Java - HttpURLConnection setFixedLengthStreamingMode() 方法

Java HttpURLConnection setFixedLengthStreamingMode() 方法允许在预先知道内容长度的情况下，无内部缓冲地流式传输 HTTP 请求正文。

如果应用程序尝试写入的数据量超过指示的内容长度，或者在写入指示的数量之前关闭 OutputStream，则会抛出异常。

声明

以下是 java.net.HttpURLConnection.setFixedLengthStreamingMode() 方法的声明

public void setFixedLengthStreamingMode(long contentLength)

参数

contentLength - 将写入 OutputStream 的字节数。

返回值

无

异常

IllegalStateException - 如果 URLConnection 已经连接或已经启用了其他流式传输模式。

IllegalArgumentException - 如果指定的内容长度小于零。

示例 1

以下示例演示了如何对具有 https 协议的有效 url 使用 Java HttpURLConnection setFixedLengthStreamingMode() 方法。在此示例中，我们创建了一个 URL 类的实例。使用 url.openConnection() 方法，我们获得了 HttpURLConnection 实例。使用 getInputStream()，我们获取网站主页的内容并打印出来 -

package com.tutorialspoint;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpUrlConnectionDemo {
   public static void main(String [] args) {
      try {
         URL url = new URL("https://tutorialspoint.com/index1.htm?language=en#j2se");
         HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
         urlConnection.setFixedLengthStreamingMode(1000L);  
		 urlConnection.setDoOutput(true);
         urlConnection.connect();  
         System.out.println("Connected.");  
         if(urlConnection.getInputStream() != null) {
            BufferedReader in = new BufferedReader(
               new InputStreamReader(urlConnection.getInputStream()));
            String content = "";
            String current;
            while((current = in.readLine()) != null) {
               content += current;
            }
            System.out.println(content);
         }else {
            System.out.println("Input Stream is null");
         }
         urlConnection.disconnect();  
         System.out.println("Disconnected.");  
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

让我们编译并运行以上程序，这将产生以下结果 -

输出

Connected.
java.io.IOException: insufficient data written
	at sun.net.www.protocol.http.HttpURLConnection$StreamingOutputStream.close(Unknown Source)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
	at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
	at com.tutorialspoint.HttpUrlConnectionDemo.main(HttpUrlConnectionDemo.java:18)

示例 2

以下示例演示了如何对具有 http 协议的有效 url 使用 Java HttpURLConnection setFixedLengthStreamingMode() 方法。在此示例中，我们创建了一个 URL 类的实例。使用 url.openConnection() 方法，我们获得了 HttpURLConnection 实例。使用 getInputStream()，我们获取网站主页的内容并打印出来 -

package com.tutorialspoint;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpUrlConnectionDemo {
   public static void main(String [] args) {
      try {
         URL url = new URL("https://tutorialspoint.com/index1.htm?language=en#j2se");
         HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
         urlConnection.setFixedLengthStreamingMode(1000L);  
		 urlConnection.setDoOutput(true);
         urlConnection.connect();  
         System.out.println("Connected.");  
         if(urlConnection.getInputStream() != null) {
            BufferedReader in = new BufferedReader(
               new InputStreamReader(urlConnection.getInputStream()));
            String content = "";
            String current;
            while((current = in.readLine()) != null) {
               content += current;
            }
            System.out.println(content);
         }else {
            System.out.println("Input Stream is null");
         }
         urlConnection.disconnect();  
         System.out.println("Disconnected.");  
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

让我们编译并运行以上程序，这将产生以下结果 -

输出

Connected.
java.io.IOException: insufficient data written
	at sun.net.www.protocol.http.HttpURLConnection$StreamingOutputStream.close(Unknown Source)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
	at com.tutorialspoint.HttpUrlConnectionDemo.main(HttpUrlConnectionDemo.java:18)

示例 3

以下示例演示了如何对具有 http 协议的有效 url 使用 Java HttpURLConnection setFixedLengthStreamingMode() 方法。在此示例中，我们创建了一个 URL 类的实例。使用 url.openConnection() 方法，我们获得了 HttpURLConnection 实例。使用 getInputStream()，我们获取网站主页的内容并打印出来 -

package com.tutorialspoint;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpUrlConnectionDemo {
   public static void main(String [] args) {
      try {
         URL url = new URL("http://www.google.com");
         HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
         urlConnection.setFixedLengthStreamingMode(1000L);  
		 urlConnection.setDoOutput(true);
         urlConnection.connect();  
         System.out.println("Connected.");  
         if(urlConnection.getInputStream() != null) {
            BufferedReader in = new BufferedReader(
               new InputStreamReader(urlConnection.getInputStream()));
            String content = "";
            String current;
            while((current = in.readLine()) != null) {
               content += current;
            }
            System.out.println(content);
         }else {
            System.out.println("Input Stream is null");
         }
         urlConnection.disconnect();  
         System.out.println("Disconnected.");  
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

让我们编译并运行以上程序，这将产生以下结果 -

输出

Connected.
java.io.IOException: insufficient data written
	at sun.net.www.protocol.http.HttpURLConnection$StreamingOutputStream.close(Unknown Source)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
	at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
	at com.tutorialspoint.HttpUrlConnectionDemo.main(HttpUrlConnectionDemo.java:18)