Java中的StringIndexOutOfBoundsException?
我尝试运行这个java程序,它会在我的webroot文件夹中返回一个网页Java中的StringIndexOutOfBoundsException?,java,Java,我尝试运行这个java程序,它会在我的webroot文件夹中返回一个网页 import java.io.DataOutputStream; import java.io.File; import java.io.InputStreamReader; import java.net.ServerSocket; import java.net.Socket; import java.util.Scanner; public class WebServer { static ServerS
import java.io.DataOutputStream;
import java.io.File;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
public class WebServer {
static ServerSocket requestListener;
static Socket requestHandler;
static Scanner requestReader, pageReader;
static DataOutputStream pageWriter;
static String HTTPMessage;
static String requestedFile;
public static int HTTP_PORT = 12346;
public static void main(String[] args) {
try {
requestListener = new ServerSocket(HTTP_PORT);
System.out.println("Waiting For IE to request a page:");
requestHandler = requestListener.accept();
System.out.println("Page Requested: Request Header:");
requestReader = new Scanner(new InputStreamReader(
requestHandler.getInputStream()));
//THis is the part where its throwing the error
int lineCount = 0;
do {
lineCount++; // This will be used later
HTTPMessage = requestReader.next();
System.out.println(HTTPMessage);
if (lineCount == 1) {
requestedFile = "WebRoot\\"
+ HTTPMessage.substring(5,
HTTPMessage.indexOf("HTTP/1.1") - 1);
requestedFile = requestedFile.trim();
}
// localhost:12346/default.htm
// HTTPMessage = requestReader.nextLine();
pageReader = new Scanner(new File(requestedFile));
pageWriter = new DataOutputStream(
requestHandler.getOutputStream());
while (pageReader.hasNext()) {
String s = pageReader.nextLine();
// System.out.println(s);
pageWriter.writeBytes(s);
}
// Tells the Browser we’re done sending
pageReader.close();
pageWriter.close();
requestHandler.close();
} while (HTTPMessage.length() != 0);
} catch (Exception e) {
System.out.println(e.toString());
System.out.println("\n");
e.printStackTrace();
}
}
}
我收到了这个错误信息。我应该在IE中获得一个网页,但我得到的只是这个错误消息
正在等待IE请求页面:
Page Requested: Request Header:
GET
java.lang.StringIndexOutOfBoundsException: String index out of range: -7
at java.lang.String.substring(Unknown Source)
at WebServer.main(WebServer.java:39)
引发此错误的原因是字符串“HTTPMessage”不包含字符串“HTTP/1.1”。因此
HTTPMessage.indexOf("HTTP/1.1") => returns -1
在我们的子串函数中,传递的是:
HTTPMessage.substring(5, -2);
因此出现了错误
要解决此错误,应首先尝试检查HTTPMessage是否包含所需的字符串,然后尝试计算子字符串。进行以下更改:
if (lineCount == 1 && HTTPMessage.indexOf("HTTP/1.1") != -1) {
requestedFile = "WebRoot\\"
+ HTTPMessage.substring(5,
HTTPMessage.indexOf("HTTP/1.1") - 1);
requestedFile = requestedFile.trim();
}
您是否在询问
StringIndexOutOfBounds
代表什么,或者为什么您的代码会抛出此异常?简单的回答是,您的代码在某个地方引用了一个索引为-7
的字符串,您需要调试发生这种情况的位置。有没有可能发生在这里:HTTPMessage.indexOf(“HTTP/1.1”)-1)
-您是否检查了此代码中的响应?似乎您希望找到该子字符串,但它实际上不在输入中?我正在尝试从http标头中提取请求的页面标题