struts1之簡(jiǎn)單mvc示例_動(dòng)力節(jié)點(diǎn)Java學(xué)院整理

更新時(shí)間：2017年09月04日 11:35:39 作者：lfsf802

這篇文章主要介紹了struts1之簡(jiǎn)單mvc示例的相關(guān)資料,需要的朋友可以參考下

先看MVC模式流程圖（其實(shí)MVC設(shè)計(jì)模式就是java中的model2。）：

就像圖上所標(biāo)識(shí)的C層主要是Servlet層控制頁面跳轉(zhuǎn)，M層就是具體的業(yè)務(wù)處理邏輯，而JSP就是所謂的V層。MVC是有別于我們所說的三層，我們平常所說的三層是UI層、BLL層、DAL層，具體的區(qū)別如圖：

從圖上能看出來，JSP和Servlet構(gòu)成了UI層，而Model層分成了BLL層和DAL層（也就是業(yè)務(wù)邏輯和數(shù)據(jù)持久層）。

從理論上認(rèn)清了MVC設(shè)計(jì)模式之后，下面開始動(dòng)手敲一個(gè)MVC設(shè)計(jì)模式示例代碼：

JSP索引頁面index.jsp：

<%@ page language="java" contentType="text/html; charset=GB18030" 
 pageEncoding="GB18030"%> 
<!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=GB18030"> 
<title>Insert title here</title> 
</head> 
<body> 
 <form action="servlet/addUser.action" method="post"> 
  姓名：<input type="text" name="username" > 
  <input type="submit" value="提交"> 
 </form> 
  
</body> 
</html>

業(yè)務(wù)邏輯代碼UserManager：

package com.bjpowernode.servlet; 
 
import java.util.ArrayList; 
import java.util.List; 
 
public class UserManager { 
  
 public void addUser(String username){ 
  System.out.println("UserManager.addUsre()--->username:"+username); 
 } 
  
 public void delUser(String username){ 
  System.out.println("UserManager.delUser()--->username:"+username); 
 } 
  
 public void modifyUser(String username){ 
  System.out.println("UserManager.modifyUser()--->username"+username); 
 } 
  
 public List queryUser(String username){ 
  System.out.println("UserManager.queryUser()--->username"+username); 
  List userList=new ArrayList(); 
  userList.add("a"); 
  userList.add("b"); 
  userList.add("c"); 
  return userList; 
 } 
}

Servlet控制代碼：

package com.bjpowernode.servlet; 
 
import java.io.IOException; 
import java.util.List; 
 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
public class TestServlet extends HttpServlet { 
 
  
 protected void doGet(HttpServletRequest request, HttpServletResponse response) 
   throws ServletException, IOException { 
   
  String requestURI=request.getRequestURI(); 
  System.out.println("request="+requestURI); 
  String path=requestURI.substring(requestURI.indexOf("/",1),requestURI.indexOf(".")); 
  System.out.println("path="+path); 
   
  String username=request.getParameter("username"); 
  UserManager userManager=new UserManager(); 
  //userManager.addUser(username); 
  String forward=""; 
  if("/servlet/delUser".equals(path)){ 
   userManager.delUser(username); 
   forward="/del_success.jsp"; 
  }else if("/servlet/addUser".equals(path)){ 
   userManager.addUser(username); 
   forward="/add_success.jsp"; 
  }else if("/servlet/modifyUser".equals(path)){ 
   userManager.modifyUser(username); 
   forward="/modify_success.jsp"; 
  }else if("/servlet/queryUser".equals(path)){ 
   List userList=userManager.queryUser(username); 
   request.setAttribute("userList", userList); 
   forward="/query_success.jsp"; 
  }else{ 
   throw new RuntimeException("請(qǐng)求失敗"); 
  } 
  request.getRequestDispatcher(forward).forward(request, response); 
 
}

這個(gè)servlet代碼主要實(shí)現(xiàn)的功能判斷是那個(gè)頁面請(qǐng)求服務(wù)器做那些操作，之后調(diào)用業(yè)務(wù)邏輯實(shí)現(xiàn)相應(yīng)業(yè)務(wù)操作。

配置Servlet：

<?xml version="1.0" encoding="UTF-8"?> 
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> 
 <display-name>test_Servlet</display-name> 
 <welcome-file-list> 
 <welcome-file>index.html</welcome-file> 
 <welcome-file>index.htm</welcome-file> 
 <welcome-file>index.jsp</welcome-file> 
 <welcome-file>default.html</welcome-file> 
 <welcome-file>default.htm</welcome-file> 
 <welcome-file>default.jsp</welcome-file> 
 </welcome-file-list> 
 
 <servlet> 
 <servlet-name>TestServlet</servlet-name> 
 <servlet-class>com.cjq.servlet.TestServlet</servlet-class> 
 </servlet> 
 <servlet-mapping> 
 <servlet-name>TestServlet</servlet-name> 
 <url-pattern>*.action</url-pattern> 
 </servlet-mapping> 
 
 
</web-app>

輸出結(jié)果：

通過上面的示例已經(jīng)對(duì)MVC設(shè)計(jì)模式有了初步的認(rèn)識(shí)，其實(shí)這個(gè)示例是對(duì)Struts框架學(xué)習(xí)的基礎(chǔ)，只有弄清楚了這個(gè)實(shí)例才能弄清楚Struts框架的實(shí)現(xiàn)原理和Struts框架使用。

那么我們?cè)趺床拍芡ㄟ^這個(gè)示例引入Struts框架呢？這個(gè)問題從IF-Eles開始。

首先我們看到了TestServlet中出現(xiàn)了許多if-else語句，這樣是非常不穩(wěn)定的，這樣的程序是非常不靈活的，以后如果有變化，那么維護(hù)是非常差的；而且我們?cè)趇f-else中出現(xiàn)了大量的字符串，這樣在coding的時(shí)候會(huì)出現(xiàn)寫錯(cuò)，這樣無形中給調(diào)試帶來了麻煩。所以去掉if-else成了我們重構(gòu)的第一步，也是我們進(jìn)行Struts框架學(xué)習(xí)的第一步。因?yàn)樵赥estServlet中出現(xiàn)了If-Else語句塊，所以讓程序變得不再靈活，讓應(yīng)付需求變化時(shí)變得笨拙。所以就承接上篇文章來重構(gòu)一下TestServlet代碼，主要是用繼承多態(tài)來進(jìn)一步對(duì)TestServlet進(jìn)行重構(gòu)。

下面進(jìn)入重構(gòu)階段：

package com.bjpowernode.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TestServlet extends HttpServlet {

 
 protected void doGet(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 
 String requestURI=request.getRequestURI();
 System.out.println("request="+requestURI);
 String path=requestURI.substring(requestURI.indexOf("/",1),requestURI.indexOf("."));
 System.out.println("path="+path);
 
 String username=request.getParameter("username");
 UserManager userManager=new UserManager();
 //userManager.addUser(username);
 String forward="";
 if("/servlet/delUser".equals(path)){
 userManager.delUser(username);
 forward="/del_success.jsp";
 }else if("/servlet/addUser".equals(path)){
 userManager.addUser(username);
 forward="/add_success.jsp";
 }else if("/servlet/modifyUser".equals(path)){
 userManager.modifyUser(username);
 forward="/modify_success.jsp";
 }else if("/servlet/queryUser".equals(path)){
 List userList=userManager.queryUser(username);
 request.setAttribute("userList", userList);
 forward="/query_success.jsp";
 }else{
 throw new RuntimeException("請(qǐng)求失敗");
 }
 request.getRequestDispatcher(forward).forward(request, response);
  }
}

首先我們看到了在每個(gè)語句塊中都出現(xiàn)了給forward賦值，其實(shí)也就是給頁面跳轉(zhuǎn)的路徑賦值，針對(duì)每個(gè)請(qǐng)求路徑判斷來賦值跳轉(zhuǎn)路徑。另外每個(gè)IF-Else語句塊中都有業(yè)務(wù)處理，我們要把這些業(yè)務(wù)處理分別放到類里面，讓職責(zé)更加單

一，這樣更加符合面向?qū)ο蟮乃悸贰?/p>

就從這里我們開始重構(gòu)，我們可以將這個(gè)跳轉(zhuǎn)路徑和業(yè)務(wù)邏輯封裝起來。

既然封裝，那么我們就抽象出來一個(gè)借口，主要完成一個(gè)方法，這個(gè)方法主要的功能就是要完成業(yè)務(wù)邏輯封裝和路徑跳轉(zhuǎn)的返回。隨后建立四個(gè)類，主要實(shí)現(xiàn)相應(yīng)的增刪改查的業(yè)務(wù)處理和處理之后的跳轉(zhuǎn)路徑返回。

代碼如下：

接口Action：

package com.bjpowernode.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public interface Action {
 
 public String execute(HttpServletRequest request,HttpServletResponse response)
 throws Exception;
}

增刪改查實(shí)現(xiàn)類：

添加用戶實(shí)現(xiàn)類：

package com.bjpowernode.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AddUserAction implements Action {

 
 public String execute(HttpServletRequest request,
 HttpServletResponse response) throws Exception {
 String username=request.getParameter("username");
 UserManager userManager=new UserManager();
 userManager.addUser(username);
 return "/add_success.jsp";
 }

}

刪除用戶實(shí)現(xiàn)類：

package com.bjpowernode.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DelUserAction implements Action {


 public String execute(HttpServletRequest request,
 HttpServletResponse response) throws Exception {
 String username=request.getParameter("username");
 UserManager userManager=new UserManager();
 userManager.delUser(username);
 return "/del_success.jsp";
 }

}

更新用戶實(shí)現(xiàn)類：

package com.bjpowernode.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ModifyUserAction implements Action {

 @Override
 public String execute(HttpServletRequest request,
 HttpServletResponse response) throws Exception {
 String username=request.getParameter("username");
 UserManager userManager=new UserManager();
 userManager.modifyUser(username);
 return "/modify_success.jsp";
 }

}

查詢用戶實(shí)現(xiàn)類：

package com.bjpowernode.servlet;

import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class QueryUserAction implements Action {

 @Override
 public String execute(HttpServletRequest request,
 HttpServletResponse response) throws Exception {
 String username=request.getParameter("username");
 UserManager userManager=new UserManager();
 List userList=userManager.queryUser(username);
 request.setAttribute("userList", userList);
 return "/query_success.jsp";
 }

}

TestServlet類重構(gòu)如下：

package com.bjpowernode.servlet;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class TestServlet extends HttpServlet {

 
 protected void doGet(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 
 String requestURI=request.getRequestURI();
 System.out.println("request="+requestURI);
 String path=requestURI.substring(requestURI.indexOf("/",1),requestURI.indexOf("."));
 System.out.println("path="+path);
 
 Action action=null;
 if("/servlet/delUser".equals(path)){
 action=new DelUserAction();
 }else if("/servlet/addUser".equals(path)){
 action=new AddUserAction();
 }else if("/servlet/modifyUser".equals(path)){
 action=new ModifyUserAction();
 }else if("/servlet/queryUser".equals(path)){
 action=new QueryUserAction();
 }else{
 throw new RuntimeException("請(qǐng)求失敗");
 }
 String forward=null;
 try{
 forward=action.execute(request, response);
 }catch(Exception e){
 e.printStackTrace();
 }
 request.getRequestDispatcher(forward).forward(request, response);
  }
}

運(yùn)行結(jié)果：

這樣TestServlet類雖然沒有徹底去掉If-Else，但是這樣的代碼變得更加簡(jiǎn)練，利用多肽實(shí)現(xiàn)業(yè)務(wù)邏輯處理和路徑跳轉(zhuǎn)返回。職責(zé)更加清晰，讓維護(hù)變得更加輕松。

package com.bjpowernode.servlet; 
 
import java.io.IOException; 
import java.util.List; 
 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
public class TestServlet extends HttpServlet { 
 
   
  protected void doGet(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
     
    String requestURI=request.getRequestURI(); 
    System.out.println("request="+requestURI); 
    String path=requestURI.substring(requestURI.indexOf("/",1),requestURI.indexOf(".")); 
    System.out.println("path="+path); 
     
 
    Action action=null; 
    if("/servlet/delUser".equals(path)){ 
      action=new DelUserAction(); 
    }else if("/servlet/addUser".equals(path)){ 
      action=new AddUserAction(); 
    }else if("/servlet/modifyUser".equals(path)){ 
      action=new ModifyUserAction(); 
    }else if("/servlet/queryUser".equals(path)){ 
      action=new QueryUserAction(); 
    }else{ 
      throw new RuntimeException("請(qǐng)求失敗"); 
    } 
    String forward=null; 
    try{ 
      forward=action.execute(request, response); 
    }catch(Exception e){ 
      e.printStackTrace(); 
    } 
    request.getRequestDispatcher(forward).forward(request, response); 
   } 
}

解決字符串問題，當(dāng)然就要用到配置文件了，用到配置文件就要有用來讀取配置文件的相關(guān)的類和方法，這里就用dom4j中的類來讀取配置文件，這里的配置文件的書寫是有點(diǎn)邏輯上的難度的。

我們來看TestServlet中的代碼，我們要在這個(gè)testservlet中實(shí)現(xiàn)讀取配置文件和path比較，還有利用多肽實(shí)例化相應(yīng)的實(shí)現(xiàn)類，最后通過實(shí)例化的實(shí)現(xiàn)類的方法來返回跳轉(zhuǎn)路徑，最終跳轉(zhuǎn)到相應(yīng)的頁面。

所以我們的配置文件就要不僅配上testservlet中出現(xiàn)的字符串，還要配置相應(yīng)的Action接口的實(shí)現(xiàn)類（我們可以利用反射來實(shí)例化該類的對(duì)象，進(jìn)而使用這個(gè)類的所有屬性和方法），另外還有跳轉(zhuǎn)路徑字符串。這樣我們的配置文件就變成了如下代碼所示：

<?xml version="1.0" encoding="UTF-8"?> 
<action-config> 
  <action path="/servlet/delUser" type="com.cjq.servlet.DelUserAction"> 
    <forward name="success">/del_success.jsp</forward> 
    <forward name="error">/del_error.jsp</forward> 
  </action> 
   
  <action path="/servlet/addUser" type="com.cjq.servlet.AddUserAction"> 
    <forward name="success">/add_success.jsp</forward> 
    <forward name="error">/add_error.jsp</forward> 
  </action> 
   
  <action path="/servlet/modifyUser" type="com.cjq.servlet.ModifyUserAction"> 
    <forward name="success">/modify_success.jsp</forward> 
    <forward name="error">/modify_error.jsp</forward> 
  </action> 
   
  <action path="/servlet/queryUser" type="com.cjq.servlet.QueryUserAction"> 
    <forward name="success">/query_success.jsp</forward> 
    <forward name="error">/query_error.jsp</forward> 
  </action> 
   
</action-config>

我們有了配置文件之后就要想法通過相關(guān)類讀取，并且實(shí)現(xiàn)相應(yīng)的功能。所以這里用dom4j來讀取完成。其實(shí)如果能把這個(gè)邏輯捋順之后就能發(fā)現(xiàn)，其實(shí)懂我們利用dom4j讀取完配置文件的時(shí)候，我們是取得的是一個(gè)配套的匹配路徑字符串、相應(yīng)業(yè)務(wù)邏輯類還有處理業(yè)務(wù)邏輯之后跳轉(zhuǎn)頁面路徑字符串。這樣我們就能直截了當(dāng)?shù)娜サ袅薸f-else。（這里可能邏輯上會(huì)出現(xiàn)一些困難，但是看到下面的重構(gòu)之后的testservlet中的代碼和讀取配置文件之后的代碼就會(huì)一目了然）。

現(xiàn)在等待解決的問題就是我們要把從配置文件取得的一整套內(nèi)容放到那里，當(dāng)然這是毋庸置疑的要放到類中。所以我們就建立一個(gè)ActionMapping類來放我們的那一整套內(nèi)容。

ActionMapping中的代碼如下：

package com.bjpowernode.servlet; 
 
import java.util.Map; 
 
public class ActionMapping { 
 
  private String path; 
   
  private Object type; 
   
  private Map forwardMap; 
 
  public String getPath() { 
    return path; 
  } 
 
  public void setPath(String path) { 
    this.path = path; 
  } 
 
  public Object getType() { 
    return type; 
  } 
 
  public void setType(Object type) { 
    this.type = type; 
  } 
 
  public Map getForwardMap() { 
    return forwardMap; 
  } 
 
  public void setForwardMap(Map forwardMap) { 
    this.forwardMap = forwardMap; 
  } 
   
}

現(xiàn)在ActionMapping類已經(jīng)有了，剩下的工作就是要利用dom4j來讀取配置文件類，具體代碼如下：

package com.bjpowernode.servlet; 
 
import java.io.InputStream; 
import java.util.HashMap; 
import java.util.Iterator; 
import java.util.Map; 
 
import org.dom4j.Document; 
import org.dom4j.DocumentException; 
import org.dom4j.Element; 
import org.dom4j.io.SAXReader; 
 
public class XmlConfigReader { 
 
   
  private static XmlConfigReader instance=new XmlConfigReader(); 
   
  ActionMapping actionMapping=new ActionMapping(); 
   
  private Document doc; 
   
  private Map actionMap=new HashMap(); 
   
  private XmlConfigReader(){ 
    try { 
      SAXReader reader=new SAXReader(); 
       
      InputStream in=Thread.currentThread().getContextClassLoader().getResourceAsStream("action_config.xml"); 
       
      doc=reader.read(in); 
       
    } catch (DocumentException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } 
     
     
  } 
   
   
   
   
  public ActionMapping getActionMapping(String path){ 
    synchronized(this){ 
       
      Object type=null; 
      /*if(action.containsKey(path)){ 
        type=action.get(path); 
      }*/ 
       
       
      Element eltAction = (Element)doc.selectObject("http://action[@path=\"" + path + "\"]"); 
      try{ 
        type=Class.forName(eltAction.attributeValue("type")).newInstance(); 
      }catch(Exception e){ 
        e.printStackTrace(); 
      } 
       
       Element eltForwards = eltAction.element("forward"); 
         
        for (Iterator iter = eltForwards.elementIterator(); iter.hasNext();) { 
          Element eltForward = (Element) iter.next(); 
          actionMap.put( eltForward.attributeValue("name"),eltForward.getTextTrim());  
        }  
       
      actionMapping.setPath(path); 
      actionMapping.setType(type); 
      actionMapping.setForwardMap(actionMap); 
       
      return actionMapping; 
    } 
  } 
   
  public static synchronized XmlConfigReader getInstance(){ 
     
    return instance; 
  } 
   
   
  /** 
   * @param args 
   */ 
  public static void main(String[] args) { 
    // TODO Auto-generated method stub 
    ActionMapping actionMapping=XmlConfigReader.getInstance().getActionMapping("/servlet/delUser"); 
    System.out.println(actionMapping.getPath()); 
    System.out.println(actionMapping.getType()); 
    System.out.println(actionMapping.getForwardMap().toString()); 
  } 
 
}

我們通過返回ActionMapping來動(dòng)態(tài)創(chuàng)建出action相應(yīng)的實(shí)現(xiàn)類，進(jìn)而完成業(yè)務(wù)邏輯和頁面跳轉(zhuǎn)，重構(gòu)之后的TestServlet代碼如下：

package com.bjpowernode.servlet; 
 
import java.io.IOException; 
import java.util.List; 
 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
public class TestServlet extends HttpServlet { 
 
   
  protected void doGet(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
     
    String requestURI=request.getRequestURI(); 
    System.out.println("request="+requestURI); 
    String path=requestURI.substring(requestURI.indexOf("/",1),requestURI.indexOf(".")); 
    System.out.println("path="+path); 
     
 
    String forward=""; 
    ActionMapping actionMapping=XmlConfigReader.getInstance().getActionMapping(path); 
    Action action=(Action)actionMapping.getType(); 
    try { 
      forward=action.execute(request, response); 
    } catch (Exception e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } 
    request.getRequestDispatcher(forward).forward(request, response); 
  } 
 
   
  protected void doPost(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
    doGet(request,response); 
  } 
 
}

我們可以清晰的看到if-else已經(jīng)沒有了，字符串也已經(jīng)沒有了。通過這篇文章對(duì)if-else還有字符串問題的解決，又一次重構(gòu)了testservlet代碼，程序相對(duì)靈活許多。通過這一次的重構(gòu)，我們已經(jīng)看到了struts框架的雛形，

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