一、使用maven和intellij構造spring mvc程式的步驟和方法:
1.使用如下命令建立一個名為CounterWebApp的web應用。
mvn archetype:generate -DgroupId=com.chf -DartifactId=CounterWebApp -DarchetypeArtifactId=maven-archetype-webapp
-DinteractiveMode=false
2.在CounterWebApp/src/main/java目錄下面建立你的原始碼的包目錄和檔案。
3.在pom.xml中配置spring mvc需要添加的依賴。
如下面的代碼所示:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.chf</groupId> <artifactId>CounterWebApp</artifactId> <packaging>war</packaging> <version>1.0-SNAPSHOT</version> <name>CounterWebApp Maven Webapp</name> <url>http://maven.apache.org</url> <properties> <jdk.version>1.7</jdk.version> <spring.version>4.1.1.RELEASE</spring.version> <jstl.version>1.2</jstl.version> <junit.version>4.11</junit.version> <logback.version>1.0.13</logback.version> <jcl-over-slf4j.version>1.7.5</jcl-over-slf4j.version> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> <!--spring core--> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> <exclusions> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>jcl-over-slf4j</artifactId> <version>${jcl-over-slf4j.version}</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.5</version> <!--<scope>provided</scope>--> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>${logback.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>net.sf.json-lib</groupId> <artifactId>json-lib</artifactId> <version>2.3</version> <classifier>jdk15</classifier> </dependency> <!-- jstl --> <dependency> <groupId>jstl</groupId> <artifactId>jstl</artifactId> <version>${jstl.version}</version> </dependency> </dependencies> <build> <!--最終產生的war檔案名稱--> <finalName>CounterWebApp</finalName> <plugins> <!-- Set JDK Compiler Level --> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.2</version> <configuration> <source>${jdk.version}</source> <target>${jdk.version}</target> <encoding>GBK</encoding> </configuration> </plugin> <!-- For Maven Tomcat Plugin --> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> <version>2.2</version> <configuration> <!--Deploy to server--> <url>http://localhost:8080/manager/text</url> <server>Tomcat7Server</server> <path>/CounterWebApp</path> </configuration> </plugin> </plugins> </build></project>
4.然後使用mvn clean && mvn install來運行程式。
5.遇到的問題和解決方案:
1)mvn install過程中遇到下面的錯誤:
Fatal error compiling: ??Ч??Ŀ??汾?? 1.7 -> [Help 1]
解決方案:
在~/.bash_profile檔案中添加下面配置。添加完後,運行source ~/.bash_profile。
alias javac='javac -J-Dfile.encoding=UTF-8 -encoding UTF-8'
alias java='java -Dfile.encoding=UTF-8'
export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8
2)這樣之後,再次mvn install的時候遇到錯誤:Fatal error compiling: invalid target release: 1.7
解決方案:
在~/.bash_profile檔案中添加一行下面的配置。添加完後,運行source ~/.bash_profile。
export JAVA_HOME='/Library/Java/JavaVirtualMachines/jdk1.7.0_60.jdk/Contents/Home'
二、建立第一個spring mvc的程式。
1.我對spring mvc的理解:
1)spring mvc的結構主要包括下面幾個部分:
DispatcherServlet:將請求轉寄給控制器。
Controller:具體地處理請求。
Handler Mapping:映射處理器,負責映射中央處理器,轉寄給Controller時的映射策略。
ModelAndView:伺服器返回的資料和視圖層的封裝類。
ViewResolver&View:視圖解析器、解析具體的視圖。
Interceptors:攔截器,負責攔截我們定義的請求,然後做處理工作。
2)spring mvc具體的處理流程如下圖所示:
2.例子的目的:在web程式中,存在一類程式,其服務端端的處理時間比較長。正因處理時間比較長,因此這類程式有可能會導致請求逾時。對於這種應用程式經常使用非同步請求的方式來解決。之前沒有使用過這種方式,因此首先寫一個極其簡單的程式。
這個程式的目的是:使用ajax的方式,每隔1s就發送一個請求到服務端。服務端會計數,如果計數達到20就返回一個finish給用戶端(表示服務端的任務完成),如果用戶端接收到服務端任務完成的訊息,就停止發送請求。
3.例子的具體實現:
直接上代碼和各個設定檔的配置
1)Controller類:
package com.chf.controller;import com.chf.services.AsyncServiceImpl;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Controller;import org.springframework.ui.ModelMap;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import javax.annotation.Resource;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.chf.util.ResoponseUtil;/** * Created by Administrator on 15-1-31. *//*There must be a Controller annotation or the application will doesn't work .*/@Controllerpublic class BaseController { @Autowired AsyncServiceImpl asyncService; @Autowired ResoponseUtil ResponseUtil;// @RequestMapping(value = "async/{key}") @RequestMapping(value = "{key}") //async/{key}? public String asyncTest(HttpServletRequest req, HttpServletResponse resp, @PathVariable String key) throws Exception { asyncService.asyncMethod(key); return "common/async"; } //@RequestMapping(params= "method=getStatus",method = RequestMethod.GET) @RequestMapping("/status") public String showAsyncStatus(HttpServletRequest req, HttpServletResponse resp) throws Exception { // HttpServletResponse resp, @PathVariable String key) throws Exception { System.out.println("in status new!!"); String status = asyncService.getProcess(null); ResponseUtil.OutputJson(resp, "{\"status\":\"" + status + "\"}"); return null; } @RequestMapping(value = "/clear") public String clearAsyncStatus(HttpServletRequest req, HttpServletResponse resp, @PathVariable String key) throws Exception { asyncService.clearCache(key); ResponseUtil.OutputJson(resp, "{\"status\":\"ok\"}"); return null; }}
2)service介面和service方法:
package com.chf.services;/** * Created by hfc on 15/10/21. */public interface AsyncService { void asyncMethod(String cacheKey) throws Exception; public String getProcess(String cacheKey) throws Exception; public void clearCache(String cacheKey) throws Exception;}
package com.chf.services;/** * Created by hfc on 15/10/21. */import com.chf.services.AsyncService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.scheduling.annotation.Async;import org.springframework.stereotype.Service;@Service("asyncService")public class AsyncServiceImpl implements AsyncService {// @Autowired// StringRedisTemplate stringRedisTemplate; Integer count = 0; @Override @Async public void asyncMethod(String cacheKey) throws Exception { int maxStep = 20; for (int i = 0; i < maxStep; i++) { Thread.sleep(2000); count++;//stringRedisTemplate.opsForValue().set(cacheKey, (i + 1) + "/" + maxStep); } } @Override public String getProcess(String cacheKey) throws Exception { count++; if(count>=20) return "finish"; return null; } @Override public void clearCache(String cacheKey) throws Exception { //stringRedisTemplate.delete(cacheKey); count = 0; }}
3)index.jsp:
<html><head> <script src="ui/js/jquery.js"></script></head><script type="text/javascript" language="JavaScript"> var timerId = null;//?????ID $(document).ready(function () {// alert("ready!"); /* ????????н?? */ timerId = setInterval(function () { getStatus(); }, 1000); getStatus(); }); /** ?????н?? */ function getStatus() { var statusUrl = window.location.href + "/status";// alert("asdf"); $.get(statusUrl, function (data) { if (data == null || data.status == null || data.status == "null") { updateStatus("ready"); return; } var status = data.status; updateStatus(status); alert("before clear"); clearInterval(timerId);//??????? alert("after clear");// var temp = status.split("/");// if (temp[0] == temp[1]) {// updateStatus("finish");// clearInterval(timerId);//???????// clearStatus();//????redis????// } }) } /** * ????????????? */ function clearStatus() { var clearStatusUrl = window.location.href + "/clear"; $.get(clearStatusUrl, function (data) { //alert(data.status); }) } /** ????????? */ function updateStatus(msg) { $("#status").html(msg); }</script><div id="msgBox"> <span>begin processing</span> <h1>current task:<span style="color:red" id="status">ready</span></h1></div><body></body></html>
4)設定檔:
web.xml:
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"><display-name>Counter Web Application </display-name><servlet> <servlet-name>mvc-dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup></servlet><servlet-mapping> <servlet-name>mvc-dispatcher</servlet-name> <url-pattern>/</url-pattern></servlet-mapping><servlet-mapping> <servlet-name>default</servlet-name> <url-pattern>*.js</url-pattern></servlet-mapping><context-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/mvc-dispatcher-servlet.xml</param-value></context-param><listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener></web-app>
mvc-dispatch-servlet.xml檔案:
<web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"><display-name>Counter Web Application </display-name><servlet> <servlet-name>mvc-dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup></servlet><servlet-mapping> <servlet-name>mvc-dispatcher</servlet-name> <url-pattern>/</url-pattern></servlet-mapping><servlet-mapping> <servlet-name>default</servlet-name> <url-pattern>*.js</url-pattern></servlet-mapping><context-param> <param-name>contextConfigLocation</param-name> <param-value>/WEB-INF/mvc-dispatcher-servlet.xml</param-value></context-param><listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class></listener></web-app>
4.啟動tomcat,並在瀏覽器中輸入localhost:8080即可。
三、注意點:
1、服務端返回json資料的格式:
1)返回資料的時候將MIMETYPE設定為:
response.setContentType("application/json;charset=utf-8");
2)JSON 資料的書寫格式是:成對的名稱和數值。
成對的名稱和數值包括欄位名稱(在雙引號中),後面寫一個冒號,然後是值:
"firstName" : "John"
因此服務端在返回的時候要注意雙引號。否則瀏覽器解析的結果不正確。
2、web.xml中通過如下來配置其Context的檔案名稱。
<context-param> <param-name>contextConfigLocation</param-name> <param-value><span style="color:#ff6666;">/WEB-INF/mvc-dispatcher-servlet.xml</span></param-value></context-param>
3.使用註解的方式來使用bean的時候,需要在mvc-dispatcher-servlet.xml配置相關的bean。只有配置後,才能使用。
4.在web.xml中有如下的配置:
<servlet> <servlet-name>mvc-dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <load-on-startup>1</load-on-startup></servlet> <servlet-mapping> <servlet-name>mvc-dispatcher</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping>
這樣所有的url都會被controller攔截。以致於在index.jsp中找不到jquery.js資源。
為瞭解決這個問題:添加了一個資源攔截配置如下:
<servlet-mapping> <servlet-name>default</servlet-name> <url-pattern>*.js</url-pattern></servlet-mapping>
5.請求過程中遇到400錯誤,都是因為請求的參數和服務端的參數不一致造成的。