使用maven搭建web工程

1、新建maven工程，取名xiaoali

在pom.xml文件添加依赖

<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/xsd/maven-4.0.0.xsd">  <modelVersion>4.0.0</modelVersion>  <groupId>xiaoali</groupId>  <artifactId>xiaoali</artifactId>  <version>0.0.1-SNAPSHOT</version>  <packaging>jar</packaging>  <name>xiaoali</name>  <url>http://maven.apache.org</url>  <properties>    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>    <spring.version>4.3.9.RELEASE</spring.version>    <junit.version>4.12</junit.version>  </properties>  <dependencies>    <!-- 首先添加springmvc依赖包 -->    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-aop</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-aspects</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-beans</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-context</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-context-support</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-core</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-expression</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-instrument</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-instrument-tomcat</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-jdbc</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-jms</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-messaging</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-orm</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-test</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-tx</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-web</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-webmvc</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-webmvc-portlet</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>org.springframework</groupId>      <artifactId>spring-websocket</artifactId>      <version>${spring.version}</version>    </dependency>    <dependency>      <groupId>junit</groupId>      <artifactId>junit</artifactId>      <version>${junit.version}</version>      <scope>test</scope>    </dependency>  </dependencies></project>

因为使用maven clean整个工程后会出现jdk版本和自己在eclipse中配置的不一样，这时候需要在pom.xml中添加jdk版本控制插件

<build>        <finalName>xiaoali</finalName>        <plugins>            <plugin>              <groupId>org.apache.maven.plugins</groupId>              <artifactId>maven-compiler-plugin</artifactId>              <configuration>                <source>1.7</source>                <target>1.7</target>              </configuration>            </plugin>        </plugins>    </build>

然后重新clean就可以了

2、配置web.xml文件

<?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"  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>xiaotb</display-name>  <!-- 默认欢迎界面 -->  <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>springMVC</servlet-name>    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>    <init-param>            <param-name>contextConfigLocation</param-name>            <param-value>classpath:spring-mvc.xml</param-value>    </init-param>    <load-on-startup>1</load-on-startup>  </servlet>  <servlet-mapping>    <servlet-name>springMVC</servlet-name>    <url-pattern>/</url-pattern>    <url-pattern>/xiaoali/login</url-pattern>  </servlet-mapping>  <context-param>    <param-name>contextConfigLocation</param-name>    <param-value>classpath:spring-context.xml</param-value>  </context-param></web-app>

3、创建spring-context.xml和spring-mvc.xml文件

spring-context.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context"xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"xsi:schemaLocation="http://www.springframework.org/schema/beans   http://www.springframework.org/schema/beans/spring-beans.xsd   http://www.springframework.org/schema/context   http://www.springframework.org/schema/context/spring-context.xsd   http://www.springframework.org/schema/tx   http://www.springframework.org/schema/tx/spring-tx.xsd   http://www.springframework.org/schema/aop   http://www.springframework.org/schema/aop/spring-aop.xsd"><!--    ----------------------------------------------------------   进行扫描类包、读取配置文件、数据源管理、AOP配置、缓存以及消息队列等配置   ---------------------------------------------------------- --><!-- 扫描类包，将标注Spring注解的类自动转化Bean，同时完成Bean的注入 --><context:component-scan base-package="com.xiaoali.controller" /><context:component-scan base-package="com.xiaoali.service" /><context:component-scan base-package="com.xiaoali.dao" /></beans>

spring-mvc.xml

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context"xmlns:util="http://www.springframework.org/schema/util" xmlns:mvc="http://www.springframework.org/schema/mvc"xsi:schemaLocation="  http://www.springframework.org/schema/beans  http://www.springframework.org/schema/beans/spring-beans-4.3.xsd  http://www.springframework.org/schema/util  http://www.springframework.org/schema/util/spring-util-4.3.xsd  http://www.springframework.org/schema/context   http://www.springframework.org/schema/context/spring-context-4.3.xsd  http://www.springframework.org/schema/mvc  http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd">  <!-- 使用默认的注解映射 -->  <mvc:annotation-driven>  </mvc:annotation-driven></beans>

启动tomcat,报错
java.lang.ClassNotFoundException: org.springframework.web.servlet.DispatcherServlet
找不到类，原因是需要在工程中导入maven依赖jar包。导入完成后重启，没有报错信息显示。

4、输入访问地址

http://localhost:8080/xiaoali/login
控制台输出：
警告: No mapping found for HTTP request with URI [/xiaoali/login] in DispatcherServlet with name ‘springMVC’
原因：扫描类包的配置应该配置在spring-mvc.xml文件中，web.xml配置中Spring初始化参数是在spring-mvc.xml中，而不是在spring-context.xml，服务的启动首先加载spring-context.xml中的配置项，然后才初始化springframework

5、package创建

controller层
UserController.java

package com.xiaoali.controller;import java.util.List;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import com.xiaoali.entity.User;import com.xiaoali.service.UserService;@Controllerpublic class UserController {    @Autowired    private UserService userService;    @RequestMapping(value= "/login")    @ResponseBody    public List<User> findUserList(){        List<User> userList = userService.findUserList();        for(User user : userList){            System.out.println(user.getName()+":"+user.getPwd());        }        return userList;    }}

service层
接口类 UserService.java

package com.xiaoali.service;import java.util.List;import com.xiaoali.entity.User;public interface UserService {    public List<User> findUserList();}

实现类 UserServiceImpl.java

package com.xiaoali.service.impl;import java.util.List;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import com.xiaoali.dao.UserDao;import com.xiaoali.entity.User;import com.xiaoali.service.UserService;@Servicepublic class UserServiceImpl    implements UserService {    @Autowired    private UserDao userDao;    @Override    public List<User> findUserList() {        List<User> userList = userDao.findUserList();        return userList;    }}

dao层
UserDao.java

package com.xiaoali.dao;import java.util.ArrayList;import java.util.List;import org.springframework.stereotype.Repository;import com.xiaoali.entity.User;@Repositorypublic class UserDao {    private User user;    public List<User> findUserList(){        List<User> userList = new ArrayList<User>();        for(int i =0 ;i<3;i++){            user = new User();            user.setName("张三"+i);            user.setPwd("A"+i);            userList.add(user);        }        return userList;    }}

entity层
User.java

package com.xiaoali.entity;import java.io.Serializable;public class User implements Serializable {    /**     *      */    private static final long serialVersionUID = -5927908541432372896L;    private String name = "";    private String pwd = "";    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPwd() {        return pwd;    }    public void setPwd(String pwd) {        this.pwd = pwd;    }}

6、启动服务输入地址

http://localhost:8080/xiaoali/login
报错：严重: Servlet.service() for servlet [springmvc] in context with path [/xiaoali] threw exception [Request processing failed; nested exception is java.lang.IllegalArgumentException: No converter found for return value of type: class java.util.ArrayList] with root cause
java.lang.IllegalArgumentException: No converter found for return value of type: class java.util.ArrayList

原因：这是因为springmvc默认是没有对象转换成json的转换器的，需要手动添加jackson依赖。
解决：手动添加jackson依赖到pom.xml文件中

<jackson.version>2.8.9</jackson.version><dependency>      <groupId>com.fasterxml.jackson.core</groupId>      <artifactId>jackson-core</artifactId>      <version>${jackson.version}</version>    </dependency>    <dependency>      <groupId>com.fasterxml.jackson.core</groupId>      <artifactId>jackson-databind</artifactId>      <version>${jackson.version}</version>    </dependency>

7、更新项目工程，重新导入maven依赖，重启服务

输入地址http://localhost:8080/xiaoali/login
访问成功，数据显示。

如果还是没有解决，在springmvc配置文件中进行如下配置

  <mvc:annotation-driven><!--     <mvc:message-converters> --><!--             <bean class="org.springframework.http.converter.StringHttpMessageConverter"/> --><!--             <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter"/> --><!--     </mvc:message-converters> -->  </mvc:annotation-driven>

我这里注释掉了，因为我不需要。ヾ(◍°∇°◍)ﾉﾞ

• 后续：整合mybatis