FLex調用servlet連接數據庫

本文轉帖自：http://blog.csdn.net/pengpeng2395/article/details/4157421#comments 

FLex調用servlet連接數據庫

前言

Flex 最重要的部分之一就是和服務器以及數據庫的通訊。Flex 提供了三個類來與服務器通訊： HTTPService，RemoteObject 以及WebService。

HTTPService 類提供了使用超文本傳輸協議（HTTP）與服務器通訊的方式。一個Flex 應用程序可以使用GET 或者POST 請求來發送數據到一個服務器並且處理這個請求返回的 XML 或者字符串。使用HTTPService 類，你可以與PHP 頁面,ColdFusion 頁面，JavaServe頁面（ jsp），Java servlet， Ruby onRails， 以及ASP 動態網頁通訊。

與Java Servlet通訊

由於本人是Java出身，所以這裏就來討論一下與Servlet的通訊方式。

建立數據庫

這裏選用MySql數據庫，首先建立如下的數據庫表

寫服務器端Java代碼

Servlet

[java] view plaincopyprint?

1. package servlet;  
2.   
3. import java.io.IOException;  
4. import java.io.PrintWriter;  
5. import java.util.List;  
6.   
7. import javax.servlet.ServletException;  
8. import javax.servlet.http.HttpServlet;  
9. import javax.servlet.http.HttpServletRequest;  
10. import javax.servlet.http.HttpServletResponse;  
11.   
12. import PODO.Product;  
13. import db.ProductDao;  
14.   
15. public class GetProductServlet extends HttpServlet {  
16.     List result;  
17.   
18.     /** 
19.      * Constructor of the object. 
20.      */  
21.     public GetProductServlet() {  
22.         super();  
23.     }  
24.   
25.     /** 
26.      * Destruction of the servlet. <br> 
27.      */  
28.     public void destroy() {  
29.         super.destroy(); // Just puts "destroy" string in log   
30.         // Put your code here   
31.     }  
32.   
33.     /** 
34.      * The doGet method of the servlet. <br> 
35.      *  
36.      * This method is called when a form has its tag value method equals to get. 
37.      *  
38.      * @param request 
39.      *            the request send by the client to the server 
40.      * @param response 
41.      *            the response send by the server to the client 
42.      * @throws ServletException 
43.      *             if an error occurred 
44.      * @throws IOException 
45.      *             if an error occurred 
46.      */  
47.     public void doGet(HttpServletRequest request, HttpServletResponse response)  
48.             throws ServletException, IOException {  
49.         result = new ProductDao().getProduct();  
50.         String xmlContent = "<?xml version='1.0' encoding='utf-8'?><products>";  
51.         response.setContentType("text/xml;charset=utf-8");  
52.         PrintWriter out = response.getWriter();  
53.         if (result != null) {  
54.             for (int i = 0; i < result.size(); i++) {  
55.                 Product p = (Product) result.get(i);  
56.                 xmlContent += "<product><name>" + p.getName() + "</name><type>"  
57.                         + p.getType() + "</type><price>" + p.getPrice()  
58.                         + "</price><num>" + p.getNum() + "</num></product>";  
59.             }  
60.             xmlContent += "</products>";  
61.             out.print(xmlContent);  
62.             out.flush();  
63.             out.close();  
64.         }  
65.   
66.     }  
67.   
68.     /** 
69.      * The doPost method of the servlet. <br> 
70.      *  
71.      * This method is called when a form has its tag value method equals to 
72.      * post. 
73.      *  
74.      * @param request 
75.      *            the request send by the client to the server 
76.      * @param response 
77.      *            the response send by the server to the client 
78.      * @throws ServletException 
79.      *             if an error occurred 
80.      * @throws IOException 
81.      *             if an error occurred 
82.      */  
83.     public void doPost(HttpServletRequest request, HttpServletResponse response)  
84.             throws ServletException, IOException {  
85.   
86.         this.doGet(request, response);  
87.     }  
88.   
89.     /** 
90.      * Initialization of the servlet. <br> 
91.      *  
92.      * @throws ServletException 
93.      *             if an error occurs 
94.      */  
95.     public void init() throws ServletException {  
96.         // Put your code here   
97.     }  
98. }  

package servlet;import java.io.IOException;import java.io.PrintWriter;import java.util.List;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import PODO.Product;import db.ProductDao;public class GetProductServlet extends HttpServlet { List result; /** * Constructor of the object. */ public GetProductServlet() { super(); } /** * Destruction of the servlet. <br> */ public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } /** * The doGet method of the servlet. <br> * * This method is called when a form has its tag value method equals to get. * * @param request * the request send by the client to the server * @param response * the response send by the server to the client * @throws ServletException * if an error occurred * @throws IOException * if an error occurred */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { result = new ProductDao().getProduct(); String xmlContent = "<?xml version='1.0' encoding='utf-8'?><products>"; response.setContentType("text/xml;charset=utf-8"); PrintWriter out = response.getWriter(); if (result != null) { for (int i = 0; i < result.size(); i++) { Product p = (Product) result.get(i); xmlContent += "<product><name>" + p.getName() + "</name><type>" + p.getType() + "</type><price>" + p.getPrice() + "</price><num>" + p.getNum() + "</num></product>"; } xmlContent += "</products>"; out.print(xmlContent); out.flush(); out.close(); } } /** * The doPost method of the servlet. <br> * * This method is called when a form has its tag value method equals to * post. * * @param request * the request send by the client to the server * @param response * the response send by the server to the client * @throws ServletException * if an error occurred * @throws IOException * if an error occurred */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); } /** * Initialization of the servlet. <br> * * @throws ServletException * if an error occurs */ public void init() throws ServletException { // Put your code here }}

數據庫連接

[java] view plaincopyprint?

1. public class MyConnection {  
2.     public Connection conn = null;  
3.   
4.     public MyConnection() {  
5.         try {  
6.             // 註冊數據庫驅動程序爲MYSQL驅動   
7.             Class.forName("com.mysql.jdbc.Driver");  
8.         } catch (java.lang.ClassNotFoundException e) {  
9.               
10.             System.err.println("mydb(): " + e.getMessage());  
11.         }  
12.   
13.         try {  
14.             conn = DriverManager.getConnection(  
15.                     "jdbc:mysql://127.0.0.1:3306/flex",  
16.                     "root", "root");  
17.         } catch (SQLException ex) {  
18.             System.err.println("conn:" + ex.getMessage());  
19.         }  
20.     }  
21.   
22.     public Connection getDbConnection() {  
23.         return conn;  
24.     }  
25. }  

public class MyConnection { public Connection conn = null; public MyConnection() { try { // 註冊數據庫驅動程序爲MYSQL驅動 Class.forName("com.mysql.jdbc.Driver"); } catch (java.lang.ClassNotFoundException e) { System.err.println("mydb(): " + e.getMessage()); } try { conn = DriverManager.getConnection( "jdbc:mysql://127.0.0.1:3306/flex", "root", "root"); } catch (SQLException ex) { System.err.println("conn:" + ex.getMessage()); } } public Connection getDbConnection() { return conn; }}

 

DAO

[c-sharp] view plaincopyprint?

1. public class ProductDao {  
2.     Connection conn;  
3.     ResultSet rs;  
4.     Statement stmt;  
5.   
6.     public ProductDao() {  
7.         conn = new MyConnection().getDbConnection();  
8.         try {  
9.             stmt = conn.createStatement();  
10.         } catch (SQLException e) {  
11.             // TODO Auto-generated catch block   
12.             e.printStackTrace();  
13.         }  
14.     }  
15.   
16.     public List getProduct() {  
17.         List list = new ArrayList();  
18.         try {  
19.             String sql = "select * from product";  
20.             rs = stmt.executeQuery(sql);  
21.             while (rs.next()) {  
22.                 String name=rs.getString("name");  
23.                 String type=rs.getString("type");  
24.                 double price=Double.parseDouble(rs.getString("price"));  
25.                 int num=Integer.parseInt(rs.getString("num"));  
26.                 Product p=new Product(name,type,price,num);  
27.                 list.add(p);  
28.             }  
29.               rs.close();  
30.               stmt.close();  
31.               conn.close();  
32.               
33.         } catch (SQLException e) {  
34.             // TODO Auto-generated catch block   
35.             e.printStackTrace();  
36.         } finally {  
37.             return list;  
38.         }  
39.   
40.     }  
41.   
42. }  

public class ProductDao { Connection conn; ResultSet rs; Statement stmt; public ProductDao() { conn = new MyConnection().getDbConnection(); try { stmt = conn.createStatement(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public List getProduct() { List list = new ArrayList(); try { String sql = "select * from product"; rs = stmt.executeQuery(sql); while (rs.next()) { String name=rs.getString("name"); String type=rs.getString("type"); double price=Double.parseDouble(rs.getString("price")); int num=Integer.parseInt(rs.getString("num")); Product p=new Product(name,type,price,num); list.add(p); } rs.close(); stmt.close(); conn.close(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { return list; } }}

 

PODO

[java] view plaincopyprint?

1. public class Product {  
2.     private String name;  
3.     private String type;  
4.     private double price;  
5.     private int num;  
6.   
7.     public Product(String name, String type, double price, int num) {  
8.         this.name = name;  
9.         this.type = type;  
10.         this.price = price;  
11.         this.num = num;  
12.     }  
13.   
14.     public String getName() {  
15.         return name;  
16.     }  
17.   
18.     public void setName(String name) {  
19.         this.name = name;  
20.     }  
21.   
22.     public String getType() {  
23.         return type;  
24.     }  
25.   
26.     public void setType(String type) {  
27.         this.type = type;  
28.     }  
29.   
30.     public double getPrice() {  
31.         return price;  
32.     }  
33.   
34.     public void setPrice(double price) {  
35.         this.price = price;  
36.     }  
37.   
38.     public int getNum() {  
39.         return num;  
40.     }  
41.   
42.     public void setNum(int num) {  
43.         this.num = num;  
44.     }  
45.   
46. }  

public class Product { private String name; private String type; private double price; private int num; public Product(String name, String type, double price, int num) { this.name = name; this.type = type; this.price = price; this.num = num; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getType() { return type; } public void setType(String type) { this.type = type; } public double getPrice() { return price; } public void setPrice(double price) { this.price = price; } public int getNum() { return num; } public void setNum(int num) { this.num = num; }}

 

部署TOMCAT

這一部分略過，如果覺得手動部署比較麻煩，我們可以使用MyEclipse插件。值得注意的是web.xml文件的配置，一定要正確配置servlet,下面我給出正確示例

[xhtml] view plaincopyprint?

1. <?xml version="1.0" encoding="UTF-8"?>  
2. <web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"  
3.  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">  
4.  <display-name>Benson</display-name>  
5.    <servlet>  
6.     <description>This is the description </description>  
7.     <display-name>This is the display name </display-name>  
8.     <servlet-name>GetProductServlet</servlet-name>  
9.     <servlet-class>servlet.GetProductServlet</servlet-class>  
10.   </servlet>  
11.   
12.   <servlet-mapping>  
13.     <servlet-name>GetProductServlet</servlet-name>  
14.     <url-pattern>/servlet/GetProductServlet</url-pattern>  
15.   </servlet-mapping>  
16.  <welcome-file-list>  
17.   <welcome-file>index.jsp</welcome-file>  
18.  </welcome-file-list>  
19.  <login-config>  
20.   <auth-method>BASIC</auth-method>  
21.  </login-config>  
22. </web-app>  

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <display-name>Benson</display-name> <servlet> <description>This is the description </description> <display-name>This is the display name </display-name> <servlet-name>GetProductServlet</servlet-name> <servlet-class>servlet.GetProductServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>GetProductServlet</servlet-name> <url-pattern>/servlet/GetProductServlet</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <login-config> <auth-method>BASIC</auth-method> </login-config></web-app>

編寫FLEX MXML

[xhtml] view plaincopyprint?

1. <?xml version="1.0" encoding="utf-8"?>  
2. <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="send()">  
3.     <mx:HTTPService id="service" url="http://localhost:8080/servlet/servlet/GetProductServlet" method="GET" />   
4.      <mx:Script>    
5.           <!--[CDATA[   
6.               private function send():void{   
7.                   //發送請求   
8.                   service.send();   
9.               }   
10.           ]]-->    
11.       </mx:Script>    
12.      <mx:Canvas x="0" y="0" width="100%" height="100%">  
13.          <mx:DataGrid x="0" y="68" width="676" height="383" id="productdata" dataProvider="{service.lastResult.products.product}" fontFamily="Times New Roman" fontSize="16">  
14.              <mx:columns>  
15.                  <mx:DataGridColumn headerText="商品名稱" dataField="name"/>  
16.                  <mx:DataGridColumn headerText="商品類別" dataField="type"/>  
17.                  <mx:DataGridColumn headerText="商品價格" dataField="price"/>  
18.                  <mx:DataGridColumn headerText="剩餘數量" dataField="num"/>  
19.              </mx:columns>  
20.          </mx:DataGrid>  
21.          <mx:ApplicationControlBar x="0" y="0" height="70" width="676">  
22.          </mx:ApplicationControlBar>  
23.      </mx:Canvas>  
24. </mx:Application>  

<?xml version="1.0" encoding="utf-8"?><mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="send()"> <mx:HTTPService id="service" url="http://localhost:8080/servlet/servlet/GetProductServlet" method="GET" /> <mx:Script> <!--[CDATA[ private function send():void{ //發送請求 service.send(); } ]]--> </mx:Script> <mx:Canvas x="0" y="0" width="100%" height="100%"> <mx:DataGrid x="0" y="68" width="676" height="383" id="productdata" dataProvider="{service.lastResult.products.product}" fontFamily="Times New Roman" fontSize="16"> <mx:columns> <mx:DataGridColumn headerText="商品名稱" dataField="name"/> <mx:DataGridColumn headerText="商品類別" dataField="type"/> <mx:DataGridColumn headerText="商品價格" dataField="price"/> <mx:DataGridColumn headerText="剩餘數量" dataField="num"/> </mx:columns> </mx:DataGrid> <mx:ApplicationControlBar x="0" y="0" height="70" width="676"> </mx:ApplicationControlBar> </mx:Canvas></mx:Application>

 

代碼重點解釋

1.       creationComplete="send()"

表明當這個Flex應用創建完成時，就發送這個HttpServer請求給Servlet

2.     url=http://localhost:8080/servlet/servlet/GetProductServlet

第一個servlet是我們服務器端的工程名

第二個servelt是servlet所在包名

GetProductServlet使我們真正的servlet名稱

3.       dataProvider="{service.lastResult.products.product}"

a. lastResult：在做了一個呼叫到一個HTTPService 之後，數據會從服務返回，並被放置到服務組件所包含的lastResult 對象。

b. 由於我們返回的是一個XML數據，所以service.lastResult.products.product就代表返回XML中products標籤下的所有product標籤內容。

c.  Product子標籤和Flex中<mx:columns>的dataField屬性相對應。

結果圖