HttpURLConnection connection = (HttpURLConnection) realUrl.openConnection();报错
时间: 2023-10-12 08:08:10 浏览: 42
这个错误可能是因为你没有处理`IOException`异常。在使用`openConnection()`方法时,需要处理可能发生的`IOException`异常。可以使用以下代码:
```java
URL realUrl = new URL(url);
HttpURLConnection conn = null;
try {
conn = (HttpURLConnection)realUrl.openConnection();
// 设置请求方式等
} catch (IOException e) {
e.printStackTrace();
} finally {
if(conn != null) {
conn.disconnect();
}
}
```
这样可以确保在发生异常时关闭连接,并且可以打印出异常信息帮助调试。
相关问题
java使用HttpURLConnection转发get报错405
以下是使用HttpURLConnection转发get请求的Java代码,其中包含了设置请求头和参数的方法:
```java
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Map;
public class HttpUtil {
public static String sendGet(String url, Map<String, String> headers, Map<String, String> params) throws Exception {
StringBuilder result = new StringBuilder();
String urlNameString = url + "?" + getUrlParams(params);
URL realUrl = new URL(urlNameString);
HttpURLConnection connection = (HttpURLConnection) realUrl.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(5000);
connection.setReadTimeout(5000);
for (Map.Entry<String, String> entry : headers.entrySet()) {
connection.setRequestProperty(entry.getKey(), entry.getValue());
}
connection.connect();
if (connection.getResponseCode() == 200) {
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
result.append(line);
}
in.close();
}
connection.disconnect();
return result.toString();
}
private static String getUrlParams(Map<String, String> params) {
StringBuilder result = new StringBuilder();
for (Map.Entry<String, String> entry : params.entrySet()) {
result.append(entry.getKey()).append("=").append(entry.getValue()).append("&");
}
String paramsString = result.toString();
if (paramsString.endsWith("&")) {
paramsString = paramsString.substring(0, paramsString.length() - 1);
}
return paramsString;
}
}
```
如果你收到了405错误,这意味着你正在尝试使用不允许的HTTP方法。在这种情况下,你需要检查你的请求方法是否正确。如果你使用的是GET方法,那么你需要检查你的URL是否正确,并且你需要确保你没有在请求中包含任何不必要的参数。如果你使用的是POST方法,那么你需要确保你已经正确地设置了请求头和请求体,并且你需要确保你的请求体中包含了所有必要的参数。
java发送http请求工具类
好的,以下是一个简单的 Java 发送 HTTP 请求的工具类:
```java
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class HttpUtil {
// 发送 GET 请求
public static String sendGet(String url) {
StringBuilder result = new StringBuilder();
try {
URL realUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection) realUrl.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
result.append(line);
}
in.close();
} catch (Exception e) {
e.printStackTrace();
}
return result.toString();
}
// 发送 POST 请求
public static String sendPost(String url, String param) {
StringBuilder result = new StringBuilder();
try {
URL realUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection) realUrl.openConnection();
conn.setRequestMethod("POST");
conn.setConnectTimeout(5000);
conn.setDoOutput(true);
conn.getOutputStream().write(param.getBytes());
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line;
while ((line = in.readLine()) != null) {
result.append(line);
}
in.close();
} catch (Exception e) {
e.printStackTrace();
}
return result.toString();
}
}
```
使用方法示例:
```java
String url = "http://www.example.com/api";
String result = HttpUtil.sendGet(url);
System.out.println(result);
String param = "name=John&age=25";
result = HttpUtil.sendPost(url, param);
System.out.println(result);
```
注:以上代码仅供参考,实际使用时需要根据具体需求进行修改和优化。