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