檔案上傳

如果您想要進行檔案上傳的動作，則您可以使用實作 org.springframework.web.multipart.MultipartResolver介面的類別，Spring提供 org.springframework.web.multipart.commons.CommonsMultipartResolver與 org.springframework.web.multipart.cos.CosMultipartResolver，分別支援Commands FileUpload及COS FileUpload。

舉個實際的例子，假設您設計了一個FileForm類別：

FileForm.java

package onlyfun.caterpillar;

public class FileForm {
    private String name;
    private byte[] contents;
    
    public void setName(String name) {
        this.name = name;
    }
    
    public void setContents(byte[] contents) {
        this.contents = contents;
    }
    
    public String getName() {
        return name;
    }
    
    public byte[] getContents() {
        return contents;
    }
}

FileForm中接受檔案上傳的屬性型態是byte陣列，使用者上傳的檔案可以藉由 org.springframework.web.multipart.support.ByteArrayMultipartFileEditor將之轉換為byte陣列並設定給FileForm，這必須在定義Controller時註冊，例如：

UploadController.java

package onlyfun.caterpillar;

import java.io.BufferedOutputStream;
import java.io.FileOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.validation.BindException;
import org.springframework.web.bind.ServletRequestDataBinder;
import org.springframework.web.multipart.
                       support.ByteArrayMultipartFileEditor;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.
                                   mvc.SimpleFormController;

public class UploadController extends SimpleFormController {
    private String path;
    
    public UploadController() {
        setCommandClass(FileForm.class);
    }
    
    protected ModelAndView onSubmit(
                            HttpServletRequest request,
                            HttpServletResponse response,
                            Object command,
                            BindException errors) 
                                        throws Exception {
        FileForm form = (FileForm) command;
        
        String storedPath = path + 
                            System.getProperty("file.separator") + 
                            form.getName();
        
        BufferedOutputStream bufferedOutputStream = 
                new BufferedOutputStream(
                       new FileOutputStream(storedPath));
        
        bufferedOutputStream.write(form.getContents());
        bufferedOutputStream.close();
        
        return new ModelAndView(getSuccessView(), 
                                "filename", form.getName());
    }
    
    protected void initBinder(HttpServletRequest request, 
                          ServletRequestDataBinder binder) 
                                            throws Exception {
        super.initBinder(request, binder); 
        binder.registerCustomEditor(
                byte[].class, new ByteArrayMultipartFileEditor());
    }
    
    public void setPath(String path) {
        this.path = path;
    }
}

依以上的設定，檔案上傳後會儲存在指定的目錄下，要使用檔案上傳的功能，您必須在定義檔中加入MultipartResolver的定義，您可以選擇使用 CommonsMultipartResolver或CosMultipartResolver，例如以下使用 CommonsMultipartResolver來定義：

mvc-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING/DTD BEAN/EN" 
"http://www.springframework.org/dtd/spring-beans.dtd"> 

<beans>   
    <bean id="urlMapping"
          class="org.springframework.web.servlet.
                   → handler.SimpleUrlHandlerMapping">
        <property name="mappings">
            <props>
                <prop key="/index.do">
                   indexController
                </prop>
                <prop key="/upload.do">
                   uploadController
                </prop>
            </props>
        </property>
    </bean> 
    
    <bean id="viewResolver"
          class="org.springframework.web.servlet.
                   → view.InternalResourceViewResolver">    
        <property name="prefix">
            <value>/WEB-INF/jsp/</value>
        </property>
        <property name="suffix">
            <value>.jsp</value>
        </property>
    </bean>

    <bean id="indexController"
           class="org.springframework.web.servlet.
                   → mvc.ParameterizableViewController">
        <property name="viewName">
            <value>index</value>
        </property>     
    </bean>    

    <bean id="multipartResolver"
          class="org.springframework.web.multipart.
                   → commons.CommonsMultipartResolver">    
        <property name="maxUploadSize">
            <value>1000000</value>
        </property>
    </bean>    
        
    <bean id="uploadController" 
          class="onlyfun.caterpillar.UploadController"> 
        <property name="formView"> 
            <value>form</value> 
        </property>           
        <property name="successView"> 
            <value>success</value> 
        </property>        
        <property name="path"> 
            <value>C:\upload</value> 
        </property>  
    </bean>
</beans>

在定義檔中，藉由設定UploadController的"path"屬性為"C:\upload"，表示上傳後的檔案會儲存在C:\upload目錄之中，接著設計一個index.jsp：

index.jsp

<%@page contentType="text/html"%>
<%@page pageEncoding="UTF-8"%>

<html>
    <head>
        <meta http-equiv="Content-Type" 
              content="text/html; charset=UTF-8">
        <title>Upload Page</title>
    </head>
    <body>
    <form name="uploadForm" enctype="multipart/form-data" 
          action="/FileUploadDemo/upload.do" method="POST">
        上載後檔案名稱: <input name="name" type="text"/><br>
        選擇檔案: <input name="contents" type="file"/><br>
        <input type="submit" value="Submit"/>  
    </form>
    </body>
</html>

在這個頁面中可以設定上傳後的檔案名稱，並可以選擇所要上傳的檔案名稱，success.jsp則設計如下：

success.jsp

<%@page contentType="text/html"%>
<%@page pageEncoding="UTF-8"%>

<html>
    <head>
        <meta http-equiv="Content-Type" 
              content="text/html; charset=UTF-8">
        <title>Upload Success</title>
    </head>
    <body>
    <h1>File: \${filename} upload successfully.</h1>
    </body>
</html>

這個專案使用到相依的Commands FileUpload，所以您要在lib目錄中包括commons-fileupload.jar檔案。