java如何与脚本（javaScript）之间相互调用二

// Imports and Javadoc not shown.
public class ScriptMortgageQualifier {
private ScriptEngineManager scriptEngineManager = new ScriptEngineManager();

public MortgageQualificationResult qualifyMortgage(
Borrower borrower,
Property property,
Loan loan,
File mortgageRulesFile
) throws FileNotFoundException, IllegalArgumentException, ScriptException
{
ScriptEngine scriptEngine = getEngineForFile(mortgageRulesFile);
if (scriptEngine == null) {
throw new IllegalArgumentException(
"No script engine on classpath to handle file: " + mortgageRulesFile
);
}

// Make params accessible to scripts by adding to engine's context.
scriptEngine.put("borrower", borrower);
scriptEngine.put("property", property);
scriptEngine.put("loan", loan);

// Make return-value object available to scripts.
MortgageQualificationResult scriptResult = new MortgageQualificationResult();
scriptEngine.put("result", scriptResult);

// Add an object scripts can call to exit early from processing.
scriptEngine.put("scriptExit", new ScriptEarlyExit());

try {
scriptEngine.eval(new FileReader(mortgageRulesFile));
} catch (ScriptException se) {
// Re-throw exception unless it's our early-exit exception.
if (se.getMessage() == null ||
!se.getMessage().contains("ScriptEarlyExitException")
) {
throw se;
}
// Set script result message if early-exit exception embedded.
Throwable t = se.getCause();
while (t != null) {
if (t instanceof ScriptEarlyExitException) {
scriptResult.setMessage(t.getMessage());
break;
}
t = t.getCause();
}
}

return scriptResult;
}

/** Returns a script engine based on the extension of the given file. */
private ScriptEngine getEngineForFile(File f) {
String fileExtension = getFileExtension(f);
return scriptEngineManager.getEngineByExtension(fileExtension);
}

/** Returns the file's extension, or "" if the file has no extension */
private String getFileExtension(File file) {
String scriptName = file.getName();
int dotIndex = scriptName.lastIndexOf('.');

if (dotIndex != -1) {
return scriptName.substring(dotIndex + 1);
} else {
return "";
}
}

/** Internal exception so ScriptEarlyExit.exit can exit scripts early */
private static class ScriptEarlyExitException extends Exception {
public ScriptEarlyExitException(String msg) {
super(msg);
}
}

/** Object passed to all scripts so they can indicate an early exit. */
private static class ScriptEarlyExit {
public void noMessage() throws ScriptEarlyExitException {
throw new ScriptEarlyExitException(null);
}
public void withMessage(String msg) throws ScriptEarlyExitException {
throw new ScriptEarlyExitException(msg);
}
}
}

// Imports and some helper methods not shown.
public class ScriptMortgageQualifierRunner {
private static File scriptDirectory;
private static Borrower goodBorrower = createGoodBorrower();
private static Borrower averageBorrower = createAverageBorrower();
private static Borrower investorBorrower = createInvestorBorrower();
private static Borrower riskyBorrower = createRiskyBorrower();
private static Property property = createProperty();
private static Loan loan = createLoan();

/**
* Main method to create a File for the directory name on the command line,
* then call the run method if that directory exists.
*/
public static void main(String[] args) {
if (args.length > 0 && args[0].contains("-help")) {
printUsageAndExit();
}
String dirName;
if (args.length == 0) {
dirName = "."; // Current directory.
} else {
dirName = args[0];
}

scriptDirectory = new File(dirName);
if (!scriptDirectory.exists() || !scriptDirectory.isDirectory()) {
printUsageAndExit();
}

run();
}

/**
* Determines mortgage loan-qualification status for four test borrowers by
* processing all script files in the given directory. Each script will determine
* whether the given borrower is qualified for a particular mortgage type
*/
public static void run() {
ScriptMortgageQualifier mortgageQualifier = new ScriptMortgageQualifier();

for(;;) { // Requires Ctrl-C to exit
runQualifications(mortgageQualifier, goodBorrower, loan, property);
runQualifications(mortgageQualifier, averageBorrower, loan, property);

loan.setDownPayment(30000.0); // Reduce down payment to 10%
runQualifications(mortgageQualifier, investorBorrower, loan, property);

loan.setDownPayment(10000.0); // Reduce down payment to 3 1/3%
runQualifications(mortgageQualifier, riskyBorrower, loan, property);

waitOneMinute();
}
}

/**
* Reads all script files in the scriptDirectory and runs them with this borrower's
* information to see if he/she qualifies for each mortgage product.
*/
private static void runQualifications(
ScriptMortgageQualifier mortgageQualifier,
Borrower borrower,
Loan loan,
Property property
) {
for (File scriptFile : getScriptFiles(scriptDirectory)) {
// Print info about the borrower, loan and property.
System.out.println("Processing file: " + scriptFile.getName());
System.out.println("  Borrower: " + borrower.getName());
System.out.println("  Credit score: " + borrower.getCreditScore());
System.out.println("  Sales price: " + property.getSalesPrice());
System.out.println("  Down payment: " + loan.getDownPayment());

MortgageQualificationResult result = null;
try {
// Run the script rules for this borrower on the loan product.
result = mortgageQualifier.qualifyMortgage(
borrower, property, loan, scriptFile
);
} catch (FileNotFoundException fnfe) {
System.out.println(
"Can't read script file: " + fnfe.getMessage()
);
} catch (IllegalArgumentException e) {
System.out.println(
"No script engine available to handle file: " +
scriptFile.getName()
);
} catch (ScriptException e) {
System.out.println(
"Script '" + scriptFile.getName() +
"' encountered an error: " + e.getMessage()
);
}

if (result == null) continue; // Must have hit exception.

// Print results.
System.out.println(
"* Mortgage product: " + result.getProductName() +
", Qualified? " + result.isQualified() +
"\n* Interest rate: " + result.getInterestRate() +
"\n* Message: " + result.getMessage()
);
System.out.println();
}
}

/** Returns files with a '.' other than as the first or last character. */
private static File[] getScriptFiles(File directory) {
return directory.listFiles(new FilenameFilter() {
public boolean accept(File dir, String name) {
int indexOfDot = name.indexOf('.');
// Ignore files w/o a dot, or with dot as first or last char.
if (indexOfDot < 1 || indexOfDot == (name.length() - 1)) {
return false;
} else {
return true;
}
}
});
}

private static void waitOneMinute() {
System.out.println(
"\nSleeping for one minute before reprocessing files." +
"\nUse Ctrl-C to exit..."
);
System.out.flush();
try {
Thread.sleep(1000 * 60);
} catch (InterruptedException e) {
System.exit(1);
}
}
}

public class MortgageQualificationResult {
private boolean qualified;
private double interestRate;
private String message;
private String productName;

// .. Standard setters and getters not shown.
}

/*
This Groovy script defines the "Groovy Mortgage" product.
This product is relaxed in its requirements of borrowers.
There is a higher interest rate to make up for the looser standard.
All borrowers will be approved if their credit history is good, they can
make a down payment of at least 5%, and they either earn more than
$2,000/month or have a net worth (assets minus liabilities) of $25,000.
*/

// Our product name.
result.productName = 'Groovy Mortgage'

//  Check for the minimum income and net worth
def netWorth = borrower.totalAssets - borrower.totalLiabilities
if (borrower.monthlyIncome < 2000 && netWorth < 25000) {
scriptExit.withMessage "Low monthly income of ${borrower.monthlyIncome}" +
' requires a net worth of at least $25,000.'
}

def downPaymentPercent = loan.downPayment / property.salesPrice * 100
if (downPaymentPercent < 5) {
scriptExit.withMessage 'Down payment of ' +
"${String.format('%1$.2f', downPaymentPercent)}% is insufficient." +
' 5% minimum required.'
}
if (borrower.creditScore < 600) {
scriptExit.withMessage 'Credit score of 600 required.'
}

// Everyone else qualifies. Find interest rate based on down payment percent.
result.qualified = true
result.message = 'Groovy! You qualify.'

switch (downPaymentPercent) {
case 0..5:   result.interestRate = 0.08; break
case 6..10:  result.interestRate = 0.075; break
case 11..15: result.interestRate = 0.07; break
case 16..20: result.interestRate = 0.065; break
default:     result.interestRate = 0.06; break
}

/**
* This script defines the "JavaScript FirstTime Mortgage" product.
* It is a government-sponsored mortgage intended for low-income, first-time
* home buyers without a lot of assets who intend to live in the home.
* Bankruptcies and bad (but not terrible!) credit are OK.
*/
result.productName = 'JavaScript FirstTime Mortgage'

if (!borrower.intendsToOccupy) {
result.message = 'This mortgage is not intended for investors.'
scriptExit.noMessage()
}
if (!borrower.firstTimeBuyer) {
result.message = 'Only first-time home buyers qualify for this mortgage.'
scriptExit.noMessage()
}
if (borrower.monthlyIncome > 4000) {
result.message = 'Monthly salary of $' + borrower.monthlyIncome +
' exceeds the $4,000 maximum.'
scriptExit.noMessage()
}
if (borrower.creditScore < 500) {
result.message = 'Your credit score of ' + borrower.creditScore +
' does not meet the 500 requirement.'
scriptExit.noMessage()
}

// Qualifies. Determine interest rate based on loan amount and credit score.
result.qualified = true
result.message = 'Congratulations, you qualify.'

if (loan.loanAmount > 450000) {
result.interestRate = 0.08 // Big loans and poor credit require higher rate.
} else if (borrower.creditScore < 550) {
result.interestRate = 0.08
} else if (borrower.creditScore < 600) {
result.interestRate = 0.07
} else if (borrower.creditScore < 700) {
result.interestRate = 0.065
} else { // Good credit gets best rate.
result.interestRate = 0.06
}

# This Ruby script defines the "Ruby Mortgage" product.
# It is intended for premium borrowers with its low interest rate
# and 20% down payment requirement.

# Our product name
$result.product_name = 'Ruby Mortgage'

# Borrowers with credit unworthiness do not qualify.
if $borrower.credit_score < 700
$scriptExit.with_message "Credit score of #{$borrower.credit_score}" +
" is lower than 700 minimum"
end

$scriptExit.with_message 'No bankruptcies allowed' if $borrower.hasDeclaredBankruptcy

# Check other negatives
down_payment_percent = $loan.down_payment / $property.sales_price * 100
if down_payment_percent < 20
$scriptExit.with_message 'Down payment must be at least 20% of sale price.'
end

# Borrower qualifies. Determine interest rate of loan
$result.message = "Qualified!"
$result.qualified = true

# Give the best interest rate to the best credit risks.
if $borrower.credit_score > 750 || down_payment_percent > 25
$result.interestRate = 0.06
elsif $borrower.credit_score > 700 && $borrower.totalAssets > 100000
$result.interestRate = 0.062
else
$result.interestRate = 0.065
end

在 Ruby 脚本中访问共享的 Java 对象时，一定要记住 Ruby 的全局变量语法。如果省略了全局变量前面的

$

RaiseException

> ant run
Buildfile: build.xml

compile:
[mkdir] Created dir: C:\temp\script-article\build-main\classes
[javac] Compiling 10 source files to C:\temp\script-article\build-main\classes

run:
[java] Processing file: GroovyMortgage.groovy
[java]   Borrower: Good Borrower
[java]   Credit score: 800
[java]   Sales price: 300000.0
[java]   Down payment: 60000.0
[java] * Mortgage product: Groovy Mortgage, Qualified? true
[java] * Interest rate: 0.06
[java] * Message: Groovy! You qualify.

[java] Processing file: JavaScriptFirstTimeMortgage.js
[java]   Borrower: Good Borrower
[java]   Credit score: 800
[java]   Sales price: 300000.0
[java]   Down payment: 60000.0
[java] * Mortgage product: JavaScript FirstTime Mortgage, Qualified? false
[java] * Interest rate: 0.0
[java] * Message: Only first-time home buyers qualify for this mortgage.

[java] Processing file: RubyPrimeMortgage.rb
[java]   Borrower: Good Borrower
[java]   Credit score: 800
[java]   Sales price: 300000.0
[java]   Down payment: 60000.0
[java] * Mortgage product: Ruby Mortgage, Qualified? true
[java] * Interest rate: 0.06
[java] * Message: Qualified!

[java] Processing file: GroovyMortgage.groovy
[java]   Borrower: Average Borrower
[java]   Credit score: 700
[java]   Sales price: 300000.0
[java]   Down payment: 60000.0
[java] * Mortgage product: Groovy Mortgage, Qualified? true
[java] * Interest rate: 0.06
[java] * Message: Groovy! You qualify.

[java] Processing file: JavaScriptFirstTimeMortgage.js
[java]   Borrower: Average Borrower
[java]   Credit score: 700
[java]   Sales price: 300000.0
[java]   Down payment: 60000.0
[java] * Mortgage product: JavaScript FirstTime Mortgage, Qualified? false
[java] * Interest rate: 0.0
[java] * Message: Monthly salary of $4500 exceeds the $4,000 maximum.

[java] Processing file: RubyPrimeMortgage.rb
[java]   Borrower: Average Borrower
[java]   Credit score: 700
[java]   Sales price: 300000.0
[java]   Down payment: 60000.0
[java] * Mortgage product: Ruby Mortgage, Qualified? true
[java] * Interest rate: 0.065
[java] * Message: Qualified!

[java] Processing file: GroovyMortgage.groovy
[java]   Borrower: Investor Borrower
[java]   Credit score: 720
[java]   Sales price: 300000.0
[java]   Down payment: 30000.0
[java] * Mortgage product: Groovy Mortgage, Qualified? true
[java] * Interest rate: 0.06
[java] * Message: Groovy! You qualify.

[java] Processing file: JavaScriptFirstTimeMortgage.js
[java]   Borrower: Investor Borrower
[java]   Credit score: 720
[java]   Sales price: 300000.0
[java]   Down payment: 30000.0
[java] * Mortgage product: JavaScript FirstTime Mortgage, Qualified? false
[java] * Interest rate: 0.0
[java] * Message: This mortgage is not intended for investors.

[java] Processing file: RubyPrimeMortgage.rb
[java]   Borrower: Investor Borrower
[java]   Credit score: 720
[java]   Sales price: 300000.0
[java]   Down payment: 30000.0
[java] * Mortgage product: Ruby Mortgage, Qualified? false
[java] * Interest rate: 0.0
[java] * Message: Down payment must be at least 20% of sale price.

[java] Processing file: GroovyMortgage.groovy
[java]   Borrower: Risk E. Borrower
[java]   Credit score: 520
[java]   Sales price: 300000.0
[java]   Down payment: 10000.0
[java] * Mortgage product: Groovy Mortgage, Qualified? false
[java] * Interest rate: 0.0
[java] * Message: Down payment of 3.33% is insufficient. 5% minimum required.

[java] Processing file: JavaScriptFirstTimeMortgage.js
[java]   Borrower: Risk E. Borrower
[java]   Credit score: 520
[java]   Sales price: 300000.0
[java]   Down payment: 10000.0
[java] * Mortgage product: JavaScript FirstTime Mortgage, Qualified? true
[java] * Interest rate: 0.08
[java] * Message: Congratulations, you qualify.

[java] Processing file: RubyPrimeMortgage.rb
[java]   Borrower: Risk E. Borrower
[java]   Credit score: 520
[java]   Sales price: 300000.0
[java]   Down payment: 10000.0
[java] * Mortgage product: Ruby Mortgage, Qualified? false
[java] * Interest rate: 0.0
[java] * Message: Credit score of 520 is lower than 700 minimum

[java] Sleeping for one minute before reprocessing files.
[java] Use Ctrl-C to exit...