Custom Predicate Judge

Introduction

• This paper describes how to customize the extension of org.apache.shenyu.plugin.base.condition.judge.PredicateJudge.
• The conditional predicate is the bridge between data and rules in the selector and serves to filter out requests that match the conditions.
• There are already seven conditional predicates including match, =, regex, contains, TimeBefore, TimeAfter, exclude.
• Please refer to judge module, add your own conditional predicates, or submit pr to the official website if you have a good common plugin.

Extension

• Create a new project and introduce the following dependencies:

<dependencies>
    <dependency>
        <groupId>org.apache.shenyu</groupId>
        <artifactId>shenyu-plugin-base</artifactId>
        <version>${project.version}</version>
    </dependency>
</dependencies>

• Create a new class CustomPredicateJudge, implements org.apache.shenyu.plugin.base.condition.judge.PredicateJudge, add annotation org.apache.shenyu.spi.Join.

/**
 * custom predicate judge.
 */
@Join
public class CustomPredicateJudge implements PredicateJudge {

    @Override
    public Boolean judge(final ConditionData conditionData, final String realData) {
        // Custom Predicate Judge
    }
}

• In the project's META-INF/services directory, create org.apache.shenyu.plugin.base.condition.judge.PredicateJudge file, add key-value as following:

script

${spi name} = ${custom class path}

${spi name} represents the name of spi and ${custom class path} represents the fully qualified name of the class. Such as:

script

custom=xxx.xxx.xxx.CustomPredicateJudge

• Package the project and copy it to the lib or ext-lib directory of the gateway (bootstrap-bin).

• In the Apache ShenYu gateway management system --> BasicConfig --> Dictionary, find the dictionary code as OPERATOR, add a new piece of data, pay attention to the dictionary name: ${spi name}.

DictionaryType: operator;

DictionaryCode: OPERATOR;

DictionaryName: ${spi name}, input your custom spi name;

DictionaryValue: When used, the value of the drop-down box, do not repeat with the existing;

DictionaryDescribe: desc your custom match strategy;

Sort: to sort;

Status: open or close.

• When adding selectors or rules, you can use custom predicate judge:

Example

• Add GroovyPredicateJudge and SpELPredicateJudge extension.

/**
 * Groovy predicate judge.
 */
@Join
public class GroovyPredicateJudge implements PredicateJudge {
    
    @Override
    public Boolean judge(final ConditionData conditionData, final String realData) {
        return (Boolean) Eval.me(conditionData.getParamName(), realData, conditionData.getParamValue());
    }
}

/**
 * SpEL predicate judge.
 */
@Join
public class SpELPredicateJudge implements PredicateJudge {
    
    private static final ExpressionParser EXPRESSION_PARSER = new SpelExpressionParser();
    
    @Override
    public Boolean judge(final ConditionData conditionData, final String realData) {
        Expression expression = EXPRESSION_PARSER.parseExpression(conditionData.getParamValue().replace('#' + conditionData.getParamName(), realData));
        return expression.getValue(Boolean.class);
    }
}

• Update org.apache.shenyu.plugin.base.condition.judge.PredicateJudge:

script

Groovy=xxx.xxx.xxx.GroovyPredicateJudge
SpEL=xxx.xxx.xxx.SpELPredicateJudge