java.lang.Object
- Torello.Browser.Example03

```
public class Example03
extends java.lang.Object
```
Demonstrates several CDP browser features without using JavaScript evaluation. This example demonstrates how to use the Chrome DevTools Protocol (CDP) from Java in order to:

Example Features:
- Launch and connect to a browser
- Navigate to a live web page
- Generate screenshots
- Generate PDF files
- Capture cookies and network events
💡 Once the fonts are installed correctly, Example03 demonstrates that CDP is fully capable of rendering:
- Unicode web pages
- Traditional Chinese text
- Complex HTML layouts
- Multi-page PDF documents
- Embedded charts and images
... directly from a completely headless browser session.

Installing & Starting Chrome:
If you are using the processor on a computer inside your office or on your laptop, there is probably not any need to install a "Chrome CDP Compliant Browser." However, if you are using a virtual machine, you might need to run a browser installations script.

⚠️ If you are running this example from a cloud-based Linux VM such as: GCP, AWS, or Azure, please review the following helper scripts for installing & starting a Web Browser instance in the cloud. Cloud based accounts do not necessarily have pre-installed browser executables.
File Explanations:
- install.sh - script installs the minimum Linux packages required to run headless Chrome.
- chinese-fonts.sh script installs additional CJK (Chinese / Japanese / Korean) Unicode fonts needed by Example03.java.
- start.sh - script launches Chrome in headless mode, with remote debugging enabled on TCP-Port 9222.
If the fonts are not installed beforehand, then generated screenshots and PDF files may contain empty Unicode square-box glyphs instead of Chinese text.

Supported Browsers:
Modern versions of these browsers are, generally, compliant with the CDP API. You may view a somewhat "extensive" explanation by Chat-GPT regarding which browsers will support the Chromium Engine CDP API, below. Thee list after the link below is a "quick summary" of what to look for when running this Java Tool.

Supported Browsers
- Google Chrome
- Chromium
- Microsoft Edge
- Brave Browser
Hi-Lited Source-Code:
- View Here: Torello/Browser/Example03.java
- Open New Browser-Tab: Torello/Browser/Example03.java
File Size: 10,202 Bytes Line Count: 296 '\n' Characters Found

Field Summary

Fields
Modifier and Type Field

protected static String chineseURL

protected static List<String> networkURLs

protected static String pdfFile

protected static String screenshotFile

Method Summary

Main Method

Modifier and Type	Method
`static void`	`main(String[] argv)`

Example Steps
Modifier and Type	Method
`protected static void`	`STEP_01_initializeBrowserAndPage()`
`protected static void`	`STEP_02_enablePageAndNetwork(WebSocketSender pws)`
`protected static void`	`STEP_03_navigateAndCollectNetworkTraffic(WebSocketSender pws)`
`protected static void`	`STEP_04_captureScreenshot(WebSocketSender pws)`
`protected static void`	`STEP_05_printToPDF(WebSocketSender pws)`
`protected static void`	`STEP_06_printCookies(WebSocketSender pws)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

chineseURL

🡇 ⇈ ⮫ 🗕 🗗 🗖

protected static final java.lang.String chineseURL

The URL used for demonstrating Network, Page, Screenshot, PDF and Cookie commands.

See Also:

Constant Field Values

Code:

Exact Field Declaration Expression:

 protected static final String chineseURL =
         "https://zh.wikipedia.org/wiki/%E4%BA%BA%E5%B7%A5%E6%99%BA%E8%83%BD";

screenshotFile

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖
```
protected static final java.lang.String screenshotFile
```
The files generated by this example.
See Also:

Constant Field Values

Code:
Exact Field Declaration Expression:

protected static final String screenshotFile = "Example03-Screenshot.png";

pdfFile

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖

protected static final java.lang.String pdfFile

See Also:

Constant Field Values

Code:

Exact Field Declaration Expression:

 protected static final String pdfFile        = "Example03-Page.pdf";

networkURLs

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖

protected static final java.util.List<java.lang.String> networkURLs

Network URLs collected by the page-level handler.

Code:

Exact Field Declaration Expression:

 protected static final List<String> networkURLs = new ArrayList<>();

Method Detail

main

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖

public static void main(java.lang.String[] argv)
                 throws java.lang.Exception

This class is intended to be invoked from the Command Line.

Throws:

java.lang.Exception

Code:

Exact Method Body:

 STEP_01_initializeBrowserAndPage();

 try
 {
     STEP_02_enablePageAndNetwork(connRec.pws);

     STEP_03_navigateAndCollectNetworkTraffic(connRec.pws);

     STEP_04_captureScreenshot(connRec.pws);

     STEP_05_printToPDF(connRec.pws);

     STEP_06_printCookies(connRec.pws);
 }

 finally
 {
     connRec.bws.disconnect();
     connRec.pws.disconnect();
 }

STEP_01_initializeBrowserAndPage

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖

protected static void STEP_01_initializeBrowserAndPage()
                                                throws java.lang.Exception

Open Chrome, close old tabs, create a new tab, and return both WebSocket senders.

Throws:

java.lang.Exception

Code:

Exact Method Body:

 Printing.notice("Initialize BrowserConn, PageConn and WebSocketSender");

 final BrowserConn browserConn = BrowserConn.getBrowserConn(9222, false);

 System.out.println(
     '\n' + BCYAN + "Example03.java: " + RESET +
     BRED + "Opened Browser Connection:\n" + RESET + browserConn.toString()
 );

 final WebSocketSender bws = browserConn.createSender(connRec);

 final Target.TargetInfo[] allTabs = Target
     .getTargets(null /* FilterEntry[] */)
     .exec(bws)
     .await();

 for (int i = 0; i < allTabs.length; i++)
     if ("page".equals(allTabs[i].type))
         Target.closeTarget(allTabs[i].targetId).exec(bws).await();

 final String targetID = Target
     .createTarget()
     .accept("url", "about:blank")
     .build()
     .exec(bws)
     .await();

 final PageConn pageConn = PageConn
     .getAllPageConn(9222, false)
     .filter((PageConn pc) -> pc.id.equals(targetID))
     .findFirst()
     .orElseThrow(() -> new RuntimeException("The Page-Connection was Not Found"));

 System.out.println(
     '\n' + BCYAN + "Example03.java: " + RESET +
     BRED + "Opened Page Connection:\n" + RESET + pageConn.toString()
 );

 final WebSocketSender pws = pageConn.createSender(connRec);

 Thread.sleep(1000);

 connRec.bws = bws;
 connRec.pws = pws;

STEP_02_enablePageAndNetwork

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖

protected static void STEP_02_enablePageAndNetwork(WebSocketSender pws)
                                            throws java.lang.Exception

Enables the two CDP domains used throughout this example.

Throws:

java.lang.Exception

Code:

Exact Method Body:

 Printing.notice("Enable Page and Network Domains");

 System.out.println('\n' + BCYAN + "Example03.java: " + RESET + "Page.enable()");
 Page.enable(null /* enableFileChooserOpenedEvent */).exec(connRec.pws).await();

 System.out.println('\n' + BCYAN + "Example03.java: " + RESET + "Network.enable()");
 Network
     .enable(
         null,   // maxTotalBufferSize
         null,   // maxResourceBufferSize
         null,   // maxPostDataSize,
         null    // reportDirectSocketTraffic
     )
     .exec(connRec.pws)
     .await();

STEP_03_navigateAndCollectNetworkTraffic

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖

protected static void STEP_03_navigateAndCollectNetworkTraffic
            (WebSocketSender pws)
        throws java.lang.Exception

Navigate to the target page and allow Network events to arrive through the handler.

Throws:

java.lang.Exception

Code:

Exact Method Body:

 Printing.notice("Navigate and Collect Network Traffic");

 System.out.println(
     '\n' + BCYAN + "Example03.java: " + RESET +
     "Navigating To: " + chineseURL
 );

 Page
     .navigate()
     .accept("url", chineseURL)
     .build()
     .exec(connRec.pws)
     .await();

 Thread.sleep(5000);

 System.out.println(
     '\n' + BCYAN + "Example03.java: " + RESET +
     BRED + "Total Network Request URL's Collected: " + RESET +
     networkURLs.size()
 );

 for (int i = 0; i < networkURLs.size(); i++)
     System.out.println("    " + networkURLs.get(i));

STEP_04_captureScreenshot

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖

protected static void STEP_04_captureScreenshot(WebSocketSender pws)
                                         throws java.lang.Exception

Capture the rendered browser page as a PNG file.

Throws:

java.lang.Exception

Code:

Exact Method Body:

 Printing.notice("Capture a PNG Screenshot");

 final String pngBase64 = Page
     .captureScreenshot()
     .accept("format", "png")
     .accept("fromSurface", true)
     .build()
     .exec(connRec.pws)
     .await();

 Files.write(Paths.get(screenshotFile), Base64.getDecoder().decode(pngBase64));

 System.out.println(
     '\n' + BCYAN + "Example03.java: " + RESET +
     BRED + "Wrote Screenshot File: " + RESET + screenshotFile
 );

STEP_05_printToPDF

🡅 🡇 ⇈ ⮫ 🗕 🗗 🗖

protected static void STEP_05_printToPDF(WebSocketSender pws)
                                  throws java.lang.Exception

Print the rendered browser page to a PDF file.

Throws:

java.lang.Exception

Code:

Exact Method Body:

 Printing.notice("Print the Page to a PDF File");

 final Page.printToPDF$$RET pdf = Page
     .printToPDF()
     .accept("printBackground", true)
     .build()
     .exec(connRec.pws)
     .await();

 Files.write(Paths.get(pdfFile), Base64.getDecoder().decode(pdf.data));

 System.out.println(
     '\n' + BCYAN + "Example03.java: " + RESET +
     BRED + "Wrote PDF File: " + RESET + pdfFile
 );

STEP_06_printCookies

🡅 ⇈ ⮫ 🗕 🗗 🗖

protected static void STEP_06_printCookies(WebSocketSender pws)
                                    throws java.lang.Exception

Print the cookies visible to Chrome for the current page.

Throws:

java.lang.Exception

Code:

Exact Method Body:

 Printing.notice("Read Browser Cookies for the Current Page");

 final Network.Cookie[] cookies = Network
     .getCookies(null /* String[] urls */)
     .exec(connRec.pws)
     .await();

 System.out.println(
     '\n' + BCYAN + "Example03.java: " + RESET +
     BRED + "Cookies Returned: " + RESET + cookies.length
 );

 for (int i = 0; i < cookies.length; i++)
     System.out.println(StrIndent.indent(cookies[i].toString(), 4));

Modifier and Type	Field
`protected static String`	`chineseURL`
`protected static List<String>`	`networkURLs`
`protected static String`	`pdfFile`
`protected static String`	`screenshotFile`

Class Example03

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

chineseURL

screenshotFile

pdfFile

networkURLs

Method Detail

main

STEP_01_initializeBrowserAndPage

STEP_02_enablePageAndNetwork

STEP_03_navigateAndCollectNetworkTraffic

STEP_04_captureScreenshot

STEP_05_printToPDF

STEP_06_printCookies