在生成的JSON末尾添加新行
我有一个基于运动衫(1.x)的休息服务。它使用Jackson 2.4.4生成JSON响应。我需要在响应的末尾添加一个换行符(cURL用户抱怨响应中没有新行)。我正在使用打印功能(在生成的JSON末尾添加新行,json,jersey,jackson,Json,Jersey,Jackson,我有一个基于运动衫(1.x)的休息服务。它使用Jackson 2.4.4生成JSON响应。我需要在响应的末尾添加一个换行符(cURL用户抱怨响应中没有新行)。我正在使用打印功能(SerializationFeature.INDENT\u OUTPUT) 当前:{\n“prop”:“value”\n} 通缉:{\n“prop”:“value”\n}\n 我尝试使用自定义序列化程序。我只需要在根对象的末尾添加\n。序列化程序是根据每个数据类型定义的,这意味着,如果此类类嵌套在一个响应中,我将在JSO
SerializationFeature.INDENT\u OUTPUT
)
当前:{\n“prop”:“value”\n}
通缉:{\n“prop”:“value”\n}\n
\n
。序列化程序是根据每个数据类型定义的,这意味着,如果此类类嵌套在一个响应中,我将在JSON的中间得到<代码> \n>代码>。p>com.fasterxml.jackson.core.JsonGenerator.java
,重写close()
,在那里我要添加writeRaw('\n')
,但这感觉非常粗糙\n
,并将ContentLength增加1。看起来不仅粗俗,而且效率低下ObjectMapper.writeValue()+“\n”
,但这对我的代码来说是相当麻烦的(需要更改很多地方)@Test
public void append_newline_after_end_of_json() throws Exception {
// Jackson 2.6:
// ObjectMapper mapper = new ObjectMapper()
// .setDefaultPrettyPrinter(new NewlineAddingPrettyPrinter())
// .enable(SerializationFeature.INDENT_OUTPUT);
// ObjectWriter writer = mapper.writer();
ObjectMapper mapper = new ObjectMapper();
ObjectWriter writer = mapper.writer().with(new NewlineAddingPrettyPrinter());
assertThat(writer.writeValueAsString(ImmutableMap.of()), equalTo("{}\n"));
assertThat(writer.writeValueAsString(ImmutableMap.of("foo", "bar")),
equalTo("{\"foo\":\"bar\"}\n"));
}
public static final class NewlineAddingPrettyPrinter
extends MinimalPrettyPrinter
implements Instantiatable<PrettyPrinter> {
private int depth = 0;
@Override
public void writeStartObject(JsonGenerator jg) throws IOException, JsonGenerationException {
super.writeStartObject(jg);
++depth;
}
@Override
public void writeEndObject(JsonGenerator jg, int nrOfEntries) throws IOException, JsonGenerationException {
super.writeEndObject(jg, nrOfEntries);
if (--depth == 0) {
jg.writeRaw('\n');
}
}
@Override
public PrettyPrinter createInstance() {
return new NewlineAddingPrettyPrinter();
}
}
更新 最后,我选择了@arachnid的解决方案,使用了
NewlineAddingPrettyPrinter
(也是2.6.2版本)。遗憾的是,Jaskson作为Json提供程序时,它不能开箱即用。在ObjectMapper
中更改的PrettyPrinter
不会传播到JsonGenerator
(请参见原因)。为了让它工作,我必须添加ResponseFilter
,它添加了ObjectWriterModifier
(现在我可以根据输入参数轻松地在pretty print和minimal之间切换):
@Provider
公共类PrettyPrintFilter扩展BaseResponseFilter{
公共ContainerResponse筛选器(ContainerRequest请求、ContainerResponse响应){
set(新的PrettyPrintToggler(true));
返回响应;
}
最终类PrettyPrintToggler扩展ObjectWriterModifier{
私有静态最终预打印器NO_PRETTY_PRINT=新最小预打印器();
私有最终布尔使用预打印;
公共预打印切换程序(布尔值usePrettyPrint){
this.usePrettyPrint=usePrettyPrint;
}
@凌驾
public ObjectWriter modify(EndpointConfigBase端点、多值映射响应头、,
对象值写入、对象编写器w、JsonGenerator g)引发IOException{
if(使用prettyprint)g.setPrettyPrinter(newnewlineaddingprettyprinter());
else g.setPrettyPrinter(无漂亮打印);
返回w;
}
}
}
尚未测试,但以下各项应能正常工作:
public class MyObjectMapper extends ObjectMapper {
_defaultPrettyPrinter = com.fasterxml.jackson.core.util.MinimalPrettyPrinter("\n");
// AND/OR
@Override
protected PrettyPrinter _defaultPrettyPrinter() {
return new com.fasterxml.jackson.core.util.MinimalPrettyPrinter("\n");
}
}
public class JerseyConfiguration extends ResourceConfig {
...
MyObjectMapper mapper = new MyObjectMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT); //enables pretty printing
// create JsonProvider to provide custom ObjectMapper
JacksonJaxbJsonProvider provider = new JacksonJaxbJsonProvider();
provider.setMapper(mapper);
register(provider); //register so that jersey use it
}
不知道这是否是“最干净”的解决方案,但感觉没有其他解决方案那么粗糙
应该产生类似于
{\n“根”:“1”\n}\n{\n“根2”:“2”\n}
但是,如果只有一个根元素,这似乎不起作用
想法来自事实上,包装(而不是子类化)JsonGenerator并不太糟糕:
servlet过滤器也不一定太糟糕,尽管最近ServletOutputStream接口被更多地用于正确拦截
我发现通过PrettyPrinter进行此操作在早期的Jackson版本(如2.4.4)上存在问题,部分原因是需要通过ObjectWriter进行正确配置:仅在Jackson 2.6中修复。为完整起见,这是一个有效的2.5解决方案:
@Test
public void append_newline_after_end_of_json() throws Exception {
// Jackson 2.6:
// ObjectMapper mapper = new ObjectMapper()
// .setDefaultPrettyPrinter(new NewlineAddingPrettyPrinter())
// .enable(SerializationFeature.INDENT_OUTPUT);
// ObjectWriter writer = mapper.writer();
ObjectMapper mapper = new ObjectMapper();
ObjectWriter writer = mapper.writer().with(new NewlineAddingPrettyPrinter());
assertThat(writer.writeValueAsString(ImmutableMap.of()), equalTo("{}\n"));
assertThat(writer.writeValueAsString(ImmutableMap.of("foo", "bar")),
equalTo("{\"foo\":\"bar\"}\n"));
}
public static final class NewlineAddingPrettyPrinter
extends MinimalPrettyPrinter
implements Instantiatable<PrettyPrinter> {
private int depth = 0;
@Override
public void writeStartObject(JsonGenerator jg) throws IOException, JsonGenerationException {
super.writeStartObject(jg);
++depth;
}
@Override
public void writeEndObject(JsonGenerator jg, int nrOfEntries) throws IOException, JsonGenerationException {
super.writeEndObject(jg, nrOfEntries);
if (--depth == 0) {
jg.writeRaw('\n');
}
}
@Override
public PrettyPrinter createInstance() {
return new NewlineAddingPrettyPrinter();
}
}
@测试
在_json()的_end_之后,public void append_newline_引发异常{
//杰克逊2.6:
//ObjectMapper映射器=新的ObjectMapper()
//.setDefaultPrettyPrinter(新的NewlineAddingPrettyPrinter())
//.enable(SerializationFeature.INDENT_输出);
//ObjectWriter=mapper.writer();
ObjectMapper mapper=新的ObjectMapper();
ObjectWriter writer=mapper.writer()。带有(new NewlineAddingPrettyPrinter());
assertThat(writer.writeValueAsString(ImmutableMap.of()),equalTo(“{}\n”);
资产(writer.writeValueAsString(ImmutableMap.of(“foo”,“bar”))),
相等(“{\'foo\':\'bar\'}\n”);
}
公共静态最终类NewlineAddingPrettyPrinter
扩展最小预打印机
实现可实例化的{
私有整数深度=0;
@凌驾
public void writeStartObject(JsonGenerator jg)抛出IOException,JsonGenerationException{
超级writeStartObject(jg);
++深度;
}
@凌驾
public void writeEndObject(JsonGenerator jg,int nrOfEntries)抛出IOException,JsonGenerationException{
超级写入对象(jg、nrOfEntries);
如果(--depth==0){
jg.writeRaw('\n');
}
}
@凌驾
公共预打印机createInstance(){
返回新的NewlineAddingPrettyPrinter();
}
}
我已经配置了prettyprint(但没有覆盖默认的PrettyPrinter
),它给了我类似JSON的信息:{\n“prop”:“value”\n}
。我想我没有清楚地表达我自己-我需要的是在整个JSON实体后面加一行新行,比如:{\n“prop”:“value”\n}\n
。我已经测试了您的解决方案,但它在功能上与我目前的解决方案没有什么不同。我已经为这个问题添加了一些示例。我已经对此进行了反驳,并且关心如何分离根对象。但我会朝这个方向走得更远,看看如果没有第二个根对象,你是否可以用最小预打印器添加一个根分隔符
@Test
public void append_newline_after_end_of_json() throws Exception {
// Jackson 2.6:
// ObjectMapper mapper = new ObjectMapper()
// .setDefaultPrettyPrinter(new NewlineAddingPrettyPrinter())
// .enable(SerializationFeature.INDENT_OUTPUT);
// ObjectWriter writer = mapper.writer();
ObjectMapper mapper = new ObjectMapper();
ObjectWriter writer = mapper.writer().with(new NewlineAddingPrettyPrinter());
assertThat(writer.writeValueAsString(ImmutableMap.of()), equalTo("{}\n"));
assertThat(writer.writeValueAsString(ImmutableMap.of("foo", "bar")),
equalTo("{\"foo\":\"bar\"}\n"));
}
public static final class NewlineAddingPrettyPrinter
extends MinimalPrettyPrinter
implements Instantiatable<PrettyPrinter> {
private int depth = 0;
@Override
public void writeStartObject(JsonGenerator jg) throws IOException, JsonGenerationException {
super.writeStartObject(jg);
++depth;
}
@Override
public void writeEndObject(JsonGenerator jg, int nrOfEntries) throws IOException, JsonGenerationException {
super.writeEndObject(jg, nrOfEntries);
if (--depth == 0) {
jg.writeRaw('\n');
}
}
@Override
public PrettyPrinter createInstance() {
return new NewlineAddingPrettyPrinter();
}
}