struts2实验02 单文件上传, 多文件上传, 文件下载

1、IDEA创建一个maven项目, 项目结构为:

.
├── FileUpload.iml
├── pom.xml
├── src
│   └── main
│       ├── java
│       │   └── shiyanlou
│       │       └── struts
│       │           ├── DownloadAction.java
│       │           ├── MultiUploadAction.java
│       │           └── UploadAction.java
│       ├── resources
│       │   └── struts.xml
│       └── webapp
│           ├── WEB-INF
│           │   └── web.xml
│           ├── error.jsp
│           ├── index.jsp
│           ├── success.jsp
│           ├── uploadFiles
│           │   └── test2.txt
│           └── uploadMultiFiles
│               ├── test.txt
│               └── test2.txt

2、在pom.xml中引入项目依赖, strtus2和servlet, 服务器容器为jetty

<?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>org.example</groupId>
    <artifactId>FileUpload</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>


    <dependencies>
        <dependency>
            <groupId>org.apache.struts</groupId>
            <artifactId>struts2-core</artifactId>
            <version>2.5.18</version>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

    </dependencies>

    <build>
        <finalName>FileUpload</finalName>
        <plugins>
            <plugin>
                <groupId>org.eclipse.jetty</groupId>
                <artifactId>jetty-maven-plugin</artifactId>
                <version>9.4.12.v20180830</version>
                <configuration>
                    <scanIntervalSeconds>10</scanIntervalSeconds>
                    <webApp>
                        <contextPath>/</contextPath>
                    </webApp>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

3、web.xml : 设置web项目的结构, 引入struts拦截器, 所有的URL的请求都必须通过struts

<?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>FileUpload</display-name>
    <filter>
        <filter-name>struts2</filter-name>
        <filter-class>
            org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter
        </filter-class>
    </filter>

    <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <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>

</web-app>

4、