无法在 Jersey 2.0 中为 Jackson 启用基于 POJO 的 JSON 绑定支持
我正在使用 Jersey 来生成 JSON(通过 Jackson 进行 POJO 映射)和 Jetty(从 main 方法开始).
它非常适合 Jersey 1.x.:
I'm using Jersey to produce JSON (with POJO mapping through Jackson) and Jetty (start from main method).
It works perfect for Jersey 1.x.:
ServletHolder sh = new ServletHolder(ServletContainer.class);
sh.setInitParameter("com.sun.jersey.config.property.resourceConfigClass",
"com.sun.jersey.api.core.PackagesResourceConfig");
sh.setInitParameter("com.sun.jersey.config.property.packages", "service");
sh.setInitParameter("com.sun.jersey.api.json.POJOMappingFeature", "true");
...
context.addServlet(sh, "/rest/*");
Server server = new Server(8080);
server.setHandler(context);
server.start();
现在我将我的项目迁移到 Jersey 2.0 并且未能在其中启用基于 POJO 的 JSON 绑定，我得到以下信息:org.glassfish.jersey.message.internal.MessageBodyProviderNotFoundException: MessageBodyWriter not found for media type=application/json, type=class business.entity.ExampleEntity, genericType=class business.entity.ExampleEntity.
Now I migrated my project to Jersey 2.0 and failed to enable POJO based JSON binding in it, I get the following:
org.glassfish.jersey.message.internal.MessageBodyProviderNotFoundException: MessageBodyWriter not found for media type=application/json, type=class business.entity.ExampleEntity, genericType=class business.entity.ExampleEntity.
显然，com.sun.jersey.api.json.POJOMappingFeature 不再有效，因为 Jersey 转到 org.glassfish
Obviously, com.sun.jersey.api.json.POJOMappingFeature no longer valid as Jersey goes to org.glassfish
文档说如下:
为了将 Jackson 用作您的 JSON (JAXB/POJO) 提供程序，您需要在 Configurable(客户端/服务器)中为 ObjectMapper(如果需要)注册 JacksonFeature 和 ContextResolver.
In order to use Jackson as your JSON (JAXB/POJO) provider you need to register JacksonFeature and a ContextResolver for ObjectMapper (if needed) in your Configurable (client/server).
但我不知道如何正确地做到这一点.
But I can't figure out how to do it correctly in my case.
我为这个问题创建了一个小项目:
I created a little project for this question:
branch master - Jersey 1.17.1 的工作示例；
branch master - worked example for Jersey 1.17.1;
分支 jersey-2.0-migration - 迁移到 Jersey 2.0 的尝试无效 - 测试失败；
branch jersey-2.0-migration - not working attempt to migrate to Jersey 2.0 - test failed;
branch jersey-2.0-migrate-client-only - 尝试将 Jersey 客户端 2.0 与工作的 Jersey 服务器 1.17.1 一起使用 - 测试失败.
branch jersey-2.0-migrate-client-only - non working attempt to use Jersey client 2.0 with working Jersey server 1.17.1 - test failed.
问题是:如何在 Jersey 2.0 中启用基于 POJO 的 JSON 绑定
推荐答案
文档有点过时了.最新的 Jackson 构建提供了一个自动发现的提供程序.将以下 jars 添加到类路径中:
The documentation is a bit outdated. The latest Jackson build provides an auto-discoverable provider. Add the following jars to the class path:
1) jackson-annotations-2.2.2.jar
1) jackson-annotations-2.2.2.jar
2) jackson-core-2.2.2.jar
2) jackson-core-2.2.2.jar
3) jackson-databind-2.2.2.jar
3) jackson-databind-2.2.2.jar
4) 杰克逊-jaxrs-base-2.2.1.jar
4) jackson-jaxrs-base-2.2.1.jar
5) jackson-jaxrs-json-provider-2.2.1.jar
5) jackson-jaxrs-json-provider-2.2.1.jar
6) jackson-module-jaxb-annotations-2.2.2.jar
6) jackson-module-jaxb-annotations-2.2.2.jar
确保将com.fasterxml.jackson.jaxrs.json"添加到jersey.config.server.provider.packages"servlet 配置属性，以便自动发现 Jackson json 提供程序.
Make sure to add "com.fasterxml.jackson.jaxrs.json" to the "jersey.config.server.provider.packages" servlet config property, so the Jackson json provider can be auto-discovered.
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