSupport {
private String username;
private String password;
private String address;
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;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String execute() throws Exception {
// TODO Auto-generated method stub
System.out.println(username + "---" + password + "---" + address);
ActionContext context = ServletActionContext.getContext();
Map<String, Parameter> map = context.getParameters();
System.out.println("username=" + map.get("username"));
return NONE;
}
}
c.模型驱动(一般使用这个方法)。继承ModelDriven类
public class DataDemo2Action extends ActionSupport implements ModelDriven<User> {
private User user = new User();
@Override
public String execute() throws Exception {
// TODO Auto-generated method stub
System.out.println(this.user);
return NONE;
}
@Override
public User getModel() {
// TODO Auto-generated method stub
return this.user;
}
}
d.属性驱动也可以封装对象,不过jsp页面的name需要作出相应的修改,如下代码就是要改成user.username和user.password
<form action="${pageContext.request.contextPath}/data3.action" method="post">
username:<input name="user.username" type="text" > <br>
password:<input name="user.password" type="text" > <br>
ok:<input type="submit">
</form>
public class DataDemo3Action extends ActionSupport {
/**
*
*/
private static final long serialVersionUID = 1L;
private User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
@Override
public String execute() throws Exception {
// TODO Auto-generated method stub
System.out.println(user);
return NONE;
}
}
上面用到的Java bean如下
public class User {
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;
}
@Override
public String toString() {
return "User [username=" + username + ", password=" + password + "]";
}
}
二、拦截器,拦截器简单的说就是用来在action之前来做一些公共的操作(比如说action的访问权限等)。
1.首先定义一个拦截器类,继承MethodFilterInterceptor,在这里可以做一些操作,比如说获取session做一些校验等:
public class LoginInterceptor extends MethodFilterInterceptor {
@Override
protected String doIntercept(ActionInvocation invocation) throws Exception {
// TODO Auto-generated method stub
HttpServletRequest request = ServletActionContext.getRequest();
Object obj = request.getSession().getAttribute("user");
Object username = request.getSession().getAttribute("username");
System.out.println(obj);
System.out.println(username);
if(obj != null && obj instanceof User && ((User)obj).getUsername().equals("admin")) {
return invocation.invoke();
}
return "failed";
}
}
2.在struts.xml中配置与具体action的关联,先在interceptors中声明,然后在action中使用,注意:如果还需使用系统内部提供的拦截器,那么需要加上一条name=”defaultStack”的拦截器配置:
<package name="demo2" extends="struts-default" namespace="/">
<!-- 必须写在action前面 -->
<interceptors>
<interceptor name="loginInterceptor" class="com.xiaoxiaohei.interceptor.LoginInterceptor"></interceptor>
</interceptors>
<!-- 必须写action在前面 -->
<global-allowed-methods>regex:.*</global-allowed-methods>
<action name="customer_*" class="com.xiaoxiaohei.interceptor.CustomerAction" method="{1}">
<interceptor-ref name="loginInterceptor">
<param name="excludeMethods">login</param>
</interceptor-ref>
<interceptor-ref name="defaultStack"></interceptor-ref>
<result name="login" type="json">
<param name="root">map</param>
</result>
<result name="failed">failed.jsp</result>
<result name="success">success.jsp</result>
</action>
</package>
三、返回json对象
1.首先引入必要的两个包:
struts2-json-plugin-2.5.8.jar
json-lib-2.3-jdk15.jar
2.把package的extends改成json-default
<package name="demo2" extends="json-default" namespace="/">
在result中定义一个param指定返回的字段(如果不指定,默认返回ModelDriven的Java bean):
<result name="login" type="json">
<param name="root">map</param>
</result>
然后在相应的action类中定义一个成员变量和上面配置的变量名一样就好,就上面的配置,我就需要定义个名为map的变量,声明get/set方法:
private Map<String, Object> map = new HashMap<>();
public String login() throws Exception {
System.out.println(user);
map.put("abc", "aaaaa");
return "login";
}
四、这里再补充说一下文件上传,就贴上代码就好,只需要注意action类的那几个file相关的变量名是固定的就好,input[type=file]标签的name名字要和action类的File对象的变量名保持一致:
<%@ page language="java" contentType="text/html; charset=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>login</h1>
<form action="${pageContext.request.contextPath}/customer_login.action" method="post" enctype="multipart/form-data">
username:<input name="username" type="text" > <br>
password:<input name="password" type="text" > <br>
file:<input type="file" name="file">
ok:<input type="submit">
</form>
</body>
</html>
public class CustomerAction extends ActionSupport implements ModelDriven<User> {
private User user = new User();
private File file;
private String fileFileName;
private String fileContentType;
private Map<String, Object> map = new HashMap<>();
public Map<String, Object> getMap() {
return map;
}
public void setMap(Map<String, Object> map) {
this.map = map;
}
public File getFile() {
return file;
}
public void setFile(File file) {
this.file = file;
}
public String getFileFileName() {
return fileFileName;
}
public void setFileFileName(String fileFileName) {
this.fileFileName = fileFileName;
}
public String getFileContentType() {
return fileContentType;
}
public void setFileContentType(String fileContentType) {
this.fileContentType = fileContentType;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
@Override
public String execute() throws Exception {
// TODO Auto-generated method stub
return NONE;
}
public String login() throws Exception {
System.out.println(user);
if ("admin".equals(user.getUsername())) {
//session
ServletActionContext.getRequest()
.getSession().setAttribute("user", user);
ServletActionContext.getRequest()
.getSession().setAttribute("username", user.getUsername());
map.put("abc", "aaaaa");
String root = ServletActionContext.getServletContext().getRealPath("/upload");
InputStream is = new FileInputStream(file);
OutputStream os = new FileOutputStream(new File(root, fileFileName));
System.out.println("fileFileName=" + fileFileName);
System.out.println("File:" + file.getName());
System.out.println("file:" + file.getPath());
byte[] buffer = new byte[500];
int length = 0;
while(-1 != (length=is.read(buffer, 0, buffer.length))) {
os.write(buffer, 0, length);
}
os.close();
is.close();
return "login";
} else {
ServletActionContext.getRequest()
.getSession().removeAttribute("user");
ServletActionContext.getRequest()
.getSession().removeAttribute("username");
return "failed";
}
}
public String loginSuccess() {
return "login";
}
@Override
public User getModel() {
// TODO Auto-generated method stub
return user;
}
}