ztree+ajax实现文件树下载功能

<dependencies>
  <!-- servlet依赖 -->
  <dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.1.0</version>
    <scope>provided</scope>
  </dependency>

  <!-- springMVC依赖 -->
  <dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-WEBmvc</artifactId>
    <version>5.2.6.RELEASE</version>
  </dependency>

  <!-- 文件上传的jar包 -->
  <dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.8.0</version>
  </dependency>
  <dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
  </dependency>
     // gson可以不要，这是我测试时使用的
    <dependency>
      <groupId>com.Google.code.gson</groupId>
      <artifactId>gson</artifactId>
      <version>2.2.4</version>
    </dependency>

</dependencies>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="Http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
  <!-- 声明springMvc的核心对象 DispatcherServlet -->
  <servlet>
    <servlet-name>web</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:sprinGConfig.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>web</servlet-name>
    <url-pattern>*.mvc</url-pattern>
  </servlet-mapping>

  <!--  注册字符集过滤器,解决post请求的中文乱码问题-->
  <filter>
    <filter-name>characterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>utf-8</param-value>
    </init-param>
    <init-param>
      <param-name>forRequestEncoding</param-name>
      <param-value>true</param-value>
    </init-param>
    <init-param>
      <param-name>forResponseEncoding</param-name>
      <param-value>true</param-value>
    </init-param>

  </filter>
  <filter-mapping>
    <filter-name>characterEncodingFilter</filter-name>
    <url-pattern>
public class MyFile {

    private int id;
    private int pId;
    private String name;
    private String url;

    public MyFile(int id, int pId, String name, String url) {
        this.id = id;
        this.pId = pId;
        this.name = name;
        this.url = url;
    }

    @Override
    public String toString() {
        return "MyFile{" +
                "id=" + id +
                ", pId=" + pId +
                ", name='" + name + '\'' +
                ", url='" + url + '\'' +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int getpId() {
        return pId;
    }

    public void setpId(int pId) {
        this.pId = pId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }
}

public class FilerService {

    // 将构建为文件对象的文件或目录放到list集合中
    List<MyFile> fileList = new ArrayList<>();

    
    public  List<MyFile> listAll1(File file , int index) {

        File[] listFiles=  file.listFiles();

        // 将文件或目录构建为对象
        for (int i=1;i<listFiles.length+1;i++){
            if (listFiles[i-1].isDirectory()){
                // 如果是目录 则url为空 pid=0说明是根目录
                MyFile myFile = new MyFile(i,0,listFiles[i-1].getName(),"");
                fileList.add(myFile);
            }else {
                // 如果是文件则拼接下载地址
                String filename=listFiles[i-1].getName();
                // 文件的id为：(目录id*100)+文件序列
                MyFile myFile = new MyFile((100*index)+i,index,listFiles[i-1].getName(),"http://localhost:8080/file/download.mvc?filename="+filename);
                fileList.add(myFile);
            }
        }
        // 判断该文件是否存在
        if (file.exists()){
            // 获取当前文件夹下的所有子文件
            File[] files = file.listFiles();
            if (files!=null&&files.length>0){
                // 对文件进行遍历
                for (int i = 0; i < files.length; i++) {
                    if (files[i].exists()&&files[i].isDirectory()){
                        // 如果是一个目录继续进行递归 直到找到文件为止 每遍历一个目录 index+1
                        listAll1(files[i],i+1);
                    }
                }
            }
        }
        return fileList;
    }

    // 制定文件的父目录
    String parentDir=null;

    
    public  String getFileName(String fileName,File dir){
        if (dir.exists()){
             File[] files = dir.listFiles();
             if (files!=null&&files.length>0){
                for (int i=0;i<files.length;i++){
                    if (files[i].exists()&&files[i].isDirectory()){
                        getFileName(fileName,files[i]);
                    }else {
                        // 如果找到传递过来的文件名则赋值给 parentDir
                        if (fileName.equals(files[i].getName())){
                            parentDir=files[i].getParent();
                            break;
                        }
                    }
                }
             }
         }
        return parentDir;
    }
}

@Controller
@RequestMapping("/file/")
public class FileDownloadController {


    // 提供访问接口
    @GetMapping("downloadIn.mvc")
    public String downloadIn(){
        return "index";
    }

    // 初始化页面数据
    @ResponseBody
    @GetMapping("init.mvc")
    public List<MyFile> test(){
        File file = new File("D:\\IDE2019\\work");
        FilerService service = new FilerService();
        // 将制定目录的文件夹 下的目录和文件构建为MyFile对象装到List集合中
        List<MyFile> listAll1 = service.listAll1(file, 1);
        // 返回JSON数据给前端进行渲染
        return listAll1;
    }

    // 提供下载接口
    @GetMapping("download.mvc")
    public ResponseEntity <byte[]> fileDownload1(String filename,httpservletRequest request) throws IOException {
        // 指定下载那个目录下的文件
        File file = new File("D:\\IDE2019\\work");
        FilerService service = new FilerService();
        // 获取到该文件的父目录
        String path = service.getFileName(filename, file);

        // 创建文件下载对象
        File downloadFile = new File(path, filename);

        HttpHeaders header = new HttpHeaders();
        header.setContentDispositionFORMData("attachment",filename);
        header.setContentType(MediaType.APPLICATION_OCTET_STREAM);
        ResponseEntity<byte[]> result = new ResponseEntity<>(FileUtils.readFileToByteArray(downloadFile), header, HttpStatus.OK);
        return result;
    }
}