java原装代码完成pdf在线预览和pdf打印及下载

前提准备：

1. 项目中至少需要引入的jar包，注意版本:

a) core-renderer.jar

b) freemarker-2.3.16.jar

c) iText-2.0.8.jar

d) iTextAsian.jar

上代码:

注释: 此类为自定义的Tag类的基类，在action中怎么放的数据，在ftl中就怎么取数据，简洁明了。

1. 自定义Tag类的基类

 /**
 * 通用的生成pdf预览和生成打印的html文件
 * 
 * @author xg君
 * 
 */
public abstract class PDFTag extends BodyTagSupport {
 private static final long serialVersionUID = 1L;
 // 标签属性变量
 private String json = "";
 private String tempDir = "";
 // 非标签属性变量
 private Map<String, Object> rootMap = new HashMap<String, Object>();
 private String templateStr = null;
 private String freemarkereConfigurationBeanName = null;
 private String fileName = null;
 private String basePath = null;
 private String fileEncoding = "utf-8";
 @Override
 public int doStartTag() throws JspException {
 setConfigParams();
 WebApplicationContext application = WebApplicationContextUtils.getWebApplicationContext(pageContext
  .getServletContext());
 doServiceStart();
 String ctx = (String) pageContext.getAttribute("ctx");
 rootMap.put("ctx", ctx);
 Map<String, Object> map = parseJSON2Map(json);
 rootMap.putAll(map);
 if (freemarkereConfigurationBeanName == null) {
  try {
  throw new CstuException("FreemarkereConfigurationBeanName不能为空!");
  } catch (CstuException e) {
  e.printStackTrace();
  }
 }
 Configuration cptFreemarkereConfiguration = (Configuration) application
  .getBean(freemarkereConfigurationBeanName);
 try {
  if (templateStr == null) {
  throw new CstuException("模板文件不能为空!");
  }
  Template template = cptFreemarkereConfiguration.getTemplate(templateStr);
  if (basePath == null) {
  throw new CstuException("文件的基本路径(父路径)不能为空!");
  }
  File htmlPath = new File(tempDir + File.separator + basePath);
  if (!htmlPath.exists()) {
  htmlPath.mkdirs();
  }
  if (fileName == null) {
  throw new CstuException("生成的html文件名不能为空!");
  }
  File htmlFile = new File(htmlPath, File.separator + fileName);
  if (!htmlFile.exists()) {
  htmlFile.createNewFile();
  }
  BufferedWriter out = new BufferedWriter(
   new OutputStreamWriter(new FileOutputStream(htmlFile), fileEncoding));
  template.process(rootMap, out);
  out.flush();
  doServiceDoing();
  // 显示在页面
  template.process(rootMap, pageContext.getResponse().getWriter());
 } catch (Exception e) {
  e.printStackTrace();
 }
 doServiceEnd();
 return SKIP_BODY;
 }
 /**
 * 配置基础参数，如
 */
 public abstract void setConfigParams();
 /**
 * 业务处理方法-开始 填充数据
 * 
 * @return
 */
 public abstract void doServiceStart();
 /**
 * 业务处理方法-执行中 备用，可空实现，若rootMap中存在双份数据则可在此处填充判断条件
 * 
 * @return
 */
 public abstract void doServiceDoing();
 /**
 * 业务处理方法-结束 清空rootMap并调用垃圾回收，也可空实现
 * 
 * @return
 */
 public abstract void doServiceEnd();

 /**
 * 将元素放入rootMap中
 */
 public void putKV(String key, Object value) {
 rootMap.put(key, value);
 }
 /**
 * 将map放入rootMap中
 * 
 * @param m
 */
 public void putMap(Map m) {
 rootMap.putAll(m);
 }
 public void clear() {
 rootMap.clear();
 rootMap = null;
 }
 /**
 * 移除元素
 * 
 * @param key
 * @return
 */
 public Object remove(String key) {
 return rootMap.remove(key);
 }
 public static Map<String, Object> parseJSON2Map(String jsonStr) {
 Map<String, Object> map = new HashMap<String, Object>();
 JSONObject json = JSONObject.fromObject(jsonStr);
 for (Object k : json.keySet()) {
  Object v = json.get(k);
  if (v instanceof JSONArray) {
  List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
  Iterator<JSONObject> it = ((JSONArray) v).iterator();
  while (it.hasNext()) {
   JSONObject json2 = it.next();
   list.add(parseJSON2Map(json2.toString()));
  }
  map.put(k.toString(), list);
  } else {
  map.put(k.toString(), v);
  }
 }
 return map;
 }
 public String getJson() {
 return json;
 }
 public void setJson(String json) {
 this.json = json;
 }
 public String getTempDir() {
 return tempDir;
 }
 public void setTempDir(String tempDir) {
 this.tempDir = tempDir;
 }
 public String getTemplateStr() {
 return templateStr;
 }
 public void setTemplateStr(String templateStr) {
 this.templateStr = templateStr;
 }
 public String getFreemarkereConfigurationBeanName() {
 return freemarkereConfigurationBeanName;
 }
 public void setFreemarkereConfigurationBeanName(String freemarkereConfigurationBeanName) {
 this.freemarkereConfigurationBeanName = freemarkereConfigurationBeanName;
 }
 public String getFileName() {
 return fileName;
 }
 public void setFileName(String fileName) {
 this.fileName = fileName;
 }
 public String getBasePath() {
 return basePath;
 }
 public void setBasePath(String basePath) {
 this.basePath = basePath;
 }
 public String getFileEnco