如何将Part转换为Blob,以便将其存储在MySQL中？

Question

如何将Part转换为Blob,以便将其存储在MySQL中？这是一张图片.谢谢

我的表格

<h:form id="form" enctype="multipart/form-data">
        <h:messages/>
        <h:panelGrid columns="2">
            <h:outputText value="File:"/>
            <h:inputFile id="file" value="#{uploadPage.uploadedFile}"/>
        </h:panelGrid>
        <br/><br/>
        <h:commandButton value="Upload File" action="#{uploadPage.uploadFile}"/>
</h:form>

我的豆子

@Named
@ViewScoped
public class UploadPage {       
    private Part uploadedFile; 

    public void uploadFile(){
    }
}

Answer 1

SQL数据库BLOB类型在Java中表示为byte[].这在JPA中进一步注释为@Lob.所以,你的模型基本上需要看起来像这样:

@Entity
public class SomeEntity {

    @Lob
    private byte[] image;

    // ...
}

至于处理Part,你基本上需要把它读InputStream成一个byte[].Apache Commons IO IOUtils在这里很有帮助:

InputStream input = uploadedFile.getInputStream();
byte[] image = IOUtils.toByteArray(input); // Apache commons IO.
someEntity.setImage(image);
// ...

或者,如果您更喜欢标准的Java API,它只是更冗长:

InputStream input = uploadedFile.getInputStream();
ByteArrayOutputStream output = new ByteArrayOutputStream();
byte[] buffer = new byte[10240];
for (int length = 0; (length = input.read(buffer)) > 0;) output.write(buffer, 0, length);
someEntity.setImage(output.toByteArray());
// ...