Java - HttpURLConnection setFixedLengthStreamingMode() 方法

Java HttpURLConnection setFixedLengthStreamingMode() 方法允許在預先知道內容長度的情況下，無內部緩衝地流式傳輸 HTTP 請求正文。

如果應用程式嘗試寫入的資料量超過指示的內容長度，或者在寫入指示的數量之前關閉 OutputStream，則會丟擲異常。

宣告

以下是 java.net.HttpURLConnection.setFixedLengthStreamingMode() 方法的宣告

public void setFixedLengthStreamingMode(long contentLength)

引數

contentLength - 將寫入 OutputStream 的位元組數。

返回值

無

異常

IllegalStateException - 如果 URLConnection 已經連線或已經啟用了其他流式傳輸模式。

IllegalArgumentException - 如果指定的內容長度小於零。

示例 1

以下示例演示瞭如何對具有 https 協議的有效 url 使用 Java HttpURLConnection setFixedLengthStreamingMode() 方法。在此示例中，我們建立了一個 URL 類的例項。使用 url.openConnection() 方法，我們獲得了 HttpURLConnection 例項。使用 getInputStream()，我們獲取網站主頁的內容並打印出來 -

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.tw/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();
      }
   }
}

讓我們編譯並執行以上程式，這將產生以下結果 -

輸出

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

以下示例演示瞭如何對具有 http 協議的有效 url 使用 Java HttpURLConnection setFixedLengthStreamingMode() 方法。在此示例中，我們建立了一個 URL 類的例項。使用 url.openConnection() 方法，我們獲得了 HttpURLConnection 例項。使用 getInputStream()，我們獲取網站主頁的內容並打印出來 -

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.tw/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();
      }
   }
}

讓我們編譯並執行以上程式，這將產生以下結果 -

輸出

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

以下示例演示瞭如何對具有 http 協議的有效 url 使用 Java HttpURLConnection setFixedLengthStreamingMode() 方法。在此示例中，我們建立了一個 URL 類的例項。使用 url.openConnection() 方法，我們獲得了 HttpURLConnection 例項。使用 getInputStream()，我們獲取網站主頁的內容並打印出來 -

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();
      }
   }
}

讓我們編譯並執行以上程式，這將產生以下結果 -

輸出

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)