Spring4 基本使用

前言

虽然现在基本上是 springboot 的天下了，但是传统的 spring4 在广大的软件企业中仍然占据很大比例。一上手能用，但是要让我从无到有搭一个spring4的开发环境出来，可能会磕磕碰碰，耽误不少时间，所以这里从无到有搭一个 spring4的开发环境出来，一步步完善，也复习下 spring 的基本用法，温故知新。

创建maven项目，引入spring4的一些核心包和常用扩展包。

我用的是spring4最新版本 4.3.24.RELEASE

pom.xml

?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.hz</groupId>
    <artifactId>admin</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <name>admin Maven Webapp</name>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <spring.version>4.3.24.RELEASE</spring.version>
        <junit.version>4.11</junit.version>
        <jackson.version>2.9.8</jackson.version>
    </properties>

<dependencies>
        <!-- junit 测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>

        <!--spring 常用模块依赖 start-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</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-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-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-jdbc</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>

        <!-- spring 常用模块依赖 end -->

        <!-- jackson json转换配置，配置-->
       <!-- 这个配置对应 RequestParams, RequestBody, ResponseBody 等注解，原始请求参数其实都在 HttpServletRequest 对象里，
         但实际上我们用spring的时候可以直接在controller方法参数里得到请求数据，String，Integer， Map, List 和自定义bean
         这个转换就要用到这个包， 不引入这个包，使用RequestBody注解就会报错-->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>${jackson.version}</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>${jackson.version}</version>
        </dependency>

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

        <!-- spring MVC 依赖 start-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- spring MVC 依赖 end-->
    </dependencies>

    <build>
        <finalName>admin</finalName>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <plugin>
                    <artifactId>maven-clean-plugin</artifactId>
                    <version>3.1.0</version>
                </plugin>
                <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->
                <plugin>
                    <artifactId>maven-resources-plugin</artifactId>
                    <version>3.0.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.0</version>
                    <configuration>
                        <source>${maven.compiler.source}</source>
                        <target>${maven.compiler.target}</target>
                    </configuration>
                </plugin>
                <plugin>
                    <artifactId>maven-surefire-plugin</artifactId>
                    <version>2.22.1</version>
                </plugin>
                <plugin>
                    <artifactId>maven-war-plugin</artifactId>
                    <version>3.2.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-install-plugin</artifactId>
                    <version>2.5.2</version>
                </plugin>
                <plugin>
                    <artifactId>maven-deploy-plugin</artifactId>
                    <version>2.8.2</version>
                </plugin>

                <!-- jetty 插件-->
                <plugin>
                    <groupId>org.eclipse.jetty</groupId>
                    <artifactId>jetty-maven-plugin</artifactId>
                    <version>9.4.18.v20190429</version>
                    <configuration>
                        <httpConnector>
                            <port>8082</port>   <!--  监听的http 端口，默认8080 -->
                        </httpConnector>
                        <scanIntervalSeconds>2</scanIntervalSeconds>
                        <webApp>
                            <contextPath>/</contextPath>
                        </webApp>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

配置web.xml

web.xml文件是web项目的启动文件，要想在web项目中使用spring，需要在这里配置spring

<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
    <display-name>Archetype Created Web Application</display-name>
    <!-- spring配置文件位置-->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:/spring.xml</param-value>  <!-- 这个文件主要配置spring beans，包括数据源，事务控制
    </context-param>

    <!-- 启动web时加载spring的配置文件 -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!-- 添加springMVC支持,单独springMVC时也需要在web.xml文件中配置 -->
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:/spring/spring-mvc.xml</param-value>   <!-- spring-mvc.xml 主要配置mvc方面，包括controller注解扫描，视图解析器， controller参数绑定（这里就要用到pom里的jackson json依赖） -->
        </init-param>
        <!-- 启动web时就加载springmvc的servlet，即启动时就加载springmvc的配置文件 -->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <!-- 拦截所有请求 -->
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <welcome-file-list><!--指定欢迎页面-->
        <welcome-file>login.html</welcome-file>
    </welcome-file-list>
    <error-page> <!--当系统出现404错误，跳转到页面nopage.html-->
        <error-code>404</error-code>
        <location>/nopage.html</location>
    </error-page>
    <error-page> <!--当系统出现java.lang.NullPointerException，跳转到页面error.html-->
        <exception-type>java.lang.NullPointerException</exception-type>
        <location>/error.html</location>
    </error-page>
    <session-config><!--会话超时配置，单位分钟-->
        <session-timeout>360</session-timeout>
    </session-config>

</web-app>

配置mvc

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:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:p="http://www.springframework.org/schema/p"
       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-4.1.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd">

<!-- spring扫描的包 -->
    <context:component-scan base-package="com.hz.*.controller"/>

    <!-- DispatcherServlet不处理静态资源,交给服务器默认的servlet处理 -->
    <mvc:default-servlet-handler />

    <!-- 启用annotation -->
    <mvc:annotation-driven />

    <!--json转换器配置， @ResponseBody,RequestBody 将请求参数转换成bean需要这个类 -->
    <bean id="mappingJacksonHttpMessageConverter"
          class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
        <property name="supportedMediaTypes">
            <list>
                <value>text/html;charset=UTF-8</value>
            </list>
        </property>
    </bean>

    <!-- 视图渲染器 ,如果搭建REST Web应用，可以不配置这个，具体REST-Web应用配置，后面再讲-->
    <!-- 视图xxx 将对应访问/WEB-INF/page/xxx.jsp文件 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"
          id="internalResourceViewResolver">
        <!-- 前缀 -->
        <property name="prefix" value="/WEB-INF/page/" />
        <!-- 后缀 -->
        <property name="suffix" value=".jsp" />
    </bean>

</beans>

项目结构

测试Controller

package com.hz.common.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.HashMap;
import java.util.Map;

@Controller()
@RequestMapping("test")
public class TestController {

    @RequestMapping("/info")
    @ResponseBody
    public Object test(Integer val){
        // contentType=application/x-www-form-urlencoded
        System.out.println(val == null ? "null" : val.toString());
        HashMap<String, Object> map = new HashMap<>();
        map.put("prop", "value");
        map.put("prop1", "value1");
        return map;
    }
}

postman测试