前言：前端使用uniapp中的uni.canvasToTempFilePath方法将画板中的内容保存为jpg上传至后端处理
uni.canvasToTempFilePath({
canvasId: 'firstCanvas',
sourceType: ['album'],
fileType: "jpg",
success: function (res1) {
let signature_base64 = res1.tempFilePath;
let signature_file = that.base64toFile(signature_base64);
// 将签名存储到服务器
uni.uploadFile({
url: "convertJpgToPdf",
name: "file",
file: signature_file,
formData: {
busiId: 'ceshi12',
token: token
},
success: function (res1) {
console.log(res1);
}
})
}
});
// 将base64转为file
base64toFile: function(base64String) {
// 从base64字符串中解析文件类型
var mimeType = base64String.match(/^data:(.*);base64,/)[1];
// 生成随机文件名
var randomName = Math.random().toString(36).substring(7);
var filename = randomName + '.' + mimeType.split('/')[1];
let arr = base64String.split(",");
let bstr = atob(arr[1]);
let n = bstr.length;
let u8arr = new Uint8Array(n);
while (n--) {
u8arr[n] = bstr.charCodeAt(n);
}
return new File([u8arr], filename, { type: mimeType });
},
java代码：
首先在pom.xml中安装依赖
<dependency>
<groupId>org.apache.pdfbox</groupId>
<artifactId>pdfbox</artifactId>
<version>2.0.8</version>
</dependency>
使用方法：
/**
* 将jpg转为pdf文件
* @param jpgFile
* @return
* @throws IOException
*/
public MultipartFile convertJpgToPdf(MultipartFile jpgFile) throws IOException {
// 保存MultipartFile到临时文件
File tempFile = new File(System.getProperty("java.io.tmpdir"), "temp.jpg");
jpgFile.transferTo(tempFile);
// 创建PDF文档
PDDocument pdfDoc = new PDDocument();
PDPage pdfPage = new PDPage();
pdfDoc.addPage(pdfPage);
// 从临时文件创建PDImageXObject
PDImageXObject pdImage = PDImageXObject.createFromFile(tempFile.getAbsolutePath(), pdfDoc);
// 获取PDF页面的内容流以添加图像
PDPageContentStream contentStream = new PDPageContentStream(pdfDoc, pdfPage);
// 获取PDF页面的大小
PDRectangle pageSize = pdfPage.getMediaBox();
float pageWidth = pageSize.getWidth();
float pageHeight = pageSize.getHeight();
// 在PDF页面上绘制图像
float originalImageWidth = pdImage.getWidth();
float originalImageHeight = pdImage.getHeight();
// 初始化缩放比例
float scale = 1.0f;
// 判断是否需要缩放图片
if (originalImageWidth > pageWidth || originalImageHeight > pageHeight) {
// 计算宽度和高度的缩放比例，取较小值
float widthScale = pageWidth / originalImageWidth;
float heightScale = pageHeight / originalImageHeight;
scale = Math.min(widthScale, heightScale);
}
// 计算缩放后的图片宽度和高度
float scaledImageWidth = originalImageWidth * scale;
float scaledImageHeight = originalImageHeight * scale;
// 计算图片在页面中居中绘制的位置
float x = (pageWidth - scaledImageWidth) / 2;
float y = (pageHeight - scaledImageHeight) / 2;
// 绘制缩放后的图片到PDF页面
contentStream.drawImage(pdImage, x, y, scaledImageWidth, scaledImageHeight);
// 关闭内容流
contentStream.close();
// 将PDF文档写入到字节数组中
ByteArrayOutputStream pdfOutputStream = new ByteArrayOutputStream();
pdfDoc.save(pdfOutputStream);
// 关闭PDF文档
pdfDoc.close();
// 删除临时文件
tempFile.delete();
// 创建代表PDF的MultipartFile
MultipartFile pdfFile = new MockMultipartFile("converted12.pdf", "converted12.pdf", "application/pdf", pdfOutputStream.toByteArray());
saveFileToLocalDisk(pdfFile, "D:/");
return pdfFile;
}
/**
* 将MultipartFile file文件保存到本地磁盘
* @param file
* @param directoryPath
* @throws IOException
*/
public void saveFileToLocalDisk(MultipartFile file, String directoryPath) throws IOException {
// 获取文件名
String fileName = file.getOriginalFilename();
// 创建目标文件
File targetFile = new File(directoryPath + File.separator + fileName);
// 将文件内容写入目标文件
try (FileOutputStream outputStream = new FileOutputStream(targetFile)) {
outputStream.write(file.getBytes());
} catch (IOException e) {
// 处理异常
e.printStackTrace();
throw e;
}
}
MockMultipartFile类
package com.jiuzhu.server.common;
import org.springframework.util.FileCopyUtils;
import org.springframework.web.multipart.MultipartFile;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
public class MockMultipartFile implements MultipartFile {
private final String name;
private String originalFilename;
private String contentType;
private final byte[] content;
/**
* Create a new MultipartFileDto with the given content.
*
* @param name the name of the file
* @param content the content of the file
*/
public MockMultipartFile(String name, byte[] content) {
this(name, "", null, content);
}
/**
* Create a new MultipartFileDto with the given content.
*
* @param name the name of the file
* @param contentStream the content of the file as stream
* @throws IOException if reading from the stream failed
*/
public MockMultipartFile(String name, InputStream contentStream) throws IOException {
this(name, "", null, FileCopyUtils.copyToByteArray(contentStream));
}
/**
* Create a new MultipartFileDto with the given content.
*
* @param name the name of the file
* @param originalFilename the original filename (as on the client's machine)
* @param contentType the content type (if known)
* @param content the content of the file
*/
public MockMultipartFile(String name, String originalFilename, String contentType, byte[] content) {
this.name = name;
this.originalFilename = (originalFilename != null ? originalFilename : "");
this.contentType = contentType;
this.content = (content != null ? content : new byte[0]);
}
/**
* Create a new MultipartFileDto with the given content.
*
* @param name the name of the file
* @param originalFilename the original filename (as on the client's machine)
* @param contentType the content type (if known)
* @param contentStream the content of the file as stream
* @throws IOException if reading from the stream failed
*/
public MockMultipartFile(String name, String originalFilename, String contentType, InputStream contentStream)
throws IOException {
this(name, originalFilename, contentType, FileCopyUtils.copyToByteArray(contentStream));
}
@Override
public String getName() {
return this.name;
}
@Override
public String getOriginalFilename() {
return this.originalFilename;
}
@Override
public String getContentType() {
return this.contentType;
}
@Override
public boolean isEmpty() {
return (this.content.length == 0);
}
@Override
public long getSize() {
return this.content.length;
}
@Override
public byte[] getBytes() throws IOException {
return this.content;
}
@Override
public InputStream getInputStream() throws IOException {
return new ByteArrayInputStream(this.content);
}
@Override
public void transferTo(File dest) throws IOException, IllegalStateException {
FileCopyUtils.copy(this.content, dest);
}
}