（例）Java生成PDF图片 iText

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import com.lowagie.text.Document;
import com.lowagie.text.Font;
import com.lowagie.text.Image;
import com.lowagie.text.PageSize;
import com.lowagie.text.Paragraph;
import com.lowagie.text.pdf.BaseFont;
import com.lowagie.text.pdf.PdfWriter;                                              import com.lowagie.text.pdf.PdfEncryption;
public class testIText extends HttpServlet {
 public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
     try{
     //设置图片大小 页面为A4
     Document document = new Document(PageSize.A4, 110, 110, 120, 140);
     ByteArrayOutputStream bos = new ByteArrayOutputStream();
     PdfWriter.getInstance(document, bos);
     //1，设置此PDF文件的权限，只有写上的是允许的。这里只允许打印，读取和保存，不允许修改等。
     int intPermissions = PdfWriter.AllowPrinting |PdfWriter.AllowScreenReaders;  
      //2，若要实现其他权限如修改等 则需要写入密码，这里是设置密码加密标准或加密类型。
      int intEncryptionType = PdfEncryption.STANDARD_ENCRYPTION_40;
      //3，要是用这个方法需要引入一个jar包（bcprov-jdk15-137.jar）。第一个参数：打开时需要的密码；第二个参数：实用其