页面静态话，释放http连接异常

页面静态化时，执行getMethod.releaseConnection();时，释放http连接异常，异常信息：

Exception in thread "main" java.lang.NullPointerException
at com.test.HtmlGenerator.createHtmlPage(HtmlGenerator.java:94)
at com.test.HtmlGenerator.main(HtmlGenerator.java:121)

解决方案：

1.确认get请求的url没有问题（比如没有被重定向），可以通过浏览器访问

2.需要的jar包：commons-httpclient-3.1.jar、commons-codec-1.10.jar，缺少commons-codec-1.10.jar包，也会报错

java代码：

import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileOutputStream;import java.io.FileWriter;import java.io.InputStream;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;import org.apache.commons.httpclient.HttpClient;import org.apache.commons.httpclient.methods.GetMethod;import org.apache.commons.httpclient.methods.PostMethod;import org.apache.commons.httpclient.params.HttpMethodParams;public class HtmlGenerator{HttpClient httpClient = null; // HttpClient实例GetMethod getMethod = null; // GetMethod实例//PostMethod postMethod = null;BufferedWriter fw = null;String page = null;String webappname = null;BufferedReader br = null;InputStream in = null;StringBuffer sb = null;String line = null;// 构造方法public HtmlGenerator(String webappname){this.webappname = webappname;}/** 根据模版及参数产生静态页面 */public boolean createHtmlPage(String url, String htmlFileName){boolean status = false;int statusCode = 0;try{// 创建一个HttpClient实例充当模拟浏览器httpClient = new HttpClient();// 设置httpclient读取内容时使用的字符集httpClient.getParams().setParameter(HttpMethodParams.HTTP_CONTENT_CHARSET, "UTF-8");// 创建GET方法的实例//postMethod = new PostMethod(url);getMethod = new GetMethod(url);// 使用系统提供的默认的恢复策略，在发生异常时候将自动重试3次//postMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler());getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler());// 设置Get方法提交参数时使用的字符集,以支持中文参数的正常传递//postMethod.addRequestHeader("Content-Type", "text/html;charset=UTF-8");getMethod.addRequestHeader("Content-Type", "text/html;charset=UTF-8");// 执行Get方法并取得返回状态码，200表示正常，其它代码为异常statusCode = httpClient.executeMethod(getMethod);if(statusCode != 200){System.out.println("静态页面引擎在解析" + url + "产生静态页面" + htmlFileName + "时出错!");// logger.fatal();}else{// 读取解析结果sb = new StringBuffer();in = getMethod.getResponseBodyAsStream();// br = new BufferedReader(new// InputStreamReader(in));//此方法默认会乱码，经过长时期的摸索，下面的方法才可以br = new BufferedReader(new InputStreamReader(in, "UTF-8"));while((line = br.readLine()) != null){sb.append(line + "\n");}if(br != null)br.close();page = sb.toString();// 将页面中的相对路径替换成绝对路径，以确保页面资源正常访问page = formatPage(page);// 将解析结果写入指定的静态HTML文件中，实现静态HTML生成writeHtml(htmlFileName, page);status = true;}}catch(Exception ex){System.out.println("静态页面引擎在解析" + url + "产生静态页面" + htmlFileName + "时出错:" + ex.getMessage());// logger.fatal();}finally{// 释放http连接getMethod.releaseConnection();}return status;}// 将解析结果写入指定的静态HTML文件中private synchronized void writeHtml(String htmlFileName, String content) throws Exception{fw = new BufferedWriter(new FileWriter(htmlFileName));OutputStreamWriter fw = new OutputStreamWriter(new FileOutputStream(htmlFileName), "UTF-8");fw.write(page);if(fw != null)fw.close();}// 将页面中的相对路径替换成绝对路径，以确保页面资源正常访问private String formatPage(String page){page = page.replaceAll("\\.\\./\\.\\./\\.\\./", webappname + "/");page = page.replaceAll("\\.\\./\\.\\./", webappname + "/");page = page.replaceAll("\\.\\./", webappname + "/");return page;}//测试方法      public static void main(String[] args){          HtmlGenerator h = new HtmlGenerator("webappname");          h.createHtmlPage("http://127.0.0.1:8080/test1/index.jsp","c:/a.html");          System.out.println("静态页面已经生成到c:/a.html");                }}

commons-httpclient-3.1.jar下载地址：http://download.csdn.net/download/kkkder/9986550

commons-codec-1.10.jar下载地址：http://download.csdn.net/download/kkkder/9986553