spring学习（四）--搭建一个简单的spring工程

本文搭建一个简单的spring工程，了解spring的IoC

1、通过Eclipse创建一个maven工程，工程名叫mySpringDemo，参考我之前笔记：https://www.cnblogs.com/gllegolas/p/11610341.html，

 2、右键工程，new --> others --> source folder，folder name输入：src/main/resources，创建resources文件夹存放配置文件

3、src/main/java目录下创建三个folder， 分别放接口、实现类、controller

 

 Girls代码：

package interfaces;

public interface Girls {

    public String getGirlsName();
}

LittleBall代码：

package serviceImpl;

import interfaces.Girls;

public class LittleBall implements Girls{

    public String girlsName;
    
    /**
     * 重写构造函数，输出信息，来确定bean初始化时间
     */
    public LittleBall(){
        System.out.println("Hello, I am little ball! I am very beautiful!");
    }
    
    public String getGirlsName(){
        return girlsName;
    }
    public void setGirlsName(String girlsName) {
        this.girlsName = girlsName;
    }
}

LittleBallController代码：

package controllers;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import serviceImpl.LittleBall;

@RestController
@RequestMapping(value="/littleController" , produces = "application/json; charset=utf-8")
public class LittleBallController {

    @Autowired
    LittleBall littleBall;
    
    @RequestMapping("/getLittleBallName")
    @ResponseBody
    public String getLittleBallName(){
        
        return littleBall.getGirlsName();
    }
    
}

 4、在src/main/resources下创建folder名为springConfig，存放spring的配置文件：

 spring-beans.xml代码：

<?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:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd ">
    
    <bean id = "littleBall" class="serviceImpl.LittleBall">
        <property name="girlsName">
            <value>I am little ball！你好，我是小丸子！</value>
        </property>
    </bean>
</beans>

spring-controllers.xml代码：

<?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:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    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/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd ">
    
    <!-- 当配置了component-scan，annotation-config可以去掉。 -->
    <!-- 在使用context标签前，必须引入命名空间context="http://www.springframework.org/schema/context"，www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd -->
    <context:annotation-config />
    
    <!-- 扫描文件（自动将controller层注入） -->  
    <context:component-scan base-package="controllers" />
    
    <!--解决返回json时候中文乱码-->
    <mvc:annotation-driven>
        <mvc:message-converters>
            <bean class="org.springframework.http.converter.StringHttpMessageConverter">
                <property name="supportedMediaTypes">
                    <list>
                        <value>application/json;charset=UTF-8</value>
                    </list>
                </property>
            </bean>
        </mvc:message-converters>
    </mvc:annotation-driven>
</beans>

5、修改pom.xml文件，引入spring框架

<?xml version="1.0" encoding="UTF-8"?>
<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>com.cmos</groupId>
  <artifactId>mySpringDemo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>

  <name>mySpringDemo Maven Webapp</name>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <spring.version>4.0.5.RELEASE</spring.version>
  </properties>

  <dependencies>
  
  <!-- springMvc框架，它依赖于spring的其他jar包，会自动导入spring的core、beans、web等jar包 -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${spring.version}</version>
    </dependency>
    
    <!-- junit测试 -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    
    <!-- servlet配置，解决jsp报错 -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
        <scope>provided</scope>
    </dependency>
  </dependencies>

  <build>
    <finalName>mySpringDemo</finalName><!-- 最终打包名称 -->
  </build>
</project>

6、修改web.xml文件，添加spring初始化配置

<?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">

    <!-- spring使用listener初始化bean（service和dao层bean） -->
    <!-- 多个xml文件中间用逗号隔开，此项如果不配置，spring默认取WEB-INF:applicationContext.xml -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:springConfig/spring-beans.xml</param-value>
    </context-param>
    <listener>
          <listener-class>
              org.springframework.web.context.ContextLoaderListener
          </listener-class>
    </listener>

    <!-- spring使用servlet初始化bean（controller层bean） -->
    <servlet>
        <servlet-name>DispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:springConfig/spring-controllers.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>DispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    
  <display-name>Archetype Created Web Application</display-name>
</web-app>

7、将项目在tomcat容器中启动，在程序启动时候，控制台会打印初始化LittleBall的日志：

访问项目controller路径:http://localhost:8088/mySpringDemo/littleController/getLittleBallName

8、以上是返回string格式数据，但是平常接触的web项目，前后台交互大多都是json格式，通过下面改造，可以让controller返回的数据变为json格式：

先引入fastjson包，在pom.xml文件中添加下面依赖：

<properties>
    <fastjson.version>1.1.41</fastjson.version>
  </properties>
<!--alibaba fastjson 格式化 -->
    <dependency>  
        <groupId>com.alibaba</groupId>  
        <artifactId>fastjson</artifactId>  
        <version>${fastjson.version}</version>  
    </dependency> 

在spring-controllers.xml中，将annotation-driven标签改为下面配置：

    <!--把返回数据变为json格式，解决中文乱码-->
    <mvc:annotation-driven>
           <mvc:message-converters register-defaults="false" >
                  <bean
                         class= "com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter" >
                        <property name= "supportedMediaTypes">
                               <list>
                                      <value> text/html; charset=UTF-8</value >
                                      <value> application/json; charset=UTF-8</value >
                               </list>
                        </property>
                  </bean>
           </mvc:message-converters>
    </mvc:annotation-driven>

在LittleBallController中添加下面方法：

    @RequestMapping("/getLittleBallNameMap")
    @ResponseBody
    public Map getLittleBallNameMap(){
        Map ret = new HashMap();
        ret.put("name", littleBall.getGirlsName());
        return ret;
    }

启动tomcat，访问：http://localhost:8088/mySpringDemo/littleController/getLittleBallNameMap，可以看到返回的数据已经将map变为json格式。