我想创建一个程序，将字符串输入到像谷歌这样的网站的文本框中(不使用他们的公共(public) API)，然后提交表单并获取结果。这可能吗？获取结果将需要使用我假设的 HTML 抓取，但我将如何将数据输入文本字段并提交表单？我会被迫使用公共(public) API 吗？这样的事情是不可行的吗？我必须弄清楚查询字符串/参数吗？
谢谢
最佳答案
理论
我要做的是创建一个小程序，它可以自动将任何表单数据提交到任何地方并返回结果。这在 Java 中很容易做到，HTTPUnit .任务是这样的:
您选择的解决方案将取决于多种因素，包括:
例如，您可以尝试以下应用程序为您提交数据:
那么grep (awk 或 sed)生成的网页。
屏幕抓取的另一个技巧是下载一个示例 HTML 文件并在 vi(或 VIM)中手动解析它。将击键保存到文件中，然后每当您运行查询时，将这些击键应用到生成的网页以提取数据。此解决方案不可维护，也不是 100% 可靠(但很少从网站抓取屏幕)。它可以工作并且速度很快。
示例
下面是一个用于提交网站表单(特别是处理登录网站)的半通用 Java 类，希望它可能有用。不要用来作恶。
import java.io.FileInputStream;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;
import com.meterware.httpunit.GetMethodWebRequest;
import com.meterware.httpunit.SubmitButton;
import com.meterware.httpunit.WebClient;
import com.meterware.httpunit.WebConversation;
import com.meterware.httpunit.WebForm;
import com.meterware.httpunit.WebLink;
import com.meterware.httpunit.WebRequest;
import com.meterware.httpunit.WebResponse;
public class FormElements extends Properties
{
private static final String FORM_URL = "form.url";
private static final String FORM_ACTION = "form.action";
/** These are properly provided property parameters. */
private static final String FORM_PARAM = "form.param.";
/** These are property parameters that are required; must have values. */
private static final String FORM_REQUIRED = "form.required.";
private Hashtable fields = new Hashtable( 10 );
private WebConversation webConversation;
public FormElements()
{
}
/**
* Retrieves the HTML page, populates the form data, then sends the
* information to the server.
*/
public void run()
throws Exception
{
WebResponse response = receive();
WebForm form = getWebForm( response );
populate( form );
form.submit();
}
protected WebResponse receive()
throws Exception
{
WebConversation webConversation = getWebConversation();
GetMethodWebRequest request = getGetMethodWebRequest();
// Fake the User-Agent so the site thinks that encryption is supported.
//
request.setHeaderField( "User-Agent",
"Mozilla/5.0 (X11; U; Linux i686; en-US; rv\\:1.7.3) Gecko/20040913" );
return webConversation.getResponse( request );
}
protected void populate( WebForm form )
throws Exception
{
// First set all the .param variables.
//
setParamVariables( form );
// Next, set the required variables.
//
setRequiredVariables( form );
}
protected void setParamVariables( WebForm form )
throws Exception
{
for( Enumeration e = propertyNames(); e.hasMoreElements(); )
{
String property = (String)(e.nextElement());
if( property.startsWith( FORM_PARAM ) )
{
String fieldName = getProperty( property );
String propertyName = property.substring( FORM_PARAM.length() );
String fieldValue = getField( propertyName );
// Skip blank fields (most likely, this is a blank last name, which
// means the form wants a full name).
//
if( "".equals( fieldName ) )
continue;
// If this is the first name, and the last name parameter is blank,
// then append the last name field to the first name field.
//
if( "first_name".equals( propertyName ) &&
"".equals( getProperty( FORM_PARAM + "last_name" ) ) )
fieldValue += " " + getField( "last_name" );
showSet( fieldName, fieldValue );
form.setParameter( fieldName, fieldValue );
}
}
}
protected void setRequiredVariables( WebForm form )
throws Exception
{
for( Enumeration e = propertyNames(); e.hasMoreElements(); )
{
String property = (String)(e.nextElement());
if( property.startsWith( FORM_REQUIRED ) )
{
String fieldValue = getProperty( property );
String fieldName = property.substring( FORM_REQUIRED.length() );
// If the field starts with a ~, then copy the field.
//
if( fieldValue.startsWith( "~" ) )
{
String copyProp = fieldValue.substring( 1, fieldValue.length() );
copyProp = getProperty( copyProp );
// Since the parameters have been copied into the form, we can
// eke out the duplicate values.
//
fieldValue = form.getParameterValue( copyProp );
}
showSet( fieldName, fieldValue );
form.setParameter( fieldName, fieldValue );
}
}
}
private void showSet( String fieldName, String fieldValue )
{
System.out.print( "<p class='setting'>" );
System.out.print( fieldName );
System.out.print( " = " );
System.out.print( fieldValue );
System.out.println( "</p>" );
}
private WebForm getWebForm( WebResponse response )
throws Exception
{
WebForm[] forms = response.getForms();
String action = getProperty( FORM_ACTION );
// Not supposed to break out of a for-loop, but it makes the code easy ...
//
for( int i = forms.length - 1; i >= 0; i-- )
if( forms[ i ].getAction().equalsIgnoreCase( action ) )
return forms[ i ];
// Sadly, no form was found.
//
throw new Exception();
}
private GetMethodWebRequest getGetMethodWebRequest()
{
return new GetMethodWebRequest( getProperty( FORM_URL ) );
}
private WebConversation getWebConversation()
{
if( this.webConversation == null )
this.webConversation = new WebConversation();
return this.webConversation;
}
public void setField( String field, String value )
{
Hashtable fields = getFields();
fields.put( field, value );
}
private String getField( String field )
{
Hashtable<String, String> fields = getFields();
String result = fields.get( field );
return result == null ? "" : result;
}
private Hashtable getFields()
{
return this.fields;
}
public static void main( String args[] )
throws Exception
{
FormElements formElements = new FormElements();
formElements.setField( "first_name", args[1] );
formElements.setField( "last_name", args[2] );
formElements.setField( "email", args[3] );
formElements.setField( "comments", args[4] );
FileInputStream fis = new FileInputStream( args[0] );
formElements.load( fis );
fis.close();
formElements.run();
}
}
示例属性文件如下所示:
$ cat com.mellon.properties
form.url=https://www.mellon.com/contact/index.cfm
form.action=index.cfm
form.param.first_name=name
form.param.last_name=
form.param.email=emailhome
form.param.comments=comments
# Submit Button
#form.submit=submit
# Required Fields
#
form.required.to=zzwebmaster
form.required.phone=555-555-1212
form.required.besttime=5 to 7pm
运行它类似于以下内容(将 HTTPUnit 的路径和 $CLASSPATH 的 FormElements 类替换):
java -cp $CLASSPATH FormElements com.mellon.properties "John" "Doe" "John.Doe@gmail.com" "To whom it may concern ..."
合法性
另一个答案提到它可能违反使用条款。先检查一下，然后再花时间研究技术解决方案。非常好的建议。
关于search - 如何在不使用 API 的情况下以编程方式执行搜索？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/1141136/