工具类代码整理

Posted 2022-05-27 root_zhb

工具类代码整理

• HttpClient
• List分割工具类
• 图片转PDF，PDF转图片

HttpClient

1、HttpClient详细使用示例

MultipartFile file = new MockMultipartFile("file", "hello-" + number + ".pdf", "application/pdf", pdfFile);
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
builder.setContentType(ContentType.MULTIPART_FORM_DATA);

ContentType fileContentType = ContentType.create(ContentType.parse("application/pdf").getMimeType(), StandardCharsets.UTF_8);
builder.addBinaryBody("file",pdfFile,fileContentType, URLEncoder.encode(file.getOriginalFilename(), "utf-8"));    

发送文件示例图

List分割工具类

1. averageAssign 平均分割
2. splitList 按照指定长度分割

public class ListSplitUtil 
    /**
     * @param list
     * @return
     */
    public static <T> List<List<T>> averageAssign(List<T> list, int n)
        List<List<T>> result=new ArrayList<List<T>>();
        int remaider=list.size()%n;  //(先计算出余数)
        int number=list.size()/n;  //然后是商
        int offset=0;//偏移量
        for(int i=0;i<n;i++)
            List<T> value=null;
            if(remaider>0)
                value=list.subList(i*number+offset, (i+1)*number+offset+1);
                remaider--;
                offset++;
            else
                value=list.subList(i*number+offset, (i+1)*number+offset);
            
            result.add(value);
        
        return result;
    
    /**
     * @param list
     * @param len
     * @return
     */
    public static<T> List<List<T>> splitList(List<T> list, int len) 
        if (list == null || list.size() == 0 || len < 1) 
            return null;
        
        List<List<T>> result = new ArrayList<List<T>>();
        int size = list.size();
        int count = (size + len - 1) / len;
        for (int i = 0; i < count; i++) 
            List<T> subList = list.subList(i * len, ((i + 1) * len > size ? size : len * (i + 1)));
            result.add(subList);
        
        return result;
    

图片转PDF，PDF转图片

图片转PDF

<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>itextpdf</artifactId>
    <version>5.4.2</version>
</dependency>

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Image;
import com.itextpdf.text.pdf.PdfWriter;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class Image2PDF 
    /*** @param picturePath 图片地址*/
    private static void createPic(Document document, String picturePath) 
        try 
            Image image = Image.getInstance(picturePath);
            float documentWidth = document.getPageSize().getWidth() - document.leftMargin() - document.rightMargin();
            float documentHeight = documentWidth / 580 * 400;//重新设置宽高
            image.scaleAbsolute(documentWidth, documentHeight);//重新设置宽高
            document.add(image);
         catch (Exception ex) 
        
    
    public static void image2pdf(String text, String pdf) throws DocumentException, IOException 
        Document document = new Document();
        OutputStream os = new FileOutputStream(new File(pdf));
        PdfWriter.getInstance(document,os);
        document.open();
        createPic(document,text);
        document.close();
    
    public static void main(String[] args) throws IOException, DocumentException 
        image2pdf("C:\\\\Users\\\\Administrator\\\\Desktop\\\\8.jpg","C:\\\\Users\\\\Administrator\\\\Desktop\\\\111.pdf");
    

PDF转图片

<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>fontbox</artifactId>
    <version>2.0.1</version>
</dependency>
<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>2.0.1</version>
</dependency>

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPageTree;
import org.apache.pdfbox.rendering.PDFRenderer;
 
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class PDFConvert 

    /**
     * PDF转图片的流
     */
    public static List<byte[]> PDF2JPG(InputStream inputStream) throws IOException 
        List<byte[]> imageData=new ArrayList<>();
        OutputStream out = null;
        if (inputStream==null) 
            throw new FileNotFoundException();
         else 
            ByteArrayOutputStream bos = null;
            BufferedInputStream in = null;
            PDDocument doc = null;

            try 
                in = new BufferedInputStream(inputStream);
                doc = PDDocument.load(in);

                PDFRenderer pdfRenderer = new PDFRenderer(doc);
                PDPageTree pages = doc.getPages();
                int pageCount = pages.getCount();
                for (int i = 0; i < pageCount; i++) 
                    BufferedImage bim = pdfRenderer.renderImageWithDPI(i, 200);
                    bos = new ByteArrayOutputStream();
                    ImageIO.write(bim, "jpg", bos);
                    byte[] var7 = bos.toByteArray();
                    imageData.add(var7);
                

//                //jpg文件转出路径
//                out = new FileOutputStream("D:\\\\abc.jpg");
//                out.write(bos.toByteArray());
                return imageData;
             finally 
                try 
                    if (in != null) 
                        in.close();
                    
                 catch (IOException var14) 
                    var14.printStackTrace();
                
                bos.close();