承上篇(使用PhantomJS實作網頁截圖功能)
是之前rasterize.js產生網頁截圖時會在指定的路徑下產生實體檔案，但有些情況下也許不希望有這些圖片檔案產生(而希望直接render到網頁中)。此時就需要改寫原本的script。關鍵API
使用renderBase64()的方法會把原本要產生的圖片用base64的編碼方式轉成字串，可以列印至 console，伺服器端的程式再去讀此字串並以base64解碼。
page.renderBase64('PNG');
改寫網頁截圖script
改寫PhantomJS附的網頁截圖sample code，放在PhantomJS目錄下的examples/rasterize.js:
var page = require('webpage').create(),
system = require('system'),
address, output, size;
if (system.args.length < 3 || system.args.length > 5) {
console.log('Usage: screenshot.js URL filename [imagewidth*imageheight|paperwidth*paperheight|paperformat] [zoom]');
console.log(' image (png output) examples: "1024*768"');
console.log(' paper (pdf output) examples: "5in*7.5in", "10cm*20cm", "A4", "Letter"');
phantom.exit(1);
} else {
address = system.args[1];
output = system.args[2];
var clipRect = null;
page.viewportSize = { width: 600, height: 600 };
if (system.args.length > 3) {
size = system.args[3].split('*');
clipRect = {top: 0, left:0, width: size[0], height: size[1]};
}
if (system.args.length > 4) {
page.zoomFactor = system.args[4];
}
page.open(address, function (status) {
if (status !== 'success') {
console.log('Unable to load the address!');
phantom.exit();
} else {
window.setTimeout(function () {
try {
if (clipRect) {
page.clipRect = clipRect;
}
var base64 = page.renderBase64(output);
console.log(base64);
} catch (e) {
console.log('Failed to capture screenshot as ' + output + ': ' + e, "error");
}
phantom.exit();
}, 200);
}
});
}
system = require('system'),
address, output, size;
if (system.args.length < 3 || system.args.length > 5) {
console.log('Usage: screenshot.js URL filename [imagewidth*imageheight|paperwidth*paperheight|paperformat] [zoom]');
console.log(' image (png output) examples: "1024*768"');
console.log(' paper (pdf output) examples: "5in*7.5in", "10cm*20cm", "A4", "Letter"');
phantom.exit(1);
} else {
address = system.args[1];
output = system.args[2];
var clipRect = null;
page.viewportSize = { width: 600, height: 600 };
if (system.args.length > 3) {
size = system.args[3].split('*');
clipRect = {top: 0, left:0, width: size[0], height: size[1]};
}
if (system.args.length > 4) {
page.zoomFactor = system.args[4];
}
page.open(address, function (status) {
if (status !== 'success') {
console.log('Unable to load the address!');
phantom.exit();
} else {
window.setTimeout(function () {
try {
if (clipRect) {
page.clipRect = clipRect;
}
var base64 = page.renderBase64(output);
console.log(base64);
} catch (e) {
console.log('Failed to capture screenshot as ' + output + ': ' + e, "error");
}
phantom.exit();
}, 200);
}
});
}
伺服機端(Java Servlet)程式
try {
long
startTime = System.currentTimeMillis();
String
targetUrl = "http://www.google.com.tw/";
String
phantomExeFileName ="C:/application/phantomjs-1.9.7/phantomjs.exe";
String
phantomJsFileName ="C:/application/phantomjs-1.9.7/myJs/screenshotBase64.js";
File
phantomExeFile = new File(phantomExeFileName);
File
phantomJsFile = new File(phantomJsFileName);
String
imageSize = "1024*768";
String execCommand = String.format("%s %s %s %s %s",
phantomExeFile.getAbsolutePath(),
phantomJsFile.getAbsolutePath(),
(targetUrl == null) ||
(targetUrl.length() ==0) ? "": targetUrl,
"png",
imageSize
).trim();
System.out.println(String.format("execCommand = [%s]", execCommand));
Scanner scanner = new Scanner(Runtime.getRuntime().exec(execCommand).getInputStream()).useDelimiter("\\A");
String cmdout = scanner.hasNext()
? scanner.next() : "";
System.out.println(String.format("cmdout = [%s]", cmdout));
byte[]
outImg = null;
if
((cmdout != null) && (cmdout.length() > 0)) {
outImg = Base64.decodeBase64(outImg);
}
OutputStream out = resp.getOutputStream();
if(outImg
!= null) {
InputStream is = new ByteArrayInputStream(outImg);
resp.setContentType("image/png");
resp.setContentLength(outImg.length);
byte[] buf = new byte[4096];
while(true) {
int r = is.read(buf, 0, buf.length);
if(r == -1) break;
out.write(buf, 0, r);
}
is.close();
out.flush();
}
long
endTime = System.currentTimeMillis();
System.out.println("total
" +
new Double((endTime - startTime) / 1000) + " seconds");
} catch
(Exception e) {
logger.error("main() - exception: ", e);
}
return resp;
