(1). 概述
上一小篇,剖析了PlaywrightImpl,它在初始化时,会委托给Driver类,所以,这一小篇是肯定少不了要剖析该类.
(2). Driver.ensureDriverInstalled
public abstract class Driver {
protected final Map<String, String> env = new LinkedHashMap<>();
// 单例模式
private static Driver instance;
// *****************************************************************
// 单例模式
// 1. 创建:Driver
// *****************************************************************
public static synchronized Driver ensureDriverInstalled(Map<String, String> env, Boolean installBrowsers) {
if (instance == null) {
instance = createAndInstall(env, installBrowsers);
}
return instance;
} // end ensureDriverInstalled
public static Driver createAndInstall(Map<String, String> env, Boolean installBrowsers) {
try {
// *****************************************************************
// 1.1 创建Driver
// *****************************************************************
Driver instance = newInstance();
logMessage("initializing driver");
// *****************************************************************
// 2. 初始化
// *****************************************************************
instance.initialize(env, installBrowsers);
logMessage("driver initialized.");
return instance;
} catch (Exception exception) {
throw new RuntimeException("Failed to create driver", exception);
}
} // end createAndInstall
private static Driver newInstance() throws Exception {
// *****************************************************************
// 1.2 读取系统环境变量,看是否有配置Driver,如果有的话,通过:PreinstalledDriver包裹一层
// *****************************************************************
String pathFromProperty = System.getProperty("playwright.cli.dir");
if (pathFromProperty != null) { // false
return new PreinstalledDriver(Paths.get(pathFromProperty));
}
// *****************************************************************
// 1.3 读取环境变量:playwright.driver.impl
// 如果环境变量没有配置,则默认值为:com.microsoft.playwright.impl.driver.jar.DriverJar
// 注意:这个类在另一个工程里:driver-bundle,这个工程很重要,呆会会深入讲解.
// 通过反射创建:Driver的实现
// *****************************************************************
String driverImpl = System.getProperty("playwright.driver.impl", "com.microsoft.playwright.impl.driver.jar.DriverJar");
Class<?> jarDriver = Class.forName(driverImpl);
return (Driver) jarDriver.getDeclaredConstructor().newInstance();
} // end newInstance
// *****************************************************************
// 2.1 初始化
// *****************************************************************
private void initialize(Map<String, String> env, Boolean installBrowsers) throws Exception {
this.env.putAll(env);
initialize(installBrowsers);
} // end initialize
// 2.2 initialize方法是一个抽象方法,预留给子类
protected abstract void initialize(Boolean installBrowsers) throws Exception;
}
(3). DriverJar.initialize
protected void initialize(Boolean installBrowsers) throws Exception {
// ... ...
// ****************************************************
// 2.3 提取Driver到临时目录
// ****************************************************
extractDriverToTempDir();
// ... ...
if (installBrowsers)
// ****************************************************
// 3. 安装浏览器
// ****************************************************
installBrowsers(env);
}
(4). DriverJar.extractDriverToTempDir
// 提取驱动程序到临时目录
void extractDriverToTempDir() throws URISyntaxException, IOException {
ClassLoader classloader = Thread.currentThread().getContextClassLoader();
// **********************************************************
// 2.3.1 从ClassPath中寻找:driver/mac目录,我断点后,发现在这个JAR包里:driver-bundle-1.27.0.jar
// 所以,能断定,在加载playwright依赖时,会加载driver-bundle-1.27.0.jar,并且这个包有点大.
// jar:file:/Users/lixin/.m2/repository/com/microsoft/playwright/driver-bundle/1.21.0/driver-bundle-1.21.0.jar!/driver/mac
// **********************************************************
URI originalUri = classloader.getResource("driver/" + platformDir()).toURI();
// **********************************************************
// 2.3.2 解压JAR包里的内容到临时目录
// **********************************************************
URI uri = maybeExtractNestedJar(originalUri);
// ... ...
}
(5). DriverJar.maybeExtractNestedJar
private URI maybeExtractNestedJar(final URI uri) throws URISyntaxException {
if (!"jar".equals(uri.getScheme())) {
return uri;
}
final String JAR_URL_SEPARATOR = "!/";
String[] parts = uri.toString().split("!/");
if (parts.length != 3) {
return uri;
}
String innerJar = String.join(JAR_URL_SEPARATOR, parts[0], parts[1]);
URI jarUri = new URI(innerJar);
try (FileSystem fs = FileSystems.newFileSystem(jarUri, Collections.emptyMap())) {
Path fromPath = Paths.get(jarUri);
Path toPath = driverTempDir.resolve(fromPath.getFileName().toString());
// ************************************************************
// 2.3.3 解压JAR包里的内容到临时目录
// ************************************************************
Files.copy(fromPath, toPath);
toPath.toFile().deleteOnExit();
return new URI("jar:" + toPath.toUri() + JAR_URL_SEPARATOR + parts[2]);
} catch (IOException e) {
throw new RuntimeException("Failed to extract driver's nested .jar from " + jarUri + "; full uri: " + uri, e);
}
}
(6). 生成的临时目录内容如下
// ******************************************************************
// playwright.sh是重点
// ******************************************************************
lixin-macbook:playwright-java lixin$ tree -L 2
.
├── LICENSE
├── node
├── package
│ ├── README.md
│ ├── ThirdPartyNotices.txt
│ ├── api.json
│ ├── bin
│ ├── browsers.json
│ ├── cli.js
│ ├── index.d.ts
│ ├── index.js
│ ├── index.mjs
│ ├── lib
│ ├── package.json
│ ├── protocol.yml
│ └── types
└── playwright.sh
(7). DriverJar.installBrowsers
private void installBrowsers(Map<String, String> env) throws IOException, InterruptedException {
// ... ...
// /Users/lixin/Desktop/playwright-java/playwright.sh
Path driver = driverPath();
if (!Files.exists(driver)) {
throw new RuntimeException("Failed to find driver: " + driver);
}
// ******************************************************************
// 3.1 调用操作系统,运行shell,这个步骤会要很长时间,会去下载所有浏览器驱动.
// ******************************************************************
// /Users/lixin/Desktop/playwright-java/playwright.sh install
ProcessBuilder pb = createProcessBuilder();
pb.command().add("install");
pb.redirectError(ProcessBuilder.Redirect.INHERIT);
pb.redirectOutput(ProcessBuilder.Redirect.INHERIT);
Process p = pb.start();
boolean result = p.waitFor(10, TimeUnit.MINUTES);
// ... ...
}// end
(8). Mac下安装浏览器后的位置
lixin-macbook:playwright-java lixin$ ll /Users/lixin/Library/Caches/ms-playwright
drwxr-xr-x 4 lixin staff 128 10 9 23:54 chromium-1024/
drwxr-xr-x 4 lixin staff 128 10 10 00:39 chromium-1028/
drwxr-xr-x 5 lixin staff 160 10 9 23:54 ffmpeg-1007/
drwxr-xr-x 4 lixin staff 128 10 9 23:58 firefox-1350/
drwxr-xr-x 4 lixin staff 128 10 10 00:42 firefox-1357/
drwxr-xr-x 16 lixin staff 512 10 10 00:00 webkit-1715/
drwxr-xr-x 16 lixin staff 512 10 10 00:46 webkit-1724/
(9). 总结
Driver的作用无非不过就是下载所有的Driver,并安装到系统目录下:/Users/lixin/Library/Caches/ms-playwright.
