com.github.connollyst.jolt.JoltTransformer Maven / Gradle / Ivy

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A Maven plugin to apply JSON to JSON transformations using the Jolt spec. Useful as part of a Maven build to transform JSON generated by one plugin to JSON consumable by another.

There is a newer version: 0.1.0.1

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package com.github.connollyst.jolt;

import com.bazaarvoice.jolt.Chainr;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectWriter;
import org.apache.maven.plugin.logging.Log;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;

/**
 * @author Sean Connolly
 */
class JoltTransformer {

    private final Log log;
    private final ObjectMapper mapper;
    private final boolean minify;
    private final Chainr spec;


    JoltTransformer(Log log, boolean minify, Path specFile) {
        this.mapper = new ObjectMapper();
        this.minify = minify;
        this.log = log;
        this.spec = readSpec(specFile);
    }

    private Chainr readSpec(Path specFile) {
        try {
            return Chainr.fromSpec(readInput(specFile));
        } catch (Exception e) {
            throw new JoltMavenException("Failed to read " + specFile + ": " + e.getMessage(), e);
        }
    }

    void execute(Path inputFile, Path outputFile) throws JoltMavenException, IOException {
        log.info("Transforming " + inputFile + " & writing to " + outputFile);
        Object inputJson = readInput(inputFile);
        Object outputJson = spec.transform(inputJson);
        writeOutput(outputFile, outputJson);
    }

    private Object readInput(Path inputFile) throws IOException {
        log.info("Reading Jolt spec " + inputFile.toFile());
        try {
            return mapper.readValue(inputFile.toFile(), Object.class);
        } catch (IOException ioe) {
            throw new IOException("Failed to read " + inputFile + ": " + ioe.getMessage(), ioe);
        }
    }

    private void writeOutput(Path outputFile, Object outputJson) throws IOException {
        log.debug("Writing transformed JSON: " + outputJson);
        try {
            Files.createDirectories(outputFile.getParent());
        } catch (IOException ioe) {
            throw new IOException("Failed to create path to " + outputFile.getParent() + ":" + ioe.getMessage(), ioe);
        }
        try {
            ObjectWriter writer = minify ? mapper.writerWithDefaultPrettyPrinter() : mapper.writer();
            writer.writeValue(outputFile.toFile(), outputJson);
        } catch (IOException ioe) {
            throw new IOException("Failed to write " + outputFile + ":" + ioe.getMessage(), ioe);
        }
    }

}