Java JSP中通过servlet检索网页
如何通过从JSP页面中作为表单参数传递的Servlet检索网页 JSP页面有一个带有文本框的表单,用于以字符串和提交按钮的形式输入url。该操作由servlet执行,servlet从传递的url获取网页并显示检索到的网页 这里是我的servlet代码`Java JSP中通过servlet检索网页,java,jsp,servlets,Java,Jsp,Servlets,如何通过从JSP页面中作为表单参数传递的Servlet检索网页 JSP页面有一个带有文本框的表单,用于以字符串和提交按钮的形式输入url。该操作由servlet执行,servlet从传递的url获取网页并显示检索到的网页 这里是我的servlet代码` import java.io.IOException; import java.io.InputStream; import java.io.PrintWriter; import java.net.Malform
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Search
*/
@WebServlet("/Search")
public class Search extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public Search() {
super();
// TODO Auto-generated constructor stub
}
/**
* @param
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String html = null;
String server = request.getParameter("browsebox");
if(server != null && server !="")
{
response.sendRedirect("browse.jsp");
}
try {
html = getWebPageFromUrl(server);
}catch(Exception e) {
System.err.println(e.toString());
return;
}
response.setHeader("serchbox", server);
response.setContentType("text/html");
PrintWriter out = response.getWriter();
if(html == null) {
out.println("<html>");
out.println("<head><title>Refresher</title></head>");
out.println("<body bgcolor=\"#ffffff\">");
out.println("<p>The servlet has received a POST. This is the reply. </p>");
out.println("</body></html>");
} else {
out.print(html);
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request,response);
}
private String getWebPageFromUrl(String urlString) throws Exception {
// Create a URL object from urlString
URL stockURL;
try {
stockURL = new URL(urlString);
} catch (MalformedURLException e) {
String msg = "Invalid url: " + urlString;
throw new Exception(msg);
}
// Open a connection to the URL
URLConnection stockConnection;
try {
stockConnection = stockURL.openConnection();
} catch (IOException e) {
String msg = "Can't open connection to " + urlString;
throw new Exception(msg);
}
// Get the InputStream from the URL connection
InputStream webPageInputStream;
try {
webPageInputStream = stockConnection.getInputStream();
} catch (IOException e) {
// Could be any server error, but the most likely is 404
String msg = "404 File Not Found: " + urlString;
//throw new WebPageGrabberException(msg);
throw new Exception(e.toString());
}
// Read the web page via the InputStream
StringBuffer webPageData = new StringBuffer(32000);
int totalBytesRead = 0;
boolean moreToRead = true;
byte[] readBuf = new byte[4096]; // Read the web page in 4K chunks
while (moreToRead) {
int numBytesRead = 0;
try {
numBytesRead = webPageInputStream.read(readBuf);
} catch (IOException e) {
moreToRead = false;
numBytesRead = -1;
}
if (numBytesRead > 0) {
totalBytesRead += numBytesRead;
webPageData.append(new String(readBuf, 0, numBytesRead));
} else {
moreToRead = false;
}
}
try {
webPageInputStream.close();
} catch (IOException e) {
// Ignore any exception that might occur
}
webPageData.setLength(totalBytesRead);
webPageData.toString();
}
}
import java.io.IOException;
导入java.io.InputStream;
导入java.io.PrintWriter;
导入java.net.MalformedURLException;
导入java.net.URL;
导入java.net.URLConnection;
导入javax.servlet.ServletException;
导入javax.servlet.annotation.WebServlet;
导入javax.servlet.http.HttpServlet;
导入javax.servlet.http.HttpServletRequest;
导入javax.servlet.http.HttpServletResponse;
/**
*Servlet实现类搜索
*/
@WebServlet(“/Search”)
公共类搜索扩展了HttpServlet{
私有静态最终长serialVersionUID=1L;
/**
*@参见HttpServlet#HttpServlet()
*/
公开检索(){
超级();
//TODO自动生成的构造函数存根
}
/**
*@param
*@参见HttpServlet#doGet(HttpServletRequest请求,HttpServletResponse响应)
*/
受保护的void doGet(HttpServletRequest请求,HttpServletResponse响应)抛出ServletException,IOException{
字符串html=null;
String server=request.getParameter(“browsebox”);
if(server!=null&&server!=“”)
{
sendRedirect(“browse.jsp”);
}
试一试{
html=getWebPageFromUrl(服务器);
}捕获(例外e){
System.err.println(例如toString());
返回;
}
setHeader(“serchbox”,服务器);
response.setContentType(“text/html”);
PrintWriter out=response.getWriter();
if(html==null){
out.println(“”);
out.println(“复习者”);
out.println(“”);
println(“servlet已收到帖子。这是回复。”;
out.println(“”);
}否则{
打印(html);
}
}
/**
*@请参阅HttpServlet#doPost(HttpServletRequest请求,HttpServletResponse响应)
*/
受保护的void doPost(HttpServletRequest请求、HttpServletResponse响应)引发ServletException、IOException{
//TODO自动生成的方法存根
doGet(请求、响应);
}
私有字符串getWebPageFromUrl(字符串urlString)引发异常{
//从urlString创建URL对象
URL-stockURL;
试一试{
stockURL=新URL(URL字符串);
}捕获(格式错误){
String msg=“无效url:+urlString;
抛出新异常(msg);
}
//打开到URL的连接
URLConnection-stockConnection;
试一试{
stockConnection=stockURL.openConnection();
}捕获(IOE异常){
String msg=“无法打开到”+urlString的连接;
抛出新异常(msg);
}
//从URL连接获取InputStream
输入流网页输入流;
试一试{
webPageInputStream=stockConnection.getInputStream();
}捕获(IOE异常){
//可能是任何服务器错误,但最有可能是404
String msg=“404找不到文件:”+urlString;
//抛出新的WebPageGrabberException(msg);
抛出新异常(例如toString());
}
//通过InputStream读取网页
StringBuffer webPageData=新的StringBuffer(32000);
int totalBytesRead=0;
布尔moreToRead=true;
byte[]readBuf=新字节[4096];//以4K块读取网页
while(moreToRead){
int numBytesRead=0;
试一试{
numBytesRead=webPageInputStream.read(readBuf);
}捕获(IOE异常){
moreToRead=false;
numBytesRead=-1;
}
如果(numBytesRead>0){
totalBytesRead+=numBytesRead;
append(新字符串(readBuf,0,numBytesRead));
}否则{
moreToRead=false;
}
}
试一试{
webPageInputStream.close();
}捕获(IOE异常){
//忽略可能发生的任何异常
}
webPageData.setLength(totalBytesRead);
webPageData.toString();
}
}
提交表单时,servlet中的内容变为空白。如果需要显示整个站点,只需重定向到它即可
response.sendRedirect(request.getParameter(“url”);
如果需要显示嵌入JSP页面中的站点,请使用iframe
(这里的fn:escapeXml()
就是为了防止可能的XSS攻击)
无论是哪种情况,您可能只希望在URL以http://或https://等开头时预先进行验证。所有内容都以代码开头。在编写代码的过程中,您在哪里遇到了问题?危险!您将看到有人输入../../../../../etc/passwd(或类似)并显示它吗?给我们一些代码,这样我们就可以看到您真正想要实现的目标。