我正在研究javas服务器界面。我使用 User.java 类作为模型，UserController 作为 Controller ，使用 index.xhtml,ViewProfile,xhtml 作为 View 。我跟踪了以下代码，我观察到 setUploadedFile(UploadedFile file){} 的 setter 方法未调用。而其他两个 setter 正在调用。并且它给出了 NullPointerException。是什么原因 ？我不明白。这是代码
UserController.java
@Named("controller")
@RequestScoped
public class UserController implements Serializable
{
private User user=new User();
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public String submit() throws IOException ,SQLException ,ClassNotFoundException, InstantiationException, IllegalAccessException
{
String fileName = FilenameUtils.getName(user.getUploadedFile().getName());
byte[] bytes = user.getUploadedFile().getBytes();
int index=fileName.indexOf('.');
String extension=fileName.substring(index);
File file;
String path;
path = "C:/Users/";
if(extension.equalsIgnoreCase(".jpg")||extension.equalsIgnoreCase(".jpeg")||extension.equalsIgnoreCase(".png")||extension.equalsIgnoreCase(".gif")||extension.equalsIgnoreCase(".tif"))
{
file=new File(path);
if(!file.exists())
{
file.mkdir();
}
path=file+"/"+fileName;
FileOutputStream outfile=new FileOutputStream(path);
outfile.write(bytes);
outfile.close();
PreparedStatement stmt;
Connection connection;
String url="jdbc:mysql://localhost:3306/userprofile";
Class.forName("com.mysql.jdbc.Driver").newInstance();
connection = DriverManager.getConnection(url, "root", "mysql");
stmt = connection.prepareStatement("insert into table_profile values('"+user.getUserName()+"','"+user.getUserId()+"','"+path+"')");
stmt.executeUpdate();
connection.close();
return "SUCCESS";
}
else
{
return "fail";
}
}
}
用户.java
import org.apache.myfaces.custom.fileupload.UploadedFile;
public class User implements java.io.Serializable
{
private String userName;
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
System.out.println("in setter of username");
this.userName = userName;
}
private String userId;
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
System.out.println("in setter of userid");
}
private UploadedFile uploadedFile;
public UploadedFile getUploadedFile()
{
return uploadedFile;
}
public void setUploadedFile(UploadedFile uploadedFile)
{
this.uploadedFile = uploadedFile;
System.out.println("in setter of upload");
}
}
index.xhtml
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html lang="en"
xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:t="http://myfaces.apache.org/tomahawk">
<h:head>
<title>Profile Demo</title>
</h:head>
<h:body>
<h:form>
<h:panelGrid columns="2">
<h:outputLabel for="userId">User Id</h:outputLabel>
<h:inputText id="userId" value="#{controller.user.userName}" required="true"></h:inputText>
<h:outputLabel for="username">Username</h:outputLabel>
<h:inputText id="username" value="#{controller.user.userId}" required="true"></h:inputText>
<h:outputLabel for="photo">Profile Picture</h:outputLabel>
<t:inputFileUpload value="#{controller.user.uploadedFile}" required="true"></t:inputFileUpload>
<h:commandButton value="Register" action="#{controller.submit()}"></h:commandButton>
</h:panelGrid>
</h:form>
</h:body>
</html>
最佳答案
<h:form>
在这里，您忘记设置正确的表单编码类型。
默认值为application/x-www-form-urlencoded这意味着所有请求参数名称和值都以查询字符串格式发送(本质上是 String!)。对于上传的文件，只会发送文件名，不会发送文件内容。这就是为什么你最终得不到具体的File .
您需要设置正确的表单编码类型。
<h:form enctype="multipart/form-data">
这样，请求参数名称和值就会以不同且更灵活的格式发送，该格式允许包含文件内容等二进制数据。然而，标准 JSF 不支持这种格式，这就是为什么您需要注册一个 servlet 过滤器来解析它并将其转换为常用的请求参数，以便 JSF 可以继续完成其工作。
<filter>
<filter-name>MyFacesExtensionsFilter</filter-name>
<filter-class>org.apache.myfaces.webapp.filter.ExtensionsFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>MyFacesExtensionsFilter</filter-name>
<servlet-name>Faces Servlet</servlet-name>
</filter-mapping>
另请参阅:
关于java - 不调用jsf中的setter方法，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14518328/