Java Dropwizard Json漂亮打印查询参数

我知道默认情况下如何漂亮地打印JSON，但我想让用户自己选择。这就是为什么我想通过QueryParam进行配置

这应该很好地打印json（如果未指定默认值为false）：

有人有没有一个好主意，不用将相同的代码复制到数千个资源？我应该和messagebody的作者一起做吗？还是传出过滤器

解决方案（感谢Alexey Gavrilov的提示）：

import java.io.IOException;
import javax.ws.rs.core.MultivaluedMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectWriter;
import com.fasterxml.jackson.jaxrs.cfg.EndpointConfigBase;
import com.fasterxml.jackson.jaxrs.cfg.ObjectWriterModifier;

public class IndentingModifier extends ObjectWriterModifier {

    private static final Logger LOG = LoggerFactory.getLogger(IndentingModifier.class);

    public static boolean doIndent = false;

    public final Boolean _indent;

    public IndentingModifier() {
        this(null);
    }

    public IndentingModifier(
            Boolean indent) {
        _indent = indent;
    }

    @Override
    public ObjectWriter modify(
            EndpointConfigBase<?> endpoint,
            MultivaluedMap<String, Object> responseHeaders,
            Object valueToWrite,
            ObjectWriter w,
            JsonGenerator g) throws IOException {
        if (_indent != null) {
            if (_indent.booleanValue()) {
                LOG.debug("Using default pretty printer, because ident is null.");
                g.useDefaultPrettyPrinter();
            }
        } else {
            if (doIndent) {
                LOG.debug("Using default pretty printer, because ident is true.");
                g.useDefaultPrettyPrinter();
            }
        }
        return w;
    }
}

根据查询参数，可以使用自定义资源方法中的对象编写器

---

查看Jackson JAX-RS提供程序存储库。

我更喜欢使用一个通用功能，即任何资源中都没有的功能，以及服务启动时的功能，例如run（）。这就是为什么我问messagebody writer是否是个好主意。在这里，我只需要注入查询参数。我认为在过滤器中这样做是一个更好的主意。在这里，您可以访问查询参数，并可以使用ObjectWriterInputer自定义输出。感谢使用ObjectWriterModifier进行的容器响应筛选为我工作。我更新了上面的解决方案。

import java.io.IOException;
import javax.ws.rs.core.MultivaluedMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectWriter;
import com.fasterxml.jackson.jaxrs.cfg.EndpointConfigBase;
import com.fasterxml.jackson.jaxrs.cfg.ObjectWriterModifier;

public class IndentingModifier extends ObjectWriterModifier {

    private static final Logger LOG = LoggerFactory.getLogger(IndentingModifier.class);

    public static boolean doIndent = false;

    public final Boolean _indent;

    public IndentingModifier() {
        this(null);
    }

    public IndentingModifier(
            Boolean indent) {
        _indent = indent;
    }

    @Override
    public ObjectWriter modify(
            EndpointConfigBase<?> endpoint,
            MultivaluedMap<String, Object> responseHeaders,
            Object valueToWrite,
            ObjectWriter w,
            JsonGenerator g) throws IOException {
        if (_indent != null) {
            if (_indent.booleanValue()) {
                LOG.debug("Using default pretty printer, because ident is null.");
                g.useDefaultPrettyPrinter();
            }
        } else {
            if (doIndent) {
                LOG.debug("Using default pretty printer, because ident is true.");
                g.useDefaultPrettyPrinter();
            }
        }
        return w;
    }
}

import java.io.IOException;
import java.util.List;
import java.util.Map.Entry;
import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerResponseContext;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.Provider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.fasterxml.jackson.jaxrs.cfg.ObjectWriterInjector;

@Provider
public class JsonPrettryPrintQueryParamContainerResponseFilter implements javax.ws.rs.container.ContainerResponseFilter {

    private static final Logger LOG = LoggerFactory.getLogger(JsonPrettryPrintQueryParamContainerResponseFilter.class);

    private static final String QUERY_PARAM_PRETTY = "pretty";
    private static final String QUERY_PARAM_T = "t";
    private static final String QUERY_PARAM_TRUE = "true";
    private static final String QUERY_PARAM_F = "f";
    private static final String QUERY_PARAM_False = "false";

    @Override
    public void filter(
            ContainerRequestContext requestContext,
            ContainerResponseContext responseContext) throws IOException {

        MultivaluedMap<String, String> queryParams = requestContext.getUriInfo().getQueryParameters();

        for (Entry<String, List<String>> queryEntry : queryParams.entrySet()) {

            if (queryEntry.getKey().equalsIgnoreCase(QUERY_PARAM_PRETTY)) {
                String valueOfLastQueryParamIndex = queryEntry.getValue().get(queryEntry.getValue().size() - 1);
                LOG.debug(String.format("Found queryPram '%s' with value '%s'.", queryEntry.getKey(),
                        valueOfLastQueryParamIndex));

                switch (valueOfLastQueryParamIndex.toLowerCase()) {
                case QUERY_PARAM_T:
                    ObjectWriterInjector.set(new IndentingModifier(true));
                    break;
                case QUERY_PARAM_TRUE:
                    ObjectWriterInjector.set(new IndentingModifier(true));
                    break;
                case QUERY_PARAM_F:
                    ObjectWriterInjector.set(new IndentingModifier(false));
                    break;
                case QUERY_PARAM_False:
                    ObjectWriterInjector.set(new IndentingModifier(false));
                    break;

                default:
                    break;
                }
                break;
            }
        }
    }
}

environment.jersey().register(JsonPrettryPrintQueryParamContainerResponseFilter.class);